Pongo - the point is, a Mk VC trop with a C wing has a top speed of about 355mph and takes about 8 minutes to climb to 20k.
I found this quote that explains the Malta Spitfire situation.
The Spitfires which had been launched from USS Wasp during April were all of the Mark VC version and were fitted with four 20mm cannon instead of the usual two cannon and four machineguns. Operating from Malta, however, this armament soon revealed its drawbacks. On the island there was a shortage of 20mm ammunition, so much so that cannon tests were prohibited; the weapons were only to be fired at the enemy. Dust was always problem, and four cannons were twice as difficult to keep servicable as two cannon; moreover the weight of the two extra cannon imposed a peformance penalty, especially in the climb. But the greatest thing to be said against the two extra cannon was that they were unnecessary; even against the Junkers 88, the toughest bomber we had to deal with, two Hispanos were quite enough. The extra cannon were soon removed from the aircraft.
Pilot Officer Michael Le Bas of 601 Sqn RAF, veteran of Operation CALENDAR, April 20th 1942.
Quoted from
Spitfire A Documentary History, by A.Price.
[This message has been edited by juzz (edited 05-08-2000).]