Sunday, February 28, 2010

Speedwing Contest Design

Today I had the final crash of the prototype speedwing. The 2200 mAh battery cantilevered over the leading edge is now about 1" shorter.... Nothing like a high speed, full throttle perpendicular impact into ice!
So, I thought it was about time to start working on the "real" design. So far, here are the major changes from the prototype:
  • Tip wing section is about 60% of the root wing section- hopefully this will avoid the nasty tip stalls of the prototype
  • Reduced wingspan to 24" from 40". Even with this major decrease in wingspan, with the increase in wing tip chord length the wing area is still close to the prototype - about 302 square inches
  • Removed winglets. They kept on breaking on the prototype. If this doesn't have enough directional stability I'll add them later.
  • Added cockpit to cover batteries, and allow longitudinal orientation of the batteries.This will also reduce the need to core out the wing as much- which should make the wing much stronger.
  • Extend spar across wing center joint. 

Estimated specs:
  • Wingspan 24"
  • Wing area 302 square inches
  • Estimated all-up weight: 1.1+ pounds ~ 500+ grams (this seems to light, but maybe it's correct)
  • Max power: 1100 watts

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