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Old Feb 09, 2013, 10:23 AM
markdrela is offline
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Cambridge, MA USA
Joined May 2001
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Originally Posted by John Walter View Post
The Miarage is a great plane. The key to its design is the balance among all is components.
A solid CF spar will weigh too much. Without changing the rest of the spar, you would simlpy tear off the tips before the main spar saw any substantial load. Also, since there is no balsa sheeting, the wing would flutter long before the main spar loads became an issue.
.007 CF on the top spar, or .014 top and .007 bottom would give more than plenty of strength.
What he said.

An even simpler way is to add "chordwise" 1/8" square basswood doublers to the top sparcap, stepped in length. The Mirage center panel is 48" long. Making the three doublers about 30", 18", 9" in length will give a nice ramp-up in the strength towards the center. I would also add a 1/8" square doubler about 9" long to the top tip sparcap.

This will double the wing's bending strength, and add maybe 8 grams.
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