Intro / a question regarding the sources for FMs

[Heywooood]

meanwhile...tick tick tick tick....is it September yet?!

[AX2]

But lively

Yes ! 

[Volkoff]

Just to clear about Soviet and German data used for airplanes modelling - engineers got every bit of information possible to check and use, in case of Soviet airplanes - we use Soviet data and tech descriptions, but in case of German airplanes - performance tuned by official german datas and tech descriptions, but in case of some things missing (such as handling characteristics tests/controls lodas and such - which i havent seen from german test sources) - gotta be supplemented with Soviet tests.

[NN_Avenger]

Wouldn't it be best to base the FM on performance calculations? They did it back in WWII ( http://kurfurst.org/Performance_tests/109F4_Datenblatts/109F4_dblatt_calculated.html )

To me it seems to be the best way to have reliable data for the FM. I am no expert and therefore I don't know if it's possible to do it without RL flight performance tests.

 

I find no official document which confirms what is written on this site. Or can one see them?

[VeryOldMan]

I have also seen it said that the Russian classified records also contain the results of German tests. 

 

 

Considering that  they grabed every piece of paper they coudl find in germany at the end of war and retrieve for study later, that is not unexpected

[JG1_Pragr]

I find no official document which confirms what is written on this site. Or can one see them?

 

Do you mean this?

 

http://www.beim-zeugmeister.de/zeugmeister/index.php?id=12&L=1.

[JG1_Pragr]

40 minutes of MW50, but 10 minutes duration of use with a break in between. Otherwise, engine failure.

 

I perfectly understand that Armitage. So in the situation of automatic vs automatic, how are different results achieved?

 

I don't see your point here. RAF often used WEP (3-5 minutes maximums) for performance testing of its planes. At least in case of maximum speed measurements. In example, climbing times of Spitfire IXs are listed too under the 5 minutes maximum. Germans had slightly different methodology, because they used 5 minutes maximums for level speed measurements while used 30 minutes setting for climbing times. So I really don't understand why there is a problem with 10 minutes limitations of MW50.

 

Btw, MW50 is not the only system of increasing engine performance used on Dora's Jumo engine.

[AX2]

Germans had slightly different methodology, because they used 5 minutes maximums for level speed measurements while used 30 minutes setting for climbing times.

 

30 minutes of MW50

 

Yes  I saw,  climbing test with more than 10 minutes of MW 50 ON ...

I thought the engine will overheats and burns .. but not 

I can´t understand 

[FuriousMeow]

I don't see your point here. RAF often used WEP (3-5 minutes maximums) for performance testing of its planes. At least in case of maximum speed measurements. In example, climbing times of Spitfire IXs are listed too under the 5 minutes maximum. Germans had slightly different methodology, because they used 5 minutes maximums for level speed measurements while used 30 minutes setting for climbing times. So I really don't understand why there is a problem with 10 minutes limitations of MW50.

 

Btw, MW50 is not the only system of increasing engine performance used on Dora's Jumo engine.

 

Why does RAF WEP matter? This was only about MW50. Someone said 40minutes of MW50, but it could only be used in short duration so it's not 40 minutes continuous which was a clarification.

[AX2]

About MW50

I think the difference, are at the height at which you fly.

On deck 7 to 10 minutes maybe...

For example  at 3000 to 5500 meters is another story .... That time of MW50 can be increased. 

Above 6500 meters  the MW50  is unusable (Water/methanol system freezes),  then you will need a GM-1 ( nitrous oxide ) Like Ta 152 had MW50 and GM -1. 

Edited September 13, 2013 by Mustang

[JtD]

There's no increased operational time with MW50 at altitude given in any manual I have seen, it doesn't make sense anyway - the stress for the engine at sea level and at 4 km is the same.

 

MW50 does not freeze at high altitude, that is what the methanol is in for. Of course, there can be exceptions. At high altitude, an MW50 system simply does not deliver a lot of extra power. The extra power with the system mainly comes from the use of an increased boost (for instance 1.7 ata instead of 1.42 ata with the DB650A), but the supercharger cannot provide the extra boost at altitude. So above the full throttle altitude, MW50 has little effect. Full trottle altitudes for instance for a DB605A is 6km, for a DB605AS 8.5km and for a Jumo213E about 10km. It should be noted that the US used the same principle with water injection with the R-2800 powered aircraft.

 

The GM-1 system works at high altitude, because the GM-1 contains oxygen it needs for the combustion, so thin air doesn't really matter. On the other hand, GM-1 does not allow the use of increased boosts, so if you engage a GM-1 system below full throttle altitude, you risk blowing the engine.

[JG1_Pragr]

Why does RAF WEP matter? This was only about MW50. Someone said 40minutes of MW50, but it could only be used in short duration so it's not 40 minutes continuous which was a clarification.

 

I never said it could be used for 40 minutes of continuous run.

I only pointed out that even as 10 minutes maximum is it still valid for maximum performance evaluation. It was reaction on your statement "And MW50 is a limited system, so max speed for a brief few minutes". All performance test in every air force was usually made under top setting conditions (generally the setting allowed for 3-5 minutes). Than it's totally irrelevant which system of overboosting engine is used. If it's increased manifold pressure or injection of auxiliary fluids (MW50, GM-1, Water etc.). Anyway, in the example mentioned above, if e.g. the one pilot flew Dora and never used the MW50 (simply because he didn't know about it, or because he feared about do anything which could damaged/destroyed the plane) his opinion of plane performance had to be quite different than the other pilot knowing what he should do.

 

Btw, I'm not sure if the MW50 was limited for 10 minutes. What I've read there had to be a 10 minutes break between two usages, but the source never mentioned any working time limit.

[JtD]

Jumo 213A Fw 190D-9 manual states the below. Guess the 10 minutes limit is obvious even if the reader does not read German.

[MackStones]

Due to a multiplicity of sources, each of which might have its own errors, biases, or incompleteness, it is difficult to ever get a completely authoritative flight model (not to mention the difficult task of trying to recreate it in a flight sim).  Moreover, despite many losses of data during and after the war, there remain sources of flight modeling data from WWII, but they often differ and it's easy for any of us to claim that the developers "porked" or "ubered" any aircraft based upon a source we might have in hand (even if not cherrypicked) - we just need to realize that the developers are relying upon another source (and presumably on a rough amalgamation of a number of sources).

 

See this post for a (way too long) discussion of these issues.  

 

http://forum.il2sturmovik.com/topic/1178-way-too-long-discourse-flight-modeling-disputes/

[JG1_Pragr]

Thank you for that attachment JtD.

[II/JG17_HerrMurf]

I'm curious about the Dora pilot getting more performance than the, for this purpose, non-Dora pilot. Weren't the 190's engine systems automatic? I know they could be over-ridden, but wasn't the intention behind the Kommandogerät to ease pilot work load and attain the best performance it could? Sure a human can disable it and probably get maximum performance out of the engine, but it just seems strange that with an automated management system, such as the 190 had, that different results could be obtained. Unless of course command-device was over-ridden.

It has driven me nuts that I can't remember where that quote came from. Maybe Wings of the Luftwaffe? I'm going through all of my Fw books now trying to see if it is mentioned anywhere.

 

On the other hand, automated systems never give you maximum performance. They attempt to provide optimal performance and lighten the load on the operator. A manually operated car with standard brakes will always outperform the automatic with version with anti-lock with a fully versed driver. If automated systems provided maximum performance (especially back in the day) they would be installed in every F1 car and MotoGP bike.