Originally posted by Nashwan
Well, the colling report shows that a 25 lbs boost climb could be maintained for 5 minutes without the coolant passing it's maximum temperature, when the rad flaps were shut, so for a considerable portion, at least, of a climb the rad flaps would be shut.
Not quite, you are misqouting the report. The report deals with the same JL 165 MkIX, which had a additional device installed to keep the rad flaps in shut position. In the report they state the "suitability" of the radiator is just enough for "temperate" conditions, but unsatisfactory for "tropical" conditions. Given that most of the report is calculations based on some flight tests with pre-determined numbers for "satisfactory results", it`s hard to say how much really it means it won`t overheat. In any case, the radiator flaps would soon open just as the temperature passes the "normal" level (about 90 deg IIRC), decreasing climb rate as mentioned. And there`s no override to that.
It should also be pointed out that the Spit VIII had a worse climb rate than the Spit IX (it was 370lbs heavier).
Yep, it`s about 200 fpm worser than the Mk. IX, which cuts in very nicely with the decrease in climb rate with clipped models, suffering from the same wingload increase.
The report notes that climb rate is increased by the use of higher boost by approx 950 ft/min, and a normal Spit LF IX should have a climb rate of 4500 ft/min+ with 18lbs boost.
It should also be pointed out Rolls Royce got a figure of 5,740 ft/min with the same underperforming Spit IX the A&AEE used.
Uhm, if a "normal" Spit could do ~4500 fpm, and increasing the boost would raise that by about 950 fpm (4500+950= 5450 fpm), than how could RR`s Spit be "underperforming at 5740 fpm?
At Rollce-Royce`s test the "same underperforming Spit IX" was very close to it`s official specs at 399 mph max speed. With the same plane A&AEE mesured 389 mph as max speed, so clearly, for some reason, in the RR tests the plane was perfectly representative of an avarage spitfire.
What condition was used for 109 climb tests? I believe you said shut, or partially shut, on Butch's board, didn't you?
I said they were about halfways open up the the FTH, and from then onwards, about 1/4-1/3 open. This is to what most German tests refer to, ie.radiators being "Automatik". Of course since the 109 pilot could override automatic control of his radiators, he could shut them more, reducing drag and increasing his climb rate at the expense of overheating - but as we know, late 109s had double the WEP time than Spits.
