Northrop F-15A / RF-61C Reporter

[fliger747]

An interesting sidelight: The main crank bearings were Lead/silver and Iridium, with about 4% Iridium. The Germans who did examine engines from shot down aircraft couldn't understand why the bearings were "contaminated" with iridium.

[warchild]

Exactly
The thing that frightened P&W though wasnt that the germans would find the Iridium, but rather do a full metalurgical analysis and get the formula. At the time, those bearings were top secret.

Still working on finding the original P-61 thread. If it exists, its buried deep..

[warchild]

Have you tried putting the web address into the wayback machine?

https://archive.org/web/

Welll, thats just it. I dont have the web address, and i cant even remember the name of the chief engineer who's history i followed to find the site.. I know the link in buried somewhere in the original P-61 project thread, but buried could very well be an understatement with as much information as we put into that thread. It's over a thousand pages if i'm correct.

[Seahawk72s]

Hi Pam,
Not sure if this is the thread you are looking for but it is extensive.

http://www.sim-outhouse.com/sohforum...H-P-61-project

[warchild]

Seahawk! Your amazing.. Thats the one all right..now to find that URL

[warchild]

Thanks to Seahawk, I've found this once again. This time, I saved it and it'll be getting backed up to Bluray disc.. Why is this document so important?? For me its because it isnt just about numbers and data. It lets you smell feel and taste the very soul of these engines, and the crazy man who made them.
In the end, it turns out there was very little these engines couldnt do below 3800HP and 150In/Hg MP.. Yeah, you read that right.. But see, That was Frank Walkers unique way of heckling the R4360 team.. Every time they made a milestone, Frank would take his little 2800, and beat them.. What we got out of it in the end, was one of the most amazing, dependable and ubiquitous engines in the world.. Its a delightful read, and provides an insight into these engines you would never expect.. Enjoy..

http://www.enginehistory.org/Biograp...WalkerWeb1.pdf

"
WATER INJECTION

In early 1943, word came down from the front office that a means must be found to

get additional power from existing engines without redesigning either the engine or

airplane it was in. While Pratt & Whitney was working around the clock to complete

the 3000HP R-4360, it was still years away and could not be fitted into existing

aircraft.

The shortest path to more power is always more manifold pressure. Since the P-47

had a turbo-supercharger which could produce surplus manifold pressure, it seemed
a good candidate for more power. The rub was that with the additional compression

of the inlet air came heating of the inlet charge which resulted in power-limiting
detonation. With the 130 PN fuel than available, Pratt & Whitney was already

getting all the power that was possible with the R-2800. Someone in the front office
suggested that water injection be tried. Perry Pratt was the Project Engineer.
Frank acquired a stock R-2800 “B” engine, serial number 5275, directly from the
production line. The only modification to the engine was a longer hollow bolt to
accommodate a second banjo fitting that supplied water to the fuel inlet of the
supercharger. Frank performed all of the initial water injection calibration by
manually adjusting the throttle, supercharger, propeller, and water injection settings.
Once the behavior of the water-injected engine was understood, Frank presented
data to the carburetor group which, under the direction Dick Coar, designed and
developed a water injection regulator and the associated carburetor modifications.
Frank got 2150 HP the first night. This was up from the 2000 hp the engine normally
produced and was the sole result of being able to use a leaner mixture at take-off
power. Until then, the engine had to be run very rich at take-off power to prevent
detonation, actually using fuel to cool the engine. It was running so rich in fact, that it
was producing less than ideal power. In later experiments, manifold pressure was
increased to simulate the output of the turbo-supercharger, and horsepower
increased dramatically.
Ultimately, the maximum power achieved on the “B” series was 2800 HP at 2700
RPM. Maximum power ever achieved on the “C” series was 3800 HP at 2800 RPM.
The maximum manifold pressure ever recorded was a staggering 150 inches of
mercury (inHg)! This was up from dramatically from the 49-inHg maximum manifold
pressure originally allowed in the R-2800 “A” series of engines.
Water injection worked by reducing cylinder inlet temperature, thereby delaying the
onset of detonation. As the water evaporated in the induction passages of the
engine, it providing a prodigious amount of cooling to the fuel charge due to the
latent heat of vaporization of the water. Cylinder inlet temperatures went from about
350qF to about 100qF. This increased the detonation margin to the point that up to

150 inHg of manifold pressure could be used. When water injection was in use, the
engine was markedly smoother, and the interior of the combustion chambers stayed
extremely clean with no carbon or varnish build-up on the piston crowns, valves, or
ring packs. Frank remembers that “There was no hard carbon whatsoever. You
could clean the top of a piston down to bare metal by wiping it with a cloth”.
German engineers tried water injection (Wassereinspritzung) on their gasoline
engines, but with limited success. Germans, who were very good at building high-
precision pumps, had perfected direct fuel injection for their large aircraft engines.
German engineers injected water directly into the cylinders as well. Since the water

did not have time to evaporate and cool the induction air, the large cylinder inlet

temperature reduction was not achieved. Frank learned of this while reviewing a

report on a captured German aircraft engine. "


"
RACING THE BIG GUYS

Early in 1942, work began at Pratt & Whitney on the R-4360, a secret monster

engine that was destined to have nearly twice the power of the stock “B” series R-

2800s that were by then in production. Pratt & Whitney used the time-honored

experimental development methodology of “Run ‘em, bust ‘em, fix ‘um” where

prototype engines were rapidly cobbled together and gotten into a test program to

find the weak points. Such was true of the R-4360. The team suffered their share of

false starts and blown engines as they made slow progress at making the engine

increasingly powerful.

The Pratt & Whitney R-4360

By the time the R-4360 team was getting 2800 HP out of the prototypes, Frank was

well into water injection development with the R-2800 “C” series engines. Unknown
to the R-4360 guys, Frank was regularly running his R-2800 at 2800 HP for 100

hours at the time. The reader must realize that each new power milestone in R-4360

development was ending with a damaged engine as each of the many parts found

its respective limit. Frank could not resist rubbing in the failures.

When the R-4360 team surpassed 2800 HP, Frank brought them over to his test cell

and extracted 2800 HP from his “little” R-2800. A month later, when the R-4360 first
produced 3000 HP, Frank summarily bettered their result at 3200 HP. Ultimately.

Frank drove the R-2800 to a whopping 3800 HP. The R-4360 team eventually

surpassed that mark, and went on to 4000 HP. Frank was tempted to try for 4000

HP on the R-2800, but finally decided against it. He did not have a good feeling
about pushing the engine past 3800 HP "

My Kind of crazy.. I love it..

Pam

[warchild]

You see, numbers are only a starting point. You can make an airplane using nothing but numbers taken from some computer generated data sheet with all the personality of a limp noodle, and well, thats what youll get; a limp noodle. Repairmen use numbers to fix things, not create things. Engineers ask: What if? and Why Not? Numbers dont provide answers. putting things together and blowing them up provides answers, and sometimes they're answers, numbers will never give you: Iridium on a ball bearing.
You want to experience a plane that when you get into your virtual cockpit, you can feel smell and taste it.. You dont want numbers. You want to step into the shoes og Jack Northrop, Kelly Johnson, Johnny Meyers, Willy Messerschmidt, all of them: see what they saw, feel what they felt, Experience things in the way that only a very fortunate few have experienced, and fall in love with the skys all over again, with each flight you make..
Numbers alone wont give you that. you have to get inside the lives and heads of the people who made them. Learn how they possibly saw things and learn what drove them day to day.. It wasnt money, and it wasnt numbers..

[fliger747]

The racing people do use some of this "tech" to boost the power in their machines. But back in the thirties, when the major breakthroughs were made to allow the evolution of power plants that powered WWII aircraft, the bearing technology, harmonic balancing, sodium cooled valves and on and on, small but important details to plug every leak in the reliability of the engine formed the basis. Always bumping against the strength of materials.

Major initial development of the Double Wasp (R2800) was actually conducted by P&W with a single row test engine, the X80 to prove the concept and work out the initial problems.

Almost all piston aircraft engines use a dual ignition and two spark plugs per cylinder. This is not normally used in automotive applications. Aside from the "backup", with the large cylinders of the big aircraft engines, dual progression of the flame front is necessary to avoid detonation which would not occur with the smaller automotive cylinders.

Another aviation pioneer was Leroy Grumman, a legitimate thinker and test pilot in his own right. He flew a captured FW190 and was reported to say "this is the plane we should have built, referring to the F6F. The result was the superlative F8F Bearcat.

Looking forward to the Reporter!

T

[WarHorse47]

Once again one or two weeks go by and you start to wonder just whatever happened to this project..

Sometimes its really hard to tell from all the side comments if a project is nearing completion or not.

So, how about an update??

[PhantomTweak]

This is not normally used in automotive applications.

Normally, no, but my ex had a 80-something Nissan 4WD pickup that had a dual spark plug system. 4 cylinders, 8 plugs, a huge (for this size engine) distributer cap, 8 separate wires, the whole nine. It was a royal PITA to time, and ensuring the right wire went to the right plug, AND was routed correctly was a nightmare. The plugs fouled all the time, too, but that was the way she drove. Honestly, the 75 Impala with a nice V-8 I bought her (before we split up) was more fun to work on. I was SO glad she rolled it down the canal bank we lived on during a heavy rain one day. That colichi clay is slicker than greased ice, when it's good-n-wet.
Totaled the truck, and she hadn't payed her insurance (hehehehe...).

Have fun all
Pat☺

[DC1973]

Once again one or two weeks go by and you start to wonder just whatever happened to this project..

Sometimes its really hard to tell from all the side comments if a project is nearing completion or not.

So, how about an update??

Hi,

Sorry for the lack of posts. I'm afraid that the Reporter will now not be completed or released.

Just kidding. It's out next week. I haven't had much to say as I've been writing the manual and the team have been producing some lovely additions such as a fuel truck and some effects ( Roger-Wilco-66 ), tweaking the FDE ( Warchild ) and I've been tweaking polygons here and there before the BETA release here at SoH. We're looking forward to seeing what everyone thinks of the RF-61C and I'll create a new post with download links as soon as it's ready

Cheers,
Dean

[thefrog]

Wooo. I had a mini cardiac arrest when I read your first line! Really looking forward to it.

[WarHorse47]

Thanks for the update, Dean.

I get a little worried when things go silent after a lot of great screenshots and dialogue on the forums.

Much appreciated.

[dharris]

PLEASE dc1973, no more false starts, blood pressure spiked! Thought I lived this long for nothing with that comment! Glad she is finally coming out, so worth the wait. Thank you

[Sundog]

Thanks for the update Dean, I'm definitely looking forward to flying it.

Regards, Ken.

[DC1973]

Just so you can all see she's still alive and kicking - sorry for the heart attacks, I couldn't help myself

[roger-wilco-66]

I would say it is on short final :-)

[Seahawk72s]

"roger-wilco-66 I would say it is on short final :-)"

That's a great looking screen shot...

[dharris]

The screenshots are incredible. Great work by all and well worth the wait, except for the near fatal heart attack! Good one!

[Josh Patterson]

You know, after seeing this image, I have to wonder what a version of the B-25 would have been like with 2800s stuck on it (or what the XB-28 could have been like or why you never see an A-26 in this position). The P-61/F-15 really was something pretty special!

[Sundog]

You know, after seeing this image, I have to wonder what a version of the B-25 would have been like with 2800s stuck on it....

It would have looked like this.

[Josh Patterson]

It would have looked like this.

Nice! Thanks for the link. Too bad the basic B-25 wing structure wasn't up to the strain that the larger ailerons and extra power put on it. Ritchie literally flew the wings off of it! I wonder how much extra speed could have been squeezed out of it if the turret had been deleted? As it was it was almost 100mph faster than a standard B-25!

[warchild]

Nice! Thanks for the link. Too bad the basic B-25 wing structure wasn't up to the strain that the larger ailerons and extra power put on it. Ritchie literally flew the wings off of it! I wonder how much extra speed could have been squeezed out of it if the turret had been deleted? As it was it was almost 100mph faster than a standard B-25!

Well, the difference is that the B-25 could carry several tons in payload The P-61 could only carry four 500 pound bombs or rocket pods or whatever.. And yt, both the p-61 and the f-15A were seven inches wider than the b-25 and only the F-15A came close to its wreight as the P-61 weights over seven thousand pounds more. The B-25 was kept light to satisfy its role as a bomber. The designer of the P-61 knew the luftwaffe used 20 and 30 mm cannon in its planes so it was purposely designed to survive whatever was thrown at it. Both planes ( B-25, P-61 ) were superlative ground support aircraft and its real hard to say which is the spititual grandfather of the A-10 warthog or even spooky shadow and spectre for that matter.

The A-26 you mentioned was a completely different animal. Originally designed to compete against the P-61. It lost, and became histories first and best attack bomber used throughout WWII, Korea, The congo, and vietnam. The P-61 didnt live that long, and meither did the B-25. Missiles and bullhockey and Jets killed them quick, but nothing could replace the A/B-26 until someone created Shadow.
Shadow was a re-purposed C-119 created to fill the interim replacement for the A-26 while they figured out a way to make a C-130 into a proper gunship. The second replacement for the A-26 became a little plane we sold/gave to the AFVN called the dragonfly, because a gunship couldnt do everything the A-26 could do. The little A-37 Dragonfly turned out to be an excellent replacement for the A-26 as iit really didnt care how fast you flew it, or how high, or how overloaded with munitions it was. It flew, no matter what you did. Kind of like a vietnamese families vesposo. It was an incredible plane too, but you see, they all start with the B-25 Marauder, the P-61 and the A-26.

[PRB]

O.T.

I was watching a U-Tube video of Kemit Weeks visiting his A-26 restoration project. One of the guys restoring said that in the Pacific they didn't like the A-26. They preferred the old B-25 due, apparently, to the fact that the engine placement on the A-26 made for poor visibility in those directions, compared to the B-25. I guess speed isn't everything! Sort of like the P-40 pilots who wanted nothing to do with those fancy pants P-51s!

Can't wait to fly this big twin!

[warchild]

ok, going to drop these here while their fresh in my head. Youll need them anyway..

Takeoff:
2700 rpm
63 In/Hg MP

Climbout:
2450 RPM
63 in/HG MP

Cruise:
2450 RPM
30 in/Hg MP

Approach:
2000 RPM
30 in/Hg MP

Landing:
2000 RPM
20 in/Hg MP till short final.

Youll need to set up an axis or a switch to control rpm if you havent already done so.
Max RPM will never exceed 2700 RPM unless you chnge something like prop MOI's.
Max MP will not exceed 63 IN/Hg, and therein lies the problem i'm going to be working on while you enjoy our beta offering.. ( Fixed )


Pam