8 wheel alignment

[Simon Hitchen]

I've read as many posts as I can find so I'm asking for some help.

I'm flying an 8 that is rock solid to wheel land but as I transition to three point or land three point it gets a little squirely. Nothing unmanageable bit since I've got the wheel pants off I thought I'd measure the alignment.

The measurements were taken with half fuel, pilot in the front, the tail on the ground and grease plates under both main wheels.

I've ordered a few 1/2 degree shims from van's. What do you guys with experience think I should do with regards to shimming.



Many thanks.

[jump4way]

Grove aircraft details a measurement procedure to know how much shim to use.

Check out http://groveaircraft.com/accessories.html

[Simon Hitchen]

Option 1 is to shim the left wheel out by 1/2 a degree to make both wheels equal and have no toe in or out in the three point attitude.

Option 2 is to shim the right wheel inboard to give both wheels 1/2 degree toe in in the three point attitude.

[Mel]

Originally Posted by Simon Hitchen

Option 1 is to shim the left wheel out by 1/2 a degree to make both wheels equal and have no toe in or out in the three point attitude.

Option 2 is to shim the right wheel inboard to give both wheels 1/2 degree toe in in the three point attitude.

You do NOT want toe-in on a tailwheel airplane!!!!!

Think about it this way, with toe-in if the aircraft starts to swerve left, centrifugal force puts more weight on the right wheel. If that wheel is toed in it will tend to pull the aircraft further left. A slight amount of toe-out will tend to pull the aircraft straight.
I learned a lot while designing a conventional gear for my Moni Motorglider. Check out "Landing Gear Design for Light Aircraft" by Ladislao Pazmany.

Another factor; if you look at other RV landing gear, Van calls for zero toe with weight off the airplane. The design of the gear toes-out slightly with the weight of the airplane on the gear.

[JerryP]

What are people using for grease plates?

[rvbuilder2002]

Originally Posted by Mel

You do NOT want toe-in on a tailwheel airplane!!!!!

Think about it this way, with toe-in if the aircraft starts to swerve left, centrifugal force puts more weight on the right wheel. If that wheel is toed in it will tend to pull the aircraft further left. A slight amount of toe-out will tend to pull the aircraft straight.
I learned a lot while designing a conventional gear for my Moni Motorglider. Check out "Landing Gear Design for Light Aircraft" by Ladislao Pazmany.

Another factor; if you look at other RV landing gear, Van calls for zero toe with weight off the airplane. The design of the gear toes-out slightly with the weight of the airplane on the gear.

Actually the spec for the rod gear airplanes has always been for very slight toe in (This is goes way back to when builders had to align the axles and drill the hole for the leg bolt them selves) It was to have a near neutral alignment when the legs were deflected under load for the reason Mel mentioned.