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Help! Simple cub does donuts

dodgebob

Junior Member
#1
My new scratch built cub wants to do donuts as I try to taxi. Left or right rudder doesn't seem to help . I throttle up a bit and then the tail comes around. It was windy but that wouldn't matter...would it? With the big rudder I would think it would track straight. But it doesn't.

Any help would be appreciated
Bob
 

Merv

Well-known member
#3
I agree with @Hondo76251, make sure the wheels spin freely. You also need to have some toe in. Point the wheels to an imaginary point 5-10 feet in from of the plane. The ultimate solution is a steerable tail wheel.
 

Ketchup

4s mini mustang
#5
The issue could also be a ground loop. It should be fixable with enough rudder throw and possibly a steerable tailwheel. You should also point your wheels slightly inward like @Merv said.
 

Hondo76251

Well-known member
#7
Lots of ways to ground loop a tail dagger. Yaw authority is a significant factor. Like was said, a steerable tail wheel helps a lot because it gives yaw control before the rudder has sufficient airflow to have meaningful control input.

Another way to overcome this is more throttle. If you notice in the video I manage to get the plane off the ground a couple times despite the stuck wheel (I was thinking it was just the ruts and bumps in my road causing me to spin off into the dirt) I'm doing this by getting into the throttle more aggressively and getting some air over the tail sooner. I'm not completely hammering it, but easing into it more quickly and at higher throttle if that makes sense. It helps that the beaver had lots of power! Lol

I see a lot of guys ground loop because of not getting airflow over the tail soon enough... in a tail dragger it's ok to commit to the takeoff and "punch it" a bit, so to speak. Been my experience tail draggers dont like long lazy takeoffs like trike planes with steerable nose gear...
 

dodgebob

Junior Member
#8
MY wheels turn freely. Maybe like you said, I just need to commit to the take off. Having never flown I'm not sure what it's supposed to feel like. A tail wheel is a good idea as the tail skid has already left the building...twice. the wind here just won't stop either .I want a fair chance at least to get the plane up far enough for a decent first flight. Next time the wind dies down.....I'm gonna send it...do or die!
 

Hondo76251

Well-known member
#11
I hand launch all the time, dont even have gear on most of my planes. I know its easier for me and it opens up more places to fly. For just starting out though I'd definitely have someone throw it for you like @Sero said..