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Old 08-14-2017, 10:04 PM
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burkefj burkefj is offline
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Join Date: Feb 2009
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Default Mig 21i(Analog) goonie....

I was trying to find a use for some 3" pro series tubing I had that was pre-cut to 21.5" long, I decided I wanted to try to do something similar to the Mig 21i Analog, which was a testbed for the TU-144 supersonic aircraft wing. I was limited to how much wing I could use by both the length of the tube and the spare depron I had left in large enough pieces. I made a nose insert using a paper cone soaked in CA glued to a .03 styrene disk with a shoulder made from some strips of body tube reduced in diameter to fit the inside.

Wingspan is 20", single 3mm carbon spar wtih elevon controls. Back edge of the wing has a cutout for the motor tube, and the vertical fin goes through the tube and glues to the top of the motor tube to help align it in place. Exposed wing area is approx 1.29 sq foot, so about 7.75 oz/sq foot wing loading compared to 5.5-6 for my kits.

Rail buttons are offset to the side so they don't get damaged by landing and I put some skids on the bottom of the tube. Did some quick indoor glide tests which gave me a conservative starting point for launch. Came out at 10 oz rtf with E-6 motor and battery and 3/4 oz of nose weight.

I did six test flights this afternoon, nice straight boost, glide was not bad, not as good as my kit planes since the wing is about 3/4 of the area of my kits and the nose is fairly draggy. It was fairly windy but did some nice near vertical touchdowns in a headwind.

I went home and added a cockpit/spine tunnel with depron sheet, rounded to shape and came up with a pseudo soviet flashy color scheme that seemed appropriate and hsnd cut and applied the vinyl markings and did some panel lines.

Came out not too bad, I was hoping it was going to look a big more graceful, but turned out more like a goonie...Oh well.

Will try to get some flight video tomorrow.

Frank
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