It is interesting to see the wide tolerance of the contractual performance of the Bf-109. The error of +/-5% on the top speed of 500 km/h translates into 10% or 50 km/h of allowed error in absolute figures. Add to that the wear of operations and you can easily have poor performers.
It would be equally interesting to know the tolerance of the British types, I would not be surprised to see higher tolerance values for the Spitfire, given the poor status of the Supermarine rigs and tools at the beginning of production (see the Leo McKinstry book on the Spitfire to have an idea about the mess of the Supermarine works in 1938-39).

PS: how nice if this variability is modeled ... it shouldn't be that difficult ...

Hi Buchon,

I agree with you but with some terminology issues. The Brits are not using the term boost as something that is turned on and off. "Boost" is just manifold pressure with atmospheric pressure subtracted, so + 6 1/4 psi boost is 21 1/4 psi manifold pressure. I assume boost was used as a term as the supercharger is boosting manifold pressure above atmospheric. Maximum manifold pressure is set by the boost controller with a cutout that can be modified to give a higher manifold pressure (+12psi) on command.

So even with the economic weak mixture setting, there is still "boost" (+2 1/4 psi). The problem is as you say, that the boost setup is wrong. From the plots to me (thanks Klem et al.) it appears that post patch the boost will read +6 1/4 psi, but give performance approximately as for +2 1/4 psi with weak mixture.

camber

Ohh, I see thanks :)

The Merlin III is a supercharged engine. So it always has "boost" by definition. What is not modelled is the "boost control cut-out" which enables to obtain more boost than regular. Regular boost is +6.25

Boost with "boost control cut-out" enabled is +12

Look at the Spitfire II (a and b) Pilot Notes, page 13 (unbiased, first hand info):

http://www.zenoswarbirdvideos.com/Im...pit2Manual.pdf

100 octanes appear as a standard, 87 as the exception, 12 lbs boost allowed up to 5 minutes, but effective only up to 10'500 ft. At least for the Spitfire IIa and IIb. The source doesn't indicate the revision date though.

I didn't find the Spifire I Pilot Notes, unfortunately. I'll check my CoD collector's edition ... :-)

Yeah i think Buchon was just having terminology/language misunderstanding.

Yeah, I mean there no boost control modeled, or at least properly, in-game now.

I think that they are working on it, if they made that performance line below of the Flight Test I think is because the properly Boost Control is coming.

They made that line I added from B6's data by incorrectly amending the Spitfire FM. They need to make the Patch boost line align with the 6 1/4 lbs (thin pale blue) line. Then it will be modelled correctly for 87 Octane, +6 1/4lbs, 3 blade constant speed propeller, i.e. the Spitfire MkI we have now.

Its the +12lbs line achieved using 100 octane and boost cutout override that we hope they are working on because without it we don't have the BoB. We have "thank god they didn't come in November 1939".

Well, this is how I see the problem (in Brits terminology)

The main problem is that the game´s FM haven´t Boost pressure changes modeled in yet.

So if you made your plane performance line over the blue line to obtain the Boost +6 1/4lbs performance (as is in pre-patch) then you will be over it always, even if cut the throttle and the needle is showing +2 1/4 psi.

The correct way is at the inverse, you should make the economic performance curve (+2 1/4 psi) and then add Boost pressure changes to the FM.

Then you have both performance lines, economic +2 1/4 psi and +6 1/4 psi.

If you watch carefully the B6 graph you´ll discover that it´s a economic performance curve (+2 1/4 psi), so my guess is that they are planing to add Boost pressure changes to the FM.

Unfortunately not, think what in Brit terminology is boost = ata.

the line B6 showed us is full speed as it is with ALL the other graphs, in a spit 1 with 87 octane fuel which happens to be 6 1/4 boost, and thats that, there is no 'Boost button', no gate to push through, full speed is just the throttle pushed all the way forward. There is nothing to be added to it at a later date.

when we are talking about boost, in this sense we do not mean what the old il2 used to call WEP.