Originally posted by Karnak
Insteresting. Now that you mention it, I vaguely remember reading something about forced closed radiators during some tests else where.
I have been trying to think of how adding 400hp added 1200ft/min of climb.
Karnak,
you can read the Detail of the tests in the JL 165`s reference to other tests, it`s a table. With some cross refernce, you can see the +25 MkVIII was also tested with force-closed radiators. I guess they wanted constant data without the thermostat interfering.
The drag effect is quite noticable from the radiator position, even during climb. For example, there are the German figures for the 109G which show 4133 fpm climb rate... if it goes by the German standards, the radiators were half open below FTH.
but I also found a Finnish test for the same model and power, than shows 4900fpm, though strangely only at low level, otherwise very similiar to the other dataset, and I was quite
.
But a finnish collegue cleared it up for me, that the Finns were climbing at a bit higher speed and not the optimal one... but with more speed they got more cooling, and the thermostat opened the radiator only at higher altitude, hence the higher values at low altitude because the reduced drag.
Other docs I have show that an opened radiator could cause as much as -50 kph slowdown... more than carrying a bomb!
Nashwan is of course mad as usual that the little secret about the test is exposed, and of course he`d want to the highest dataset available. He would want the Spitfire in minimum drag position without the real life inaduquate cooling, all the others in their normal drag position. Always the double standards.
Why not I`d say, but then lets either have :
a, All aircraft`s ROC referring to minimal drag position of the radiator, not just the Spit
b, All aircraft`s ROC referring to normal drag position of the radiators, not all except the Spit.
There are some points needed to be corrected, he claims :
Other aircraft, like the 109, had radiators set at certain positions for certain tests.
No, the Bf 109 had manual or automatic radiator flap control. The pilot could set any setting or leave it automatic. He used minimum drag setting to attain high speeds, of course.
A Spitfire had only autotmatic control, thus the pilot had no say when the radiators opened due to overheating and added more drag. This changed on the MkIX and later, previous Marks had only manual.
Another difference between the Spit and 109 is that the Spit`s radiators have only two positions (open and closed), while the 109`s has infinitive number of gradual positions between totally closed and half-meter wide open.
For example, most German speed tests were done with radiators almost closed, something that could only be done for short periods.
I`d like to see evidence that 'almost closed' radiators could only be used for short periods of the 109 - which is your Nashwan`s own tale of course. But, he is a notorious liar we all know.
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.
Your source about the 109 cannot maintain maximum boost for 10 minitues? That`s laughable nonsense.
For example, the DB 605A engine of the Bf 109 notes in it`s engine manual that the engine is allowed to handle 115 degrees for exactly 10 minutes. Which shows AH`s modelling is correct.
