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hughlb2
07-31-2004, 11:20 AM
No this isn't another Spit IX questionhttp://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

My question is this - Radiator flaps when opened, on most aircraft, look like they would cause significant drag.

I always understood the purpose of these devices was to allow a greater or lesser amount of heated air to be removed from the engine, if this is the case, why do they also have to be a seemingly massive aerodynamic problem?

Surely there must be a reason, the designers spend so much time streamlining an airframe, why not streamline the radiator flaps? Why couldn't they be designed to slide open (flush to the airframe)instead of swing open? It just seems really strange.

[This message was edited by hughlb2 on Sat July 31 2004 at 12:26 PM.]

hughlb2
07-31-2004, 11:20 AM
No this isn't another Spit IX questionhttp://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

My question is this - Radiator flaps when opened, on most aircraft, look like they would cause significant drag.

I always understood the purpose of these devices was to allow a greater or lesser amount of heated air to be removed from the engine, if this is the case, why do they also have to be a seemingly massive aerodynamic problem?

Surely there must be a reason, the designers spend so much time streamlining an airframe, why not streamline the radiator flaps? Why couldn't they be designed to slide open (flush to the airframe)instead of swing open? It just seems really strange.

[This message was edited by hughlb2 on Sat July 31 2004 at 12:26 PM.]

Taylortony
07-31-2004, 01:58 PM
Because it forms a convergent divergent duct which creates an increased flow through the radiator, also you need to remember that the air passing through the radiator expands in size to heat, therefore the diameter of the raditaor exhaust need to be larger otherwise the airflow would stagnate. The likes of the mustang design actually produced a small amount of thrust over the drag imposed by the doghouse shape.

1.JaVA_Razer
07-31-2004, 02:30 PM
also, they could've made it more streamlined and squeezed another 30 or 40 km/h out of it but at what cost? making it would be more complex I think so fewer aircraft would be produced,aircraft which where seriusly needed

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Cragger
07-31-2004, 03:12 PM
Wasn't it the He-100 or something that had surface dispersion cooling system or something. Used lines under the surface of the wings to disipate the heat instead of a standard box fin radiator. Was extremely fast for her time but wasn't accepted for military use due to the complex cooling system that was projected to be highly vulnerable to enemy fire. That and the typical political bs that kept the 109 around forever.

http://www.warbirdsresourcegroup.org/LRG/he100.html

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IL2-chuter
07-31-2004, 03:38 PM
Skin cooling is very inefficient (the surface needs to be very large) but is indeed very low (non) drag. The Curtiss Schneider Cup racer in the Smithsonian has skin rads and they take up a huge amount of area. Being a riveted structure, you should probably have a dedicated leak crew. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif It's No Doubt easier to maintain a fleet of aircraft with easily replaced radiators (I imagine even more so in combat)

The problem of P-38 skin intercooler (slash wing anti-ice) was leaking and volume (manifold pressure lag and surge). http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif


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VOL_Hans
07-31-2004, 03:46 PM
Cragger, the reason that the He-100 was kept out of combat was not political.

The cooling system on that aircraft makes the entire plane a flying radiator! Any hits at all ruin the aircraft. It also limits other developments of the aircraft. A larger engine needing more cooling would require new radiators on the airframe.

The He-100 was also built more like a light-weight show off aircraft than a true fighter.

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johann_thor
07-31-2004, 04:41 PM
very untrue - the he-100-d was a serial production variant with weapons and ammo. also there was a simple solution of using a crude "normal" radiator that could be dropped if surface cooling was not working.

there were of course showoff variants before the D. but be sure - the He100-d was ready for action in the beginning of the war.

pourshot
07-31-2004, 06:33 PM
The Spitfire was designed for surface cooling but the idea never worked well enough for production. However one positive spin-off was the wings leading edge, it was supposed to be used as a steam condensing tank but later became a very usefull long range full tank in the PR Spits.

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