Bf109 test data

[Kurfürst]

Originally Posted by klem

OK, I understand but have a couple of questions.

Swiss test: You seem to use the 'Original VDM' curve. I don't know what the other curves represent so can you please explain? I picked up somewhere that the test was at 1.35ata. Can you find a source for that?

The Swiss test is a comparison of various propellers and the original VDM (German) produced propeller. 1,35ata is coming from the fact that the engine is listed as the "Aa" type, and that the test is run at "Vollgas" - literally full throttle (not the 1-min WEP though), which is 1,35ata for the Aa.

Other than that, sadly I do not have the rest of this report, and I would be glad if someone has it.

V15a: This was conducted at 1.31ata at low level and 1.3ata above 3,300m. How can I reproduce that in CoD? (I don't usually fly the 109).

The answer is that you probably should not - V15a was tested (actually two test runs - one clocked for low altitude on four way course, the other at different course at high altitude after insturment calibration) while running below the nominal boost pressure (1,35) and the results were re-calculated for that nominal boost (that's the slightly displaced higher spec line).

How can we be sure which 109 engines are supposed to be modelled in CoD (or which should be)?

1.35ata in game is a clear indication of the Aa, and IIRC the game's engine related files also show Aa specs.

What should be is a different question - any of the above engines in fact, but I guess 1C had to choose the one which they had the best documentation for. Ideally we would have a gazillion Emil types with similiar chaos as with Rotol, DH, 87 and 100 octane Spits and Hurries.. but it's impossible to tell how many had A-1 old, A-1 new s/c, or Aa, apart from that Aa amounted to about 1/3 of all 601 production

We can tell the number of Ns, because they were relatively rare..

Bottomline is, since we have Aa variant, we should have the Aa specs. The Aa is a bit better at low altitude (ca. +50 PS), an A-1 with the new supercharger is better at high altitude (ca. +50 PS again).

What configuration does the "Handbook" represent?

If you mean the complex graphs with landing take off distance times etc., I guess it's a 'generic' 109E. I am pretty sure that performance difference between E-1 and E-3 were marginal. They were exactly the same, even the wing was the same, expect for a bulge for the cannon on the E-3 and that the cannon was put into the other wing weapon bay than the E-1. They could be rather easily converted.

Engine is certainly 601A-1, probably early one. Problem is the engine ratings are not shown, and in these kind of papers it was quite common to use 30-min (1.2x-ish ata) ratings instead of full power. IIRC comparison of the Handbook with RAE's testing of the "French 109E(-3)" point strongly to that the handbook indeed shows 30 min performance only and not the full ratings.

EDIT: I can't seem to find weights of the Swiss and V15a aircraft. Also, was the V15a version a fully loaded military configuration?

No idea on the Swiss aircraft. I don't have the full report and it seems nobody does.

The V15a weights are unknown, although it's noted that the aircraft is serial production form, with 4 MGs installed. Exhaust covers were missing and the engine cowling was 'raw' (I suppose this means unpainted), the rest of the aircraft had standard camoflage. the s/c inlet was squarish and looks very much like the standard one on the Emil; they expected that a rounded intake would work better (as we know this waited until the 109F). All in all Mtt expected further improvements in performance with these added. Ammo may or may not be installed, or ballasted, but in any case, a few dozen kgs in or out has next to no effect of a fighter's top speed. Landing gear retracted, tailwheel out. radio antenne.

All in all it was pretty much the stock (DB 601Aa powered) E-1 in every way.

Thanks,

Your welcome.