Well, first a little back-story. My dad built 2, 1/4 scale Sig Piper cubs. One with full wing and one with clipped wing. Both had FT-120 engines. Only the clipped wing version had ever been flown, and i was told by the person that flew it, it was very light on power, and to be careful not to turn during takeoff. OK engine hasn’t ran in 15 years, so it took a few days of work to get it back into running order. I put a new zinger wood prop 16x8 on the clipped wing, and it was running max rpm 6600, (this sound right?). I taxied around a bit, and gave her full throttle. Climbed slowly to about 10' and the left wing started to drop. I gave it right aileron but there was no effect. There left wing just kept dropping until it knife-edge into the ground, OUCH!!!! There was no doubt in my opinion from flying full scale aircraft it was the dreaded take-off stall i was warned about. It was not in a hard climb, in-fact it was almost level. I really feel the FT-120 is to small for it. Anyway, i bought a new FT-160 from tower and put it in the full wing cub to avoid further crashes . I put a 18x6 prop on it, but I can only get 5500 RPM!? Isn’t that less pulling torque than the FT-120 with a 16x8 @ 6600 RPM? I am afraid to fly it until I can talk to someone who has experience with the FT-160 and can give me an idea what RPM it should be turning with a 18x6. Any help would be GREATLY appreciated!

The FT-160 should turn an 18-6 prop better than 7000 RPM. Check for valve lash adjustment problems, and old fuel. Maybe the carb isn't opening all the way?

It's gotta do better than 5500 on the ground, or I'd send it back.

I am in the process of finishing a 1/4 scale of the Fokker D-V11. Which has a
7 foot wingspan, it will weight close to 30 lbs when finished. Sould not a Super Tigre 2500 glow , or Zenoah G-38 or G-45 give you more power. ??? Other then that, I am constructing my bird around a weed eat motor which will give it more power then necessary. With the weed eater engine it will give me more flying time and
this bird will fly slow as it is not built for speed or some acrobatics.
I know what you mean my a wing hitting the ground, makes you want to just
cry for all the work that was put into the bird. Hope this might help you.

worpsped

I am flying a old Super Cub 103" wingspan with a Supertiger 90. It flies very well and scale. It is not the greatest climber but handles very well. Doesn't like to roll but has beautiful loops.

I need ft-120 cam followers...for an old one. anyone know where to find them??


Icould use an exploded view of the old ft-120 also.

The biggest reason for these large cub type aircraft to lose it on take-off is lack of flying speed. Unless you get it up to flying speed before lift off it's gonna stall and roll in. I've done it way to many times. Ya just can't "horse" these birds into the air!