Focke Wulf 190A - Revisited

[Ivan]

The Focke Wulf 190A was one of my early projects for Combat Flight Simulator.
It was originally done with very little research as to actual flight performance.
The visual model was done pretty much by eyeball measurement of a few drawings and an old MPC / Airfix 1:72 scale FW 190A model kit.

It was first released here probably a bit over 10 years ago and has been updated about three times in all.
The first update was to add a pilot once I had built a pretty fair model of a pilot's head and shoulders.
The second update was to reshape the cowl opening and add an animated cooling fan.
The third update was to add some bulges on the sides of the cowl.
Somewhere along the way it also got a reshaped fin and rear antenna mount.

This revisit is its latest update to bring it closer to current standards hopefully without any major reworking. My son once complained about one of my other models that there was no opening for the landing gear to retract into. This update was started to address this complaint.

The first screenshot looks generally pretty good but actually shows plenty of errors which will become obvious later.

The second screenshot shows a gap between the inner gear door and the underside of the fuselage. There also appears to be a visual issue with the main gear door but I didn't see this when taking the screenshot.

The third screenshot shows the original panel lines and gear doors which are somewhat incorrect.

[Ivan]

Early models of the FW 190A often had inner landing gear doors but when the centerline equipment rack was installed, the inner landing gear doors were not installed. The ETC-501 rack for drop tanks and bombs became standard starting with the FW 190A-7. It would have been very rare for a late model 190A not to have either the ETC-501 or ETC-503 racks, but since my intent was to build a pure "air-superiority" aircraft, I chose to have the gear doors rather than an equipment rack.

The first screenshot shows a revised shape for the inner gear doors and a removed separation line on the lower part of the outter landing gear doors. This line would have shown where a small additional fairing would have been installed IF there were no inner landing gear doors. The lower edge of the additional fairing would be parallel with the ground line. The inner gear doors are closer to the fuselage underside now. A new wheel well is also shown.

The second screenshot shows the landing gear wells which were built by taking the gear doors and rotating them until they were close to the same plane as the underside of the wing and then doing minor adjustments for shape. The outter and inner gear doors fit together surprisingly well. The wheel wells were also adjusted to be closer to the curvature of the underside of the wing.

The third screenshot shows the revised panel lines on the wings and also the new outline of the landing gear doors with most of the major corrections shown.

- Ivan.

[Ivan]

Contrary to popular wisdom, there apparently (from photographic evidence) were quite a few FW 190As with a centerline ordnance rack AND inner gear doors. I found that out when doing a bit more poking around for information on the FW 190A. The bombs are typically centered around 1/2 to 2/3 chord of the wing which implies that they are well behind the aircraft Center of Gravity.

If Extensions to the Main Gear Fairings are installed, the inner gear doors can not be installed, but there can be no conclusion if the extensions are missing. The easiest way to tell from a distance whether or not the extensions to the Main Landing Gear fairings are installed or not is to look at the lower edge of the Main Gear Fairings.

If the lower edge of the fairing mostly lines up with the aircraft centerline but with a small bend at the aft corner that lines up with the ground line, the fairing extension is NOT installed.

If the lower edge of the fairing mostly lines up with the ground line with a small bend at the front corner that lines up with the aircraft center line, the fairing extension IS installed.

- Ivan.

[Ivan]

FW 190A Armament Details:

Early models of the FW 190A were armed with machine guns in the wings.
The FW 190A-0 pre-production aircraft had variations in armament with just about every aircraft.
The FW 190A-1 had the following:

2 x MG 17 7.92 mm MG on the cowl
2 x MG 17 7.92 mm MG mounted in the wing roots
2 x MG FF 20 mm Cannon mounted in the wings outboard of the landing gear

The more common versions generally had the following for gun armament:

2 x MG 17 7.92 mm MG on the cowl
2 x MG 151/20 20 mm Cannon mounted in the wing roots
2 x MG FF 20 mm Cannon mounted in the wings outboard of the landing gear

Eventually, the outboard 20 mm cannon were replaced with additional MG 151/20s

2 x MG 17 7.92 mm MG on the cowl
2 x MG 151/20 20 mm Cannon mounted in the wing roots
2 x MG 151/20 20 mm Cannon mounted in the wings outboard of the landing gear

Eventually, the cowl machine guns were replaced with MG 131 heavy machine guns.
The larger machine guns did require more room, but the bulges were much less disfiguring than for the Messerschmitt 109G series.
I consider this to be the definitive armament version for the FW 190A series aircraft.

2 x MG 131 13.2 mm MG on the cowl
2 x MG 151/20 20 mm Cannon mounted in the wing roots
2 x MG 151/20 20 mm Cannon mounted in the wings outboard of the landing gear

Other common versions had the outboard 20 mm cannon replaced with MK 108 30 mm cannons which added a bit of weight (FW 190A-8/R2).

Late versions such as the FW 190A-9 typically had the outter wing cannon removed to save a fair amount of weight.
The FW 190F ground attack aircraft typically also did not have any outter wing guns.

The FW 190G ground attack versions went a step further and removed the MG 131 cowl machine guns as well.

- Ivan.

[Ivan]

All of the information up to this point is fairly easy to find. The information to be presented here is a bit less commonly available and has been gathered from quite a few and often contradictory sources:

Excluding gun pods and external packs, the FW 190A had guns in one or more of the following locations:

Cowl:
2 x 7.92 mm MG 17 with 850 rounds per gun --- Ammunition weight for 2 x 850 rounds was 54 Kg
2 x 13.2 mm MG 131 with 475 rounds per gun --- Ammu ition weight for 2 x 475 rounds was 81 Kg. Depending on the source, weight could vary from 77 Kg to 84 Kg which may depend on the combination of ammunition types being used.

Wing Root:
2 x 7.92 mm MG 17 with 1000 rounds per gun --- Ammunition weight for 2 x 1000 rounds was 63.5 Kg
2 x 20 mm MG 151/20 with 250 rounds per gun --- Ammunition weight for 2 x 250 rounds was 110 Kg. Some sources list this as 100 Kg but I believe the higher number to be more likely to be correct.

Outter Wing:
2 x 20 mm MG FF with 60 rounds per gun --- Ammunition weight for 2 x 60 rounds was 25.2 Kg. Some sources list this as 37 Kg but I believe that includes the drum which would stay with the aircraft until it landed.
2 x 30 mm MK 108 with 55 rounds per gun --- Ammunition weight for 2 x 55 rounds was 65 Kg
2 x 20 mm MG 151/20 with 140 rounds per gun --- Ammunition weight for 2 x 140 rounds should be 61.6 Kg. This is also listed as 64 Kg at times. Perhaps this was because of different ammunition used in the inboard and outboard guns.

Most of this information comes from the "Ladeplan" (Load Plan) document from several variants of the FW 190A.

- Ivan.

[Ivan]

The FW 190A had either two or three internal fuel tanks.

Two fuel tanks were installed below the cockpit:
The forward tank had a capacity of 233 liters.
The rear tank had a capacity of 292 liters.

On aircraft that were equipped with MW50 (Water-Methanol) injection, a 115 liter tank was installed in the fuselage behind the cockpit.
If MW50 was not installed, a 115 liter fuel tank could be installed in its place behind the cockpit.

Some models of the FW 190A could carry a 300 liter drop tank on the centerline under the fuselage.
Long range Fighter-Bomber versions sometimes carried a 300 liter drop tank under each wing with ordnance being carried on the centerline rack.

Assuming Aviation Gasoline weighs 6 pounds per Gallon:
233 liters = 369.3 pounds
292 liters = 462.8 pounds
115 liters = 182.3 pounds
300 liters = 475.5 pounds

Taking into account the density of Methanol and Water and the reduction in volume when they are combined, 115 liters of Water-Methanol should weigh 236.6 pounds.

The FW 190A could carry a maximum of 58 liters of Engine Oil which would weigh 115 pounds.

Please note that the stock FW 190A has THREE internal fuel tanks installed as can be seen by the fuel selector. This would indicate that MW50 could not be installed which might explain why the WEP does not work.
In actual service, MW50 reduced the service life of the engines and was very hard on spark plugs. The damaged plugs could explain why Arnim Faber's FW 190A-3 always had a rough running engine.
Instead of MW50, late models of the FW 190A sometimes used additional fuel sprayed into the supercharger intake as a anti-detonant (C3 Einspritzung). This will be discussed in a later post.

- Ivan.

[Ivan]

One might ask WHY we should be interested in Fuel and Ammunition weights for an aircraft.
The weight of the aircraft with installed equipment, and crew but without the disposable loads such as Fuel and Ammunition is needed for the AIR file.

My own experience has been that if the Fuel and Ammunition weight is known, it is generally more reliable to subtract them along with the weights of other consumables from the aircraft's loaded weight to arrive at the weight to be used in the AIR file. The alternative method is to use the "Empty Equipped" weight or "Basic Weight" as the US Military calls it and add the weight of the Crew.

The problem in the case of the FW 190A-8 is that this model was in production for a very long time and varied quite a lot in the matter of installed equipment. The loaded weight without external stores varies from a minimum of about 4250 Kg to a maximum of around 4400 Kg.

Some of the differences are easily explainable such as whether or not the 115 liter fuel tank is installed or if the MW50 tank is installed, installation of an auto pilot, and differences in power adders and different engine installations. Most of these differences are much less obvious and often contradictory. Even original German documents list loaded weights from 4300 to 4400 Kg.

The "Zero Fuel Weight" I originally used for prior versions of the AIR file is 7902 pounds and this review with more accurate data hopefully will arrive at a number that is not too different. One might ask where I came up with this number to begin with and why it isn't 7900 instead of implying a greater accuracy with 7902. 7902 tells me how I originally arrived at this number.

A fairly reliable early source gave the Empty Equipped weight of the FW 190A-8 at 7652 pounds. I simply added 200 pounds for the pilot and his equipment which is pretty typical and another 50 pounds for other assorted equipment such as flare guns and other assorted optional or survival equipment.

- Ivan.

[Ivan]

In the case of revisiting the FW 190A-8, I was not convinced that the Zero Fuel Weight in the AIR file was accurate.
The 7902 lbs estimate is reasonable but with better data, perhaps we can come closer.
(I will leave some of the conversions between kilograms and pounds to the reader.)

The same source that lists 7652 lbs empty, equipped also lists a loaded weight of 4380 kg. The problem is that the difference between 4380 kg (9656 lbs) and 7652 lbs is more than the load that we can account for by 212 lbs:
Fuel ----------- 1014.4 lbs
Ammunition -- 556.9 lbs
Pilot ----------- 220.5 lbs

Some of the factors affecting this may be:
Does Empty Equipped include Engine Oil or other fluids (Hydraulic)?
Is there other equipment that is not properly included as part of the aircraft such as survival gear, flare guns?
Are extra bomb racks mounted and considered expendable stores?
Are the weights we are using for the Fuel and Ammunition correct?

Are the "Empty Equipped Weight" or "Loaded Weight" even correct?
My attempt is to represent an "Air Superiority" or Interceptor configuration with full fuel and ammunition but no external stores. Is this the configuration that was being described in the book?

The Loaded Weight of the FW 190A-8 is given as 4300 kg in one German flight test and 4350 kg in another. The 4250 kg loaded weight can be calculated by using a specification for the FW 190A-8R-2 aircraft (4350 kg) armed with two MK 108 30 mm cannon replacing the outboard MG 151/20 cannon. If we substitute the weights of the 20 mm cannon and ammunition, we arrive at 4250 kg.
The FW 190A-8 manual gives the weight of a fully loaded aircraft as 4400 kg.

Without being sure of the actual Loaded Weight of the aircraft I chose to work from the various component weights of the airframe and equipment and the disposable loads to see what the resulting loaded weight would be and how close it would be to the weights listed in the manual and test documentation. Because the weights listed in different sources do not completely agree, I also had to experiment to see which combinations were most plausible.

....

[Ivan]

....

Basic Airframe
----------------
Fuselage ------------ 345.2 kg
Undercarriage ------ 258.3 kg
Control Surfaces --- 120.8 kg
Flight Controls ----- 32.3 kg
Wing Assembly ---- 475 kg
Engine ------------- 1661.3 kg
Paint --------------- 2 kg

Total --------------- 2894.9 kg

Note that while the manual page is quite detailed in certain areas, for equipment, it only lists categories for weight instead of weight of specific equipment.
For equipment weights, a better source of information is the FW 190A-8 Ladeplan. This is the information which is used to calculate the weight and balance of the aircraft so its weight MUST be accurate (at least for a specific aircraft) and even the offsets must be accurate.

For Equipment, I chose the following:
Standard Armour for A-8 ---------- 137.8 kg from FW 190A-8 Manual
MG 151/20 Cannon ---------------- 4 x 42 kg
MG 131 Heavy MG ----------------- 2 x 29.5 kg
Cowl Guns Equipment ------------- 15.41 kg
Inboard Wing Guns Equipment --- 39.87 kg
Outboard Wing Guns Equipment -- 25.79 kg
115 Liter Fuel Tank ---------------- (30 kg)
Oxygen Equipment ----------------- 15.87 kg
Radio -------------------------------- 39.1 kg
IFF ---------------------------------- 11.18 kg
Gun Firing Equipment ------------- 11.75 kg
Winter Emergency Kit ------------- (25 kg)
Signal Pistol ------------------------ (0.69 kg)
Medical Kit ------------------------- (0.94 kg)
ETC 501 Rack ---------------------- 60.7 kg

The weights in parentheses are ones I chose not to include:
The 115 Liter fuel tank was standard equipment on the FW 190A-8 and I believe it would have been included in the structural weight of the aircraft as were the other two fuel tanks. If this tank was not installed, other equipment such as a MW 50 tank would be installed in its place.
The Winter Emergency Kit would have been specific to where the aircraft was operating in my opinion.
The Signal Pistol and Medical Kit were light items and would reasonably have been included in the 100 kg weight of Aircrew.

The total weight of equipment listed here was 584.5 kg which is pretty close to the 594.8 kg of unspecified equipment listed in the aircraft manual. It is certainly within the range of variations from one particular airframe to the next.

....

[Ivan]

....

The "Equipment" listed for each gun position is the difference between the weight of the bare weapon and the weight specified in the Ladeplan. I believe this would be the gun mounts, ammunition boxes and synchronising gear which would not need to be installed if there were no weapon in place.

In addition to the weights already specified, the aircraft can be expected to carry some amount of Engine Oil.
The oil system had a total volume of 58 Liters but a typical load would be a bit less than that presumably for expansion when heated.
The weight of oil specified in testing of a captured aircraft was 115 lbs.

With the information listed, the resulting loaded weight was 4347.2 Kg or 9584 lbs which seems reasonable.
The Zero Fuel Weight for the AIR File under these conditions would be 7977.3 lbs which is a bit higher than the earlier estimate but differs by less than 1%.

- Ivan.

[Ivan]

The FW 190 in experimental versions was equipped with the BMW 139.
When this engine ran into difficulties in development, the BMW 801 was substituted.

The BMW 801 also had its share of initial development issues which mostly involved overheating.
The first operational versions of the FW 190A were equipped with the BMW 801C rated at 1560 HP.
In late 1942, the engine was updated to the BMW 801D-2 which offered 1700 PS (1670 HP) at Take-Off at the time.

Beginning in late 1944, the BMW 801 TU became available in very limited numbers.
This engine had much higher ratings and gave 2000 HP at Take-Off.
Aircraft with the TU engine were redesignated FW 190A-9.

The higher output E and F series of the BMW 801 never reached production but some features were incorporated into production D series engines.
Thus although the lack of designation change of the BMW 801D-2 is misleading, the D-2 in production at the end of the war was quite a bit better than the one from 1942.

The power available at Sea Level did not greatly increase (from 1700 PS to 1800 PS or 1750 HP) but the altitude performance was quite a bit better.

The performance figures from captured FW 190's is also misleading because the Allies never tested a fully capable Air Superiority version of the aircraft:
Arnim Faber's FW 190A-3 had a derated engine and probably damaged spark plugs as well as evidenced by the engine's rough running and test pilots' perception of its unreliability.
Other captured examples were ground attack versions.

- Ivan.

[Ivan]

In an attempt to finish up the visual model of the FW 190A, I decided that the dark Wheel Wells should have a texture applied. There is a fair amount of equipment that is visible in the wheel well, most obvious of which is the inboard Wing Cannon.

The texturing was somewhat tedious but only involves 3 polygons per side and there was plenty of room in the Top-Bottom texture files. There were no great issues encountered in doing this and I believe the result is a distinct improvement over black wheel wells. It looks pretty good from most angles which is all you can really expect from a 2D part.

One other thing that has bothered me a bit is that the top of the Canopy Glass on the early / mid production FW 190A has a subtle curve. My version is a bit more coarse. I figured that I could get the shape I wanted by using only 4 additional polygons in the Canopy. Since resource use in AF99 wasn't particularly high at 28 Components and 1173 Parts, I believed I had quite a lot of working room.
A quick check showed that the new shape was pretty much what I wanted, so the project went directly to SCASM.

After the first few changes in SCASM, I found that I had a bit of an issue that wasn't visible when I was checking out the Canopy....

I guess I have a bit more work to do tonight....

- Ivan.

[Ivan]

After looking at the wire frame of the model a bit, I found a couple places that could be altered to use fewer polygons without affecting the resulting model. This FW 190A was one of my first projects (from 2001) and back then, I did not try to be economical when designing. I also didn't really understand yet what the sonsequences were of more polygons. (They are NOT all good.)

Although I found several areas, I settled on only re arranging the Fin. The changes do not detract from the visual model in my opinion because the original pieces were very very close to planar. The changes reduced the polygon count to 1169 and nothing is visibly altered.

The Dark Green Spinner is shown on AI flown aircraft. I have no idea how to reproduce this effect, but I like the result even though I achieved it accidentally on purpose:
Animations don't work with AI flown aircraft such as in Quick Combat. When this happens, the second model of the spinner is shown without animation. The animated Blue and White Spiral Spinner is shown when flown by a Human Pilot and the Green Spinner is hidden.

The frontal screenshot shows a few other changes since the original release:
There is now a Pilot (!)
The Engine Cooling Fan is Animated.
The Spinner is Animated
There is an Intake Bulge on each side of the Lower Cowl

One other thing worth mentioning is that the some of the changes done by Aircraft Animator are NEVER saved.

Apparently if you try to animate DEPLOYED Flaps, it doesn't save anything:
It recalculates the new animation each time you open AA.
It seems to save the animation if you are animated RETRACTED Flaps such as the ones on my P-47 Thunderbolts.

The Transparent Disc associated with the Spinning Propeller is saved, but the Radius is only saved to 0.1 meter accuracy:
The default disc radius calculated for this model is 1.7 meters. The FW 190A uses a 3.30 meter diameter propeller and my model is fairly accurate in that respect. I found that a 1.67 m radius works fairly well because 1.65 m shows too much of the Propeller Blur that I have in my model. Strange thing is that AA will animate the model with 1.67 m, but will round off the number the next time AA is started on the same model.

Now I get to re-do the SCASMing part again. I'm glad I was just starting when this problem showed up.

- Ivan.

[Ivan]

The screenshots from the last post looked pretty good to me....

After redoing some of the SCASMing, I found that there was an intermittent bit of weirdness from the INTERNAL 3D view from the cockpit! Guess I need to go back and take out a few more polygons or SOMETHING.

Looks like my original idea of converting this to a FW 190D won't be happening after all.

- Ivan.

[Ivan]

Not quite sure what caused the interior view glitch, but after a compile and even adding a few more polygons, I can't seem to reproduce it. In the original visual model years ago, there was another odd interior view of the front canopy frame that seems to have gone away with a couple revisions that should not have affected anything.

The SCASM adjustments are still not complete, but it has all been converted to BMP texturing which let my son modify the textures to his own personal scheme.

This project is so old that EVERYTHING needs to be reviewed and possibly adjusted. The first thing to do was to check out the original aircraft to see what was still useable The handling was still quite good as was the agility. The roll rate is VERY high and AI pilots still can't fly it.
(I tried to fix the AI issue at some point, but could not get it AI-Flyable without losing a lot of the roll rate.)

Initial Flight Test with no adjustments:
345 mph @ SL
391 mph @ 12,500 ft

It would not break 400 mph at any altitude without MW 50 injection.
As stated earlier, the BMW 801D-2 engine was significantly improved without a designation change and late war aircraft were easily capable of 400+ mph. A FW 190G-3 tested by the US Military was found to be capable of 415 mph @ 22,000 feet WITHOUT the use of WEP. This performance level is what one might expect from a contemporary Fighter variant such as the A-8.

Before making performance adjustments to the Flight Model, Fixing anything that would alter the aircraft weight seemed to be in order. THIS is where things got VERY interesting.

The DP file significantly added to the aircraft weight. The original ammunition weights were the typical "Projectile Only" weights as in all the stock CFS aircraft. That alone added a few hundred pounds to the Loaded Weight. The Bomb load was changed from 3 to 4 x 250 Kg bombs.

A 115 Liter fuel tank was added to the Flight Model and the other two tanks were moved to their proper locations.
The typical FW 190A-8 did not use MW50 for WEP. While it COULD mount a MW50 tank behind the cockpit, typically there was a Fuel Tank installed there. The stock FW 190A showed this by having a Fuel Selector for Three fuel tanks instead of two as it would with MW50.

A review of drawings of the FW 190 shows that all three fuel tanks are either at or behind the aircraft CoG. The Forward tank is mounted behind the Wheel Wells. The location of the fuel may be a reason that some pilots flying the captured FW 190 complained that there was too much weight on the Tail Wheel for good ground handling.

.....

The first simulator test with all the weight adjustments showed that things had gotten much uglier. The earlier aircraft was quite well behaved other than for AI pilots, but the new version would wiggle and bounce on the runway even with the engine off.

Dumping the fuel from the 115 liter Aft Fuel Tank would cure the bounce (!), but that was not an acceptable answer.
A LOT more guessing, experimentation, and editing of spreadsheets to predict numbers (over a couple days) gave me a workable though not perfect solution.

The aeroplane now sits steady with no fuel or ammunition (7977 pounds)
With full fuel and ammunition, it does not bounce (9600 pounds)
With full fuel, ammunition and ONE Bomb, it is still steady (10,150 pounds)
With TWO Bombs, it starts to wiggle but doesn't rotate on the runway (10,700 pounds)
With FOUR Bombs, it dances quite well and will rotate on the runway in time (11,800 pounds)

Further adjustments in the direction I was heading only made the aeroplane start to wiggle when empty.
Until, I learn a bit more, this is as good as it will get for a while. If anyone has ideas, please feel free to post suggestions.

Adjusting engine power a bit gave
357 mph @ SL
411 mph @17500 ft
406 mph @22500 ft

It still needs some tuning for altitude performance but it's getting there....

- Ivan.

[Ivan]

I had commented earlier about the extra texturing of the Wheel Wells, but never included a screenshot.
I recently took this old project up for a spin and was pleasantly reminded.

- Ivan.

[smilo]

...always been one of my favorites.

[aleatorylamp]

Hello Ivan,
Wow! First time I´ve seen textured wheel-wells! Nice detail.
Cheers,
Aleatorylamp

[Ivan]

Hello Smilo,

This is one of my favourites also.
It is really annoying that I do not have a working development machine so that I can fix a few details and re-release this project. Even in its current state, it is much improved over the version that is here now.


Hello Aleatorylamp,

I took the time to texture the Wheel Wells because they just looked too bare without anything.
I was thinking that if there were additional projects to follow from this one, doing things once would benefit the future projects. So far, the FW 190D has not been started even though its flight model was the basis for the Engine Performance Tuning Tutorial.

- Ivan.