So this is what happened. I bought a used Cox Cub airframe for $8 and
equipped it with two used servos I found in a swap meet (rudder and
elevator) and a 4-channel, single conversion 72MHz receiver that a friend
gave me. I had never used any of these components before. Range check was
kind of short compared to dual conversion or DSP receivers, so I decided to
fly not too far. Enough for a 30ish-inch wingspan.
First flight. Perfect takeoff. Gaining altitude to trim safely. After 20
seconds or so, the airplane banked left drastically, as if a glitch had
happened. As a consequence, the airplane stalled and spinned down, crashing.
I had some control during the spin, but nothing to save the airplane from
crashing. When this happened, the airplane was about 150ft away, and the
transmitter antenna was horizontal (fully extended). I don't remember where
it was aimed.
Interestingly, the only broken parts were the propeller (although I was
using a prop saver...), and the rudder servo. I opened it, and found that
some gears had been stripped.
I guess that a glitch did happen, and it forced the servo to a extreme
rotation, stressing the gears and breaking them. Is this possible? Any other
By the way, I bought a few used (and maybe abused, who knows?) servos in the
swap meet. Any advise on how to test them and figure out which servos are
about to fail?
- posted 14 years ago