Monday, 21 April 2014

Symmetrical Armin wing slope soarer

This symmetrical Armin wing was designed specifically for aerobatic slope soaring. After two frustrating weeks of bad winds I finally got the chance to test it.

1.4m wingspan
20mm thick
140mm (5.5") chord plus 50mm (2") ailerons

Here's the proper maiden flight in 10-15kn NW. The wind was slightly off slope to the left but the glider behaved beautifully, a delight to fly and aerobatics worked nicely. Inverted flight was excellent, rolls and loops worked well too. It's quite a light weight at 480g and needed some ballast from a bigger battery when the wind picked up.

A few days ago in desperation I tossed it off the dune in 30kn and it did fly but exhibited some frightening elevator flutter. That flight was more survival than flying so it didn't count as the maiden.
The large aerobatic elevator with some area forward of the hinge contributed to the flutter, as well as sloppy linkages, short control arms, loose servo mount and a dodgy tape hinge.  The flutter only happened on launch into 30kn so it's not an issue in normal conditions.

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