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  #1  
Old 06-14-2017, 04:27 PM
Simon Hitchen Simon Hitchen is offline
 
Join Date: Apr 2006
Posts: 185
Default 8 wheel alignment

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.
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  #2  
Old 06-14-2017, 06:36 PM
jump4way jump4way is offline
 
Join Date: Sep 2008
Location: Coolidge, AZ
Posts: 225
Default

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

Check out http://groveaircraft.com/accessories.html
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  #3  
Old 06-15-2017, 08:20 AM
Simon Hitchen Simon Hitchen is offline
 
Join Date: Apr 2006
Posts: 185
Default options

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.
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Titan XIO-360
Sensenich Prop, Cummins Spinner
Final assembly finished. Working on the final details before inspection
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  #4  
Old 06-15-2017, 08:29 AM
Mel's Avatar
Mel Mel is online now
 
Join Date: Mar 2005
Location: Dallas area
Posts: 9,559
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Quote:
Originally Posted by Simon Hitchen View Post
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.
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<n168tx(at)flytx.net>
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RV-6 Flying since 1993
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Last edited by Mel : 06-15-2017 at 08:56 AM.
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  #5  
Old 06-26-2017, 08:45 AM
JerryP JerryP is offline
 
Join Date: Jul 2007
Location: Kent,Washington
Posts: 1
Default Grease Plates to measure to/out

What are people using for grease plates?
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  #6  
Old 06-27-2017, 08:12 AM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 6,676
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Quote:
Originally Posted by Mel View Post
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.
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