109E-4 Speed

[Wotan]

Here's the tests I did of the AH2 109E-4

109E-4 100% fuel 2 x 20mm / MGFF 60 RPG, fuel mod set to lowest value.

SL

Military Power – SL 37.6 MP @ 2400 RPM = 285 MPH

Emergency Power – SL 40.5 MP @ 2400 RPM = 292 MPH

5k

Military Power – 5000 FT 37.6 MP @ 2400 RPM = 304 MPH

Emergency Power – 5000FT 40.5 MP @ 2400 RPM = 311 MPH

10K

Military Power – 10000 FT 37.6 MP @ 2400 RPM = 323 MPH

Emergency Power – 10000 FT 40.5 MP @ 2400 RPM = 330 MPH

15K

Military Power – 15000 FT 37.6 MP @ 2400 RPM = 341 MPH

Emergency Power – 15000 FT 40.5 MP @ 2400 RPM = 344 MPH

MP falls off drastically at 20k. WEP adds no MP boost but the E-4 gains about 3 mph.

20K

Military Power – 20000 FT 32 MP @ 2400 RPM = 329 MPH

Emergency Power – 20000 FT 32 MP @ 2400 RPM = 332 MPH

22.5K

Military Power – 22500 FT 28.5 MP @ 2400 RPM = 320 MPH

Emergency Power – 22500 FT 28.5 MP @ 2400 RPM = 323 MPH

Here's the most "prolific" DB601A numbers I have found:

DB601A-1

SL@1100PS@2400rpm@1.40ata (1' minute)
SL@990PS@2400rpm@1.30ata (5' minutes)
SL@910PS@2300rpm@1.23ata (30' minutes)
SL@810PS@2200rpm@1.15ata

4.5km@1020PS@2400rpm@1.30ata (5' minutes)
5.0km@960PS@2400rpm@1.23ata (30' minutes)
5.7km@890PS@2400rpm@1.15ata

4.9km@860PS@2200rpm@1.15ata
5.5km@800PS@2200rpm@1.10ata

10km@500PS@2400rpm@0.70ata

The AH2 109E-4

@ Emergency Power = 40.5 MP @ 2400 RPM

converted to ata=

40.5 / 28.96 = 1.398ata (rounded 1.40ata)

Mil Power = 37.6 MP @ 2400 RPM

37.6 / 28.96 = 1.298ata (rounded 1.30ata)

The AH2 109 Emergency Power (40.5; 1.40ata) can run for 5 min.

@ "Military Power" (37.6; 1.30ata) runs unlimited.

Hohun posted this chart (based on his calculation I assume) in the Spit 1 speed thread.

http://www.x-plane.org/users/hohun/spit_vs_me109_speed.gif

Hohun's chart

SL

1.23 ata (35.5 mp) @ 2300rpm = 465km/h (289mph)

1.30 ata (37.6 mp) @ 2400rpm = 480km/h (298mph)

4500m

1.23 ata (35.5 mp) @ 2300rpm = 556km/h (345mph)

1.30 ata (37.6 mp) @ 2400rpm = 574 km/h (357 mph)

AH2

SL

37.6 MP (1.30ata) @ 2400 RPM = 285 MPH (458km/h)

40.5 MP (1.40ata) @ 2400 RPM = 292 MPH (470km/h)

15K

37.6 MP (1.30ata) @ 2400 RPM = 341 MPH (548km/h)

40.5 MP (1.40 ata) @ 2400 RPM = 344 MPH (554km/h)

Since I am wholly unqualified to explain the differences I was hoping some one could help me out.

Is the AH emergency setting 1.40ata (40.5mp) or really 1.30ata? If so theres still a difference in speed that grows the higher up we go.


TIA

[HoHun]

Hi Wotan,

>Since I am wholly unqualified to explain the differences I was hoping some one could help me out.

First, let me point out that my diagram actually lists two different DB601A-1 engined versions of the Me 109E, one with the early "DB601A-1 (4.0 km)" - as I've called it for lack of a better designation - and the Battle-of-Britain era "DB601A-1 (4.5 km)".

The difference between these is the full throttle height, which is the bracketed value.

>Is the AH emergency setting 1.40ata (40.5mp) or really 1.30ata?

In real life, it seems that the 1.40 ata setting was never implemented. I've seen mention of the 60 s limit being enforced by a clockwork timer, but it appears that never made it into the Me 109E.

The Aces High settings seem to be OK with regard to the time limits, but the nominal boost appears to be off. Though the 5 min setting at sea level had a higher rpm than the 30 min setting, it appears that above full throttle height, 2400 rpm were allowed indefinitely. Accordingly, the small difference between Climb Power and WEP at high altitude might be correct.

(Maybe it's actually identical, and you measured Climb Power top speed before the aircraft had achieved full speed?)

>If so theres still a difference in speed that grows the higher up we go.

Hm, 520 km/h @ 6.9 km indeed seems very slow to me for a Me 109E with either engine.

Regards,

Henning (HoHun)

[gripen]

Well, according to HoHun's graph the Bf 109E with the DB 601N  at 2400rpm could reach over 560km/h at 10000m. As for comparison the Kennblatt of the Bf 109F-1 and F-2  gives 520km/h (2400rpm) and 540km/h (2600rpm) at 10000m with the DB 601N. Go figure.

gripen