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Dragonfly MK-II 3 airfoil conversion

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trifoils

Well-Known Member
Joined
May 21, 2016
Messages
111
Location
Tehachapi & Palmdale, CA
The quickie style aircraft caught my eye when I was a little kid. I saw one at a local fly-in and couldn't believe something so small could actually carry a man into the air and back again. As years passed the idea of building or buying one came and went several times. There were many selling points - stall resistance, simple structure, speed, elegance (landing gear on the wing tips - is that possible?)

By the time I was in school finishing my degree I had read enough pilot reports of extremely high landing speeds, poor ground handling, broken canards from PIO, and the bug / rain trim problem. Somehow I made it to the yahoo Q-bird forum (this was over 10 years ago) and these problems were well known. There were many ideas for how to update the design but no real breakthroughs, except one user by the name of leon who had experimented with adding a horizontal stabilizer in X-Plane, the flight simulator. I decided to get the sim and experiment with the same idea.

It worked very well and changed the personality of the plane, especially in slow flight. Stock tandem wing planes had such a slick glide path and low approach angle it was not easy to set them down where intended, but adding the stabilizer opened up many possibilities for flaps and other control system changes, including using the same airfoil on both wings. I played with my own version of a tandem wing + tail for a couple years and came up with a refined hot rod with real STOL capability.

Years passed and I never built the prototype I designed in X-Plane, but recently decided to investigate how a stock Dragonfly MK-II would react to having all pitch control via conventional stabilizer. It worked very well in the sim and small RC models, so I have decided to try it on a real aircraft. The aerodynamics behind the idea (original custom design and the retrofitted dragonfly MK-II) can be seen in the X-Plane forum:

T-tail Quickie Derivative - Custom Designs - X-Plane.Org Forum

dragonfly MKII - Custom Designs - X-Plane.Org Forum

The aircraft itself was a craigslist find, and will need a full inspection before proceeding with the modifications. It was finished but never signed off and the engine has a few hours of run time. I will be changing the panel and landing gear, in addition to adding the tail.
 
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