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Re: I keep forgetting to talk about the compressor wheels.. Posted by John Williams [Email]  (#1982) [Profile/Gallery]
(more from John Williams) on Fri, 9 Dec 2005 14:00:12
In Reply to: Re: I keep forgetting to talk about the compressor wheels.., vigge, Fri, 9 Dec 2005 02:42:09 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I wish I knew enough of the specifics to talk about it knowlegably...
The airplane prop, I feel is a good example of how thrust is lost, the prop is a air pump, the turbo is a air pump... The same prop at sea-level moves more air, I know this for a fact, I just cannot explain in science terms to prove it, but there is no question that props loose efficiency at altitude, I am a pilot, I have to dial in more pitch to get back some of the efficency lost to the altitude... The turbo blades cannot be pitched up, so whatever air they push at sea-level, they cannot duplicate it at a mile high... We have electric motors that turn props, they will have enough thrust to fly the plane at sea-level, not enough to fly the plane in Denver. THere is no engine loss, its only prop efficency loss...
My turbo is pushing less air here than at sea-level, this means a loss in pressure, it cannot duplicate sea-level pressure at the same rpm, its basic physics.... I could go with a bigger turbo and get back some of the loss, but not all... I am not sure how much of a loss there really is up here, but I do believe there is a loss and would put it between 10-15% at least... This is information from my own experiences with airplanes and air density and the loss I incure trying to race a mile high. Not all of it applies, but I do know the same pitched turbo blade will move less air up here than it will at sea-level. This combined with all the other factors that make up the engine power, makes me feel the 10-15% loss is very real... I have also felt it in my friends Suby turbo... We definetely lost some power, I just do not know for sure how much it was.... I also touched on the fact that I will be close to maxing out my turbo and this will mean it will be running outside its efficeincy range and creating heat, which is the enemy of power of course... There are many factors that come into play... I am not sure how you can say I am not loosing that much with such surety???
Thanks for playing,
John
posted by 65.114.20...
, Thu, 1 Dec 2005 10:47:40, Tue, 6 Dec 2005 20:13:50, Wed, 7 Dec 2005 06:04:12, Wed, 7 Dec 2005 21:37:05, Fri, 9 Dec 2005 14:00:12 <-- Viewing This Message, Wed, 7 Dec 2005 21:12:55, Fri, 9 Dec 2005 13:44:33, Sat, 10 Dec 2005 10:06:48, Sat, 10 Dec 2005 16:32:03, Sun, 11 Dec 2005 04:05:03, Sun, 11 Dec 2005 09:31:34, Sun, 11 Dec 2005 14:41:26, Mon, 12 Dec 2005 13:21:10, Fri, 2 Dec 2005 08:11:38, Thu, 1 Dec 2005 15:50:21, Thu, 1 Dec 2005 16:58:28
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