109 e4 performance

[Crumpp]

what the manufacturer would like to achieve

No it is NOT what the manufacturer would like, hope, might, or any other passive, obscure description.

As it is labeled, it is what the manufacturer guaranteed and what was accepted by the customer.

but does not say anything about the overall performance, especially top speed.

Sure it does. You do understand that these are complicated machines and they don't just roll off an assembly line into the squadron ready line.

A newly manufactured aircraft is one of the most dangerous things in aviation. It is unproven.

A very thorough inspection is completed before the first test flight. The manufacturer will put the aircraft thru a test flight period to ensure it reaches its numbers before turning it over to the customer who again goes thru their own prescribed regiment of test/inspections before accepting it.

When an airframe reaches the end of the assembly line, it was not uncommon for it to remain there for a month or so as it was tweaked and refined before being accepted.

Undercarriage tests followed before the aircraft was lowered onto its wheels and rolled out of the final assembly hall. It was then led to the firing stand to test its weapons and also for centring the compass on the rotable compass adjustment stand. After fuelling, and a last check of all functions, the engine was subjected to a test run, whereafter the Bf-109 stood ready for a works flight. In the initial test flight it was climbed to 8,000m (26,250ft), the aircraft and the engine was thoroughly checked out and performance data compared with that required. In the event that faults were found, these would be recorded and eliminated after the landing. This was then followed by a works test flight in which it could be established how many of the faults had been rectified. Where no further faults were determined on this flight, the aircraft was then release for acceptance by the BAL. In Regensbug, several pilots (Obermeier, Lohmann and others) were authorised by the RLM to carry out Bf 109 acceptance flights for the BAL. After their acceptance by the BAL, the aircraft were then taken over by the Luftwaffe.

Nest of Eagles: Messerschmitt Production and Flight-testing at Regensburg 1936-1945", de P. Schmoll, Classic Publications (2010).

[Crumpp]

There were 2 types of engines used by LW - Db601A and DB601Aa which had little different power output.

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.

Otherwise we would have to believe that Germany exported more powerful engines than they used in their own aircraft. That does not make any sense and would be a first in the history of the world.

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

[Al Schlageter]

Auszüge aus Flugzeugdatenblatt (aircraft data sheet) Bf 109 E-1, E-3 nach L.Dv.556/3 @ http://www.rolfwolf.de/daten/E4/Emil.html

Motorleistungen DB601A

Kurzleistung (1 min) 1100PS bei 2400 U/min 1.4 ata

Startleistung 990PS bei 2400 U/min 1.30 ata

Steig/Kampflleistung 910PS bei 2300 U/min 1.23 ata

Volldruckhöhe 4000m

How do the speeds match for:

Höchstgeschwindigkeiten in Steig/Kampfleistung

0km - 460km/h

1km - 480km/h

2km - 500km/h

3km - 520km/h

4km - 540km/h

5km - 555km/h

6km - 555km/h

7km - 550km/h

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

[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.

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.



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.

[Robo.]

Originally Posted by Crumpp

No it is NOT what the manufacturer would like, hope, might, or any other passive, obscure description.

As it is labeled, it is what the manufacturer guaranteed and what was accepted by the customer.

In perfect world: sure. In our world and especially during the war: no.

Again - 500 +- 5% means they tried to achieve 500 but it was more likely that most of the time, they made it closer to the -5% in so called real life. I am not saying that they were failing to stay within margins.

Originally Posted by Crumpp

Sure it does. You do understand that these are complicated machines and they don't just roll off an assembly line into the squadron ready line.

Oh yes, please read again what I wrote before, thank you.

Originally Posted by Crumpp

A newly manufactured aircraft is one of the most dangerous things in aviation. It is unproven.

A very thorough inspection is completed before the first test flight. The manufacturer will put the aircraft thru a test flight period to ensure it reaches its numbers before turning it over to the customer who again goes thru their own prescribed regiment of test/inspections before accepting it.

When an airframe reaches the end of the assembly line, it was not uncommon for it to remain there for a month or so as it was tweaked and refined before being accepted.

Of course, I don't disagree at all, this is all well known facts and we can go as far as comparing the later 109 models leaving various factories. Of course there was a difference and variation in real life. The question is what data to use in order to have the a/c close to the real life performance. My opinion is that manufacturer's data should be considered as on the optimistic side.

[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.

[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.

Originally Posted by Kwiatek

....

Quite close with tested captured 109 E-3 by French :

You all realize that the French test obtained about 494 kph at 600m altitude and in extrapolating to 0m something around 480 kph? At rpm = 2400.

The pression d'admission about 1000 (unit I cannot read). My guess is that they speak here of ATA pressure. Just not sure what kind of unit they used as I cannot decypher the scale label.

[Kwiatek]

Here is French 109 test raport :

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

We got from French test :

With radiator open

2.5 km - 490 km/h - 2400 RPM - 960 mm. ( 1.3 Ata)
5.0 km - 520 km/h - 2400 RPM - 870 mm.


With radiator close:

5.0 km - 570 km/h - 2400 RPM - 880 mm.

There is 50 km/h difference between radiator open and close at 5 km alt.

In chart there is about 475-480 km/h at 2400 RPM at 1000 mmHg which mean that test was done at ab. 1.35 Ata - probably radiator somewhere in the middle position (looking at 5 km maxiumum speed - 550 km/h) so with higher ATA then in previous data ( 1.3 Ata - 460-467 km/h).

So it confirmed previous data for E-3

1.3 Ata

0- 460-467 km/h - depend of radiator settngs, and sort of plane

1.4 Ata (Db601A) - about 485-490 km/h

1.45 Ata (Db601Aa) - 500 km/h.

109 E-4 would be little slowier then E-3 beacuse of more draggy windscreen - it could be about 5 km/h slowier ( the same E-3 with new windscreen)