A friend of mine is building a Legacy and has a question....

Hey, ask anyone on the rec homebuilt group if they've ever built any
Lancairs and then ask them if they used a 1 degree toe-in on the main
landing gear for the 320, the Lancair 4 or the Legacy. I test drove
mine today and almost lost control of it in yaw on the runway because
it's dead nuts on center with the mains. No where in the manual does it
say you need toe-in, but I have a sneaking hunch that I need a half
degree on each main to keep it from being divergent. I'm going to just
do it if I can't get a response from someone who might know. The
****ing factory doesn't even know....dumb ****s. They are about to go
bankrupt and I can see why!


I forget what toe-in and how much I used on my RV-6....


John

Have you asked this on the Lancair mail line?

On 20 Apr 2006 21:48:34 -0700, "ELIPPSE"
wrote:

Have you asked this on the Lancair mail line?

John, it's my understanding that you need a little toe out on a tail
dragger and a little toe in on the tri-gears. I know the toe out works
on a tail dragger and I don't know the exact logic on a tri-gear.

Ed Sullivan

"Ed Sullivan" wrote in message
...
On 20 Apr 2006 21:48:34 -0700, "ELIPPSE"
wrote:

Have you asked this on the Lancair mail line?

John, it's my understanding that you need a little toe out on a tail
dragger and a little toe in on the tri-gears. I know the toe out works
on a tail dragger and I don't know the exact logic on a tri-gear.

Ed Sullivan

That is my understanding as well. I my recollection is mainly of an
article(s) in Sport Aviation several years ago which outlined some of the
issues the repair volunteers had seen in the course of getting aircraft
headed home from OSH. An additional personal observation is that camber can
influence or mimic either toe-in or toe-out in a nose-up or tail-up
attitude. Perhaps a call to EAA would be usefull.

Peter

John, it's my understanding that you need a little toe out on a tail
dragger and a little toe in on the tri-gears.


I agree that taildraggers will need toe out and tricycle kit toe in.

This is since:-

Taildragger with toe out.
You are going along the ground straight and level when some
perturbation causes the aircraft to point left of its track.
The aircraft will tend to roll to the right and the vertical
force on the right hand wheel will increase at the expense
of the left hand wheel (since the aircraft still weights the same).
Since the right hand wheel is toed out the aircraft will
begin to turn to the right thereby moving everything back
towards balance.
In a word there is stability.

Taildragger with toe in.
You are going along the ground straight and level when some
perturbation causes the aircraft to point left of its track.
The aircraft will tend to roll to the right and the vertical
force on the right hand wheel will increase at the expense
of the left hand wheel (since the aircraft still weights the same).
Since the right hand wheel is toed in the aircraft will
turn further to the LEFT thereby reinforcing the
original perturbation.
In a word there is instability.


Tricycle with toe out.
You are going along the ground straight and level when some
perturbation causes the aircraft to point left of its track.
The aircraft will tend to roll to the right and the vertical
force on the right hand wheel will increase at the expense
of the left hand wheel (since the aircraft still weights the same).
Since the right hand wheel is toed out the aircraft will
turn further to the LEFT thereby reinforcing the
original perturbation.
In a word there is instability.


Tricycle with toe in.
By similar argument - stability



I have experienced severe oscillation in the case of a trailer
being towed behind a car where the trailer had a lot of toe in due to
crash damage.

After a bit of thinking I realised what might be causing the issue and
reduced the amplitude or the oscillation at any particular speed
by letting some air out of the tires of the trailer. This
allowed the tyres to operate at a greater slip angle.
I could then proceed at 28mph instead of 20mph a big improvement.

I have never previously found any use for this
knowledge ^h^h^h^h^h^h opinion.
Hope it is right and helps out.

wrote)
I have never previously found any use for this knowledge ^h^h^h^h^h^h
opinion.
Hope it is right and helps out.


http://www.familycar.com/Alignment.htm
Had to make sure I had the terms right.


Montblack

On Fri, 21 Apr 2006 17:32:22 -0500, "Montblack"
wrote:

wrote)
I have never previously found any use for this knowledge ^h^h^h^h^h^h
opinion.
Hope it is right and helps out.


http://www.familycar.com/Alignment.htm
Had to make sure I had the terms right.

Disclaimer (Don't try this at home)

You could always set about 2 or 3 degrees toe out with a bit of
negative caster. That way the results will be predictable to an almost
certainty and he'll never have a case of bordome on any landing.

As to the toe in, I thought that really was about 2 degrees.

BTW the nose gear on the Deb and Bonanzas has a negative caster. Your
feet are always moving if you plan on even trying to simulate a
straight taxi. That wheel wants to go any where but straight ahead.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


Montblack

"Roger" wrote in message
...
On Fri, 21 Apr 2006 17:32:22 -0500, "Montblack"
wrote:

wrote)
I have never previously found any use for this knowledge ^h^h^h^h^h^h
opinion.
Hope it is right and helps out.


http://www.familycar.com/Alignment.htm
Had to make sure I had the terms right.

Disclaimer (Don't try this at home)

You could always set about 2 or 3 degrees toe out with a bit of
negative caster. That way the results will be predictable to an almost
certainty and he'll never have a case of bordome on any landing.

As to the toe in, I thought that really was about 2 degrees.

BTW the nose gear on the Deb and Bonanzas has a negative caster. Your
feet are always moving if you plan on even trying to simulate a
straight taxi. That wheel wants to go any where but straight ahead.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


Montblack

Roger, I think you mean negative camber. Hilarious nonetheless!

Peter

I have an old NACA study on LG geometry that addresses toe and camber
somewhere on my shelf, I'll look for it.

Great!!

Remove "123" for my email address.

John

Richard Riley wrote:
I have an old NACA study on LG geometry that addresses toe and camber
somewhere on my shelf, I'll look for it.