Bf109 test data

[IvanK]

A good selection on the WWII aircraft performance site. Interesting comment on items 13 and 14 ... the ones with 500Kmh IAS at sea level.

[klem]

Originally Posted by IvanK

A good selection on the WWII aircraft performance site. Interesting comment on items 13 and 14 ... the ones with 500Kmh IAS at sea level.

Thanks for your inputs guys.

IvanK I am disregarding items 13 and 14 as they have no 'provenance', i.e. no acknowledged testing organisation although the speed test is close to the V15a tests so they are possibly based on a prototype perhaps simplified for publication.

For interim information: I am testing the 109E-3 at 1.3ata and 2400rpm, radiator 1/4 open which aligns with the Swiss tests which are very close to the handbokk figures until 5,000m where they fall away more than the handbook. The French tests at 1.3ata 2400rpm produced better results to 4,000m but it was probably an E-1 and curiously the radiator was open to 4,000m due to cooling problems. The average of all the six data sets I have is quite close to the handbook, 2%-3% above handbook at low altitude and matching the handbook in the 4,000m to 7,000m region. In any case, the CoD 109E-3 is below all those figures and is looking like 93-95% of handbook figures at altitudes to 1,500m and around 98% at 5,000m. I still have more tests to do at other altitudes.

Of course I don't know if the various figures are supposed to be max speeds or just representave performance at those power settings so I don't know of we can compare them with Spitfire Max Speeds. We can at least see if CoD 109s are perfoming near to those historical tests - or not.

I'll post results here when I finish.

[Ze-Jamz]

Interesting Klem..thanks for yer hard work

[Kurfürst]

I.

The Me 109E had at least four fitting and used during the Battle of Britain, with different boost and outputs.


1. The DB 601A-1 with the old type supercharger, 1.30 ata for five min and 990 PS, and 1.40 ata for 1 min and 1100 PS. Rated altitude being 4000m.

2. The DB 601A-1 with the new type supercharger, 1.30 ata for five min and 990 PS, and 1.40 ata for 1 min and 1100 PS. Rated altitude being 4500m.




3. The DB 601Aa with the old type supercharger, 1.35 ata for five min and 1045 PS, and 1.45 ata for 1 min and 1175 PS. Rated altitude being 3700m (altitude output was otherwise very much like the DB 601A-1 / old s/c, though it is an open question wheter the new s/c was fitted to the Aa as well. So far no evidence to that though.)
This is the type we have in the sim.



4. The DB 601N, 1.35 ata for five min and 1175 PS. Rated altitude being 4800m. (there was a second type of 601N, mounted in one in the 109F had better supercharger and IIRC 5200 m rated altitude)



II.

Therefore, it is pointless to compare our 601Aa equipped Emils performance (1.35ata) to real life tests of DB 601A-1 equipped Emils at 1.3ata. It makes about as much sense as checking Spitfire I performance from the crayon +12 boost graph to actual tests of serial production +6 1/4 boost tests.

It should of course match the real life DB 601Aa at 1.35ata (V-15a, Baubeschreibung "5%" specs, Swiss trials of serial no. 2404 - these all have Aa, although it's quite clear the Swiss graph is only showing high speed supercharger, ie. Hohenlader performance - note the almost exact match between V15a Hohenlader and the Swiss single speed graph)



III.

Misc. comments

1. The "French 109" was an E-3, not an E-1: WNr. 1304. Besides the aerodynamic differences between the E-1 and E-3 are marginal, probably in the order of 1-2 kph. It seems to loose manifold pressure continously with altitude - I suppose the use of French lubrication of oils instead of German synthetics may be at culprit (since the hydraulic coupling was using this oil). It had a DB 601A-1 and operated at 1,3ata, ie. lower boost/power than our E-1/E-3/E-4s.

2.

The WNr. 1791 and 1792 tests can be easily forgotten given that
- this was never a performance tests, but a speed comparison with various fittings: As it notes clearly - Geschwinigkeitsunterscheid - comparison of speed

-as a result only the relative values (guns in / out, slats sealed/not sealed) were interesting Mtt AG in these tests, they were not made to get absolute values.

- they do not have the same 1.35ata Aa engine as our Bf 109E has, but a weaker 601A at 1.3ata, which developed about 55 HP less.

- in addition report clearly notes the engine outputs were not corrected for guaranteed engine performance, which means we/they have no idea how much those engines were developing. Again, given that all those two reports were supposed to show was what's the speed difference with this thing on and that thing off this hardly concerned Mtt at the time.

3. The fact that Mtt. accepted the V15a trial results and guaranteed them within 5% for the ca. 4000 Emils produced needs very little comment.

4. The "nazi propaganda" (pathethic, even for Mike ) aka 500 kph curves for the 109E w. DB 601Aa (confirmable from engine specs) come from Bf 109 E Baubeschreibung, Chapter V. Leistungsblatter (Performance sheets), from 1939.

It's one chapter from a 75 page document describing the airframe, powerplant, equipment, armament, performance, as well as the all the instruments.

It's hardlly a two page "marketing material" as some like to pretend - besides the fact that the specs are guaranteed and are based on flight tests.

[klem]

Originally Posted by Kurfürst

I.

The Me 109E had at least four fitting and used during the Battle of Britain, with different boost and outputs.


1. The DB 601A-1 with the old type supercharger, 1.30 ata for five min and 990 PS, and 1.40 ata for 1 min and 1100 PS. Rated altitude being 4000m.

2. The DB 601A-1 with the new type supercharger, 1.30 ata for five min and 990 PS, and 1.40 ata for 1 min and 1100 PS. Rated altitude being 4500m.

[image removed]


3. The DB 601Aa with the old type supercharger, 1.35 ata for five min and 1045 PS, and 1.45 ata for 1 min and 1175 PS. Rated altitude being 3700m (altitude output was otherwise very much like the DB 601A-1 / old s/c, though it is an open question wheter the new s/c was fitted to the Aa as well. So far no evidence to that though.)
This is the type we have in the sim.

[image removed]


4. The DB 601N, 1.35 ata for five min and 1175 PS. Rated altitude being 4800m. (there was a second type of 601N, mounted in one in the 109F had better supercharger and IIRC 5200 m rated altitude)

[image removed]


II.

Therefore, it is pointless to compare our 601Aa equipped Emils performance (1.35ata) to real life tests of DB 601A-1 equipped Emils at 1.3ata. It makes about as much sense as checking Spitfire I performance from the crayon +12 boost graph to actual tests of serial production +6 1/4 boost tests.

It should of course match the real life DB 601Aa at 1.35ata (V-15a, Baubeschreibung "5%" specs, Swiss trials of serial no. 2404 - these all have Aa, although it's quite clear the Swiss graph is only showing high speed supercharger, ie. Hohenlader performance - note the almost exact match between V15a Hohenlader and the Swiss single speed graph)

[image removed]

III.

Misc. comments

1. The "French 109" was an E-3, not an E-1: WNr. 1304. Besides the aerodynamic differences between the E-1 and E-3 are marginal, probably in the order of 1-2 kph. It seems to loose manifold pressure continously with altitude - I suppose the use of French lubrication of oils instead of German synthetics may be at culprit (since the hydraulic coupling was using this oil). It had a DB 601A-1 and operated at 1,3ata, ie. lower boost/power than our E-1/E-3/E-4s.

2.

The WNr. 1791 and 1792 tests can be easily forgotten given that
- this was never a performance tests, but a speed comparison with various fittings: As it notes clearly - Geschwinigkeitsunterscheid - comparison of speed

-as a result only the relative values (guns in / out, slats sealed/not sealed) were interesting Mtt AG in these tests, they were not made to get absolute values.

- they do not have the same 1.35ata Aa engine as our Bf 109E has, but a weaker 601A at 1.3ata, which developed about 55 HP less.

- in addition report clearly notes the engine outputs were not corrected for guaranteed engine performance, which means we/they have no idea how much those engines were developing. Again, given that all those two reports were supposed to show was what's the speed difference with this thing on and that thing off this hardly concerned Mtt at the time.

3. The fact that Mtt. accepted the V15a trial results and guaranteed them within 5% for the ca. 4000 Emils produced needs very little comment.

4. The "nazi propaganda" (pathethic, even for Mike ) aka 500 kph curves for the 109E w. DB 601Aa (confirmable from engine specs) come from Bf 109 E Baubeschreibung, Chapter V. Leistungsblatter (Performance sheets), from 1939.

It's one chapter from a 75 page document describing the airframe, powerplant, equipment, armament, performance, as well as the all the instruments.

It's hardlly a two page "marketing material" as some like to pretend - besides the fact that the specs are guaranteed and are based on flight tests.

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?

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).

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

What configuration does the "Handbook" represent?

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

Thanks,

[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.

[klem]

OK, thanks. I'll keep the V15a, Swiss and Handbook curves only and plot the CoD 109E-3 against them.

I'll start the tests again at 1.35ata, 2400rpm, 1/4 radiator.

I guess we don't have access to the manual 2-speed gearing, perhaps its automatic. That might account for the strangely shifting plot I got first time but... I'll start again.

[1984]

Originally Posted by Kurfürst

...

sorry, if..., but what you can tell about soviet trials of emil? 440 km/h at SL (5 min 1.35 ata (980mm))...