Ooooh....I got another one.
Many years ago, when I was about 14 or so, I won a Cox J-3 in a raffle. One long, particularly boring summer afternoon, I thought that I would set an endurance record with this J-3. I made some extensive fuselage modifications, to include the removal of the 1/2oz stock tank and the installation of an EIGHT OUNCE GRW metal tank!
Took it to the culdasac down the street and set it down--the landing gear buldged under the weight. Cranked it up and, screaming its poor little guts out, my pit crew released it.
...it didnt move...
Slowly, it started rumbling forward. After about a lap, the wings started to flex (If you've ever seen the Rutan "Voyager" takeoff footage, it looked allot like that) and after about 3 laps total, it broke ground.
To say this thing flew like an elephant would be very kind. "So this is what Lindburgh felt like" I thought. After about 20 minutes, it had burned up enough fuel that the tank was starting to slosh around, and the model became very pitch sensitive. I think at the 35 minute mark, that sloshing of fuel became too much. A sudden CG changed caused a stall and subsequent crash.
But it was fun