Bf109 test data

[Winger]

Originally Posted by *Buzzsaw*

Salute

Nothing is ever simple, there are no easy ways to arrive at 109 performance figures which are 'exact'.

The German figures are qualified with a note that different engines of the same type, (DB601A, N, etc.) can vary from +2.5/-2.5 percentage difference in engine horsepower output. That can easily add up to 20 kilometers per hour difference between different aircraft when we are talking about top speed at altitude.

The British, American and Swiss figures are done with aircraft which are either captured or export variants, which might or might not perform up to German standards.

In addition, often tests are done at different boost levels, or with radiators either open or shut.

Some of the German documents may or may not have figures which are inflated, as they are intended to provide information for potential foreign buyers, and obviously a higher performance aircraft is more likely to sell.

All of the above means that one has to be VERY careful in the study of the various tests/figures, and not jump to hasty conclusions.

What we do know is that the 109E was a very competitive and dangerous aircraft, capable of taking on the Hurricane and Spitfire in the aerial combat arena. And vice versa.

You could also change the "German" to "English" here...

[Al Schlageter]

Originally Posted by Winger

You could also change the "German" to "English" here...

You do have examples you can post, yes?

[csThor]

On the Bf 109 E-3/b, E-4/b and E-7 and the engine thingy. Do not distinguish the bomb carriers too much, especially not when talking about the engine. IIRC not a single E-3/b was produced (unsurprising since the E-3 went out of production even before the Luftwaffe even thought about using the 109 as Jabo) so any potential aircraft of that type would be converts. Although this is somewhat doubtful since they would most likely be upgraded to E-4 standards at the same time and labeled E-4/b afterwards, anyway.

IMO the E-4 (and E-4/b) would be the most probable candidates for the 601Aa while E-1 and E-3 should feature the 601A. IMO, of course.

[41Sqn_Banks]

According to rather old FM files there is a DB601A and DB601Aa. The Bf 109 uses the DB601A, only the He-111 P uses the DB601Aa.

Both engines have the same FTH (4500m), max boost (1.35) and WEB (1.45) values. The difference that I found:
- DB601Aa has a higher ramming factor
- DB601Aa has a constant speed propeller

[Robo.]

Originally Posted by 41Sqn_Banks

According to rather old FM files there is a DB601A and DB601Aa. The Bf 109 uses the DB601A, only the He-111 P uses the DB601Aa.

Both engines have the same FTH (4500m), max boost (1.35) and WEB (1.45) values. The difference that I found:
- DB601Aa has a higher ramming factor
- DB601Aa has a constant speed propeller

So it is safe to state that the DB601 family is not modelled correctly regarding FTHs and max MAPs and the engine of any Emil in the sim is a mix of both Aa and A-1.

[Kurfürst]

IMHO the realistic max speed for the Bf 109E series, based on the V15a trials and the official specs and the French trials etc., are:



At SL.

DB 601Aa, 1,35 ata (1045 PS) : 498 km/h (V15a @ 1.35 = 498 km/h, Baubschrb.5% @ 1.35 = 500 km/h)
DB 601A, 1,30 ata (990 PS) : 489 km/h (V15a @ 1.31 ata = 493 km/h, French109 1.3ata = 485 km/h)*

DB 601Aa, 1,45 ata (1175 PS) : 515 km/h*
DB 601A, 1,40 ata (1100 PS) : 506 km/h*

Similiar boost in speed up ca. 1500 m, above: essentially 1.3/1.35ata performance levels, but boost is maintained, and fuel consumption increased to ca. 375 lit/h.

* Calculated from 1.3ata / 1,35ata results for 990 PS / 1075 PS

At altitude.

DB 601Aa, 1,35 ata : 570 km/h @ 4800 m (V15a @ 1.35 = 572 km/h, Baubschrb.5% @ 1.35 = 570 km/h, Swiss 109E-3a = 564 km/h)

DB 601A, 1,30 ata : 562 km/h @ 5200 m (V15a @ 1.33 ata = 562 km/h, French109 1.3ata = 485 km/h; 1942 Emil chart with 601A = 562 @ 5200)


P.S. Note that atmospheric conditions in the V15a and French trials are very close (+5, +6 Celsius) which explains as well why the results match so well.

Note that the 1942 Emil chart is again based on the V15a results. Given the weight it probably includes the armored bulkhead.

If CloD's 'standard day' is different from German (British) Standard day for which these figures were corrected to, then they should be re-calculated to CLOD standard day first.

[JtD]

Originally Posted by Kurfürst

At SL.

DB 601Aa, 1,35 ata (1045 PS) : 498 km/h (V15a @ 1.35 = 498 km/h, Baubschrb.5% @ 1.35 = 500 km/h)
DB 601A, 1,30 ata (990 PS) : 489 km/h (V15a @ 1.31 ata = 493 km/h, French109 1.3ata = 485 km/h)*

493 of V15 @1.31 were done at 500m altitude, at SL this was extrapolated to 485.

[SiThSpAwN]

Just a a side note, me being someone that is in no way an expert on all this stuff, but it almost seems that what is being talked about here is almost out of the realm of what the CloD FM can calculate properly. As an example, how does it calculate weight correctly if its only based on either full or empty, no inbetween.

Now maybe I just dont understand their FM data and perhaps there are calculations going on that I dont see, but as you expend fuel, ammo, etc, the weight and flight characteristics will change.

So are we asking too much of the CloD FM? Would be interesting to hear what the programmer had to say about it, what knowledge he had on flight models, engineering background, etc... or if he is just a programmer punching in numbers without too much thought into what they actually are... if that makes any sense.

Not trying to rain on anyones parade or anything, just mostly a comment on the level the current FM could actually handle. And if throwing all this data around really matters if the FM itself can even really handle it.

[bugmenot]

Originally Posted by Kurfürst

IMHO the realistic max speed for the Bf 109E series, based on the V15a trials and the official specs and the French trials etc., are:



At SL.

DB 601Aa, 1,35 ata (1045 PS) : 498 km/h (V15a @ 1.35 = 498 km/h, Baubschrb.5% @ 1.35 = 500 km/h)
DB 601A, 1,30 ata (990 PS) : 489 km/h (V15a @ 1.31 ata = 493 km/h, French109 1.3ata = 485 km/h)*

DB 601Aa, 1,45 ata (1175 PS) : 515 km/h*
DB 601A, 1,40 ata (1100 PS) : 506 km/h*

Similiar boost in speed up ca. 1500 m, above: essentially 1.3/1.35ata performance levels, but boost is maintained, and fuel consumption increased to ca. 375 lit/h.

* Calculated from 1.3ata / 1,35ata results for 990 PS / 1075 PS

At altitude.

DB 601Aa, 1,35 ata : 570 km/h @ 4800 m (V15a @ 1.35 = 572 km/h, Baubschrb.5% @ 1.35 = 570 km/h, Swiss 109E-3a = 564 km/h)

DB 601A, 1,30 ata : 562 km/h @ 5200 m (V15a @ 1.33 ata = 562 km/h, French109 1.3ata = 485 km/h; 1942 Emil chart with 601A = 562 @ 5200)


P.S. Note that atmospheric conditions in the V15a and French trials are very close (+5, +6 Celsius) which explains as well why the results match so well.

Note that the 1942 Emil chart is again based on the V15a results. Given the weight it probably includes the armored bulkhead.

If CloD's 'standard day' is different from German (British) Standard day for which these figures were corrected to, then they should be re-calculated to CLOD standard day first.

DB 601A, French109 1.3ata = 570 km/h @ 5000 m - 5500 m - Closed Radiators
http://kurfurst.org/Performance_test...formanceT.html



Regards

[klem]

Originally Posted by Kurfürst

....................................

If CloD's 'standard day' is different from German (British) Standard day for which these figures were corrected to, then they should be re-calculated to CLOD standard day first.

No, the CoD results should be converted to Standard Day (which my test mission does) to ensure all results are on a level playing field when they are compared (109, Spitfire, Hurricane etc)

I'll try to finish the 109 tests this weekend. It won't be "max speed tests" but a test at 2400 / 1.3 and 2400 / 1.35 to compare with historical charts and avoids arguments about what max speed power settings should be.