Merlin II/III could hold 12lb boost to over 10,000ft in a Hurricane and higher in a Spitfire:
http://www.wwiiaircraftperformance.o...-l1717-cal.jpg

Wow, the data does not match. It is that simple.

It does not mean there is not good data out there, it just means these charts presented are not it.

The fan plot for the Spitfire is for a Merlin XX engine.

I agree it looks simplistic, but technically it is sound and I see no reason it not being an original document. No reason for it being one either, but I will accept it on face value as I see no reason to mistrust Mr.Williams on this issue. If you have more than a gut feeling, I'm willing to re-evaluate my opinion.

It's not with ram effect. That's painfully obvious from all the engine and plane data on 6.25lbs around. The power level generated by the engine on this chart has the designation "all out level" and that's all there is to it. Assuming otherwise is like assuming "combat" power is only available when the aircraft is in actual combat.

And which Spitfire version would that be? ;)

I shall do the math to prove that 400kph was the cruise speed and that in turn was the reason to set the fixed trims to that speed - not your graph? :eek:

You are right, e.g. AP 1590B states 890 bhp at sea level and 1030 bhp at 16,250 ft for +6.25 and 3,000 rpm. The chart is obviously without RAM effect.

I have put in a request to the Rolls Royce Heritage Trust part of Rolls Royce to see what they say. The NA don't seem to have anything that would satisfy everybodies requirements. I wouldn't hold your breath as it might take forever but should at least deliver a definitive reply.

Do you know where cruise speeds are located on the Power and thrust curves?

Need me to show you.....????

Spitfire III, AFAIK only the prototype was built.

http://imageshack.us/a/img17/1140/summary1k.jpg

http://imageshack.us/a/img109/7506/fanclnsml.jpg

The 2nd (lower) page is not a Spitfire III. Spitfire III had a wingspan of 30 ft 6 in (9.3 m) and wing area of 220 square feet and for 6000lb that gives a wing loading of 27.3lb.