109 e4 performance

[Crumpp]

There is certainly some changes from the early 1939 data.

I really don't think development was static in Germany for 18 months before the Battle the Britain.

If the Höchstzulässige Horizontal-Bodengeschwindigkeit (Maximum horizontal ground velocity) is 485km/h, how can the max speed at 0km be 500kph?

There are other ratings the engine was approved besides climb and combat power....

We know for a fact, C3 fuel was in use during the Battle of Britian.....

Automatik propellers (CSP) also were used during the Battle of Britian that were not in use in February 1939 as the the other data is dated.

Pick your poison....

We don't know the exact conditions, perhaps it is the performance with the automatik propeller?

[Crumpp]

My opinion is that manufacturer's data should be considered as on the optimistic side.

Noted and accepted.

For the discussion, what is your aviation experience and background. Not that your opinion is not valid, just so we all know where it is coming from.

[Robo.]

Originally Posted by Crumpp

Noted and accepted.

For the discussion, what is your aviation experience and background. Not that your opinion is not valid, just so we all know where it is coming from.

Of course it is valid, you're extremely kind to take it in account Much appreciated.

Now tell us how do you think the E-4 performed like.

[Kwiatek]

C3 fuel was used only in Db601N engines not in DB601.

Also automatic prop pitch for 109 E didn't change its maximum speeds.

So i think all difference at sea level speed is in radiator settings and type of engine - Db601 A or DB601 Aa which had more power at the lower alts then 601A and surly difference in tested planes.

[Al Schlageter]

Originally Posted by Crumpp

There are other ratings the engine was approved besides climb and combat power....

We know for a fact, C3 fuel was in use during the Battle of Britian.....

Automatik propellers (CSP) also were used during the Battle of Britian that were not in use in February 1939 as the the other data is dated.

Pick your poison....

No kidding!!!

If the speeds for Steig/Kampfleistung (1.23ata) are not met by the game 109 then there is certainly a problem with the speed of the game 109. Speeds should be check for Start/Notleistung (1.30ata) as well.

The Bf109E-1, -3, -4 with DB601A engines DID NOT use C3 fuel. They used B4 fuel. Only 109Es with the DB601N engine used C3 fuel. C3 fuel was scarce, unlike British 100 octane fuel, and was only at certain bases. The DB601N engine was not that reliable as was the quality of the c3 fuel.

Oliver Lefevre (109 guru):

"The Speed curve which appear in the Export manual" (Yugoslavia) "seems to have been made up... Keep in mind that it was an Mtt manual not an RLM one and that it was for export."

On 1.4 ata usage

"The technical documentation is quite clear that it should not be used at high altitude, that it put some extra strain on the engine and that only in cases were take-off run was an issue should it be used. This was primarily designed for fighter/bombers and bombers carrying heavier load on take-off, keep in mind that the 109 was not the only a/c relying on the 601."

On Bf109E production numbers

"Here is the data i have based on production blocks, there is probably some innacuracy in the E-7 / E-7/N and E-7/Z department...

E-1 = 1086
E-1/B = 107
E-3 = 1406
E-4 = 250
E-4/N = 20
E-4/B = 212
E-4/BN = 15
E-5 = 29
E-6/N = 9
E-7 = 419
E-7/N = 3
E-7/Z = 17
E-8 = 60
Total = 3633"

The Russian testing was with a DB601Aa engine powered Bf109E.

[Crumpp]

So basically the French achieved 494 kph at 600 m with rpm 2400 and 1.303 atm pression d'admission
Extrapolating pessimistically to 0m they got 478 kph with rpm 2400 and 1.289 atm pression d'admission

Quick ballpark of the data to standard conditions….

478 kph TAS x 0.539956803 nautical miles at +5C = 258KTAS

We don't have a piece of the puzzle which is the atmospheric pressure for that day. I am not looking for it but if somebody finds it, I will refine the calculation.

258KTAS x 1.0299 SMOE for our density altitude Temperature difference = 265 KTAS

265KTAS / 0.539956803 = 492kph

492 kph is within 1% of Mtt stated mean of 500kph over a range of 5%.

If we had the pressure and I wasn't using some quick rules of thumb of a standard atmosphere chart but did the full calcs, I bet it would give even better agreement. The French might have had an optimistic performing Bf-109!!

The French test results give very good agreement with Mtt's published figures for the type.

[Crumpp]

"Intake pressure".

1 ata is a technical atmospheres (at = technical atmosphere, a = absolut) and 1 at equals 735mm HG. Which makes 990mm 1.35 ata.

1 atm is a physical atmosphere and 1 atm equals 760 mm HG.

Some experts can't tell the two apart and come up with 1.28 ata for 980mm, which is wrong.

Well please, read the French report and enlighten us as to what units the French are using for pressure....

If you are as smart as you think then Google French units of measure.

While the French did use metric, they had their own unique system.

http://en.wikipedia.org/wiki/Units_o...ment_in_France

I don't know what they used but it is not the German Technical Atmosphere and the test was not flown at a 5 minute rating for the duration.

Pffft.....back to ignoring you until you have something to contribute.

His reply was on a bad tone but he might be right with respect of atm being not equal to ata. I myself was not sure if atm = ata that's why I used atm for my calculation.

Unfortunately there is little information about the outdated ata but 1 at (technichal atmosphere = pressure produced by a column of 10m water) is equivalent to 735.56 torr (almost identical to 735.56 mmHg). ata is with a reference point of 0 (I assume 0m that is sea level), so this would be the pressure produced by a 10m column of water at sea level. That's what wiki told me.

I am quite sure they used the ata gauge in the plane to measure it and then translated it into mmHg.

There is one minor uncertainty with respect to the French measurement of the manifold pressure however. The mmHg values depend on the knowledge of the density of mercury. This knowledge may have evolved since ww2 so there is a slim risk that they used a different mercury density for their mmHg units. However I think there is quite a weak chance that knowledge on density of mercury evolved so much that the mmHg values would be impacted by this to the precision that is of interest here.

So basically the French obtained 494 kph at 600m with 2400 rpm and 1.346 ata.
Extrapolating pessimistically to 0m they would have obtained 478 kph at 0m with 2400 rpm and 1.332 ata.

The ingame performances are still enormously off these values.

[Crumpp]

So basically the French obtained 494 kph at 600m with 2400 rpm and 1.346 ata.

Where do get that? The French NEVER used the German technical atmosphere.

The French were instrumental in forming the ICAO in 1912 and adopting a standard atmospheric model of that organization, the ISA.

The ISA uses 760mm as 1 ATA.

Once more, the 1.28 corresponds to the 1.3 ata rating. There is NO 1.35ata rating cleared for the DB601A according to any documentation I have seen.

[Crumpp]

So basically the French obtained 494 kph at 600m with 2400 rpm and 1.346 ata.
Extrapolating pessimistically to 0m they would have obtained 478 kph at 0m with 2400 rpm and 1.332 ata.

READ the report!! (You are not the only one either, I did not pay attention to some details either)

The limitations of their own instrument measurements:

Due to that, there is an uncertainity about the results. This uncertainty is about 2 to 3%. Thus maximum speed is 570km/h +/-15km/h.

The data is not converted standard conditions.

Nevertheless, during the level flight testing done under 5000 meters (external temperature = +6°C on ground
and -17°C at 5000 m.)

If you do convert it to standard conditions then the French conclusion is correct:

In general, the first tests made at the Center concerning the
Messerschmidt 109 appear to confirm the performances claimed by the
Germans.

http://kurfurst.org/Performance_test...formanceT.html