Spit IIa is now so much more inferior to the 109

[41Sqn_Banks]

Originally Posted by Kwiatek

There is definilty bug in SPitfire MK II engine.

According to manual Spit MK II should have power settings:

- climbing power (30 minutes) - +9 lbs at 2850 RPMs
- max all level (5 minutes) - 9 lbs at 3000 RPMs

In Clod there is engine broken after flying at +6 1/2lbs at 2850 RPMs after ab. 10-15 minutes continous flying

If you apply +9 lbs at 2850 RPMs you could fly ab. 2-3 minutes then engine broke.

It is not correct that you cant even fly 30 minutes at 6 1/2 lbs 2850 RPMs if you should be able to fly such time with +9lbs 2850 RPMs.

Other hand Bf 109 E could fly all time at 1.35 Ata power settings without problem if it was only 5-minutes emergency power.

I don't know if you had a look at the merlin em files so far. I've looked at them a year ago, so maybe this has changed, but at that time the Merlin III and XII were very identical. The nominal rpm was 2600 RPM for both. I assume that normal rpm is the value that can be maintained without critical overheat.
My impression is that the Merlin XII - as we have it know - is modeled more like a Merlin III running 100 octane (with +8? instead of +12 emergency boost).

[Kwiatek]

Originally Posted by 41Sqn_Banks

I don't know if you had a look at the merlin em files so far. I've looked at them a year ago, so maybe this has changed, but at that time the Merlin III and XII were very identical. The nominal rpm was 2600 RPM for both. I assume that normal rpm is the value that can be maintained without critical overheat.
My impression is that the Merlin XII - as we have it know - is modeled more like a Merlin III running 100 octane (with +8? instead of +12 emergency boost).

Hmm i didnt look at emd file for CLod yet. But if it is true like you said so there is obviously error in engine data which probably casue problem with Merlin XII power limiation in game.

Luckly i checked today spitfireperformacne site and i found interesting data for Merlin III at 87 octan fuel which i didnt see before:



So for Merlin III at 87 octan fuel we have:

max take off - +6 1/4 at 2850 RPM
climbing - +6 1/4 at 2600 RPM
All-out level flight - +6 1/4 at 3000 RPM

With 100 Octan fuel modification Merlin III power settings was rised to:



So with Merlin III at 100 Octan we have:

take off - +6 1/4 at 3000 RPM
1/2 hr climbing - +6 1/4 at 2850 RPM ( below 20 000 ft) and at 3000 RPM (above 20 000 ft)
all-out level flight - +6 1/4 at 3000 RPM ( 5 minutes)
emergency power - +12 lbs at 3000 RPM ( 5 minutes)


Of course for Merlin XII nomial RPM should be 2850 not 2600 the same like with Merlin III at 100 Octan fuel.

[41Sqn_Banks]

Originally Posted by Kwiatek

So for Merlin III at 87 octan fuel we have:

max take off - +6 1/4 at 2850 RPM

...

So with Merlin III at 100 Octan we have:

take off - +6 1/4 at 3000 RPM

It's interesting to note that publications from 1938 and 1939 give maximum take-off engine speed of 2850 rpm for both Merlin II and III. Publications from 1940 give 2850 for Merlin II and 3000 rpm for Merlin III. The increase is not associated with the use of 100 octane fuel.

[Kwiatek]

Originally Posted by 41Sqn_Banks

It's interesting to note that publications from 1938 and 1939 give maximum take-off engine speed of 2850 rpm for both Merlin II and III. Publications from 1940 give 2850 for Merlin II and 3000 rpm for Merlin III. The increase is not associated with the use of 100 octane fuel.

Hmm interesting have you some documents with such Merlin power settings? I miss really manual ( pilot notes) for Spitfite MK1 and Hurricane MK1

[Crumpp]

from 1938 and 1939 give maximum take-off engine speed of 2850 rpm for both Merlin II and III

It also shows maximum boost at emergency power at 12,500ft as +10.55lbs at 3000 rpm for the Merlin III when you use boost override or pull the tit on 87 Octane.

Absolutely NOTHING to do with the use of 100 Octane fuel.

[Kwiatek]

Originally Posted by Crumpp

It also shows maximum boost at emergency power at 12,500ft as +10.55lbs at 3000 rpm for the Merlin III when you use boost override or pull the tit on 87 Octane.

Absolutely NOTHING to do with the use of 100 Octane fuel.

Yep it is also interesting

[Crumpp]

Yep it is also interesting

I thought something like this might be discovered when I saw the 1937 instructions for boost cut out in the RAF Training Manual......

[41Sqn_Banks]

Actually this is not the emergency power rating, these are the results from the power test to determine to performance of the engine.
As +12 boost has a FTH of 10,000 feet this is the power achieved with throttle valve fully open.

[Ernst]

Originally Posted by Kwiatek

Yep it is also interesting

Are the SPITFIRE FMs at UP 3.0 RC4 yours?

[Crumpp]

The power figures on the engine Inspection and Test Certificate come from "test bed conditions", either at RR, RAE or the dynamometer at AAEE, i.e. the engine wasn't even mounted in an airframe and the engine surely wasn't running at 12,500 feet without an airframe.

Sure it was running at 12,500 feet on an altitude test stand.