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PostPosted: Wed Feb 05, 2020 7:00 pm 
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<S>
I just wanted to give a heads up and a more detailed description on what's coming for the Fw 190 series, P-51D, and P-47D-25. These changes will be included in the FL2077 update planned for release in early March.

The Fw 190 series
This was among the first flightmodels we remodeled back in 2017 with the new FM Team, and the Focke Wulfs have seen several fixes since then. However with flight trial speed data brought up by Grumpy, I've rechecked the speeds of the Fw 190's. When modeling them several years ago I didn't know much about min/max RAM effects for engines, and as such modeled their engines straight out of engine power graphs from WW2. These however show only horsepowers for min RAM. I remember I had a problem with the Fw 190's since if setting their dragco to give them the correct speed at the deck, they severly underperformed speed wise at high altitudes. As such I made a compromise and set their dragco to have them at the correct speed at 15000 ft, which resulted in their speed being faster than ww2 data at low altitude, this since the dragco used was lower than their real life dragco. The graph below shows the current Warbirds performance (green) of the Fw 190D-9 vs it's WW2 data (red). As can also be seen the engine's FTH shiftings for min RAM are at lower altitudes than for the max RAM of the data. You can find the red line data for a standard production Fw 190D-9 at this link:
http://www.wwiiaircraftperformance.org/ ... 9test.html


Image


When now rechecking the Fw 190 series, with a lot more flightmodeling experience, I quickly realised this min/max RAM issue. I've remodeled the engines for max RAM performance at top speed during these last weeks, and coupled with an increase to their dragco, they now hit the speed data from WW2 trials perfectly. What this means to the Focke Wulfs of Warbirds is that they all will have more horsepowers at high altitudes, but they will all take a hit to their speed at low altitudes. Much of the fighting in the Legacy arena is done at the deck, and Fw 190 pilots still have a great fighter, but need to be aware that it will be somewhat harder to outrun enemy fighters when down low, and keeping one's energy is now more important. The new higher dragco also has a small detrimental effect to the Fw 190's sustained turn rate, except at high altitudes where the higher dragco is balanced out by the increase in available horsepowers. All Fw 190's still handle the same way as before, so there are no changes to how they maneuver. Below are a few graphs showing their top speed with the new engine settings, and also comparing to a few contemporary fighters.


Image Image Image


The P-51D
At 100/130 fuel the P-51D could run a manifold pressure of 61" Hg for 15 minutes, and 67" Hg for 5 minutes. However with 150 grade fuel it could use a MAP of 72" Hg, and with the better fuel, would also be able to run Military power for longer than 15 minutes before overheating. Studying the manifold pressure vs time limit curves of several ww2 fighter engines, the best estimation is that the P-51D most likely could use the 61" Hg for at minimum 25 minutes with 150 grade fuel. As such the P-51D, which is using 150 grade fuel in Warbirds, will be less prone to overheating at Bst1 with the next update in early March.


The P-47D-25
The P-47D is currently being discussed by the FM Team, and it is possible it will be given the 44-1 fuel (150 grade) with the next update. With 44-1 fuel the Thunderbolt can use 70-72" Hg of manifold pressure instead of a MAP of 65" Hg, and with the 44-1 fuel it's top speed will even be a few mph faster than the P-51D above 15000 ft, according to available flight trial data. The 9th AF only used 100/130 fuel for it's Jugs, but in the 8th AF, stationed in Britain, it seems that 100/150 fuel was of widespread use among P-47 units since early 1944. As such the P-47D-25 will probably be allowed a MAP of 70" Hg for WEP, while the P-47D-22 retains it's MAP of 65" Hg.

Here is a link to flight tests conducted with 44-1 fuel for the P-47D, using a MAP of 70" Hg.
http://www.wwiiaircraftperformance.org/ ... 26167.html

Here is an excert from an interesting interview with Robert Johnson, pilot of the 8th AF.

Another thing that is often forgotten is that most 8th AF groups were operating their planes over boosted. P47 groups were getting P47M performance out of many of their planes in late 43' through 44':

56thFG
Robert Johnson's P47

As to the speed of his P-47; Pratt & Whitney tech reps were largely
responsible for giving Gould the secrets of horsepower production in the
R-2800. Engines with the same wastegate modifications were tested at P&W and produced in excess of 2,700 hp on the dynometer, and did so for hundreds of hours at full throttle. The later "C" series R-2800 (used in the P-47M and N) generated 3,600 hp during similar endurance testing. It should not be a surprise that a P-47D-5-RE should attain similar speeds to the P-47M with 2,800 hp with slightly greater drag. Gould also filled all gaps in seams and waxed Johnson's Jug to reduce parasite drag.

By the Spring of 1944, there wasn't a P-47 in the 56th that hadn't been
field modified like Johnson's. Ask any of the surviving crew chiefs. When
150 octane fuel became available in early '44, 72" MAP became the standard
for combat operations. While this setting was never incorporated into the
standard issue pilot's manual, it is easily found in 8th AF Fighter Command
technical bulletins and operational instructions.



Image


<S>
/Robert


Last edited by Robert on Fri Feb 21, 2020 9:39 pm, edited 1 time in total.

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PostPosted: Sun Feb 09, 2020 6:52 pm 
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Joined: Wed Jan 11, 2017 10:54 am
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The Fw 190D-9 will also have it's max recommended dive speed set to historical 480 mph, down from 510 mph, which was a data misunderstanding by me back in 2017. The Fw 190A models retain their max recommended dive speed of 466 mph.

Thanks to player feedback an issue was also found where the F6F-5 Hellcat starts shaking uncontrollably at auto trim above 440 mph. The cause has been found and this will fixed with the update.

The C-47's internal structure is also being compared to other bombers and the fuselage hitpoints of the C-47 are being discussed, and might get lowered.


Cheers!
/Robert


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