Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Mirage on January 24, 2011, 01:47:38 AM
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does anyone have the gear ratio that is used for the cooling fan on a BMW 801 engine?
I think it was set to spin about 3 times faster then the engine but am not sure, as the Fan in AH seems to be linked rights to the prop
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3.12 times the prop speed. A quick search on the internet does wonders....
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Is this that cowl cover they put over radial 190's? Didn't that cause massive overheating?
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No, that's not what it is.
Does it matter what speed it moves in AH? You can't visually tell the difference when looking at your plane in F3 mode. It only matters that it DOES move. No need to nitpick, because it doesn't actually effect the real cooling of the engine (it's cosmetic only)
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No, that's not what it is.
Does it matter what speed it moves in AH? You can't visually tell the difference when looking at your plane in F3 mode. It only matters that it DOES move. No need to nitpick, because it doesn't actually effect the real cooling of the engine (it's cosmetic only)
He never asked for it to be changed, it was a question. Relax...
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No, that's not what it is.
Does it matter what speed it moves in AH? You can't visually tell the difference when looking at your plane in F3 mode. It only matters that it DOES move. No need to nitpick, because it doesn't actually effect the real cooling of the engine (it's cosmetic only)
I wasnt refering to the 190's we have in game, I was just asking, because the only source I found that said it was wiki,and the 190's in AH have it linked to the prop as I said, I was just interested in how fast the real thing spins :)
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Is this that cowl cover they put over radial 190's? Didn't that cause massive overheating?
and no, the Fw 190 V1 had an extremely tight cowl so it caused big heating problems, so the revised it and gave it the cowl that the 190's in our game have, but it still had cooling problems for the read row of cylinders, so they added a 10 blade fan, which was later revised to a 12 blade cooling fan (although I am pretty sure they never completely solved the problem, so the rear row of cylinders always ran a bit hot)
here is a picture of Fw 190V-1
(http://t0.gstatic.com/images?q=tbn:ANd9GcTTLw1d8nfdM1JnWXbjYHq1f1ihOVOx2JS0VYQqL9DoLUeAgf-0hA&t=1)
and this is our 190A + F with the revised cowl
(http://farm1.static.flickr.com/216/493996657_fa834f1620.jpg)
as you can see, the later cowl is still quite tight compaired to other radial fighters (with some exeptions)
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Yeah the test pilot said "it was like having his feet in a fire" or something to that affect.
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"Having my feet in a fireplace" ;)
this was still evident after the V-1, so they fixed this by adding cooling slots, and also they moved the cockpit back 10in
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Why didn't they just open up the cowling more...? lol
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Why didn't they just open up the cowling more...? lol
I believe it was because Kurt Tank wanted the radial engine to be more sleek and aerodynamic and sexy looking... :D Then again, I am no Luft expert.
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I believe it was because Kurt Tank wanted the radial engine to be more sleek and aerodynamic and sexy looking... :D Then again, I am no Luft expert.
pretty much, the BMW 801 wasnt a hp monster like american radials, therefor they needed it to be as streamlined as possible to attain the speeds it did
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He never asked for it to be changed, it was a question. Relax...
Well said.
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"Why didn't they just open up the cowling more...? lol"
That is because any venting will cause speed loss as the air starts to run hindered through engine compartment.
Eg. you could imagine that in Dora as the radial cooler is closed it would cause more drag than if it was open to let the air pass through it, but that is not the case, it is actually the opposite.
There was a NACA document where the effects were examined, can't seem to find it now...
-C+
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if you find it, feel free to PM it too me ;)
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Quite a many documents about the subject:
Here is the one I referred to:
http://naca.central.cranfield.ac.uk/reports/1940/naca-wr-l-489.pdf
Other documents on subject:
http://naca.central.cranfield.ac.uk/reports/1940/naca-report-698.pdf
http://naca.central.cranfield.ac.uk/reports/1940/naca-report-687.pdf
http://naca.central.cranfield.ac.uk/reports/1941/naca-tn-813.pdf
http://naca.central.cranfield.ac.uk/reports/1941/naca-report-719.pdf
http://naca.central.cranfield.ac.uk/reports/1941/naca-report-720.pdf
;)
-C+
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Thanks! :)
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3.12 times the prop speed. A quick search on the internet does wonders....
The prop turned 0.54:1 of the engine. An external gear on the casing of the epicylic unit drove the cooling fan through a lay shaft at 1.72 time the engine speed. That works out to ~3.18. This on on an A-3.
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to give people an Idea of how much of the engine was concealed by the cowl, here is a picture, in the plane the cowl would actually come over top of the fan a little
(http://fw190.hobbyvista.com/norwayengine.jpg)