Very squirrelly tail wheel controllability

[redhawk]

Hello out there,
In the operation of my new -8 I recently purchased (I'm a former -4 owner),
It is noticeably "squirrly" on taxi out and especially on landing after the tail comes down (almost ground looped it the other day - thought my rocket steering link broke or went over center!!). I have checked my toe in and out and have determined its slightly toed in.
I am wondering if my steering link really did lock over center as I felt I had no control for a few seconds when it made a hard right !
Has anyone ever thought of using dual rocket steering links - one for each side?
I would think this might solve the erratic steering problem?
My rocket link rod ends are as far out as they could be to fit the steering arm on my new Aviation Products tailwheel.
Maybe I should go back to the chain set up !?
Thanks for your comments....

[SmilingJack]

Are you sure the tailwheel locking pin is engaged?

If not, remove it, clean it and relube it.

Good luck and congrats on the new 8!

[N941WR]

Replace the link with springs until you get used to the -8 and/or figure out what is going on with your landing gear.

[MikeT]

I know everybody has their opinion, but if you have any toe in it WILL be squirrly. I have experienced it on a cub and on snowmobiles. The cure is 0 toe or slight toe out. Speaking from experience.

[Neal@F14]

One rocket link is plenty enough as long as your toe-in/toe-out is correct and the rocket link is adjusted correctly. I had some issues with the tailwheel pin not locking on the RV-8 but it really wasn't that squirrely. Turned out I needed to carve the locking pin's slot in the control arm a bit deeper per Vince Frazier's instructions and that fixed the missed-locking issue.

[Mel]

Mike has it right. I discovered this while designing the landing gear for my Moni Motorglider.

Got most of my design information from Pazmany's book on landing gear design.

Think of it this way; if you have toe-in and you begin to swerve left, centrifugal force places more weight on the right wheel. If this wheel is toed-in, it will cause the aircraft to swerve MORE to the left. On the other hand if the wheel is toed-out slightly, it will cause the aircraft to be pulled straight.

I know there is a lot of controversy on this subject, but when I built my gear originally, I had a small amount of toe-in. The airplane was quite unstable on the ground. After research, I shimmed for a small amount of toe-out and the airplane became a "pussy-cat"!

Also if you look at the standard RV gear attached to the engine mount, the standard set-up is for straight ahead without weight on the gear. Now, because of the gear design, when you apply weight to the gear, the wheels will actually toe-out slightly as the gear spreads.

BTW, before you "A" drivers jump in, a tricycle gear configuration is entirely a different matter.

[Steve Barnes]

When I had my RV 4, I removed both springs on the tail wheel and it worked perfectly except for one thing. Taxiing in a X wind contributed a lot to brake wear. To save my brakes the springs are back on.

Steve

[roadrunner20]

Originally Posted by Mel

Think of it this way; if you have toe-in and you begin to swerve left, centrifugal force places more weight on the right wheel. If this wheel is toed-in, it will cause the aircraft to swerve MORE to the left. On the other hand if the wheel is toed-out slightly, it will cause the aircraft to be pulled straight.

I know there is a lot of controversy on this subject, but when I built my gear originally, I had a small amount of toe-in. The airplane was quite unstable on the ground. After research, I shimmed for a small amount of toe-out and the airplane became a "pussy-cat"!

Also if you look at the standard RV gear attached to the engine mount, the standard set-up is for straight ahead without weight on the gear. Now, because of the gear design, when you apply weight to the gear, the wheels will actually toe-out slightly as the gear spreads.

Mel,
I've not measured my toe-out with the gear hanging but it appears to be toed out quite a bit. I've only done taxi testing right now but there appears to be some scuffing on my right tire.
How did you shim out to correct to achieve a toe-out? From the engine mount? I would like to remove some toe-out.

[Snowflake]

A second rocket link won't help you because you can probably already overpower the locking pin on the tailwheel with one link. A second one would just add weight.

[Adam]

Mel,
What is the best way to check for toe in toe out?