109e vrs Spit 1

[gripen]

Andy,
IMHO that F-4 chart is more clear and thats the way I prefer it, no need to argue about that. Anyway, the F-4 and MiG-21 are that conventional fighters which could not maneuver outside conventional flight envelope. I mean planes like the F-16 which can do stalled maneuvers (outside conventional flight envelope).

gripen

[HoHun]

Hi MW,

Sorry for the late answer - I spent quite some time trying to convert the Me 109's wing loading in lbs/sq ft to boost pressure in ata. It took me a while to realize ... ;-)

>Perhaps more relevant would be the 1200 B.H.P at 12,000 ft. posted.  Does this seem correct to you?  

Actually, it seems to be a bit too much :-) The DB601A engine chart I've seen (undated - might be 1937 numbers) says 1005 HP at that altitude. Take-off power was 1100 - 1200 HP with a maximum altitude to 500 - 1500 m. This was limited to 60 s - enforced by a clockwork timer.

(I don't think the RAE actually bench-tested the engine, so it may be a nominal value anyway.)

>I'm surprised no one picked up that the Spit was only running at +6.5 lbs/sq. ft.  Running at +12 lbs. with 100 octane fuel would increase the power of the Merlin III by about 25% at 12,000 feet, according to the engine charts I have.   Now that would make a difference

The Me 109E and the Spitfire I/II were subject to constant modifcations. Do you think it would be possible to recognize the exact equipment and engine status of the tested Spitfire from the weight and power data?

From the use of +6.5 lb/sq. in. (sq. ft. is for wing loadings, ask me :-), I'd say that the Spitfire was in the condition prior to the release of 100 octane fuel in March 1940?

Regards,

Henning (HoHun)

[mw]

Sorry HoHun, but something must be getting lost in the translation.  I think your criticism is that I mistyped ft. for lbs.?  If so you'll be pleased to know that the the bloke who drafted the chart made an error when he wrote B.H.P - 1200 on the 109 portion of the chart. The text of the reports show 1100 hp as max power at 2400 RPM at 12,000 ft.

>Do you think it would be possible to recognize the exact equipment and engine status of the tested Spitfire from the weight and power data?

Well, yes, in allot of cases for Spitfires I could.  Of course I have all the reports that show condition of planes and weights and loading, so  I'm somewhat familiar with the numbers and they have meaning to me.

Frankly the +6.5 lbs/sq.in. is in white on black in the chart.  Sorry, but is was just so obvious to me.  Futhermore, two reports I have with that first curve specify that fuel used was 87 octane.  I apologize for not sharing that information earlier. It wouldn't have changed the basic premise that the Spit I could out-turn a Me 109E though.

All this doesn't alter my view that it likely wasn't the 109 that was not "entirely up to the manufacturer's specifications with regard to power", but rather its a certainty that BoB Spit Is had more power than that chart shows.

"The Me 109E and the Spitfire I/II were subject to constant modifcations."  Yes they were. The charts are an interesting snapshot in time.  I know the 109E7 had more power as did the Spit II.  But I've no interest playing that game out.  I should think that what would be of the most interest to people on this board would be representative performance of the BoB era varients.  I can shed some light on that, but guess what...I dont have all the answers myself.

[mw]

Hi again HoHun:

>I spent quite some time trying to convert the Me
109's wing loading in lbs/sq ft to boost pressure in ata. It took me a while to realize ... ;-)

I wasn't sure if you were being serious or not with that comment.  The following info may be of interest and may, or may not, help your case:

Top Level speed 109:

355 m.p.h. at 16,400 ft., 2400 r.p.m. +2.3 lb/sq.in. boost pressure.  Radiators closed.

From another report:
Take-off power:  1175/2500
Rated h.p. at 2400 r.p.m. at 3.75 lb/sq.in. boost pressure at 15,000 ft. : 1100
Power loading: (lb/b.h.p) 5.07
Wing Loading: 32.1

[Vermillion]

MW, I noticed you've been posting here alot more recently.

Nice info and flight test data you keep posted on your website.

You flying here now?

[gripen]

There are several versions of RAE Bf 109 reports around, mw'sversion seems to be from the PRO. After war Aeronautical council published huge amount of RAE reports and these versions are very clear  and neat. Luckily they published Bf 109 report too and it should be easy to find  a copy from technical libraries around  Britain, mine is ordered from the British library.

gripen

[HoHun]

Hi MW,

>I think your criticism is that I mistyped ft. for lbs.?  

No, I really, honestly mistook the wing loading value for the boost pressure and got confused by that. I noticed your typo meant that you came close to making the same mistake, but unlike me managed to avoid it :-)

>The text of the reports show 1100 hp as max power at 2400 RPM at 12,000 ft.

Ah, that seems more likely. As I said, my engine chart indicates even less than that, but it's not dated, and I guess it's possible the engine got uprated to the values indicated in the report.

>Sorry, but is was just so obvious to me.  Futhermore, two reports I have with that first curve specify that fuel used was 87 octane.  

Roger on 87 octane, it leaves a lot of potential for the Spitfire.

>I should think that what would be of the most interest to people on this board would be representative performance of the BoB era varients.

Certainly! That's why I'm asking for the exact configuration - the Spitfire was in a pre-Battle of Britain configuration obviously, and (not knowing the date of the report), I'd imagine that the Me 109E probably was captured and tested before the Battle of Britain as well, or they'd have used a Spitfire running on 100 octane as reference.

Regards,

Henning (HoHun)