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#31
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Hershey bar wing vs composite wing - how much drag?
("cavelamb himself" wrote)
And a LOT of the drag is from cooling the engine! There is an ideal place for big gains. Ercoupe, Cessna 172, Piper Warrior: How much drag would be eliminated it the prop was spun from, say, a (hypothetically capable) electric motor - of the same weight as the engine? An electric motor that needs little of the cooling air (drag) required by the gas engines. WAG, is a LOT ...33%? Whatever the guesstimated drag number settled on, what then would that number mean in cruise speeds, or fuel burn? 10% improvement? 20% improvement? 30%? Montblack |
#32
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Hershey bar wing vs composite wing - how much drag?
DR wrote:
Hi, I don't see why a composite should be heavier: For carbon composite, the Young's modulus is ~70GPa for a density of 1.3 g/cm3. Al has the same Young's modulus but twice the density (2.7 g/cm3). For glass the strength is about half but again the weight is halved too -so it's not a gain over Al. I think the composites excel in their lack of rivets and joining pieces tho... Last I knew, Young's modulus was a measure of stiffness, not strength. Matt |
#33
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Hershey bar wing vs composite wing - how much drag?
"Montblack" wrote in message ... ("cavelamb himself" wrote) And a LOT of the drag is from cooling the engine! There is an ideal place for big gains. Ercoupe, Cessna 172, Piper Warrior: How much drag would be eliminated it the prop was spun from, say, a (hypothetically capable) electric motor - of the same weight as the engine? An electric motor that needs little of the cooling air (drag) required by the gas engines. WAG, is a LOT ...33%? Whatever the guesstimated drag number settled on, what then would that number mean in cruise speeds, or fuel burn? 10% improvement? 20% improvement? 30%? Montblack You're on the right track if you can work with a semi-trailer sized battery or a 500 mile extension cord. ;-) KB |
#34
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Hershey bar wing vs composite wing - how much drag?
("Kyle Boatright" wrote)
You're on the right track if you can work with a semi-trailer sized battery... I'm putting you down for 18%. Montblack I’m a little overweight and my log book’s way behind Nothing bothers me tonight I can dodge all them scales all right Six days on the road and now I’m gonna make it home tonight |
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