The 5700 fpm was measured in Spit IX test and noted for the VIII when the coolant radiator flaps were overridden and force-closed. With the standard way of measuring climb rate in other spitfire tests, with the radiators open,
What Isegrim isn't saying, of course, is that the
other tests he's talking about had radiators
forced open.
Other aircraft, like the 109, had radiators set at certain positions for certain tests. For example, most German speed tests were done with radiators almost closed, something that could only be done for short periods. In AH, though, which doesn't model complex engines/cooling settings, the 109 can maintain such speeds for 10 minutes, in other words the AH 109 can maintain closed radiators/maximum boost for 10 minutes, something the real life 109 couldn't do.
The Spitfire had automatic radiators, that would open when the coolant temperature reached 115 c. Below that temperature they would close (closed on the Spitfire actually means half open, as the radiators cannot fully close)
So, what Isegrim is arguing for is climb figures for the Spitfire with radiators fully open. 109 figures are given with radiators half open, 109 speed figures with radiators almost fully closed.
AH doesn't model the extra drag from opening radiators, why should it do so for the Spitfire?
From cooling trials of the Spitfire LF IX, running at 25 lbs boost, after climbing at maximum power from 2,000 ft, overheating occured at 25,000 ft, under temperate summer conditions. That takes 6 minutes 17 secs, AH would of course have cut the power long before this, before the overheating would have occured. In fact, AH would have cut the power for a 25 lbs Spitfire LF IX at about 21,000 ft.
In normal service, the Spitfire would begin a climb with radiators closed, they would only open some time into the climb, this is modelled in AH by the system of automatically shutting off WEP after a pre determined time.
That's how it works for all aircraft in AH, having an extra penalty of forcing the radiators open on the Spitfire would be unfair unless the same rules are applied to other aircraft.
I have been trying to think of how adding 400hp added 1200ft/min of climb.
It's actually about 1,000 ft/min.
An extra 1,000 ft/min for the Spitfire LF IX would be about 20 - 25% better climb rate, 25 lbs boost added 25% more power. Weight was the same.
