Bomb loads

[hubbabubba]

We do tend to work on the basis of preconceived ideas sometimes. This is not bad in itself; if we were to re-invent the wheel every morning, we would still be driving ox-powered chariots.

As I was about to give my two cents of wisdom about CFS1 bomb loads to Ivan in another thread, I went for a little survey of all the aircraft of a "plain vanilla" CFS1 installation, just to see how the originals creators dealt with bomb loads. Here are my findings;

• B17g = 8 x 500lbs
• B24j = 10 x 500lbs
• B25j = 6 x 500lbs
• Bf109e = 3 x 183.7083lbs
• Bf109g = 3 x 183.7083lbs
• Bf110 = 2 x 551.125lbs
• Do17z2 = 8 x 1100lbs
• Fw190a = 3 x 183.7083lbs
• He111h = 4 x 551.125lbs
• Ju87a = 5 x 220lbs
• Ju88a = 4 x 1100lbs
• Mosquito = 1 x 500lbs
• P38 = 1 x 500lbs
• P47d = 3 x 166.6667lbs
• Spitfire_MkI = 3 x 166.6667lbs
• Spitfire_MkIX = 3 x 166.6667lbs
• Tempest = 1 x 500lbs

When you know that bomb destructive power is all the same, whatever its weight, it is a bit surprising to find that the Dornier has the same destructive power as the B-17G, but with more than twice the weight!

I know this because I experimented on that very subject. I was making a DP file for a Sopwith Triplane and I wanted the pilot to be able to drop "bomblets" - in fact hand grenades or armed mortar shell - by the side of his cockpit, around a dozen. I made them light, a couple of pounds or so, with a damage-effect in consequence, and it was working perfectly... until I realized that I was blowing buildings with my hand grenades the same way a 500lbs was. I later found that rockets and bombs are delivering the same destructive power, no matter what the entry 1d1*xyz says. Bombs are "fixed" to a certain degree of destruction, same thing with rockets, but with lesser destruction in the latter case.

For this reason, I think that, as a norm, all bombs weigh should be set at 500lbs (8000oz) in the DP file. If I want to drop hand grenades from a triplane, I will have to "cheat" my own rule...

I wish that M$ had given us a way to adjust destructive power in accordance with bombs' weight, but this is not to be.

This leaves us with stock fighter-bomber carrying unrealistic loads, Germans are carrying three 183.7083lbs (83.32868kg) bombs while the Allies have three 166.6667lbs (75.59874kg) loads. Both are "underweight".

Again, not worth crying over spilled milk!

I then went checking another aspect; number of bombs an aircraft can carry. Popular belief says that it is limited, some sources say 20 bombs maximum, past that, you'll drop "phantom" bombs that will make "clang" as they are released, but will not actually explode.

Well, this is a load of c**p!

Modifying the RAF662 B-17G load to 100, I was able to drop them in Free Flight and in Multiplayer environment. They all dropped and they all exploded with visual craters to prove it!

This mean that I will have to review my "philosophy" about bomb loads.

Before, I was in favor of adjusting the loads by using the 10 x 500lbs usually found in the most-used multiplayer B-17(F & G) from RAF662 and JO, but now I may have to revised that.

Here is a short list of bomb loads I had prepared before making that last finding;

• B-17G = ±6000lbs
• B-24J = ±7000lbs
• Lancaster = ±12000lbs
• B-29 = ±12000lbs
• A-20 Boston MkIII = ±4000lbs
• B-25J = ±5000lbs
• B-26G = ±4000lbs
• A-26 = ±4000lbs
• Wellington = ±5000lbs

This list is very subjective and open to interpretation and debate, I know.

I took average loads for medium range mission in the case of heavy bombers but maximum load for medium-light bombers, as range is less important. Almost every site has his own numbers. These are mostly coming from a quick search at Wikipedia, with a few variants of course!

My first idea was to take the 10 x 500lbs as a standard for the B-17, and adjust the other in proportion with that standard. This explains why the Lancaster and the B-29 have such a low numbers (I thought a was limited to 20 bombs, top, remember).

But now, I don't know.:isadizzy:

Maybe the B-17 should carry 12 x 500lbs load afterall.

Your takes on this will be greatly appreciated. Join the debate...

[Ivan]

Hello Hubbabubba,
Thanks for the summary. Strangely enough, I believe we are again approaching things from different angles. (Why is that not a surprise?

I know that all bombs have the same destructive effect which is grossly unfair, but am trying to approach it from the aircraft loadout and weight standpoint. With a light medium such as the A-20 or B-25, it isn't really that hard. The A-20 typically flew missions with 2000 pounds of bombs in an internal bomb bay. It could carry an additional 2000 pounds on external racks. I figure some number of 500 pounders can represent this without having too many or too few bombs.

With a B-17, on a long range mission, you might have 4000 pounds of bombs but on a very short range, close support mission, the plane can lift over 17000 pounds of bombs. 500 pounders make sense with a 4000 pound bomb load. They don't make sense with 17000 pounds of bombs.

A Corsair often carries a single 500 pounder. When Lindbergh was flying in the Pacific, he carried a 2000 pounder and TWO 1000 pounders on a mission. No matter what the weight, he should only have 3 shots or bullets.

A FW 190 has the same issue: 550 pounds up to around 4000 pounds.

The question here is what weight of "bullet" and number of rounds make sense in allowing the player to choose a reasonable weight of ordnance and not have some ridiculous number of tries at bombing.

Actually, the real question I was asking was for this case:
A A-20 can carry 4000 pounds maximum but only 2000 on a typical mission.

Should its default bombload be 0, 2000 pounds, or 4000 pounds?

- Ivan.

[hubbabubba]

The only point I disagree with you, Ivan, is that we are disagreeing...

I, too, want bomb loads to reflect actual weigh and number. Now that I know that I can pretty much install whatever number I need, I would do a DP file with these entries for the Boston MkIII;

[GUNSTATIONS]
(...)
gunstation.X=3,43,8,0.00,0,0,0,0,0,0,1d1*6000,0,0, 0,0,0,0,0,0,0,0,8000
(...)
[guns.X]
gun.0=4,0,0,0,0,0,0,0

So, four 500lbs in the internal bomb bay to be loaded by the player.

In all the pictures I have, only two show external bombs being carried on pylons outside the engines' nacelles, and the two pictures are from A-20 of D-Day period. Being 500lbs bombs, it still only makes 3000lbs bomb load.

[Dave Cumming]

I haven't looked around to find out what bombloads the real aircraft carried but planes like the Lancaster are limited by the dimensions of their bomb bays. It could be that it could only carry a maximum of 8 bombs in 4 rows of two each. As bombs got bigger, less of them could be fitted into the bomb bay.

The DP file weight setting is used to calculated the weight of munitions carried and I think you should default the maximum load for the plane to the typical bomb size it carried. - Lancaster might therefore be limited to 8 1,000lb bombs as this was the largest bomb that would use all its hooks (or whatever the technical word is for what holds each bomb!)

I know that this is unfair given that every bomb from a grenade to a Grand Slam has the same destructive effect but it should make the aircraft performance as realistic as possible.

Dave

[hubbabubba]

Well, Dave, the Lancaster would be wilfully put at a disadvantage, and I can't go along with that.

But the reverse situation is even worst! You could put 80 100lbs bombs.

I'm in favour of "equal weight for equal destruction" proposition. The choice of 500lbs is not made randomly. The British used GP500 and, later, MC500. The Americans used M43 and. later, M64. The Germans used the SC250. I don't have numbers for the Japaneses - Ivan surely does -, but they probably had a ±500lbs bomb in their arsenal.

This was a fairly common bomb to be used for almost all kind of targets as payload on about everything that could fly and carry bombs.

Granted, German SC250 was a bit more "potent", but only marginally.

I'm speaking here for the multiplayer community; above historically accurate bomb loads, we're yearning for fairness.

[Ivan]

Hi Dave, Hubbabubba,

What would your choice be for something like a SBD Dauntless. As a Scout Bomber, it would carry one 500 pounder. On an attack mission, it might carry a single 1000 pounder.

What about the FW 190? It might carry a single 550 pound bomb or something adding up to almost 4000 pounds. Giving the plane seven 550 pound bombs is somewhat unfair but would be reasonable from a performance and weight standpoint.

For fighters, I typically use a default of no bomb load. What should the default be for a bomber? Should it vary as to the type of bomber?

- Ivan.

[hubbabubba]

Hello Ivan

Default should always be zero. It is the player's duty, in multiplayer games, to make sure he has its payload.

I would bet that 7x500lbs (or 548lbs for the SC500) would make t/o quite challenging in a FW 190! Soaring with the stock one with, remember, 3x183.7083lbs is already not that evident!

A FW with seven SC250 under it... must look like a flying grapes' cluster!

[Ivan]

Hi Hubbabubba,
The ground attack version of the FW 190 COULD carry almost 4000 pounds of bombs. I don't think it was really carrying a cluster of 250 kg bombs, but there was probably at least one 1000 kg bomb since it was capable of carrying a torpedo.

Regarding handling, the stock FW is a plain & simple Piece O' Crap, so I don't think it proves much that it misbehaves with just a couple hundred pounds. It moves like a pig with NO bombs!

Are OTHER bomber DPs typically done with a default of no bombs?

Should we spec out a DP for the B-29 with 40 x 500 pound bombs as a normal load? Seems to me that this is too many. We may be short changing the B-29 but it should have fewer bombs.

BTW, perhaps disagree was too strong a word. We are approaching the issue from different angles. (Disagreeing with you disagreeing with my disagreeing....)

- Ivan.

[hubbabubba]

Should we spec out a DP for the B-29 with 40 x 500 pound bombs as a normal load?

Why not? It was a superlative hauler;

The B29 was designed to fly at 400 mph when it was not loaded. It was able to fly at 30,000 feet and to carry a 2000 lb bomb load 5,000 miles. However, on smaller distances, the B29 was capable of carrying sixteen 500lb bombs in its after bomb bay and another sixteen 500lb bombs in its forward bomb bay.

dixit- http://www.fighter-planes.com/info/b29.htm

Although they have their numbers mixed-up, it still makes 16000lbs of 500lbs bombs.

I would certainly like to know more about the operational history of the B-29 during the Pacific Campaign. The growing pains problems of its engines forced the USAAF to "lighten" their payloads, I've been told...

[Ivan]

On the matter of loadouts being the responsibility of the pilot, do Fighter DPs default to zero ammunition carried for the guns as well?

If the Lancaster could haul 22000 pounds of bombs, it gets to carry 44 x 500 pound bombs?

Regarding the loadout of the A-20:
http://www.nationalmuseum.af.mil/fac...et.asp?id=2981
A-20G-20 to A-20G-45
The refinements incorporated into the A-20G beginning with block 20 were primarily improvements to armament. Most notably, the twin .50-cal. flexible machine gun mount was replaced by an electrically driven turret also equipped with twin .50-cal. machine guns. Another major improvement was the strengthening of the wings to enable the aircraft to carry four 500-pound bombs on wing hard points outboard of the engines. The A-20G could also be equipped with a 374-gallon drop tank, mounted in the bomb bay, for extended range for ferry missions.

Regarding the B-29, apparently engine fires were a pretty big problem. I have a book about the B-29 that might be useful.

- Ivan.

[hubbabubba]

On the matter of loadouts being the responsibility of the pilot, do Fighter DPs default to zero ammunition carried for the guns as well?

In our MP games, I have never heard a player say; "Darn'it! I forgot to drop my bullets before entering!"

All flyable stock a/c are defaulting bombs to zero. Only some AI a/c are defaulting to a full load.

If the Lancaster could haul 22000 pounds of bombs, it gets to carry 44 x 500 pound bombs?

When it was carrying 22000lbs, its not "bombs" but "a bomb"; the Grand Slam. Most defensive armament and a big chunk of the belly was removed.

In a recent mission, we used RAF662 Lancaster to drop Tall Boys. We would simply drop all 10 bombs in a single salvo. I wouldn't mind, if I was to model such Lancaster, to create an AIR file reflecting the gain in weight and a DP file with 44x500lbs, as long as they are released, again, in a single salvo.

Concerning the Boston-Havoc, I think smilo is trying to create the British Boston MkIII. Like me, he got interested in the Fourth of July 1942 bomb raid that was done with three Boston of the 226 Bomber Squadron "borrowed" by the Americans.

[Ivan]

Hi Hubbabubba,
From the book "Aggressors (Volume 3) Interceptor vs. Heavy Bomber", the bomb load listed for the B-29 in several places is 20,000 pounds. I'll check if I have other references. I am pretty sure I don't have any that detail the loads of the B-29, but perhaps one of the sources will quote a "Basic Weight" or "Empty Equipped".

For comparision purposes, the same book lists the following bomb loads for other aircraft:

B-24H-5 - 12,800 pounds
Lancaster B Mk.I - 14,000 pounds
B-17G-65-DL - 9,600 pounds
Halifax B Mk.II Series I - 13,000 pounds

This book has lots of really cool pictures. Illustrator is Rikyu Watanabe.

- Ivan.

[Ivan]

Good Night Hubbabubba. Seems like we both got here at the same time.

- Ivan.

[hubbabubba]

Hello Ivan

This post was ready two weeks ago... and kept changing ever since!
Every time I was about to post, a new last minute research unearthed new discoveries, and many of these new discoveries had some influence on my original opinions.

Your post about the B-29 20,000 lbs load was the trigger. I tend to concentrate more on war in ETO and North-Africa than on the Great Patriotic War, the Eastern Front, and the CBI (China - Burma - India) and PTO. I'm accustomed to Allied heavy bombers payloads, and the B-29 figures stand out in comparison.

THE B-29 MYTH CONFRONTED TO OPERATIONAL REALITY

I have to say that I was a bit annoyed by the "Wikipedia consensus syndrome";

Specifications (B-29)

Boeing B-29 SuperfortressData from Quest for Performance[27]
(...)
Performance
Maximum speed: 357 mph (310 knots, 574 km/h)
Cruise speed: 220 mph (190 knots, 350 km/h)
Stall speed: 105 mph (91 knots, 170 km/h)
Combat range: 3,250 mi (2,820 nmi, 5,230 km)
Ferry range: 5,600 mi (4,900 nmi, 9,000 km, (record 5,839 mi, 5,074 nmi, 9,397 km[18]))
Service ceiling: 33,600 ft (10,200 m)
Rate of climb: 900 ft/min (4.6 m/s)
Wing loading: 69.12 lb/sqft (337 kg/m²)
Power/mass: 0.073 hp/lb (121 W/kg)
Lift-to-drag ratio: 16.8
Armament

Guns:
10× .50 in (12.7 mm) caliber Browning M2/ANs in remote controlled turrets
2 x .50 in and 1× 20 mm M2 cannon in tail position (the cannon was eventually removed as it proved unreliable in service )
B-29B-BW - All armament and sighting equipment removed except for tail position; initially 2 x .50 in M2/AN and 1× 20 mm M2 cannon, later 3 x 2 x .50 in M2/AN with APG-15 gun-laying radar fitted as standard.
Bombs: 20,000 lb (9,000 kg) standard loadout

- http://en.wikipedia.org/wiki/B-29
If you dig a bit and go have a look at "Quest for performance - The Evolution of Modern Aircraft" NASA History Office ( http://www.hq.nasa.gov/pao/History/SP-468/cover.htm ), the site from which Wikipedia is quoting BTW, you find a more, shall we say, nuanced description;

(...)A maximum payload of 20 000 pounds could be carried for 2800 miles; on a typical operational mission, 12 000 pounds of bombs could be carried for a distance (one way) of 3700 miles.(...)

- http://www.hq.nasa.gov/pao/History/SP-468/ch5-3.htm

Unfortunately, people tend to think that the B-29 Superfortress was capable of carrying 20,000 lbs at 33,600 ft over a range of 3,250 mi all at once! This impression is comforted by a multitude of WEB sites that are simply parroting Wikipedia, what I have described as the "Wikipedia consensus syndrome".

I don't contest that the B-29 could carry 20,000 lbs of bombs.

But it was the exception rather than the rule during WWII. Here is a more "down to earth" description of the capabilities of the Superfortress;

VITAL STATISTICS AND DIMENSIONS
(...)
Bomb Capacity: 5,000 pounds of bombs over 1600 mile radius at high altitude.
12,000 pounds of bombs over 1600 mile radius at medium altitude.
20,000 pounds of bombs maximum over short distances at low altitude.
High Explosives (H/E) and incendiary bombs were carried, either exclusively or mixed for effect depending on target & mission.

John M. Campbell, "Boeing B-29 Superfortress", AMERICAN BOMBER AIRCRAFT VOL.II, Schiffer Military History Book, p. 27

I must tell you that I had to dig through a lot of books to find anything worthy about bomb loads! B-29 "nose arts" are clearly having precedent over technical issues. Some of these books are even misleading; in one of them, caption for a picture was stating clearly that the B-29 could carry internally only 10,000 lbs! Thinking it was a typo, I found the same mention under another picture in the same book! Another book was showing a B-29 carrying two Grand Slam (in reality, they were Tallboys), mentioning that it could carry a full load of bombs internally at the same time! That would make for a hefty 64,000 pounds of bombs! Considering that, to be effective, the "earthquake" bombs had to be dropped from at least 25,000 feet - Barnes Wallis proposed a bomber going to 40,000 feet! -, we must assume that such a bomber was about to blow its own airfield!

Incidentally, the B-29 did carried 2x12,000 bombs and 1x22,000 "earthquake" ... experimentally only. But some WEB sites, probably influenced by these pictures and books, are letting people believe that it was an operational load.

Operational records are hard to find and, to say the least, sketchy. But I was able to find here and there "snippets" of information.

First USAAF raids on Japan were made from central China;
At 1616 hrs on 15 June, the first of the 58th BW's 68 B-29s took to the air from the wing's bases at Chengtu. Each aircraft carried a payload of only two tons for the mission, which saw the 58th targeting steel factories at Yawata, on the northern coast of Kyushu Island. Since the operation was a very long-range, and fuel conservation was critical, it had been decided that each aircraft would make its own way to the target rather than fly in massed formations. Altitude would be between 8500 - 11,000 ft.
(...)
Sixty-two arrived at their destination, and at 2338 hrs (China time) they began dropping their 500-lb GP (general purpose) bombs.

Koji Takaki & Henry Sakaida, "B-29 Hunters of the JAAF", Osprey Aviation Elite #5, pp. 6 - 9

Distance "as the crow flies", from south of Chengtu (better known as Chengdu now) to north of Kyushu, was around 1,370 nmi, which translate roughly in a 3,153 miles round-trip. (a nifty site you can go to for distance calculations; http://www.daftlogic.com/projects-go...calculator.htm ) Two tons of 500 lbs bombs means eight bombs per aircraft.

We are pretty far from the numbers boasted all around of an aircraft capable of carrying 20,000 lb of bombs up to 33,600 ft on a range of 3,250 (Wikipedia)! It could probably do all those things, but not all at the same time.

Bomb load was always a trade-off between distance and altitude;

On 20 August, four groups from XX Bomber Command (40th, 444th, 462nd and 468th), comprising 76 aircraft, took off from their bases in China. (...) Each B-29 carried one-and-a-half tons of 500-lb GPs intended for the iron and steel factories at Yawata.
(...)
The Superfortresses, now 67 strong, were flying in threes and fours, and arrived over Yawata at between 20,000 and 26,000 ft.

Koji Takaki & Henry Sakaida, "B-29 Hunters of the JAAF", Osprey Aviation Elite #5, pp. 12 - 13

For the same distance, B-29 had to leave at the bomb dump two 500 lb bombs each to double their altitude.
Brigadier-General H. Hansell, then Chief of Staff of the newly formed XXth Air Force, was somewhat disappointed by results obtained;

The initial operations of the XX Bomber Command in India and China did not go well. Logistic problems had been expected, but the operational tactics were not yielding results even when the B-29s had sufficient gas and bombs to attack their targets. Brig. Gen. Kenneth B. Wolfe was using night operations exclusively. The coke oven targets (prescribed as first priority) did not present good radar images and were not easily seen at night. In consequence, the bombs were not being placed on their targets. As Chief of Staff of the Twentieth Air Force, I prodded General Wolfe to improve bombing results. I requested daylight bombing of the coke ovens in the Mukden area in Manchuria, where Japanese fighter defenses were not very effective. The available B-29 force was deemed by some to be too small to penetrate the air defenses of the Japanese islands themselves. Others of us believed it could be done. As a matter of fact, the XXI did pierce the air defenses of Tokyo in raids from the Marianas later in the year, with only one wing of B-29s -- the same strength available to the XX. General Wolfe vigorously denied that his B-29s could fly in formations in daylight to these targets. He also categorically said B-29s could not reach their targets in daylight in formation from the Marianas. This assessment dealt a real body blow to the operational plans of the XXI. Wolfe was the only air commander having actual experience with the airplane, and he was the real expert and final authority on the technical aspects of the B-29 itself.
I directed Colonel Combs, Chief of Combat Operations for the Twentieth, to conduct practice tests to confirm or refute this contention that the B-29 had insufficient range to operate in formation as required. He went to Eglin Field, Florida, and set up a test run over the Gulf of Mexico simulating the flight from the Marianas to Tokyo and back. Simulated bombloads of 8,000 pounds were carried as well as full loads of ammunition. Combs could muster but 3 B-29s for the test, but it was run with wartime combat tactics imitated as closely as possible, including the nature of the formation itself. That is to say, the test entailed initial assembly, loose formation en route, climb to 30,000 feet for the bomb run, tight defensive formation in the areas of potential fighter interception, and retention of that formation until beyond the range of enemy fighters, then return to base in loose formation.
The aircraft all returned successfully to the original base, Eglin Field, but gasoline reserves were admittedly too low. Though the operation was feasible, much remained to be learned about fuel consumption and daylight tactics if large formations were to be flown over those distances. Upon receiving the report of the test, General Wolfe still did not move from the stand he had taken. The B-29 was a magnificent engineering achievement, but it was new and different and it had new engines that we did not fully understand.

Haywood S. Hansell, Jr., USAF Retired; The Strategic Air War Against Germany and Japan: A Memoir, http://www.ibiblio.org/hyperwar/AAF/...Hansell-4.html

When bombing operations started from the Marianas, distance was marginally better. Again, "as the crow flies", it was still a good 1,270 nmi between Saipan and Tokyo, which makes for a 2,923 miles to-and-from. But now, XXI Bomber Command could bomb the hearth of Japan; Honshu island and its cities. It was also easier to get fuel, bombs and other goods; no need to airlift everything over "the Hump".

Brigadier-General H. Hansell, put in charge of operations for the XXI Bomber Command, was adhering to the established "high-altitude daylight precision bombing" doctrine - he was, in fact, a co-author of APW-42 memorandum on that very subject!
( Haywood S. Hansell, Jr., USAF Retired; The Strategic Air War Against Germany and Japan: A Memoir, http://www.ibiblio.org/hyperwar/AAF/...Hansell-2.html )

When, on 24 November 1944, 111 B-29s took off from Saipan, they were carrying two-and-a-half tons (5000 lbs) of 500 lbs and incendiaries each. Seventeen Superfortresses had to abort, only 23 reached their main target; the aircraft Nakajima's engine factory at Musashino (target No 357) of ill-fame, 59 others went for secondary targets, 6 could not release their bombs due to mechanical failures! To nurse their fragile engines, bombers would only get to 27,000 ft for their bomb-runs as they were near the Japanese coast.
(Koji Takaki & Henry Sakaida, already cited, pp. 29 - 31)

According to Capt. Stanley Samuelson, pilot of "Snafuperfort", his load was 10 500 lbs in the rear bay, the front bay being occupied by 8,000 gallons of extra fuel tanks.
(The Diary of Capt. Stanley Samuelson, http://home.att.net/%7Esallyann4/samuelson3.html)

Brigadier-General "Possum" Hansell candidly explained why;

On November 24, 111 B-29s of the 73d Bombardment Wing, XXI Bomber Command, took off on the trip toward Japan. They represented over 90 percent of the B-29s on Saipan. Some of the crews had arrived less than a week before, and their first takeoff was for Tokyo. Each lift-off was an ordeal. As noted earlier, the B-29 was originally designed for a gross weight of 120,000 pounds. By urging and pleading, we had convinced the engineers at Wright Field to raise the allowable gross takeoff weight of the B-29s to 132,000 pounds. Now, to carry every gallon of gas that could be pumped aboard, they were taking off at 140,000 pounds! A faltering engine would spell the end for any aircraft.

Haywood S. Hansell, Jr., USAF Retired; The Strategic Air War Against Germany and Japan: A Memoir, http://www.ibiblio.org/hyperwar/AAF/...Hansell-5.html

PICTURE HERE ; A 313th B/W B-29 during its bomb run over Osaka, oozing oil all over the wing... and the tail as well! Some Superfortresses were unofficially dubbed "Flying Grease Gun" or "Lubricating Lady", one was officially named "Snafuperfort" (see mention above) by its crew because it was constantly in need of repairs. That crew went missing... on a replacement aircraft! The new crew modified the name so it would read "Sna p fort", they completed their tour and the aircraft went through WWII!

When climbing to ±30,000 ft , the B-29 bomb loads were limited to 2 - 3 tons top, 4,000 to 6,000 lbs, and this is a very generous estimation.

Hansell's credo was being disproved missions after missions; target No 357 was still standing and running at nearly 100% capacity after six raids (it would take twelve to finally clubber it)! Furious jet stream winds going at 100 to 250 MPH, constantly changing weather over targets, mechanical failures, especially of engines, poor radar training, inadequate radars, everything concurred to mediocre accuracy in bombing.

As the story goes, when Major-General Curtis LeMay took charge of XXI Bomber Commands, he soon realized that precision bombing was not yielding the expected results, and had the B-29 "strip to the bones" to get as much incendiaries devices they could carry at low altitude for raids at night. This version is a very "crude" interpretation of what really happened, but we will stick to it for this thread. It may be worthy of another debate in some other section of SOH.

Tokyo was the first target, in Japan that is, to be subjected to this new method on the night of 9 - 10 March 1945;

LeMay's tactics were indeed radical. The B-29 would be stripped down so they could carry six tons of incendiary per plane. They flew at night at an altitude between 5,000 and 10,000 feet. Since enemy fighters would not be a problem, the planes flew and bombed singly.

Charles Griffith, The Quest / Haywood Hansell and American Strategic Bombing in World War II, Diane Publishing, p. 198. Whole book available HERE

A mission summary gives some precisions on the bomb loads;

Average bomb load 13,880 lbs. 73rd wing, 12,857 lbs, 3l3th Wing and 9,672 lbs. 314th Wing. Average gas reserve 1044 gallons.

http://www.20thaf.org/missions/040.htm

It is interesting to note that bomb loads were inversely proportional to the island from which they had to take off; bombers from Saipan were carrying 4,128 lbs of bombs more than those stationed on Guam.

Lt Robert Copeland, a copilot of the 73th described its plane load;

We're carrying 40 M-18 incendiary clusters. No guns will be carried.

http://flgrube1.tripod.com/id13.html

This gives us a 347 lbs for the "M-18" incendiary cluster. The same site does describe the "bomblets" as being M-69. If so, they were M19 incendiary clusters, each carrying 38 M-69 napalm "bomblets". "M-18" cluster bomb simply does not exist.

As incendiaries goes, they were always in clusters (also described as "cassettes" or "bundles"), with the exception of the AN-M76 incendiary; a 500 lbs GP bomb filled with gel gas (napalm) and magnesium. All these devices were roughly equating to a 500 lbs bomb, in term of loading capability. More on that subject later...

Seeing that losses were staying "within reasonable limits", LeMay applied the same technique of night low-flying to precision-bombing as well, aided by radar, and pretty soon, to daylight bombing, seeing Japanese defenses crumbling. Once Iwo Jima conquered, and runways repaired and enlarged, Superfortresses could be diverted there, so planners got a bit more adventurous. On some missions, up to 100 B-29s had to land there as they were dangerously low on fuel.

Little by little, loads started to increase and, by the end of the war, bombers would carry a full complement of bombs, getting close to 20,000 lbs ( http://www.20thaf.org/missions/297.htm ) and, at least once, going over that 20,000 lbs mythic number ( http://www.20thaf.org/missions/322.htm ).

But we must be reminded that the B-29s were no longer these giant bombers festooned with guns and flying over 30,000 feet...

TO BE CONTINUED... NEXT TIME: BOMB BAYS AND BOMBS

[Ivan]

Hello Hubbabubba,
I'll admit up front that I haven't done more than skim through your message. It has enough detail that I will need to print out a copy to read.

Regarding the B-29, its missions from China were not indicative of capability because of the logistics of flying supplies over the Hump. Its early high altitude missions were also not terribly successful. The missions were brought down later so that they could actually hit something because bombing from the Jet Stream simply didn't work. The side effect was to make them also vulnerable to fighter intercepts. Denisch is a much better authority on the subject than I am.

Regarding aircraft loadouts, a general statement can easily be made: An aircraft may be capable of carrying a large bomb load, a full ammunition load for the guns, or a full internal fuel (and perhaps drop tanks as well) but NOT all at the same time. The limiting factor sometimes is the number of hardpoints (yeah, a modern term) but more often is the maximum take-off weight.

Yes, there is room to load 25,000 pounds of bombs AND a full internal fuel load of 1500 gallons of fuel but not without exceeding the T-O weight limitations. I believe this is something that needs to be in a Read-Me file for a CFS aircraft. The REAL bomber pilots had charts to calculate loads and moments to make sure the aircraft stayed in trim during the entire flight. As a minor related note, the B-26 bomber was packed with spares and other related equipment in a specific manner for delivery flights. When the USAAF received them, they just simply unpacked stuff and tried to fly the bombers. The bombers often broke their nose gear when landing in such a condition because they were severely out of balance and had too much weight on the nose gear!

Regarding the idea of forcing virtual pilots to choose loadouts, the US Navy charts on most of their WW2 fighters shows only a partial ammunition load and partial fuel load on a "Fighter" mission. The full ammunition and internal fuel load was only specified for a "Fighter Overload" mission but that might also include drop tanks. This is what suggested to me that a partial ammunition load perhaps should be the default even for a fighter.

Thanks for doing the research. I WILL print out your post to read in detail.
- Ivan.

[hubbabubba]

Actually, Ivan, the research is, for a former lawyer like me, part of the fun. I cite my sources whenever I can so people can make their own opinion and, if they are so inclined, go and dig deeper.

I will refrain from making more comments as many of the points you're making will be addressed in near-future "installments".

The question of bomb loads is something I was already curious about, this discussion is just a good pretext to start digging. And why not letting other SOH readers profit from my discoveries?

BTW, I'm not trying to boast here; much of what I report is newly acquired knowledge, and I admit it openly.

[hubbabubba]

BOMB BAYS AND BOMBS

Dave made a good point; the size of the bombs being loaded influences the total tonnage almost as much as distance and altitude planned for the mission.

The heaviest loads were reached with GP/HE 500 lbs while the lightest would be by hauling mines and heavy bombs. I had to explore that aspect to make sense of the loading capabilities of the Superfortress, and I may as well share my discoveries with you guys.

The bomber had two internal bomb bays, in which it could carry bombs or cargo or extra fuel. Bombs were attached by their suspension lugs (Hi! Dave ) to a shackle. That shackle, with the bomb attached to it, was hoisted into the bomb bay and hooked on a bomb rack alongside a bomb release station. Once in place, the bombs would receive their fuses and the wire that would armed the fuses on train release. On bombardier's command, bomb were released in salvos or in train. In salvo, bombs were jettisoned unarmed all at once, the arming wire not being pulled. In train, bombs were release one by one according to a predefined pattern implemented by the intervalometer, the shackle was retaining the arming wire. Vanes or other mechanisms, until now impeded by the arming wire, would arm the bombs on their way down and make them "live". According to their uses, bombs would explode on contact or after a certain delay or at a certain altitude... or never.

This is the short version. Now the long one;

Bomb racks look like large steel frames. They were bolted into the bays on each sides, right and left. Smaller bomb racks could be bolted, hanging in the center. They were smaller because of the pressurized passageway permitting crew members to go from the front to the rear pressurized cabins and back, bomb bays were not being pressurized.

Each bomb bay could accommodate four side racks, two right, two left, for the 100, 300, and 500 lbs bombs. For the 1,000, 1,600, 2,000, and 4,000 lbs bombs, only one rack per side.

Four central racks could be install for 100 and 300 lbs bombs, two right and two left, front and rear. Only two central racks for the 500 lbs bombs, front and rear. No central rack for the heavier bombs.

Changing the rack's configuration was feasible but took some time, as they were strongly bolted to the airframe. Side racks #1 (right) and #4 (left) were used for bombs up to 1,000 lbs. Side racks #6 (right) and #7 (left) were used for heavier bombs. Central racks #2 (right) and #3 (left) were used for 100 and 300 lbs bombs. Central racks #5 were used for 500 lbs bombs. Changing the number of release stations and spacing them on a rack was easier; they could be inserted by hands and removed with a screwdriver.

Racks, release stations, and shackles should never be oiled! Oil would freeze at high altitude and seize material. Mechanics and ground crew, out of habit, would forget that; "a bit of oil wont hurt". Well, it did.

Stories of bombers having to make the trip to Tokyo only to realize that bombs would not drop, are plenty full. Inspections were made, and many pieces had to go into a "gasoline bath" to remove any trace of oil. Rust was to be removed by sanding or filing, this applied as well to bomb bay's doors hinges and opening mechanism.

While British were using a single suspension lug system, Americans went for two lugs equidistant from the center of equilibrium. They would eventually install both lug systems on all bombs for operational interchangeability.

Here are the maximum loads for each major bomb weights in a B-29;

100 lbs; four side racks per bay, each holding seven bombs, and four central racks per bay, each holding three bombs, for a total of eighty bombs.

300 lbs; four side racks per bay, each holding five bombs, and four central racks per bay, each holding two bombs, for a total of fifty-six bombs.

500 lbs; four side racks per bay, each holding four bombs, and two central racks per bay, each holding two bombs, for a total of forty bombs.

1,000 lbs; two side racks per bay, each holding three bombs, for a total of twelve bombs.

1,600 lbs; two side racks per bay, each holding three bombs, for a total of twelve bombs.

2,000 lbs; two side racks per bay, each holding two bombs, for a total of eight bombs.

4,000 lbs; two side racks per bay, each holding one bomb, for a total of four bombs.

The only load that gets to 20,000 lbs is made of 500 lbs bombs. Any other combinations is lighter. This information was taken from;
- USAAF, The B-29; PLANE COMMANDER TRAINING MANUAL FOR THE SUPERFORTRESS, reprint from Lulu.com, pp. 47 - 49, extracts available HERE
- AAF, BOMBARDIERS' INFORMATION FILE, Section 7 "Armament", available HERE

During WWII, the B-29 carried three main types of offensive payloads; Single bombs, Cluster Bombs, and Mines;

- General Purpose (GP) High-Explosive (HE) single bombs.

These bombs were used against specific targets in precision bombing attacks or as "roof blower" during incendiary attacks. The 500 lbs bomb was the most widely used, but 1,000, 2,000 and 4,000 lbs LC (light case) saw service. The 100 and 300 lbs were rarely used on the B-29. The SAP (Semi Armor Piercing) was not used as far as I can tell on Japan main archipelago, but I could be wrong.

The 100 lbs GP bomb was mostly the M30 or AN-30 and was 101 lbs heavy (54.2 lbs of TNT, Amatol or Tritonal, for a ratio explosive/total weight of 54%), 38.5 inches long and 8.2 inches in diameter. The later model AN-30A1 was a bit longer (44.8 inches). They all had dual lugs system with double lugs 14 inches apart.

The 300 lbs bombs M31 or AN-M31 weighed 262 lbs (132 lbs of TNT, Amatol or Tritonal, ratio of 50%) and was 47.8 inches long and 10.9 inches in diameter, later replaced by the AN-M57 and AN-57A1, weighing 250 lbs. All equipped with double lugs 14 inches apart or single lug.

PICTURE HERE; A 250 lbs AN-M57 standing on a wooden box at the museum. Worth noticing; that bomb has all the appearance of a live one! The nose fuse is in place and no safety pins or arming wire is visible. Being in the USAF museum, I doubt it is really, but if I was wandering around in the woods and saw such a bomb, I would stay as far from it as I can and I woul call 911.

The early 500 lbs bombs may have been M43 or AN-M43 bombs, weighing 512 lbs and filled with 262 lbs of Amatol, TNT, Composition B (Comp.B), or Tritonal, the explosive ratio being therefore 51%. Length; 59.2 inches. Diameter; 14.2 inches. Lugs 14 inches apart. It was replaced by the M64 or AN-M64 bomb, weighing 524 lbs and filled with TNT (267 lbs for a ratio of 51%) or Amatol (262 lbs for a ratio of 50%). Length and diameter identical. Double lugs 14 inches apart plus single lug on the opposite side.

PICTURE HERE; 22x500 lbs GP bombs about to be loaded aboard. Tail fins were only installed just before loading. They are always attached with one fin aligned with the suspension lugs to minimize space taken.

PICTURE HERE; The man in the forefront is installing the tail burster and will, after that, attach the fin on this 500 lbs bomb. Bombs behind him are already tail fuzed and we can see shackles on some of them. Nose and tail fuses will be installed only once the bombs are in their stations, the releases on "lock". Nose fuses have an integrated burster charge while tail fuses are "pistols" with separate bursters.

PICTURE HERE; AN-M64 Comp.B are being tail-fuzed in the front bomb bay. The upper-left nose of the bomb shows that the nose plug has been removed and awaits its fuse. The bomb just behind that one still has its nose plug. Arming wires are not in place yet.

PICTURE HERE; AN-M64 Comp.B being nose-fuzed in the aft bomb bay. Safety pins are being removed and arming wires are in place.

PICTURE HERE; ±30x500 lbs bombs dropped in train with intervalometer set at very short intervals or jettisoned in salvo. I would favor the latter; the aircraft from which the picture is taken is way too close if they are on the bomb run, and the copilot have better things to do!

The 1,000 lbs bombs was the M44 or AN-M44 bomb early on. It had a weight of 967 lbs, of which 538 lbs of TNT, Amatol, Comp.B, or Tritonal (56% ratio). Length; 69.5 inches. Diameter; 18.8 inches. Two lugs 14 inches apart. Replaced later by the M65 or AN-M65. Weight; 997 lbs, 530 lbs of explosives (53% ratio). Same length and diameter. Double lugs 14 inches apart and single lug.

The 2,000 lbs bomb, the M34, was a 2,053 lbs bomb filled with 1,150 lbs TNT, Tritonal or Amatol (56% ratio). Length; 92.8 inches. Diameter; 23.4 inches. Replaced by the AN-M66 and AN-M66A1, almost identical but with three suspension lugs; one single and two spaced 30 inches apart.

PICTURE HERE; 2,000 pounders being "christened" while tails and shackles are being installed. How do I know that these are 2,000 lbs and not 1,000 lbs? Check the shackles on them, especially on "MARGE JAY"; the arms that will fit in the release station are not at the center but a bit forward. This indicates that the shackle is a D-6 type, only used for 2,000 pounder. Arming wires are already in place on "YOU'LL GET A BANG OUT OF THIS ONE", and the protective nose plug is removed.

Finally, the M-56 LC (light case) 4,000 lbs "family", weighing 4,201 lbs (3,244 lbs of Amatol, 77% ratio), or 4,514 lbs (3,519 lbs of Amatol, 78% ratio), or 4,535 lbs (3,515 lbs of Tritonal, 78% ratio), complete the HE/GP arsenal of the B-29. Length; 117.25 inches. Diameter; 34.3 inches. Double lugs system only 30 inches apart.

PICTURE HERE; Two civilians attaching a tail to a practice 4,000 lbs LC bomb. The unfinished aircraft behind and the neat hangar suggest that they were in the U.S. and about to test the bomb to see how and where it would fit. The bomb has no suspension lugs visible BTW, and no markings.

All these bombs had nose and tail fuses, mostly of the "vane type". Proximity fuses were used to detonate them above the target, increasing the blast effect. Tail-only fuses were also used with retarding mechanism for higher penetration (short delay) or zone interdiction (long delay).

Bombs under 2,000 lbs had a 14 inches suspension lugs system and could be hanged under a B-7 or B-10 shackle. 2,000 lbs bombs used D-6 shackle and 4,000 lbs bombs used D-7 shackles, both using a 30 inches spacing lugs system.

Operations analysis section of the 8th Air Force had realized that 500 lbs bombs were doing the job as well, if not better, than heavier ones;

The destructivity of three high explosive bombs used in the Paris area on comparable targets in the period of April to December 1943 was carefully analyzed. All of the targets were single-story steel-framed buildings. The analysis revealed that on such targets one ton of 500-pound general purpose bombs fuzed .025 caused the same damage, approximately 6,400 square feet, as one ton of 1,000-pound general purpose bombs. Furthermore, one ton of 500-pound general purpose bombs fuzed .01 did approximately 16,000 square feet of effective damage.
(...) According to these statistics, half as many missions were required to destroy a target of one-story steel-framed buildings if 500-pound general purpose bombs fuzed .01 were used instead of 500- or 1,000-pound general purpose bombs fuzed .025.

Charles W. McArthur, Operations analysis in the U.S. Army Eighth Air Force in World War II, American Mathematical Society, p. 67, extracts found HERE

So, it is not surprising to see that it was the most common ordnance used.

The AN-M76 incendiary bomb, basically an AN-64 weighing 475 lbs, filled with 180 lbs (38% ratio) of gas gel and magnesium, was loaded like a normal 500 pounder. Despite being one of the largest single incendiary bomb, it was one of the least effective. When general Hansell was ordered by general Arnold, under protest, to conduct experimental bombing mission with incendiary, he used the AN-M76 with the same techniques he had professed since the beginning of the XXI Bomber Command campaign. Results were no better than with GP/HE bombs, almost to the relief of Hansell.
(http://www.b-29s-over-korea.com/fire...ebombing2.html)

I have not made much research on "pumpkin bombs", used to test ballistic property of the Fat Man nuclear bomb. Suffice to say that it was weighing about 10,000 lbs and was dropped from a British-style single hook shackle attached centrally in the front bay. For more information, go HERE.

NEXT TIME - CLUSTER BOMBS

[hubbabubba]

CLUSTER BOMBS

- Cluster bombs, incendiaries and fragmentation;

Single incendiary dropped from high altitude were ineffective; fires were too scattered to create the "firestorm effect" that had been observed in Germany. The AN-M76 bomb would still be used, but most incendiary ordnance was to be made of smaller incendiary projectiles, "bomblets", on the principle that many fires are better than one, no matter how big the bomb.

The most used would be the M47 100 lbs chemical bomb;

The body of this bomb is made of 1/32-inch sheet metal rolled and lap welded into a
cylindrical shape 8-inches in diameter. The nose is hemispherical and welded to the body as is
the box type tail fin assembly, which forms the tail taper of the bomb body. The over-all length
is-45 inches excluding fuze. The burster well is screwed into the bomb body by means of pipe
threads to make a gas-tight seal at the nose. It is held in place at the tail of the bomb body by an
attached cone in the inner side of the fin assembly. It is internally threaded to receive a sleeve,
which has a groove in its lower portion to seat the fuze, which is pressed in place. Around the
bomb body are two suspension bands 14-inches apart which provide suspension lugs for
horizontal suspension. One blade of the fixed box type tail assembly is in line with the
suspension lug.(...)
The Bomb may be loaded with an incendiary filler of rubber and gasoline in the field. The
base filling is gasoline supplemented by one of the four different incendiary ingredients as
follows:
1. LA-60. Consists of crude latex or sap in combination with caustic soda, coconut oil, and
water
2. Crepe rubber (CR). This is crude latex but is reduced to a solid by precipitation and
kneading.
3. LA-100. This is crude latex dried until it is approximately 100 percent solid.
4. Smoked rubber sheets (SR) a crude latex, which has been dried over a smoky fire until it is
approximately 100 percent solid.
When loaded with the incendiary filler the Bomb Fuze M108 (Nose) with a 1-pound black
powder Burster Charge M7 is used. This burster charge bursts the bomb and scatters and ignites
the filler. When filled, the body weighs 85 pounds of which 65 pounds is incendiary filler. This
is a typical example of the scatter type of incendiary filler.
(...)
The M47A1 was designed to replace the 100-pound M47. The M47 was found to
have too thin a wall section, and in handling and storage, it developed leaks due to corrosion and
rough treatment. Consequently, the wall thickness was increased from 1/32 inch to 1/16 inch, and
coating inside with acid-proof black paint protected the case. This special inside coat of paint
was to provide a resistance of 100-pound pressure.(...)When loaded with Incendiary Oil, it weighs
94 pounds, of which 65 pounds is incendiary oil.

Anonymous, BOMB, CHEMICAL, 100-POUND M47 SERIES, PDF available HERE

The bomb had many shortcomings;

(...)The M-47, a 100-pound gasoline jell-filled, could not be carried in economical loads in either the B-17 or the B-24, and it had too much trail to be set into the bombsight with the bombing tables then available. (Trail is the lagging of the bomb behind the plane, caused by the resistance of the air.)

Charles W. McArthur, Operations analysis in the U.S. Army Eighth Air Force in World War II, American Mathematical Society, p. 65, extracts found HERE

The operations' analysts found ways to compensate trail with a "false disc speed" inserted in the bombsight. Since bombing in Japan was to be done at low altitudes against areas, pinpoint accuracy was not a problem. But their best "invention" was a simple and effective way to bunched together six bombs in a single bomb station;

They (the analysts) worked with the Ordnance and Chemical Warfare Sections to devise ways of loading the bombs to achieve maximum loads. In particular, the subsection succeeded in increasing the loads of M-47 incendiaries. With little help from the States, the Eight Bomber Command , particularly the Chemical Warfare Section, developed and had manufactured its own equipment for increasing the loads of the M-47s by clustering the bombs on their racks.

Charles W. McArthur, Operations analysis in the U.S. Army Eighth Air Force in World War II, American Mathematical Society, p. 65 - 66, extracts found HERE

This "equipment" is well describe in the following pictures and was extensively used in B-29;

PICRURE HERE; This is the "kit" invented to load one 500 lbs bomb station with six M-47A1 bombs; a marvel of ingenuity and simplicity, all rolled in one. The first bomb was hanging "normally" under the shackle. Ten steel cables (two per bombs) were hanging by a crimped large loop going over the lugs of the first bomb. At the other end of each cable, a springhook to be attached to the suspension lug. Each pair of cables was of a specific length for each bomb. Upon release from the shackle, each loop, until now maintained between the lug of the first bomb and the shackle, was coming loose. The "multi-braids" arming wire was arming each bomb on its way down.

PICTURE HERE; Two views of the M47A1 cluster, almost ready to go, hanging from the rack. Release station is on "lock" and safety pins are still in place. We can clearly see why no cluster could be hanged on the central rack, the cluster is almost three bombs wide. Central rack mounted cluster would "overlap" side ones.

PICTURE HERE; Testing the M-47A1 clusters. The lines you see on the pictures were made intentionally to measure dispersion and distribution. Clusters disintegrate upon release and are scattered evenly on the target.

I have stumbled recently on a site dedicated to the B-29 in Korea "police action" where it is mentioned that the maximum load of a B-29 carrying 100 lbs bombs was 192 bombs. (HERE) If you get all the side racks, minus the central racks, loaded with a cluster of six, you'll get 32 stations by six bombs; 192. I suspect that a "kit" similar to the one used for the M-47 was created for normal 100 pounders. But I doubt that it was used during WWII, since only one mission reports the drop of hundred pounders.

So, if we assemble all the information available on the M47, we can approximate that 6 bombs x 32 stations x 94 pounds = 18,048 lbs. Lets round it up to 18,100 lbs to take into account the "kits" used.

One last remark about the M47; when you see a picture of hundred of 100 lbs bombs standing on their tails near a B-29, you can almost bet that they are M47 waiting to be filled with gasoline before being fused and clustered in the bomb bay, not American propaganda making a show of strength.

Even though clustered, M47 were still bombs, not bomblets, or "sub-munitions" in modern parlance.

These incendiaries devices would be much lighter and were never intended to be release singly. British incendiaries were first being used, for testing and because Americans had none, but they soon started making their own. The first to be produced in mass was the M50 bomblet.

The 4 lbs AN-M50A1 was weighing 3.7 lbs. It was an hexagonal tube of magnesium alloy 21.3 inches long and 2.9 inches wide across the flats. AN-M50A2 and AN-M50A3 would follow and were identical. They where filled with Magnesium/Thermite and were tail fuzed.

PICTURE HERE; M50 bomblets (second starting from the top). Thermite (called "Thermate" in the picture, a variety of thermite with additives) needs high temperature to ignite while magnesium, as anyone old enough to remember flashbulbs will know, ignites quite easily. M54 bomblets (under the M50s on the above picture) are using thin steel tubing instead of magnesium. Thermite quantity is proportionally bigger but shape, size, and weight are approximately the same.

Thermite bomblets would burn furiously at temperature capable of melting, even igniting, steel. Thermite was, and still is, being used to destroy enemy guns and tanks, melting breeches and engine blocks. Being mostly made of rust powder, it can't be extinguished by oxygen deprivation. Water and wet tatami, the main tools of Japaneses firefighters, were useless. Only a shovel and a large sand bucket could do the job, the bomblet being left to burn until sand had vitrified all around it. But even that option was not for the faint hearted; many bomblets had explosives charges to injure or kill firefighters and passerby.

PICTURE HERE

But the M50-M54 bomblet was only burning at one place and, although the fire was quite intense and "plumes" of ignited thermite would fly around, it could be contained if swiftly attended to. The British equivalent were superior in that respect; small thermite or white phosphorus (WP) "pellets" charges would be scattered while the body was being consumed. ( see HERE )

Many bomblets were "duds", as they needed to impact nose first. An empty portion (±1/3th) of the tube was acting as a drag tail but the "thermals", wind up-drifts, caused by already burning ground fires would toss and turn them all around. In fact, thermals would toss B-29 as well, enough to be reported at debriefings ( see HERE , HERE , and HERE ).

This personal account is even more colorful;

One of the best stories to come out of the Twentieth Air Force relating to the dangers of the thermals was told by the crew of aircraft number 21, whose commander was Captain William "Buck" Senger of the 61st Squadron. After bombing Tokyo on this attack, all the men swear that their plane did two loops over Tokyo Bay before it was righted at an attitude of about 4,000 feet. Some of the people say that a B-29 cannot be looped under any circumstances, but the men of Senger's crew think otherwise. They said they did it!

HERE

Magnesium was, and still is, a costly material. Natural rubber was also becoming scarce after the fall of producing countries into Japanese hands and stocks were better used for making tires, gasket seals and hoses, to name some. Americans scientific and industrial communities put their noses to the grindstone;

(...) Army Air Corps officers went to England and studied the Nazi blitz. The Chemical Warfare Service, which had been urging the Air Corps to adopt incendiary weapons, sent one of its expert, Colonel J. Enrique Zanetti, a Columbia University chemistry professor on active duty, to London in June 1941 to analyze fire raids, then put him in charge of its own incendiary program. A few days after Pearl Harbor it set up an incendiary laboratory at the Massachusetts Institute of Technology. The National Defense Research Committee, established in 1940 to coordinate the military work of American scientists, created an incendiary weapons section. NDRC specialists worked with the Arthur D. Little Company, the E.I. du Pont Corporation, Eastman Kodak, the Standard Oil Development Company, and other chemical suppliers and users to develop fire weapons. The Standard Oil group soon devised a small, extremely efficient bomb, designated the M-69, which ejected napalm from its tail. This was the jellied gasoline product created chiefly by Harvard University chemist Louis F. Fieser, a leading figure in the NDRC program.

Ronald Schaffer, "Wings of judgment: American bombing in World War II", Oxford University Press, p. 108

Professor Louis F. Fieser and his team at Harvard University created a brownish powder substance (HERE), made of coprecipitated aluminium salts of naphthenic and palmitic acids (HERE), hence the name; Na-Palm.When mixed in appropriate quantity with gasoline, it would make a sticky jelly, which would also be known as napalm by extension.

The powder, very stable, could be shipped to operation theaters and used instead of natural rubber, although it is not certain that it was done since rubber-producing territories were back under Allied control and stocks of latex and natural rubber could be replenished.

But the mixture powder-gasoline proved stable enough to pack it into weapons stateside, seal it, and send it "ready to use". The most popular container would be the M69 bomblet. The M69 was again an hexagonal tube, most compact and stable geometric form for clusters, of 19.5 inches long and 2.9 inches wide across the flats, made out of steel, much cheaper than magnesium. They each contained 2.8 lbs of napalm in a cheesecloth pouch. Contact detonator and a delay fuse were in the nose of the bomb, the ignition and expulsion being performed by to black powder/magnesium/oil bags.

PICTURE HERE

Planning for the testing of new-generation U.S. incendiary bombs began in February 1943 and by May the tests were underway at Dugway Proving Ground, Utah. The designs under comparative test included the M-47 (...); the M-50 (...) and the M-69 (...).
(...)
The thorough tests at Dugway, which ran for four months, left little to the imagination. B-17s and B-24s flying in combat formations released live bombs from normal bombing altitudes over carefully replicated residential structures in two prototypes "enemy villages" built by the Army's Chemical Warfare Service. The Japanese village consisted of 12 two-story row houses and the German town included six assorted-design houses. Cost had been no object and the structures were as authentic as the builders could erect. They were of the same construction and furnished as they typically were in Japan and Germany, including the same woods, same dimensions, even the same paints, interior and exterior. For example, the Japanese residences had smooth plastered walls and sliding paper screens to divide the rooms; included were tatami mats, sitting pillows, low tables, charcoal braziers, even chopsticks on the tables. The Japanese homes were lined up on narrow streets, precisely 8 feet wide, as in Japanese cities.
Records were kept on each bomb hit; where it entered the building, the path it followed through the structure, where the incendiary action took place, and the fire result achieved. The comparative effectiveness of the bombs was categorized as follows; Class A, a fire that burned out of control after six minutes of attempts by trained fire guards to put it out; Class B, a fire that was ultimately destructive if unattended; and Class C, a fire that went out when unattended, with no destruction resulting. The M-69 proved to be the clear winner, creating far more Class A fires than its competitors. They would be manufactured by the millions and delivered by ship to the Marianas for the B-29 raids in 1945.

Stewart Halsey Ross, "Strategic bombing by the United States in World War II: The Myths and the Facts", McFarland, pp. 107 - 108, extracts available HERE

For information about Dugway Proving Ground, go see a slide show HERE

PICTURE HERE: HERE

A version, the M-69WP, had a sealed WP (white phosphorus) plastic container at the base that was shattered during its expulsion, forming a dense cloud and spreading around chard of incandescent white phosphorus igniting the napalm. The M-69WP was not differentiated from ordinary M-69. The M69X was "booby trapped" with half a pound of TNT or Tetryl set to explode about six minutes after impact to deter firefighting. They where all externally similar and of the same weight.

Another bomblet, the M74, was being developed as an improvement over the M-69. But it saw very limited operational use and, in fact, the M-69 and its variants - M-69W (WP) and M-69X (TNT) - were still predominant during the Korean war. Weighing 8 lbs, of which two were for the "pyrogel" (known as "PT1" by the War Department) incendiary substance. It was 19.4 inches long (tail retracted) and 2.8 wide across the flats. The streamer was replaced by a telescopic shrouded tail fin assembly. The "Popular Science" magazine of May 1945 report that;

The fuse in this bomb is described by a conservative former professor of chemistry (???) as "super-instantaneous." It is an all-ways fuse, which means that it goes off regardless of the angle or direction from which the bombs hit the target.

Volta Torrey & al., "How we fight Japan with fire". Popular Science, p. 108, ailable HERE

This article is certainly very informative, but the information herein is to be taken into context. This was a document published in wartime and, most certainly, read by "not-so-friendly" people. To take only one example, the M69 is described as being "always" explosive - we know it wasn't the case and that only M69X were.

The superlatives arguments made for the M74 over the M69 appear to be a blend of facts and fiction. For example, if the fuse was to be triggered from any angle, what is the need for an elaborate extensible tail? The triggering mechanism described just after that seems perfectly maladapted to aerial transport. In fact, the triggering could be done from different angles, but it was preferable to hit nose or tail first. Hitting sideway could do the job, but only if the shock has violent enough. Other discrepancies are revealing; in one line, it is said that pyrogel is shot out by the tail while picture caption says that it is by the nose! The same caption talks of a "dome-shaped" nose and, fortuitously, the G.I. is holding the M-74 bomblet in such a way as to hide that nose. We now know that the nose of the M74 was as flat as any other bomblet! I can imagine frightened Japaneses staying away from unexploded bomblets having lost their dome-shaped noses! In fact, the "goop" was exiting by the tail, being pushed by a dome-shaped piston inside the tube.

Pyrogel is, incidentally, a "beefed-up" version of napalm in which magnesium, metal oxides and tar, to name a few ingredients, are added to intensify the heat and prolong the burning. It was more often dubbed "goop" by G.I.s, and "PT1" by official documents. But it never replaced napalm. It doesn't even has a "stub" at Wikipedia, which says a lot (lol!). I will have to conjecture here that this "goop" was unstable due to its composition. If you know more on the subject, why not share with the rest of us?

Although many bomblets were tried by the USAAF, these were the "mainstay" of the firebombing campaign against Japan.

CLUSTERS

It must be stressed here that bomblets and clusters nomenclature is in itself very confusing. Many works are confounding one with the other, calling a bomblet by its cluster's name or designating a cluster as being the bomblet itself. To add to this confusion, many cluster pictures are mislabeled, often being used to represent another type of cluster. And, finally, as if it was not complicated enough, Army nomenclature would go at variance with rules and regulations. If you know better, please do not hesitate to correct what follows.

AN-M50 bomblet was packaged in two quick-opening clusters; AN-M6 100 lbs (34 bomblets) and AN-M7 500 lbs (128 bomblets). The AN-M17 was an aimable 500 lbs cluster, containing 110 bomblets.

AN-M54 bomblet was packaged in two quick-opening clusters; AN-M8 100 lbs (34 bomblets) and AN-M9 500 lbs (128 bomblets). It may have been used in aimable cluster similar to the AN-M17 but it is not sure, especially since the M54 was phased-out rapidly when it was observed that it had too much penetration and ignited fewer fires than the M50 and the M69. (see HERE)

AN-M69 bomblet was packaged in one quick-opening cluster; M-12 100 lbs (14 bomblets). The bomblet was mostly packed in a 500 lbs (38 bomblets) aimable cluster officially known as the AN-M19, but the mention only starts to appear on the beginning of August 1945, a few days before Hiroshima and Nagasaki atomic bombing. (see HERE) Before that, mention was made of "E46" or "E-46", and I believe that it was an interim nomenclature, "M" prefix was reserved to approved standard equipment ("E" for experimental maybe?). This is an educated guess based on personal accounts (HERE), third party research (F J Bradley, "No Strategic Targets Left", Turner Publishing Company. p. 34, extracts available HERE), reports on chemical plants (HISTORY OF ROCKY MOUNTAIN ARSENAL COMMERCE CITY, COLORADO, found HERE, and disposal of dangerous material site (HERE), but I would venture to say that the E46 was a 500 lbs aimable cluster of 38 bomblets with an E6R2 cluster adapter (HERE).

AN-M74 bomblet was only packaged in aimable cluster. It was officially going to be the M31 cluster but this nomenclature never appears in 20th Air Force Mission Summaries. But mention of a certain "E48" or "E-48" (see HERE) lead me to believe that it was an interim designation for a 500 lbs cluster of 38 M74 with the E6R2 adapter (see above paragraph).

Quick-opening clusters were only an expedient to pack more bomblets in bomb bays. They were suspended from 100 or 500 lbs bombing stations, their functioning was purely mechanical;

(...) When the cluster is released from an aircraft, the arming wire is withdrawn, freeing the clusters buckles. The cluster buckles open, releasing the strapping bands. The adapter opens, allowing the bomblets to fall individually to the target.

Department of the Army and the Air Force, May 1957, "TM 3-400 TO11C2-1-1", p. 41, available HERE.

This description of the M12 cluster applies to all other quick-opening clusters. It was a major problem for the 8th AF;

(...)the M-50, a four-pound magnesium bomb in 100- or 500-pound quick-opening clusters was not sufficiently aimable. Furthermore, its quick-opening clusters endangered other aircraft in the formation.

Charles W. McArthur, Operations analysis in the U.S. Army Eighth Air Force in World War II, American Mathematical Society, p. 65, extracts found HERE
The "quick-opening" clusters talked about were the AN-M6 (100 lbs) and M7 (500 lbs).

This was not an American-specific issue;

(...) The mainstay of the Command throughout the war was the 4-lb. magnesium I.B. The main (and very serious) difficulty met in the use of this weapon was its lack of aimability when dropped from small bomb containers, which resulted in incendiary attacks being widely dispersed and tending to fall downwind from the target with consequent great risk to our own aircraft froms showers of loose bombs over the target area.

Sir Arthur Travers Harris, "Despatch on war operations, 23rd February, 1942, to 8th May, 1945", Routledge, p. 94 , extracts available HERE.

Americans and British worked arduously to develop an "aimable" cluster that would not open on release. They were still experimenting when war in Europe ended;

(...) The story of the development of clustered incendiary projectiles makes a sad reading, and there can be no doubt that the failure to produce a satisfactory cluster before the end of the war enormously reduced the efficiency of our incendiary attacks.

Sir Arthur Travers Harris, "Despatch on war operations, 23rd February, 1942, to 8th May, 1945", Routledge, p. 95 , extracts available HERE.

Americans faired better. An "aimable" cluster, the AN-M17, was developed for the M50 bomblet, overcoming the difficulties. By reducing slightly the number of M50 bomblets in a cluster, from 128 to 110, it was possible to encase the bundles and attach a tail and a nose to the casing, giving the whole ensemble ballistic characteristics.

PICTURE HERE; CAPTION- An inspector with the Chemical Warfare Service's New York Procurement District writes a birthday greeting to Adolf Hitler on a cluster of M50 incendiary bombs at the Unexcelled Manufacturing Company. REMARKS- This M17 cluster is still missing its tail.
photo from HERE.

The M17 cluster were used in Europe see HERE, as an example among many, and were the mainstay of the incendiaries used along with the M47. Some M69 were probably used, but it was done piecemeal and only on an experimental basis, if ever.

The M69 was certainly earmarked for Japan and, from the first mention of E-46 to the M19, it was always being used in aimable clusters, at least from Marianas' B-29. The M74, if it was used, came in the form of the E-48 cluster.

Here comes the basic question (some will say "finally"); how much were these clusters weighing?

They were all quoted as being "500 lbs" clusters, but, as we have seen with GP/HE bombs, ordnance seldomly equals any given number. Many documents are using the "#" symbol instead of "lbs". This is only a "caliber", to use military parlance, a nominal charge simply stating that XYZ ordnance can be treated as 100, 300, 500, 1600, 2000, or 4000 lbs loads. A good example is the M47 which, when made of six 94 lbs, was approximately 564 lbs, but was often referred as a "500 pound cluster".

The M19 is the best documented when it comes to weigh;

The cluster is approximately 59½ inches long, 14¾ inches in diameter, and weighs approximately 435 pounds.

Department of the Army and the Air Force, May 1957, "TM 3-400 TO11C2-1-1", p. 42, PDF available HERE.

PICTURE HERE; REMARKS; The M19 and M21 clusters are indistinguishable one from the other as they share the same M23 cluster adapter set, the only difference is that the former carry AN-M69 and the latter AN-M69X. We can see the two arming wires going to the rear where the two fuses are.

PICTURE HERE; REMARKS; This diagram shows how the M23 adapter is being fuzed. If the LONG fuse does not do the job, the SHORT one will!

Others will have to be deduced since the TM 3-400 I found dated from 1957. If you have earlier copies, I would appreciate having one.

The E46 was probably about the same weigh since it is reported (see mentions above) that it was carrying 38 M69 bomblets as well.

PICTURE HERE; REMARKS; This cluster adapter, an interim A6R2, was certainly inspired from the M17. Only one fuse, and only one arming wire, is visible.

The E48, carrying 38 M74 weighing 8.5 lbs each, we have to add 38 x (8.5 - 6.1) = 91.2 lbs. This gives us 526.2 lbs.

The M17 is the hardest to evaluate since we have no direct data. It was made of two bundles of 55 M50 bomblets, each weighing 3.7 lbs, so 110 x 3.7 = 407 lbs. We have to add the weigh of the adapter cluster itself. This should not be more than 200 and less than 150 lbs, for a cluster weighing between 607 and 557 lbs.

PICTURE HERE; REMARKS; This is a view of the belly of a M17 cluster, the detonating cord v-channel running under is clearly visible.

PICTURE HERE; REMARKS; As this view shows, the M17 cluster had a nose fuse, here not installed. Like the A6R2, the rear of the second bundle is not entirely covered. This lead me to believe that both clusters were not tail fuzed, as the detonating cord would have damaged the unprotected bomblets.

PICTURE HERE; REMARKS; Drawing diagram showing the M17 workings.

PICTURE HERE; REMARKS; This earlier version extract of TM 3-400 would suggest that the M23 adapter was used with the M74 bomblets. According to the same document, it would have weighed 323 + 190 = 513 lbs. No M20 cluster was ever mentioned in missions summaries.

Of all these clusters, only the M17 could be significantly heavier than the M64 GP bomb. In theory, all 40 bomb stations could carry one of these clusters. But we know that it was never the case. The M50 bomblet was a "filling gap" ordnance because of M69 insufficient stocks. The second highest average load of the XXI , 19,979 lbs, was attained by "E48, 500# incendiary clusters to open 5,000 feet above Target" (HERE), the first being a load of M64 (HERE).

Even if the following precisions are not essential to the comprehension of the topic being discussed, the bomb loads of the B-29 during WWII, it is an intriguing aspect of bombing that I find worthy of mentioning, if only to satisfy my own, and maybe your, curiosity; how do these aimable clusters could open at a given altitude?
Well, in fact, they weren't! All WWII American aimable clusters depended on timed vanes-type fuses. Here is the general way it worked;
1- Cluster is released from the aircraft and starts free falling;
2- The arming wire(s) is retained by the shackle and the vane(s) start to spin, eventually arming the fuze;
3- A timer clockwork mechanism, preset by the ordnance officer in the bomb bay, explode a primer charge at the end of the set period of time;
4- The primer charge activates a detonating cord. This explosive device was already well known in the mining and demolition industry. It is a very fast acting cord used to detonate many charges almost simultaneously. Its explosive nature is also used as a "quick cutter". The detonating cord, running in a v-shaped "gutter" along the cluster, cuts the steel bands maintaining the container, It can also blow-out the nose and/or the tail fairings;
5- In the case of the M23 cluster adapter, a "fail safe" device, if the detonating cord has not worked, will ignite a second detonating cord that will sever the tail. As the tail fly away, it will pull a wire that was holding straps buckles, opening them and liberating the container;
6- Bomblets fly away from the container and are dispersed in the air stream turbulence. Their safety plunger springs out or the safety pin is ejected, arming the bomblets;
7- Depending on the type;
- M50 or M54: they fall and hit nose first with the help of their empty tube tail. On impact, a firing pin hits the primer cap by inertia. This primer ignites the first-fire mixture, and this mixture ignites the thermite (or thermate) which burns and, in the case of the M50, ignite the magnesium casing.
- M69: they fall and hit nose first with the help of a gauze streamer. On impact, a firing pin hits the primer cap by inertia. This primer set fire to a slow-burning compound, acting as a 3 to 5 second delay fuse, which ignite two bags of black powder/magnesium/oil mixture. The explosion of these bags eject the cheesecloth bag up to a hundred yards, along with a WP shattered cup in some case, and set fire to the globs of napalm scattered around up to fifty yards around.
- M74: they fall nose first with the help of a metallic shrouded tail that springs out in flight, but can hit at any angles, providing that the shock is hard enough. If they hit nose first, the primer is projected againts the firing pin, if they hit tail first, the firing pin is projected against the primer and, if they hit sideway, the funnel-shaped interior of the fuse gets pin and primer in contact. The primer explosion ignites the first-fire mixture, which ignites the exploding charge that throws away the PT1 mixture (pyrogel) up to fifty yards around as well as a WP shattered plastic cup which ignites the mixture.
All these bomblets may be containing small explosive charges aimed at slowing firefighting response.

Mankind really has a gift when it comes to hurting or killing each others...

Most cluster munition was incendiaries, but some was fragmentation, again to make firefighters think twice before entering a bombed zone.
One type of fragmentation bomb was extensively used; the M41.

PICTURE HERE

The M41 fragmentation bomb (...) has a charge-weight ratio of approximately 15 percent. (...) The overall length of the bomb is 22.2 inches and its diameter about 4 inches. A long rod of square wire 0.44 x 0.44 inch is tightly wrapped about a light cylindrical casing 0.11 inch thick to form the main body of the bomb. The cylinder is filled with TNT or other explosives. The ends are sealed with steel plugs. The nose plug contains a cavity for an instantaneous fuse, and the tail plug has a threaded hole to take the tail fins.
(...)
When an M41 bomb falls, 250 revolutions of the propellerlike blade, on the nose of the bomb, are required before the bomb is armed. This process permits the collarlike safety block located just ahead of the propeller to fall away, which in turn permits the striker head to be driven into the fuse upon impact.
(...)
The effect of wrapping the bomb cylinder with square wire is to produce a large number of fragments, each of which is a piece of rod 0.4 inch to 1 inch long (...). These fragments are much more effective per pound of metal than the usual long, narrow shell fragments.

Found HERE.

PICTURE HERE

Twenty of them were suspended under a steel pole, maintained in place by spacers and held together by steel straps with the same buckle release system as describe above for the M23 adapter. This cluster was called M26 or T4E4, it was 52.6 inches long and weighed 416 lbs. The AN-M26A1 was a quick-opening cluster while the AN-M26A2 could be fuse-delayed to release the bombs nearer to the ground in a more compact grouping. Both could be suspended on a 500 lbs station.

PICTURE HERE

A very useful document, from which most of the information not directly quoted comes from, is "AMERICAN AIRCRAFT BOMBS 1917 - 1974", author unknown, found HERE.

Some "exotic" loads were not mentioned here, such as leaflets' bombs (also called "bull**** bombs"), or photoflash bombs. Same thing with "500#" clusters dubbed "E-28" or "E-36". Maybe in some future thread about uncommon loads.

NEXT TIME: MINES AND CONCLUSION

[hubbabubba]

MINES

B-29 laying mines HERE .

The 313th Bombardment Wing was assigned by General LeMay to sow mines on the main approaches to Japan. Accommodating the B-29 to mines' payload was easy. The 2,000 and 1,000 mines were not much different, in size, weight, and shape, than GP/HE bombs. The 58th B/G and USN aircraft had already carried mines before, and suspension lugs were not "field modification" but were fitted at the factory.

LeMay selected the 313th Bombardment Wing (VH), then establishing itself at North Field, Tinian. Its planes were equipped with the AN/APQ-13 radar, suitable for the task at hand, and minor modifications to provide anchorage for parachute static lines could be done locally.

Wesley Frank Craven & James Lea Cate, "The Army Air Force in World War II; Volume Five - THE PACIFIC: MATTERHORN TO NAGASAKI June 1944 to August 1945, Office of Airforce History, reprint Diane Publishing Co., p. 665, available HERE

When we think "sea mines", big balls with antennas all over them pop in our minds. These were WWI contact mines, still used in WWII, but relatively easy to sweep. The mines carried by the 313th BW were quite different. They were all influence "bottom mines" - also confusingly known as "ground mines" !!! Three types would be used; the 2,000 lbs Mark 25 and the 1,000 lbs Mark 26 and 36. The Mark 25 was effective at a depth of up to 150 feet while the Mark 26 and 36 could lay at 60 feet maximum. (Charles R. Reyher, "Memoirs of a B-29 Pilot", Merriam Press, p. 107, extracts available HERE

Exact figures are difficult to find;

Mark 25 HERE

Mark 25
Aircraft laid magnetic mine. Mod 1 had A5 acoustic trigger, Mod 2 had A6 pressure trigger and Mod 3 also had an acoustic trigger. Depending upon the flight gear, these were 22.4D x 87.2-93L inches (56.9D x 221.5-236L cm) and weighed 1,950-2,000 lbs. (885-907 kg) with a charge of 1,274 lbs. (578 kg) Torpex, HBX or TNT.

see HERE

Mark 25 being hoisted in the aft bay of a B-29, click HERE.

Three Mark 25 under a Douglas Skyraider, click HERE.

Mark 26
Aircraft laid magnetic mine. (...) Total 1,000-1,072 lbs. (454-486 kg) with a charge of 465 lbs. (211 kg) TNT or 520 lbs. (236 kg) Torpex.

see HERE

Length; 1.74m (68.5 inches), Diameter; 473.20mm (18.63 inches).

according to ORDATA; http://maic.jmu.edu/ordata/Mission.asp

Mark 26 side view HERE and HERE REMARK; Note the pointed nose for comparison with the Mark 36.

View "astern" of a Mark 26 HERE

Mark 36
An improved Mark 26 Mod 1 with a larger explosive charge and a slanted nose for improved underwater trajectories. Total 1,024 lbs. (464.5 kg) with TNT charge of 570 lbs. (258.5 kg) or 1,082 lbs. (490.8 kg) with Torpex charge of 638 lbs. (289.4 kg). Magnetic fuzed using a MM2 exploder. Basic version was acoustic, Mods 2 was a low-frequency acoustic and Mod 3 was pressure activated.

see HERE

Mark 36 refurbished to serve as a "hunting mine" in training exercises HERE REMARKS; The slanted nose (or "bow" in Navy parlance) made the Mark 36 look like a "baby" Mark 25. That configuration permitted the bomb to dive sideway and land at the bottom on its side, letting the nose sensors do their job.

But, in "A SUMMARY OF UNDERWATER ACOUSTIC DATA" (PDF available HERE), I found a scaled drawing of all these mines with their measurements. I would give this document more credence as it was part of a scientific report examining acoustic echoes signatures, where exact dimensions are crucial. I have made this composite drawing based on this document with 2,000 and 1,000 HE/GP bombs, all to the same scale, for comparison purpose;

PICTURE HERE

Even if you add the ± 6 inches of the parachute gear, these mines are still pretty close match to their bombs "counterparts".

The B-29 could carry twelve 1,000 lbs mines or seven 2,000 lbs, or a combination of the two. (Maj. John S. Chilstrom, "Mines away!; The significance of U.S. Army Air Forces minelaying in World War II", SAAS of USAF, p. 28, PDF available HERE)

If you compare the bombs and mines capacity, you will notice that 1,000 lbs bombs-or-mines loads were the same while 2,000 lbs was only seven mines against eight bombs. This was more a question of weight restriction than any lack of space.

To increase the lift potential, LeMay removed from the B-29's .50 caliber ammunition and two crewmen.

Wesley Frank Craven & James Lea Cate, "The Army Air Force in World War II; Volume Five - THE PACIFIC: MATTERHORN TO NAGASAKI June 1944 to August 1945, Office of Airforce History, p. 665, already cited above.

Despite all that, the B-29 never carried more than 13,500 lbs of mines, much less than GP/HE/LC or incendiary bomb loads.(see HERE for Mission's résumé).

Mines were subject to a strange arrangement between the Navy and the Army;

The Navy, has it had promised, provided technical assistance and logistical support, gearing its production and shipping programs to meet 313th Wing's requirements.

Wesley Frank Craven & James Lea Cate, "The Army Air Force in World War II; Volume Five - THE PACIFIC: MATTERHORN TO NAGASAKI June 1944 to August 1945, Office of Airforce History, p. 665, already cited above.

Command channels and logistics channels were complex. LeMay requested mines from Commander Navy Task Force 94, Tinian who in turn sent the request for mines to Commander Mine Craft, Pacific Fleet, Oahu. The latter sent the request to to the Chief of Operations, Washington D.C. who in turn sent the request to the Bureau of Ordinance, Washington D.C. The Bureau sent the mines to the Navy Assembly Depot number 4 on Tinian.

F.G. Bradley, "No Strategic Targets Left", Turner Publishing Co., p. 70, extracts available HERE.

The Navy was not only furnishing the mines, their personnel would "fine-tuned" them;

The Navy established Mine Assembly Depot #4, consisting of two officers and forty enlisted men, on Tinian and began to stockpile mines for Operation STARVATION. Three Mine Assembly Officers were brought in from Eniwetec and a Mine Modification unit of five officers and forty enlisted men was brought in from Pearl Harbor.

Capt. Gerald A. Mason, "OPERATION STARVATION", SAAS of USAF, p. 10, PDF available HERE

Mark 26-26-36 mines were "influence" mines;

In World War II, the belligerents developed complex "influence" mines, triggered by a ship's physical "disturbance." The first of these were magnetic, actuated by a steel hull; there were also acoustic, which detected propeller or machinery noise; and finally, pressure, which sensed movement through the water. Designers next combined firing methods, making them even more difficult for an enemy to thwart.

Maj. John S. Chilstrom, "Mines away!; The significance of U.S. Army Air Forces minelaying in World War II", already cited above, p. 12.

The Mine Assembly Depot #4 team could not change the detection system, or systems, that were installed at the factory stateside, but they could adjust the sensibility of these systems to fill specific tactical demands. A less sensitive mechanism would only detonate on the passage of a large ship, a more sensitive one would widen the coverage of each mines. They also had control over the delay at which the mine would activate once laid, from right now to months later. Another possible adjustment was a counter, adjustable from 1 to 9, that would let some ships pass over, but would detonate once the preselected number was up;

One example of a versatile aerial mine from World War II was the U.S. Navy’s Mark 25. The Army Air Forces laid many of these in 1944-45 and almost half of the mines laid in "Operation Starvation," the mining of Japan’s home waters, were versions of this mine. Assembled, it weighed approximately 2,000 pounds, which included 1,250 pounds of explosive. The weapon looked much like a bomb with the exception of a half-slant shape to the nose (for improved underwater trajectory) and the parachute pack at the tail. After the mine left the aircraft a static line opened the parachute, which lessened the shock as the mine entered the water. The Mk. 25 could be dropped from any altitude above 200 feet, at a maximum speed of 230 miles per hour, and used in water depths of 16 to 150 feet. Once the mine settled to the bottom it armed itself according to pre-flight settings and awaited its prey. Different models featured unique firing mechanisms (for magnetic, acoustic, or pressure actuation), clock starters and delays, ship counters, and redundant safety features. The minefield planner could select the Mk. 25 (or a smaller mine, such as the 1,000 pound Mk. 26) with modifications tailored to the specific water depth, type of vessels, traffic frequency, and minesweeping capability.

Maj. John S. Chilstrom, "Mines away!; The significance of U.S. Army Air Forces minelaying in World War II", already cited above, pp. 12 - 13.

Navy liaison officers would also participate in the planning phase of the mission;

Upon receipt of the field order, naval mining officers designed and plotted the minefield based on the depths of water, shipping routes, and grid densities specified by Twenty-first Bomber Command.

Capt. Gerald A. Mason, "OPERATION STARVATION", SAAS of USAF, p. 11, already cited above.

But this was AAF show for the rest;

The 313th Wing carried out an extensive experimental program to determine mine-laying tactics for the B-29 aircraft, making maximum use of the radar equipment consistent with the previous training of the crew radar operators. Radar-navigator specialists taught these tactics to all crews, and additional instruction in mine warfare was undertaken. Eight A-6 “supersonic” bombing trainers* were set up in a Quonset on the line. Each Group was allotted two hours per day to practice radar-mining procedures. Ten men were trained during each period with particular attention to target identification. A series of practice flights were completed in which two crews flew in each airplane. Each crew made one dry run, two runs dropping 100 pound water filled practice
bombs (with a mine adapter fixed to the nose of the bomb to simulate the trajectory of a mine), and one mine release (1000 pound MK 26 Mine).
All ordnance and armament personnel in the Wing were also given training in mine handling and loading prior to the first mining mission.

Capt. Gerald A. Mason, "OPERATION STARVATION", SAAS of USAF, pp. 10 - 11, already cited above.

*- For a very thorough description of what a "Supersonic" Trainer was, go HERE.

The mining was done at night from altitude varying from 1,000 ft (see HERE) to 26,460ft (see HERE), but mostly at 10,000 feet or under. Mining was done in such a way as to take into account shipping routes, depth, and previous drops. "Precision bombing" was taking a different meaning;

Tactical planning was left to the 313th Wing. Approaches and mine-laying runs were influenced by the presence of enemy antiaircraft defenses, heights of mountains surrounding the area under attack, location of good initial points, and the availability of radar aiming points for individual aircraft.
(...)
All mine-laying runs were planned as nighttime radar runs with the possibility of visual runs on the targets should they be visible. Two methods were used to establish aircraft on the mine line. Aircraft would either position the aircraft relative to a radar significant point of land ahead of the aircraft and start laying mines at specified range; or, pass over the radar significant point of land and drop at a specified time based on the ground speed of the aircraft. In both cases the drift of the mine after release, caused by wind, was calculated and taken into account. Release altitude could vary from several hundred to 30,000 feet.
(...)
Upon receipt of the field order, naval mining officers designed and plotted the minefield based on the depths of water, shipping routes, and grid densities specified by Twenty-first Bomber Command. The wing radar navigator met with wing operations to decide upon Initial Points (IPs) clear of antiaircraft defenses, with definite radar points and on a bearing suitable for mining axis of attack. Next, the wing radar navigator made an overlay for each run – one for each aircraft. Multiple radar aimpoints for each run, slant ranges, intervals for drops and distances were marked on flimseys, which could be laid over the radar scope. The wing radar navigator attended general and special briefings within the Groups, clarifying each navigator’s run and making suggestions. Upon completion of the mission, navigators turned in their plots, which now contained the crew’s speculation of where they dropped their mines. Wing radar personnel plotted the drops as determined by radarscope pictures. Records of individual runs contained the briefed run, crew’s estimated run, and the run as determined by radar pictures taken on the run. This data was compiled for each force and forwarded as a report to Twenty-first Bomber Command Headquarters.

Capt. Gerald A. Mason, "OPERATION STARVATION", SAAS of USAF, pp. 10 - 11, already cited above.

Minefields would be sowed mainly in the Shimonoseki Strait, "a narrow waterway between Kyushu and Honshu considered "the single most vulnerable point in the enemy's shipping position" since it was crucial to movement on the Inland Sea and along Japan's east coast" (Maj. John S. Chilstrom, "Mines away!; The significance of U.S. Army Air Forces minelaying in World War II", already cited above, p. 30), but would cover, in a five phases plan, all majors ports on the east and west coasts of Honshu and Kyushu, and even Korean ports from which goods and raw material from the Asian continent under Japanese influence were imported.

In the deadly "cat n' mouse" that ensued between minelayers and minesweepers, the latter was quickly overwhelmed. First mines dropped were a mix of acoustic and magnetic mines to which the Japaneses found parades, but this was done at great expense in manpower and money. As the campaign progressed, "unsweepable" mines, pressure or low frequency, had the Japaneses cornered and powerless.

The campaign was far from perfect though. Numerous mines fell on land, where they were recuperated and analyzed, or at depths rendering them useless. Some mines would disintegrate on contact with water because of parachute's malfunctions, others would explode prematurely, sometimes without a ship in sight, because of oversensitivity and rough seas caused by storms.

For more details, read Chilstrom and Mason's essays, already cited.

The mining campaign, started late in March 1945, would not have been at all if some "mines advocates" had not pressed the matter to their superiors, Army, Air Force and Navy alike! The reasons for this disdain of mines' warfare were a mix bag of rigid thinking and human nature desire for immediate results. First mines laid around Japan were "dead weight" brought by submarines short of torpedoes!( see HERE; Frederick M. Sallagar, "Lessons from an Aerial Mining Campaign (Operation "Starvation")", USAF RAND, pp. 6 - 7, PDF available HERE ).

General Hansell was objecting to the mining campaign on the basis that it would interfere with the "precision bombing" campaign already waged. It would not start in earnest before LeMay's appointment at the helm of the XXI. Hansell would eventually concede, but reluctantly only, that it was a mistake;

When Maj. Gen. Curtis LeMay later took over the XXI Bomber Command, his decision to launch a massive mining operation was a sound one. Adequate forces had been assembled. Tactics and techniques had been worked out (many of them by LeMay). Since mining was not dependent on weather, it was possible to achieve continuity of operations. I think General LeMay did not view mining at night as (...) abandonment of selective targeting. Moreover, the night mining, like the night urban bombing, could be carried out regardless of cloud cover at the target. It is quite clear I could have endorsed mining as an aspect of strategic bombardment against the Japanese transportation system rather than as an auxiliary aspect of the sea blockade. I probably could have persuaded General Arnold to stretch my target priorities as prescribed by the Joint Chiefs to include aerial mining when sufficient aircraft became available. I doubt if I could have, or should have, devoted most of the command's air power to this purpose in the initial phase of strategic attack against Japan, when first priority was prescribed as destruction of the Japanese aircraft industry.

see HERE

Precision bombing is not only the capacity to drops bombs, or mines, in a pickle barrel. It is the ability to hurt you enemy where it causes the most damages to its ability to make or continue the war. In that sense, if you can't hit the pickle barrel, choose a wider barrel...

The mining campaign was such a success that it belittled others bombing missions. The oil refinery that the 315th BW was flattening were dry. The cities incinerated were filled with hungry citizens incapable to work in their "feeder" factories due to lack of raw material. The industrial plants so intensively bombed were seeing their production dwindle by lack of sub assemblies from the "feeder" plants and by forced dissemination of the production due to the bombing that, after all, was not so ineffective as thought after all. Unfortunately, most of these effects couldn't be assess tangibly during the war. The U.S. Strategic Bombing Survey had that to say;

In the Survey's opinion those air units which had anti-shipping attacks as their prime mission and employed the required specialized techniques, equipment and training achieved against ships the best results for the effort expended.

United States Strategic Bombing Survey Summary Report (Pacific War), Destruction of the Japanese Merchant Fleet ; available HERE, Summary report starting HERE

In the final assault on the Japanese home islands we were handicapped by a lack of prewar economic intelligence. Greater economy of effort could have been attained, and much duplicative effort avoided, by extending and accelerating the strangulation of the Japanese economy already taking place as a result of prior attacks on shipping. This could have been done by an earlier commencement of the aerial mining program, concentration of carrier plane attacks in the last months of the war on Japan's remaining merchant shipping rather than on her already immobilized Warships, and a coordinated B-29 and carrier attack on Japan's vulnerable railroad system beginning in April 1945.
We underestimated the ability of our air attack on Japan's home islands, coupled as it was with blockade and previous military defeats, to achieve unconditional surrender without invasion. By July 1945, the weight of our air attack had as yet reached only a fraction of its planned proportion, Japan's industrial potential had been fatally reduced, her civilian population had lost its confidence in victory and was approaching the limit of its endurance, and her leaders, convinced of the inevitability of defeat, were preparing to accept surrender. The only remaining problem was the timing and terms of that surrender.

United States Strategic Bombing Survey Summary Report (Pacific War), Hindsight ; available HERE

CONCLUSION
The B-29 Superfortress was a giant among giants during WWII.

Re-reading some passages, I caught myself writing things like "it would "only" carry 6 tons of bombs"! Most other contemporary heavy bombers would not even wonder to carry such a load over the Channel. This airplane could only be compared to itself when we look at the time period.

But the argument, often made, that it was the only bomber capable of delivering "THE" bomb is forgetting the Lancaster, which, with the Halifax, were the only contenders. Both being British a/c was their worst disadvantage.

When Superfortresses were engaged in Korea "police action", B-36 and B-52 bombers had relegated the B-29 to the "medium" bomber stable. But, from their Japanese bases and with makeshift Koreans emergency strips, they would routinely carry payloads of 20,000 lbs plus. (see; Robert F. Dorr; "B-29 Superfortress units of the Korean War", Osprey Combat Aircraft #42)

This time, they would go "all guns blazing" as Yaks and MIGs would be buzzing all around them. They would also fly to their "intended" altitudes of 30,000 + feet for the same reason, but, this time, their foes would climb even higher! And, despite all the adjusting, tweaking, and modifications, engines would still overheat, leak oil and catch fire... from time to time.

But CFS1 is a WWII game first and foremost. I think that, if used in "Marianas missions", the B-29 AIR file should reflect the shortcomings and allow large payloads only if the aircraft stays below 20,000 feet. The DP file of such an aircraft should only have tail guns, if any, and bombs should be 500 lbs each, "mimicking" all possible payloads.

If rigged for the "high altitude precision bombing", it could carry all its defensive armament... but with consequent payload.

Ivan submitted the argument of weight balance, but CFS1 places the load at the CoG, no matter what. How to circumvent that?

I have recently found a way to "provoke" system failures. The system was used in one of our game and worked perfectly. We could, this way, recreate engines' failures.

The only air-worthy remaining B-29 is grounded, as far as I know. I just hope that it will be repaired... and that its engines won't catch fire like the other B-29 that was being restored.

The Superfortress was a "payloads' emporium", carrying about anything worth dropping. This "tour", if not exhaustive, should give you an honest idea of the American bomb arsenal during WWII. Other, I'm sure, will complete that list with more "exotic" weapons and, I hope, with "lighter" weapons used in light bombers and fighter-bombers. I did went "off subject" a few times but, believe me, I exercised restraint. So much stuff...

Maybe in future threads...

It was certainly a compelling subject that answered some of my questions regarding heavy bombers and their deadly freights.

I hope it will answer some of yours.

PICTURE HERE; War is waste! This is the "Superfort Graveyard" at some Marianas airfield. Ground crew have robbed the dead of any valuable spare parts... but I'm sure we would have had quite a picnic exploring these fallen giants.

Hubbabubba

[Ivan]

Just a major bump because it seemed relevant to the development of bombers here.

Some of these thread had some really good information so should we keep an easily accessible archive of them?

- Ivan.

[hubbabubba]

Too bad so many links have gone AWOL...

Good thing I decided to make my "Fun with SCASM" in HTML zipped format. The guy who wrote "Les paroles s'envolent mais les écrits restent." was obviously living long before WWW.

[Ivan]

Hello Hubbabubba, et al.

In this thread, we have gone through a pretty exhaustive discussion about what the appropriate standard size of a bomb should be for a CFS aeroplane in general and also what the appropriate bomb loads should be for various aircraft.

Hubbabubba has also given us pretty detailed coverage of bomb technology and practices which make for good academic discussion but also serve to remind us how rudimentary and primitive the "Bomb" has been handled in Combat Flight Simulator.

While the question of appropriate loadouts will always be debatable, there is another aspect of CFS bombing that has always bothered me: Attacking a Target.

With a small bomber such as a SBD Dauntless or Ju-87 Stuka carrying just one bomb, the technique is pretty simple:
Fly a path over the target.
At the appropriate time, press the bomb trigger (4) to release the single bomb.
Fly away.

The technique doesn't change much when there are 2 or 3 bombs being carried.
Just tap the bomb trigger (4) as many times as needed when over the target.
.......
NOW consider what happens when flying a larger bomber carrying many more bombs.
Imagine flying over the target in a B-29 with 40 x 500 pounders.
Is it reasonable to expect the Pilot / Bombardier to press the bomb trigger 40 times and distribute her bomb load over two or three counties?

I believe not.
Ideally there should be a means of dropping ALL the bombs quickly as a salvo.

The recent "Fun Flying" with a B-25 Mitchell was also intended to test different ideas to see if this could be done in CFS.
The B-25C is a fairly typical Medium Bomber. I decided that the version I built should be capable of carrying up to 5,000 pounds of bombs or 10 x 500 pound "bullets". (Default Bomb Load will be a subject for later discussion.)
Over a dozen flights were made (not including crashes) to test different configurations of DP file in attempts to determine the best way to allow the entire bomb load to be salvoed quickly.

The Standard Configuration
There is a single GunStation which has a single Gun which has 10 Bullets

The behaviour of this configuration is pretty well known. Each Trigger press releases a single bomb.


Multiple Guns
There is a single GunStation which has 10 Guns which each have 1 Bullet

I found it was actually impossible to implement this configuration. At most 8 Guns could be configured.
When using this configuration, it proved to only be possible to drop ONE bomb. The remaining 7 bombs would still show in the HUD and did not respond.


Multiple GunStations
There are 10 GunStations which each have a single Gun which each have a single Bullet

Each Trigger press dropped ONE Bomb. Repeated presses also dropped a single bomb. This result surprised me. One would have expected multiple gun positions responding to the same trigger to all fire at the same time but apparently the rules for Bombs are not the same as for other types of armament.

Thus ended the first series of flights which proved to be a bit less fun than expected.

.......

(More to Follow.)

[Ivan]

After achieving no success with the DP modifications, I started thinking:
Combat Flight Simulator has been out for two decades.
Others certainly have found the handling of bomb loads to be a problem and if it were so easy to resolve, someone else probably would already have found a solution.

I didn't think remapping to one of the other Weapon Triggers was likely to work.
Other than the Gun and Cannon Triggers, the other Triggers appear to be very specific, non-controllable features.
In looking over Settings for possibilities for reassignments, I noticed that although Gun and Cannon were set to auto repeat, Rockets and Bombs were not.

I changed the Settings for the Bomb Trigger to auto repeat and found that with the exception of multiple Guns in a single GunStation, I could drop the entire bomb load very quickly by just holding down the Bomb Trigger!
The sound was of two bomb releases.

The INTERESTING Thing was that the bomb impact craters seemed for form a different pattern with different configurations of the DP File.
I decided to make a quantifiable comparison of impacts by making each bomb run from 2000 feet.
Here are the results:

(The B-25 Mitchell is flown over the Bomb Craters at 100 feet for a relative size comparison)

The First Screenshot shows:
1 GunStation, 1 Gun, 10 Bombs per Gun - The Default Configuration

The Second Screenshot shows:
1 GunStation, 10 Guns, 1 Bomb per Gun - Note that there is only ONE impact crater

The Third Screenshot shows:
10 GunStations, 1 Gun, 1 Bomb per Gun - Compare the distance between first and last impact

.......

[Ivan]

Bomb runs were repeated with very similar results.

Just out of curiosity, I wondered what would happen in an extreme case with MANY bombs.
The Mitchell's bomb load was replaced with 100 x 50 pound bombs and the bomb run was repeated.
Attached are two screenshots of those bomb craters.

The First Screenshot is with the B-25 at 100 feet altitude but the entire length of the craters cannot be seen from this altitude.

The Second Screenshot is with the B-25 at a much greater altitude.

These tests show that the combination of GunStations and Bombs can determine the length of the bomb pattern that is dropped in a salvo from an aircraft.

From these tests, I know how I will configure the DP in my B-25C.
Hopefully these tests can give other people ideas that can be used in developing new projects.

- Ivan.

[Ivan]

The B-25 Mitchell in most of its versions had a maximum Take-Off Weight of 33,500 pounds.

The Zero Fuel Weight of the MitchellC is 22,750 pounds.

The Disposable Loads are as follows:
The typical B-25C carried either 5 or 6 x .50 cal Browning HMG.
Two were in a Dorsal Turret
Two were in a Ventral Turret
One was a flexible mount in the Nose.
Some aircraft carried an additional fixed .50 cal that could be fired by the pilot.

The DP file gives each gun a 1000 round ammunition load so the total ammunition is either 5000 or 6000 rounds.
.50 cal ammunition early in the war was 5 ounces per round (later it became 4.8 ounces) so MG ammunition would weigh

1562.5 pounds
or
1875 pounds

Fuel was carried in a Main and Auxiliary Tank in each wing.
Main Tanks - 184 Gallons each
Aux Tanks - 151 Gallons each
Total Fuel - 670 Gallons == 4020 pounds

The DP file allows for a maximum bomb load of 5000 pounds.
In reality, the Mitchell could carry additional loads externally, but that is not accounted for in the DP.
(A 2000 pound Torpedo could be carried externally.)

As configured for CFS, the MitchellC with full bomb load would have a loaded weight of either
33,332.5 pounds with ammunition for 5 MG
or
33,645 pounds with ammunition for 6 MG.

It seems like the pilot may need to make some choices if he wants to stay at or below the Maximum Take-Off Weight.

- Ivan.