Control stick length

[Barton]

Help! I recently bought a PA-12 with a lot of PA-18 mods including o-320 engine (with original engine mount), PA-18 tail, gear and flaps. Its a great airplane EXCEPT the stick forces are really high and it requires a LOT of trimming for slow flight. The STC for the -18 tail required the installation of the bungee/spring. This means that with the trim set one dot up the forward push on the stick to raise the tail for takeoff is FIRM. Takeoff with one notch of flaps and trim set one dot up requires a FIRM PULL and the stick forces remain until the airspeed reaches about 85 mph indicated. In order to slow fly the airplane you must use all up trim available at 40 mph indicated and still have significant back pressure. To slow fly at 40 indicated with trim set for about 75 and slightly nose high is almost a two handed operation. My 115 pound wife can barely 3 point the airplane even with my 210 in the back seat and when she's sitting on her cushion her arms are so short she's pulling UP on the stick as much as AFT. Keeps pulling the stick grip off.

Should we need to use all the trim available on every short field landing? Its been years since I flew a
PA-18 but I don't remember them being that way.

The stick will barely clear the bottom of the panel going forward. If my thumb is on top of the grip Ill scrape it off. I don't know if the stick is stock length or not but it measures 14-1/2" from the pivot to the top of the grip. I'm thinking of making a longer stick with an S bend in it in hopes of reducing the stick forces and making it easier to be more precise and fluid with the motion. Of course I could fly it like the former owner did and just say landing speed is 60-65mph but that seems kind of silly. I mean I have an airplane that can be flown slowly and will land really short when I want to that's why I bought it. If I'd wanted a 172 I'd have bought one. Has anyone any input on this? Have you built a longer stick? I see UNIVAIR has an extended stick but it's still straight so wouldn't work for me. I have to have an S bend to allow forward movement of a longer stick.

Thanks for any input.

 

[DENNY]

The problem is not the stick. You put a lot of weight on that long mount up front. If I am trying to get in short and have to brake hard I always do full nose up trim. I have to hold stick forward until the flare than I just take forward pressure off and it flares with no problem. If full nose up trim works than that is what I would do. If that don't work you could put some weight as far back in the tail as possible. After that things get harder and cost more. Change to short mount up front or cut the tail to give you some more travel back there. Make sure you have full travel of the stabilator, don't go by dots, count number of turns from full nose up to full nose down, Your stabilator is there to help you make full use of it!!
DENNY

 

[cubpilot2]

If you still have the original 12 torque tube installed then you will have heavier stick forces then those that have switched to the PA-18 style tubes which use shorter "crank-arms" giving better leverage. I think that there is nearly 1 1/2 inches difference between the two. I think I recall hearing through a friend of a friends cousin that some PA-12 tubes were shortened to the same spec as the 18....

This isn't going to help your weight and balance issues any but will reduce the stick pressures a lot.

 

[mike mcs repair]

Shorten the bungee spring cable on top evevator. It was set for a much lighter nose original weight

 

[stewartb]

First things first. Make sure your jackscrew yoke is installed correctly.

If you have an -18 torque tube in there you wouldn't have full aileron deflection.

 

[cubpilot2]

Good discussion on this here:

http://www.supercub.org/forum/showt...ns-PA12-Vs-PA18&highlight=pa12+aileron+travel

You should get the same aileron deflection with the 18 torque tube if you install the "extension" as on the original.
If you forget then you will have a travel problem.

 

[skywagon8a]

Make sure that you have full nose up trim available. The stabilizer should touch the top longerons when in the full nose up position. This doesn't address the high control pressures.