[camber]

Originally Posted by Crumpp

What data are you looking at camber?

The B6 data was that posted by B6 (1c representative) about the post-beta patch CloD performance in this thread (i.e. sim not historical data):

http://forum.1cpublishing.eu/showthread.php?t=31450

Originally Posted by Crumpp

If it is this:

http://www.spitfireperformance.com/n3171.html

Then you are not at the same engine settings as this data. This data is 6.5lbs @ 3000 rpm at 16,500 feet.

Agreed on the rpm. However the boost in the posted link for N3171 is stated as +6 1/4 psi nominal, and during the top speed test table it is listed as +6.1psi at 16500ft. The CloD Merlin failed within minutes at rpm> 2700 and FTH, and max available boost at or just below FTH is +6.2psi for the SpitI (and Spit II). So 2700rpm, +6.2psi was tested as CloD max practical height performance(BTW 3000rpm at same boost did not indicate any speed increase in the moments before the engine failed, rad open)

Originally Posted by Crumpp

On that report, the data is only between 7% to 5% off from the reported figures at the lower rpm. We don't know the weights, so the data could be spot on or it might be off.

In order to make a definative statement we need:

1. Atmospheric conditions
2. Speed at same engine settings
3. weights of the aircraft

I think an interesting issue is the difference in TAS we have calculated, me using a rather simple thumb rule (TAS = IAS + 2% increase per 1000ft), you with a more rigorous approach. Eg for Hurricane:

Rotol Hurri = 235mph IAS@15500 ft

My calculation (2% rough rule) gives 305mph TAS, your calc gives 286mph. Thanks for providing a more rigorous calculation.

I actually hadn't checked whether how the Hurri compares at height to the B6 data and RAE Hurri tests, I just did a quick offline Hurri sim test in response to a question from Kwiatek...sounds like from your analysis it is not too bad. Earlier I was referring to the Spit and 109 data which (for Spits) showed TAS at FTH being too low for both the B6 data (hence what 1c intended the patch to allow) and historical RAE tests. The 109 is pretty good at height according to my 2% rule calc (i.e about the average Messerchmitt guaranteed spec). It might drop under with your calc method, I guess an important consideration is what are the equations in the simulation of how IAS and TAS relate.

Cheers, camber

P.S I should note my IAS speeds at height are from offline, and Snapper has noted some oddities and discrepencies for the SpitII between online and offline