109 e4 performance

[robtek]

When i read the tenor of some the posts here, i really wonder if there would be the same energy afforded to downgrade the vmax. of the Spit Ia.

[CaptainDoggles]

Originally Posted by robtek

When i read the tenor of some the posts here, i really wonder if there would be the same energy afforded to downgrade the vmax. of the Spit Ia.

People get emotionally invested in their favourite plane and/or its traditional adversaries.

[robtek]

Facts vs facts would be much easier, opinion vs fact or vice versa is a neverending story.

Originally Posted by Robo.

Can you please convert 990 mmHg to ata for us please

I know a bit French and atmospheric pressure is pression atmosphèrique (et non pression d'admission comme on peut lire en bas d'echelle) - even for engineers. Perhaps with some poetic freedom they would have written pression ambiante. It is however written pression d'admission and this is a technical term. I checked and the most suitable translation are inlet pressure or manifold pressure.

See translation here:
http://dictionary.reverso.net/french...'admission.

I have no clue what exactly they address here as pression d'admission and of course this is open to debate. I am however quite sure that they don't mean atmospheric pressure. Perhaps a Frenchman could tell if one is around?

EDIT: My calculator sais that 980 mmHg = 1.289 atm (=ata?)
and 990mmHg are 1.303 atm

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

[CaptainDoggles]

Originally Posted by 41Sqn_Stormcrow

Perhaps a Frenchman could tell if one is around?

Je ne suis pas "Francais" mais bien sur je suis Canadien. "Pression d'admission" veut dire "Manifold Pressure". Il ne fait aucun doute.

Pour "atmospheric pressure" je dirais "pression atmospherique".

EDIT: My calculator sais that 980 mmHg = 1.289 atm (=ata?)
and 990mmHg are 1.303 atm

Yep. 990 mmHg (torr) is equal to ~1.32 bar or ~1.303 atmospheres (ATA on the German gauges).

[Crumpp]

990 mmHg mainfold preassure is 1.34 Ata

Yep, I read the doc and converted 980mm. Later I confused it with the 990mm he was asking about.

Facts vs facts would be much easier,

Of course. Who cares about opinions? I have one, you have one, and everyone knows what they are like....

Facts are the engineer firm of Mtt entered into a contract to deliver the stated performance. The customer (RLM) held that firm accountable and tested each airframe delivered to ensure it met the contractual agreements in place.

Works the exact same way in today's aviation marketplace!!

[JtD]

Originally Posted by CaptainDoggles

pression d'admission

"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.

[Kurfürst]

Originally Posted by Kwiatek

500 km/h could be probably reached with DB601Aa motor which had 1175PS power output at sea level at 1.45 Ata 2500 RPM.
a
These is 75 PS more then with 601A ( 1100 PS).

Also these data above is probably for old supercharger (4.0 km FTH).

There are data where 109 E-3 reached - 467 km/h at deck - so a few km/h more, so probably also maximum speed ( at 1.4 Ata) would be little higher then 485 km/h - about 490 km/h. It could be difference in radiator position.

http://www.wwiiaircraftperformance.o...109e3-1792.jpg

Regarding the 1792 serial number Bf 109E-3 trials you posted, note the following note by the tests makers at the bottom for 467 km/h:

"These speeds has been corrected for normal (standard) temperature, and correct manifold pressure regulator settings (I guess that is the German way of saying: nominal boost) but not for the guaranteed (ie. nominal) output of the engine."

In other words, this test is for unknown power from the engine. All engines vary in output, sometimes quite considerably, and this would effect results. I would hazard to guess that the airframe may have been a poor one (remember: 500 km/h means anywhere between 475 and 525 is okay for service acceptance), and the airframe may have been a bit down on power.

Here's for example another Emil tests, showing the performance with the engine slightly down on power (developing 45 horsepower less than it should, lower figures) and corrected to nominal engine output (higher figures). This is actually the only test I've seen where anybody measured the used engine's output on a engine test bench.

With the sligthly down-on-power state for the DB 601Aa engine we have in the sim, this Bf 109E (V15a prototype actually, but its identical to the serial E-1 model), radiator 1/4 open, they got 493 km/h at 0m, and correcting the figure for the nominal full power output, 498 km/h.



Also 1.3ata is for the 601A-1 engine, the 500 km/h speed is understood for the slightly more potent 601Aa (though I do not believe, based on tests, that the difference would be greater than 10 kph at low level). So for an airframe just hitting the 475 km/h bottom of the acceptance limit, and having the bit less powerful 601A 467 km/h seems quite understandable.

Note though - COD seems to have choosen to model the DB 601Aa version for the Emil.

However this would represent a sub-standard aircraft. There were such, of course, but it begs the question, why would the premiere LW fighter aircraft of 1940 would be represented as a sub-par example, while RAF fighters using the performance of avarage good planes....?

Especially as the new COD engine is capable of simulating wear and such.

These is power output with newer supercharger which rised maximum speed at FTH - with old there was 555 km/h with new one it was 570 km/h.

I don't think so, the French trials of 1304 confirmed the 570 km/h top speed (and I believe it wasn't even full 1.3ata at altitude), and it is known for certain that 1304 had the old type supercharger.

[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.