[zapatista]

Originally Posted by pstyle

Actually, not too far off and I'm a red-mostly pilot.

Black 6's Figure for "the patch" - as I read them:
Spit 1a: Max level speed:
@6000m / 19,700ft: 350 mph (563 km/h)
@3000m / 9,850ft: 303 mph (489 km/h)

Figures from the weblinks posted:
Spit 1a: Max level speed:
@6000m / 19,700ft: 355 mph
@3000m / 9,850ft: 320-355 mph (depending on fuel 87/100)

So the patch is 1.4% on the low side at 6000m (I can live with that)
And the patch is 5% on the slow side at 3000m if you're assuming 87 octane, but a more significant 14% on the slow side if you're using 100 octane

I'd like to see sea-level Flight model information for the above, but it seems to me the model is very close to the 87 octane fuelled spit 1a. VERY CLOSE. And I am now happy to accept that.

The real question is - will/should they model 100 octane?

its like a perpetual ground hog day here

extensive information has been provided on this issue this from various sources in the last year in this forum, it is CONCLUSIVE AND BEYOND ANY DOUBT that hurricanes and spitfires had 100% octane fuel available, and just by your own quoted figures that would give them at least a 14% speed disadvantage

to quote but a few sources

Gavin Bailey concluded that "The actual authorisation to change over to 100-octane came at the end of February 1940 and was made on the basis of the existing reserve and the estimated continuing rate of importation in the rest of the year." (ref 33). As of 31 March 1940 220,000 tons of 100 octane fuel was held in stock. (ref 34)

and

The Co-ordination of Oil Policy Committee noted in the conclusions of their 18 May 1940 meeting with regard to the "Supply of 100 Octane fuel to Blenheim and Fighter Squadrons" that Spitfire and Hurricane units "had now been stocked with the necessary 100 octane fuel". (ref 35) The Committee recorded that actual consumption of 100 octane for the 2nd Quarter 1940 was 18,100 tons. (ref 36)

and

Jeffrey Quill recalled: It was only shortly before the Battle of Britain that we changed over to 100 octane. It had the effect of increasing the combat rating of the Merlin from 3000 rpm at 6 1/2 lb boost (Merlin III) or 9 lb boost (Merlin XII) to 3,000 rpm at 12 lb boost. This, of course, had a significant effect upon the rate of climb, particularly as the constant speed propellers (also introduced just before the battle) ensured that 3,000 rpm was obtainable from the ground upwards whereas previously it was restricted by the two-pitch propellers. It also had an effect upon the maximum speed but this was not so significant as the effect upon rate of climb. (ref 37)

and ........Wood and Dempster wrote in their book "The Narrow Margin":

As it turned out, aviation spirit was to prove no worry for the R.A.F. By July 11th, 1940, the day after the Battle of Britain opened, stocks of 100 octane petrol used in the Merlin engine stood at 343,000 tons. On October 10th, twenty-one days before the battle closed, and after 22,000 tons had been issued, stocks had risen to 424,000 tons. With other grades of aviation spirit total stock available on October 10th, 1940, was 666,000 tons. Oil reserves were 34,000 tons. (ref 38.)

source: http://www.spitfireperformance.com/spit1vrs109e.html

there is no excuse for still allowing these types of errors in CoD !!