[TomcatViP]

Originally Posted by *Buzzsaw*

+12 boost does not confer a lot of advantages over 10,000 ft.

The Spit II would be slightly slower than the Spit I, speeds at sea level were approx. 310mph.

Note that would mean the Spit would be faster than the 109 at sea level, but would fall behind it over approx. 15,000 ft when 1,4/1.45 ata is used by the 109. (my understanding is the 109 had a limitation of 1 minute at 1.4 ata) Since there are no charts showing speed/climb for the 109E at 1.4/1.45 ata, the developers are going to have to do an approximation as for the Spit II at +12. Of course, the increase in speed is not linearly related to the increase in horsepower, (990 PS for 1.3 ata vs 1100 PS for 1.4) so the 8% gain in horsepower will not result in a 8% gain in speed, as the drag factor multiplies very quickly and there is a lot of Hp required for each additional mph/kph. The 109 would pull away even when using only 1.3 ata at alts over approx. 21,000 ft.

Reports from the actual battle confirm the 109's preferred to stay over 20,000 ft and not engage on the deck. This fit with their escort mission, since the bombers were most often at between 16,000-20,000 ft.

Thanks to Mike Williams for his links from his Spitfire site:

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

+1

good post.

If I do remind well at alt ard 30kft the Spitfire IIa was supposed to be notably better. The early 1940 Cirkus were mostly flown at this alt.