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This thread is privately moderated by maguro, who may elect to delete unwanted replies.
Mar 31, 2017, 08:07 AM
OpenTX University Staff
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The airplane would be in the 8-10 lb range with a span of 7-8 feet or so. It just needs sufficient spar strength to absorb the loads both in flex and torsion. Large foam wings run the risk of flutter without the proper stiffening. It is certainly doable. The E-flute Carbon-Z Cub is a fine example of large strong foam structures. Heck, if you wanted to, you could hot wire the KF notch into Carbon-Z Cub wings.
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Apr 04, 2017, 10:33 AM
Flying one day at a time....
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Quote:
Originally Posted by maguro
The airplane would be in the 8-10 lb range with a span of 7-8 feet or so. It just needs sufficient spar strength to absorb the loads both in flex and torsion. Large foam wings run the risk of flutter without the proper stiffening. It is certainly doable. The E-flute Carbon-Z Cub is a fine example of large strong foam structures. Heck, if you wanted to, you could hot wire the KF notch into Carbon-Z Cub wings.


Well, until a few months ago, I too might have held a similar view regarding size (wingspan) and weight for that amount of power.


However, following a series of experiments with the KFm4 symmetrical section on 3-D/aerobatic designs, I'm now not so sure. Currently, it looks like there maybe some benefits (specifically for KFm4 3-D/aerobats) in using far higher wingloading and power loadings than is currently typical of KFm4 foamie designs.

That is the reason I started the thread on KFm sections and high power. So far it is looking like an area that few (if any) have explored.


If it proves a fruitful area (it may not, of course), then my recent experiments would suggest that your initial estimate (of 8 to 10 pounds weight and 7 to 8 feet wingspan) could be out by as much as a factor of two for a 1000 Watt KFm4 section aerobatic plane. In other words, perhaps 4 pounds weight and just 4 feet wingspan might be nearer the mark - outrageous though that may seem.


Anyway, I would not encourage anyone to try such high wing and power loadings unless the airframe has been properly designed to cope structurally with the consequential stresses.

Dave
Last edited by pardshaw; Apr 04, 2017 at 10:52 AM.


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