Bf109 test data

[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.

[Kurfürst]

BTW how do you measure TAS?

[klem]

Originally Posted by Kurfürst

BTW how do you measure TAS?

There are two ways I use.

One is to take the CoD C# Parameter Z_VelocityTAS for TAS which I have been doing because I was finding the calculated value to be fair bit off the game parameter (which I have now fixed and is very close to game paramater now, see second method below).

The second method is to calculate from the IAS (I_VelocityIAS), converting through Pressure Altitude, i.e. adjusted from actual baro pressure to Standard Day Pressure and then to Density Altitude which adjusts it again taking into account actual Temperature vs Standard Day Temp.

Formulas are here:
http://williams.best.vwh.net/avform.htm#Altimetry

See "Relationship of pressure and indicated altitude:" for Pressure Altitude
and
"Relationship of pressure and density altitude:" for Density Altitude.

My full method is here:
http://forum.1cpublishing.eu/showpos...6&postcount=10

.....although I have tweaked the .cs file since then simply to correct the calculated TAS. I'll try to replace the zip file over the weekend. I'm currently working on a Bf109 set.

Beware of the indicated airspeed C#parameter Z_VelocityIAS as it seems to be wrong and far too close to Z_VelocityTAS even at altitude.

[Kodoss]

from "Radinger, Schick, Otto: Messerschmitt Bf109" Aviatik Verlag

V-15
BF-109, W.Nr. 1773; D-IPHR
Engine DB-601A, W.Nr. 140 with one-stage compressor [4km full pressure] (einstufiger Lader, 4km Volldruckhöhe), 1100 PS
VDM-Verstellschraube with 3,10m diameter
400l fuel tank
armory: 2MG 17 in fuselage, 2MG 17 in wing

Half hour flight on 4. Feb. 1938 in Augsburg and tested at the same day in Rechlin.
In April back in Augsburg and used as prototype for Bf-109 T-series wing tests.

interesting is that that both prototypes suffered power loss in full pressure height.
V15: 146PS in 3900m height tested on 6. 7. and 9 May 1938
V15a: 200PS 26. April 1938
How this problem was solved is unknown to the authors since there is no report.


EDIT: By the way L.Dv.556/3 says for E-1, E-3

height / Max. Speed
0 km / 460 km/h
1 km / 480 km/h
2 km / 500 km/h
3 km/ 520 km/h
4 km / 540 km/h
5 km / 555 km/h
6 km / 555 km/h
7 km / 550 km/h

Max. allowed horizontal speed at SL 485 km/h

Engine: DB-601A (full pressure height 4 km)
at SL:
1min. power 1175 PS at 2500 rev/min
5min. power 1015 PS at 2400 rev/min
30min power 950 PS at 2300 rev/min
continuous power 860 PS at 2200 rev/min

power in height:
5min. power in 3,7km 1100 PS at 2400 rpm
continuous power in 4,1km 1050 PS at 2400 rpm
continuous power in 4,5km 1000 PS at 2400 rpm
economic continuous power at 3,85km 975 at 2250 rpm

VDM-Verstellschraube 3,10m diameter

[*Buzzsaw*]

Originally Posted by Kodoss

from "Radinger, Schick, Otto: Messerschmitt Bf109" Aviatik Verlag

V-15
BF-109, W.Nr. 1773; D-IPHR
Engine DB-601A, W.Nr. 140 with one-stage compressor [4km full pressure] (einstufiger Lader, 4km Volldruckhöhe), 1100 PS
VDM-Verstellschraube with 3,10m diameter
400l fuel tank
armory: 2MG 17 in fuselage, 2MG 17 in wing

Half hour flight on 4. Feb. 1938 in Augsburg and tested at the same day in Rechlin.
In April back in Augsburg and used as prototype for Bf-109 T-series wing tests.

interesting is that that both prototypes suffered power loss in full pressure height.
V15: 146PS in 3900m height tested on 6. 7. and 9 May 1938
V15a: 200PS 26. April 1938
How this problem was solved is unknown to the authors since there is no report.


EDIT: By the way L.Dv.556/3 says for E-1, E-3

height / Max. Speed
0 km / 460 km/h
1 km / 480 km/h
2 km / 500 km/h
3 km/ 520 km/h
4 km / 540 km/h
5 km / 555 km/h
6 km / 555 km/h
7 km / 550 km/h

Max. allowed horizontal speed at SL 485 km/h

Engine: DB-601A (full pressure height 4 km)
at SL:
1min. power 1175 PS at 2500 rev/min
5min. power 1015 PS at 2400 rev/min
30min power 950 PS at 2300 rev/min
continuous power 860 PS at 2200 rev/min

power in height:
5min. power in 3,7km 1100 PS at 2400 rpm
continuous power in 4,1km 1050 PS at 2400 rpm
continuous power in 4,5km 1000 PS at 2400 rpm
economic continuous power at 3,85km 975 at 2250 rpm

VDM-Verstellschraube 3,10m diameter

Salute

Thanks for the information, your books quotes for horizontal speed of E1 and E3 types agree with this test approx. time period of E-1/E-3 production, as per this table:



I am not convinced there were two aircraft, each would typically be numbered differently if the system used in the numbering of all the other prototypes was followed. It seems more likely, the designation 'a' might mean the same plane with a different engine installation or some other equipment.

The fact V15 was being used as a test bed for a potential 109T model in April at the same time as Kurfurst's test, is a likely indicator of why its performance envelope in that test was completely different than a standard E model and why speeds were so high at sea level. Carrier borne fighter aircraft require more performance at lower altitudes, the final 109T was built with the DB601N engine using higher octane fuel, not with the DB601A using the standard 87 octane variety. With the note that the engine was allowed to rev to 2500 rpm, not standard in the DB601 in this time period, see table below, it may be there was an attempt to gain power at takeoff and at lower altitudes. Whether or not V15 was being tested with higher octane fuel is a question which needs to be answered.



In any case, the fact seems to be that V15's test was not representative of a standard E-1.

[Robo.]

Originally Posted by 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.

There was a theory that the Aa low alt performance (take-off HP) was desirable for the JaBo variants and therefore Aa DBs were primarily used for /B variants. Only 25% 601s were Aas. This theory is supported by the fact that every JaBo 109 examined after being shot down has had Aa engine (AND the bomb rack installed.) I am aware that this is just a theory and it is not mine after all, but it makes sense.

Maybe you are right and the numerous engine overhauls would cause for majority of the later BoB Emils flying with Aas despite the lower overall number of 601 made (e.g. one airframe could have several engines installed during its lifespan). What we have now is a DB 601 with A-1 FTH and Aa rating, that is certainly incorrect.