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Old 14th January 2005, 18:50
Anders Jonsson Anders Jonsson is offline
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Anders Jonsson
Inconsistancy in quoted Me 109 G6 performance?

Hi,

Does anyone know if the numbers stated for the Me 109 G6 performance below are correct?

Max speed 387 mph and sea level climb rate of 4560 ft/min?

I have seen the top speed figure quoted many times before and to be honest, I was always suprised that the top speed of the "Beule" was so low.

From a performance chart I have from Me works Augsberg, I read off 620 km/h at 6.7 km altitude. So this seems consistent. However, when I look at the climb performance I read off only 16.5 m/s which equates to only about 3257 ft/min. These numbers above are for the power setting "Steig und Kampfleistung".

The same Me Augsburg document gives a top speed of 637 km/h (396 mph) with "Start und Notleistung" but no climb performance numbers.

However, the power setting "Steig und Kampfleistung" was to my understanding what the DB 605 A engine was limited to during at least some part of 1943.

I have some questions based on the above:

1) There seems to be an inconsistancy in the quoted performance. Does the top speed refer to "Steig und Kampfleistung" and the climb rate to "Start und Notleistung" or have I missed something?

2) Was the "Start und Notleistung" setting for the DB 605 A engine ever released and made officially available?

3) Are there any accounts that pilots actually used the "Start und Notleistung" through field modifications by bypassing the "Steig und Kampfleistung" limit and if so, how frequent was this use?

Regards,
Anders
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Old 14th January 2005, 20:38
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Juha Juha is offline
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Hello I have time only for a short reply
The max speed depended on many variables and is always problematic and also varied from plane to plane.
2) IIRC after some internal strenghtening (for ex. pistons?) the "Start und Notleistung" power setting was allowed for DB 605A, at least in LW.
IIRC there was a switch in the cockpit which allowed the use of "Start und Notleistung" in Bf 109 G. It was ordered to be disabled before the internal strenghtening of engine was completed/a strenghtened engine was changed in place. And of course if one can disable a switch one can also enable it. But I have no knowledge that that was done against the order. Early DB 605As had enough reliability problems without someones intentionally overboosting them. All this info is unchecked, now I must spend a little time with my child.

Juha
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Old 14th January 2005, 23:25
olefebvre olefebvre is offline
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DB605 was cleared for 1.42ata operation in october/november 1943 following various enhancement to the original design.
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Old 15th January 2005, 11:37
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Juha Juha is offline
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Hello again
Finnish AF flew performance test on Messerschmitt Bf 109G-2 a/c code MT-215 on 5 Apr, 1943. The result was max speed 636km/h (TAS) at 6700m and c. 520km/h (TAS) at sea level. Climbtime to 7000m was 6'20" and to 5000m a little bit over 4min. I figured out the climb times from not a perfect graph, so some caution here. MT-215 was carrying full ammo and had 400l petrol at start.Tests were flown in "Steig und Kampfleistung". Radiator flap position had very big influence on speed and also on climb. Up to 50km/h at sea level. So at a warm day the figures were clearly worse.
I have for a long time suspected that the 386 or 387mph max speed was flown by a Bf 109G-6 night fighter with 20mm gun gondolas under wings, which had landed in error to Manston in May? 1944 (was that the plane that became TP814, a Bf 109G-6/U2 with 20mm gun gondolas under wings?). But I have no proof on that.

Juha
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Old 15th January 2005, 13:02
Anders Jonsson Anders Jonsson is offline
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Hi again,

Olefebvre, just to make sure I got it right: the clearence you menttion above to 1.42 ata is for the DB 606A series? I know other 605 variants were cleared for the higher boost pressure but I just want to make sure we are talking about the G6 engine?

Juha, I think you may be right about the gun gondolas but I do not know either. The document I referenced to above contains a chart showing the speed difference for a 109 K4 with and without gondolas. The speed difference is about 9.5 km/h at s/l and about 11 km/h at 9.5 km altitude and I guess the gondolas would have similar or less impact on a G6 considering that a K4 is a much cleaner a/c aerodynamically.

For the K4 the test figures are W=3330 to 3370 Kg without gondolas and W=3450 to 3570 Kg with gondolas. The G6 is pegged at 3350 Kg in the test but I have no detailed knowledge on G6 weights. Perhaps it can be deduced from the weight stated if this is with or without gondolas but since fuel status and other variables are not given in the chart I do not know. Perhaps someone in this forum can help out here?

Regards,
Anders
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Old 15th January 2005, 16:23
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Juha Juha is offline
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Hello
nothing very noteworthy but in RAF Yearbook 1975 E. Brown writes that he clocked 384mph(618km/h) at 23,000ft (7 010m) when he flew a Bf 109G-6/U2 that had landed in error at Manston on 21 July 44. I think this was the plane that became TP814 and in the photos I have seen on it it had gun gondolas. Also in the article Brown writes that he used in take-off 1.3 atas boost. So probably he also used same boost when he checked the max speed

Juha
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