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FT Sea Otter troubles

#1
Hey everyone! After reading at this forum for years here is my first post!

I just build a Sea Otter but I'm having an hard time making it fly. It just wants to dive nose down, despite of the full back on the elevator, so right after launching it, it dives in the grass. The CG is 70mm after the leading edge, as "prescribed" in the plans. Now I'm playing around with the motor angle, tilting it up like a bixler, but it still has the same attitude.
I'm missing something here, with that motor mounted high up, it just makes the airplane tilt. Honestly I'm completely lost here:)

any tips will be greatly appreceated, I really want to fly this plane!
 

Ketchup

4s mini mustang
#2
First off, welcome to the forums! I have never flown a sea otter, but I know some ways in which you could find out what the problem is. You should try a glide test with the plane, just throw it without throttle. If the plane glides straight then your problem is because of thrust, and if it doesn’t then your problem is because of something else like cg. Also, check to see if your elevator is moving in the right direction (when the elevator goes up the plane should go up).
 

Hondo76251

Well-known member
#3
Are you hand throwing it?

This can be tricky due to the low airspeed of a hand launch, especially in a bird with a high mounted engine (ie: if your wings aren't making lift, and your motor is producing thrust it can be a fast ride to the ground and there isn't much the elevator can do about it)
 
#4
Peter says in the video on this plane that thrust angle isn't needed as the tail is directly in the prop wash which help keeps it straight.
As Hondo points out the wings don't have any prop wash and therefor no artificial lift when launching. I would make sure I have enough elevator throw and all the controls are going in the right direction. Then when launching give it a bit more throttle and a harder toss. Also most water planes you can use grass as a runway and just take off as if you had wheels.