Inaccurate performance data for BOB fighters in COD comparing to RL data

[41Sqn_Banks]

Originally Posted by Kurfürst

Interesting. Do you what was changed with A.L. 31?

No, I think only that part and a para about air/sea rescue dinghy equipment. It's the last A.L. incorporated in the manual. It must have been between December, 1943 (the date of A.L. 30) and June 1944 (when the amendments were incorporated into the manual).

Another interesting point that it appears that +12 lbs was banned at that time for combat use ("5 min all out level"), the maximum allowed was +9, with +12 was only cleared for take off purposes up to 1000 feet. It appears that +12 was not cleared for combat use during the Battle of Britain, and was added only later.

Indeed interesting. The Merlin XX did have exactly the same limits when introduced, as can be seen here: http://www.wwiiaircraftperformance.o...s-10june40.jpg and was eventually increased to +12 boost in November, 1940, see:
http://www.wwiiaircraftperformance.o...xx-15nov40.jpg
And 3,000 rpm for climb above 20,000ft in December, 1940, see:
http://www.wwiiaircraftperformance.o...xx-11dec40.jpg

Also note that even the amended AP 1565 A Pilot's Notes for Spitfire I that comes with the Collector's Edition gives the "All out" limit with 3,000 R.p.m and +6 1/4 lb/sqn.in., and this is dated January 1942. The +12 boost is given under a own paragraph called "combat concessions" on the following page.

Also note that AP 1565 A Vol. I gives the +6 1/4 for "All out", however the description of the "boost cut-out" gives +12 boost. Note that A.L. No.6 is dated July, 1940.

the override control can be used for short periods only, but only when 100 octane fuel is used.

AP 1590B Vol. I Merlin II, III and V Aero-Engines A.L. No. 4 dated November 1940 also gives "maximum level flight (5 minute limit) of +6 1/2 but contains a detailed description of the +12 boost use for emergency.

It seems like there was a difference between "all out" and "emergency/combat" power (5min limit in the amended Spitfire II Pilot's Notes is called "combat" instead of "all out"). However, it would be interesting to find a reference when +12 boost and 3000 rpm for climb was actually cleared for the Merlin XII for combat/emergency. Possibly at the same time as higher limits were introduced for Merlin XX (November 1940 and December 1940).