Wednesday, July 11, 2012

First Scratch-Built RC Plane

I just finished the maiden voyage of my first scratch built plane, named appropriately as "One".  The first flight was a rolling take off ramping up to full thrust but as the plane lifted off, the wings bowed  backward forming a "U" and it lost lift and tilted back to the ground.  Thinking that a lighter plane may not have the same effect on the wings, I took off the landing gear and attempted a hand launch.  While it flew for about ten seconds, a gust hit the plane and bent the wings again.  Luckily they were reinforced plentifully with packing tape, a last minute decision that I'm glad I did.  The plane lost control and nose-dived into a pile of mulch.  I decided that I needed a wing spar or struts for further reinforcement to test whether the plane will even fly at all.  I went home, cut a notch at the top of the wing and laid a 1/4" carbon fiber spar the length of the wing, then secured it with more packing tape.  The final product was both flexible and stiff where it needed to be.  Happy with the upgrades, I just had to try one more time.  
We walked to a nearby field and ,before hand launching, I tested the controls.  No servos.  Good thing I didn't just pin the throttle and toss it!  I opened the wing to find the receiver pushed to the front of the battery compartment, both servo wires pulled from their plugs.  It seems on a nose crash, the unsecured receiver has some room to move.  I plugged the servo wires back in, tested the connections, and re-installed the wing.  Confident on my repairs, I pinned the throttle and launched the plane.  Another successful ten seconds, up until the plane veered left and plummeted into the ground.  Hmmmm, no right rudder.  Upon re inspection, I noticed the control arm for the rudder had an s-curve, plenty of tension for a left rudder, but on pushing for right, it just bent between my the wire guides.  I moved the wire stays a few notches out, provided more leverage, less push on the control arm and decided, against better judgement that I wanted one more try to fly it.  
Hesitatingly, I spun up the throttle, prepared to launch, and one second before throwing it, the propeller spun off its shaft and flew into the air like a bumble-bee.  It spun up about 20 feet, turned and headed for the ground, all the while, buzzing through its revolutions.  I was still holding my plane in launch position when the propeller hit the ground.  That was sign enough that it was time to call it a day and make some much needed adjustments.  Plane One will fly. For how long, is to be determined.  



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