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toe in toe out adjustments RV8

bubba

Member
My RV8 will not track on take off and landing, making it very easy to ground loop(making me a professional at ground looping)on the landings . I can land and take off other tailwheel planes, so it must be something wrong with the airplane setup.

where can I get written instructions on the checking the toe in toe out and cambre.


What springs replacements are recommended on the tail wheel.

If anyone else can give some advice on this matter,please do so.

bev long
[email protected]
 
There are several ways to set toe-in. I used a Dunlop alignment rig that I had leftover from my racing days.

Strings run parallel to the wheels (not tires) or straight boards or straight angle iron/aluminum can also be used. I set mine with the tail in the air (level flight). If I recall, I set a slight toe-out.

Camber is difficult since the weight on the plane will change camber slightly. I didn't mess much with camber.

Shims are available fro Van's to make adjustments in both camber and toe.

I did not like the springs on the tail wheel; too much slop. I went to the "Rocket" link and like it much better. Over 900 landings so far.

YMMV
 
Van's construction manual has instructions on how to do it. But if you bought yours and are not the builder, then you probably don't have those.
1. Roll the airplane onto an area with a flat clean floor. Roll back and forward a short distance a few times, ending on a forward roll to make sure the wheels are in their natural position.
2. Jack the tail to level attitude.
3. Drop plumb bob at tailwheel and at centerline of fuselage at firewall. Don't use the spinner or anything on the engine mount since the engine is set slightly off fuselage centerline. Make marks on floor where the plumb bob points.
4. With those two plumb bob marks on floor, connect them to make a centerline on the floor.
5. make some 4-ft lengths of aluminum angle, or channel, or really straight 1x1 wood strips, and a couple of big blocks, like cinder blocks.
6. Set the sticks against the outside surface of the tires, horizontal, and just below or just above the axle. Not where the tire is deformed from ground contact. Use the blocks to put enough pressure on the sticks to keep them in position.
7. Measure to the floor centerline mark from the front and rear of each stick. Four measurements.
8. Calculate toe-in or toe-out of each wheel separately and shim accordingly.Shims are available from Vans. (If you are math challenged and uncomfortable doing the toe-in calculation, PM me)

The two wheels may be quite different. That's why you do each wheel separately. Lots of opinions about whether slight toe-in or toe-out is good. My opinion - you should strive for ZERO toe in. For me, it took 1/2 degree on one side, and 1.5 degrees on the other. The shims go between the landing gear strut and the axle. Be sure to torque those four bolts well that hold the axle on.

This can make a huge difference in how squirrelly or docile your RV-8 is on landing.

Note to set the toe-in with the airplane nearly level because that gives the most weight on the wheels. If you do a 3-point landing, there is much less weight on the wheels. The squirrellyness is because the airplane is mostly still flying, not as much because of the wheels.
 
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The squirrellyness is because the airplane is mostly still flying, not as much because of the wheels.

Agreed. That rudder is very good controlling the yaw compared to the wheel's traction on the ground.

Van's construction manual has instructions on how to do it. But if you bought yours and are not the builder, then you probably don't have those.

Even though it's extremely overpriced, you can also get the plans and manual (and a whole lot of other obsolete spam that has nothing to do with your model plane included, apparently to justify the high price charged) on a $1 flash drive from Van's for $10.00 plus shipping. Of course they could also save everybody the shipping and 1 week wait by offering it as a download. Without all the extra stuff not needed it's a pretty small file.
 
Bev,
I spent many hours trying to tame my RV-8. While your RV-8 is in the shop getting the toe in checked, check out your tail wheel as I described here. I'm curious to know if you have the same thing going on as I did.

http://www.vansairforce.com/community/showthread.php?t=164442

Yes, there are a few potential issues to look at on the tailwheel.

An obvious hint that there is an issue with the tailwheel is if you have no difficulty keeping straight with the tail up on a wheel landing, but it gets really squirrelly when you put the tailwheel down.

Friction/stiction can easily make it very treacherous.

Another thing I have seen is that the two bolts that hold the swivel bushing onto the spring can allow the whole tailwheel assembly to rock back and forth if they are not tight in their holes and snug. I replaced mine with taper pins and have never had a problem since. But that motion can amplify a steering input as the assembly flops from one side to the other.

Finally, you should be aware that the standard 'rocket link' geometry is asymmetrical because of the setback of the attachment to the rudder from the location of the rudder hinge. To compensate for this, a swept link was developed that results in symmetrical steering left and right, and does not release the tailwheel to swivel at full rudder deflection. It takes the combination of full rudder plus stretching the link springs.
 
After you have adjusted the main wheels toe in/out alignment and you find the plane still doesn't roll out straight, check the tail wheel swivel to see if its swivel shaft is vertical. If it at all leans to the side, it will make the plane unstable in roll out.
Another thought is if full rudder deflection is applied during roll out correction, this would release the tail wheel into full swivel mode and you basically have no steering control left other than brakes.

& I see Steve beat me in mentioning chain adjustment.
 
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My RV8 will not track on take off and landing, making it very easy to ground loop(making me a professional at ground looping)on the landings . I can land and take off other tailwheel planes, so it must be something wrong with the airplane setup.

where can I get written instructions on the checking the toe in toe out and cambre.


What springs replacements are recommended on the tail wheel.

If anyone else can give some advice on this matter,please do so.

bev long
[email protected]

When I first started flying my own -8, I found it to be a little unpredictable and squirrely on landing roll-out, particularly while transitioning from wheel landing attitude to 3-point. Nothing scary, just uncomfortable. After a hand full of flights this way, I went ahead and rechecked the wheel-toe. I found that I did have it set up pretty much to plans, with just perhaps a hint of toe-in (0.1 to 0.2 degrees) which I originally thought was too small to bother adjusting since Van's smallest shim was 1/2 degree. Anyway, I decided to install the 1/2 degree wedge shims (sold by Van's) between the axles and the gear-legs to give a slight amount of toe-out instead of toe-in. This slight change really made a tremendous amount of difference in stability on landing roll-out and now the plane tracks straight and predictably. I never would have believed this small adjustment could make such a difference in handling if I didn't experience it first hand. My father who also flies the plane had the same observations.

Skylor
 
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Actually, Van's has said they are working on making the construction manual and plans available via download.

But your complaining above is pretty petty. I'm sorry I pointed you to it.

Seriously? I didn’t know we could only be cheerleaders here. I’ve read plenty of threads telling others about bad service or overpriced items from other companies but if it’s about Van’s it’s taboo? How are they supposed to correct something if they don’t know about it and what about that plane AOG?

I have told everyone about how great the support they gave me on a weekend until 12:30 AM but then when I placed my order and told them the next day that I was AOG they said they couldn’t guarantee it would get to me 4 days later so I cancelled those items, ordered them on Aircraft Spruce the following day and got them 2 days later.

Why’s petty about that?
 
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Even though it's extremely overpriced, you can also get the plans and manual (and a whole lot of other obsolete spam that has nothing to do with your model plane included, apparently to justify the high price charged) on a $1 flash drive from Van's for $10.00 plus shipping. Of course they could also save everybody the shipping and 1 week wait by offering it as a download. Without all the extra stuff not needed it's a pretty small file.

Really? $10 is over-priced for a complete set of Vans Aircraft's proprietary copyrighted plans and instructions? How much do you think it would cost you if you tried to get a duplicate set of blue-prints for your house? How about your car?

The $10 doesn't just cover the cost of the memory stick. It also covers the labor of "duplicating" the memory stick as well as other overhead costs and expenses required to produce a product...

It used to cost $55 to buy a hard-copy of the preview plans/manual, so I think $10 is quite a bargain for this level of documentation.

I do agree that sometimes Vans shipping speed leaves a bit to be desired when compared to Amazon or Aircraft Spruce, but then Van's is a much smaller operation than either of those other two sources. I would generally rather Vans keep their parts prices reasonable than fund the overhead resources required to have a just-in-time shipping department.

Skylor
 
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