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Toe-in best practice and technique

Old 11-03-2020, 07:03 AM
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skunkwurk
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Default Toe-in best practice and technique

Hi Fellas,

How do you measure toe-in? How much is too much or too little? I've always eyeballed it but I figure some of you may have a more measured/methodical approach.

Thanks in advance for your help.
Old 11-03-2020, 07:24 AM
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Eyeball a little toe in
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skunkwurk (11-03-2020)
Old 11-03-2020, 07:32 AM
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ravill
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Yep, the ole eyeball technique!
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Old 11-03-2020, 07:37 AM
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lol - nice! hehe
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Old 11-03-2020, 07:53 AM
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AEROSHELDON
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I eyeball it as well. I do like to put a long straightedge on the hub to make it easier to see how it is pointed.
Old 11-03-2020, 12:32 PM
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Eye ball as well..... with some carbon fiber rods.....attached to the wheels with rubber band.
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Old 11-03-2020, 12:34 PM
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I got to the field one day and a guy had a target about 30 yards out and laser pointers on the struts and centerline.

Some people are too smart I think
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skunkwurk (11-03-2020)
Old 11-03-2020, 12:43 PM
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Originally Posted by BarracudaHockey View Post
I got to the field one day and a guy had a target about 30 yards out and laser pointers on the struts and centerline.

Some people are too smart I think
‘Just like the master scale war plane builders......just watch out when they fly’s 😂

Must have been an engineer......simple problem, complicated solution...
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skunkwurk (11-03-2020)
Old 11-03-2020, 01:02 PM
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I like the carbon fiber rod idea. I saw a video posted by Canadian Man where he used a similar method. I'm not trying to over complicate things, I agree that we can get too carried away with simple tasks. I think the 30 yard target comment was hilarious.
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Old 11-03-2020, 01:58 PM
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I have covered it in RCJi more than once 😉

Removable wings like this, one piece wing it’s best to put it on the fuselage and reference off each side. I use 2’ long rods and set around 3/8” wider at the rear.



Old 11-03-2020, 02:25 PM
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Originally Posted by skunkwurk View Post
Hi Fellas,

How do you measure toe-in? How much is too much or too little? I've always eyeballed it but I figure some of you may have a more measured/methodical approach.

Thanks in advance for your help.
Hi

Actually a little toe out works better in jets. Less prone to zig zag

Center as best as possible and open a little bit. 1 or 2 degrees in each wheel is enough

BR
Nuno
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JackD (11-04-2020)
Old 11-03-2020, 02:27 PM
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Originally Posted by Dave Wilshere View Post
I have covered it in RCJi more than once 😉

Removable wings like this, one piece wing it’s best to put it on the fuselage and reference off each side. I use 2’ long rods and set around 3/8” wider at the rear.


Hi Dave,

This is exactly what I was looking for. I've just been eyeballing until this point. I did not have actual numbers to work off of. The 3/8" value at the rear using the 2' rod is a simple process I can easily replicate on all my planes. Thanks, Dave!
Old 11-03-2020, 02:45 PM
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Toe out is is a complete no no! Toe in pushes down the light load/raised wheel.
Eyeballs can be good, but now airframes are generally straight measuring is better 🙂
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skunkwurk (11-03-2020)
Old 11-03-2020, 02:52 PM
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CARS II
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I go straight, it gets a bit of toe in from the struts/wheels when they flex in on the run, has worked perfectly for me.
Old 11-03-2020, 06:00 PM
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ravill
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Toe out is no good. It actually increases straight line instability. You can look up all the car racing set ups. Toe in is what you want.
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Old 11-03-2020, 07:15 PM
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this video should explain at least the flaps setup I did the video long time ago
Old 11-03-2020, 07:22 PM
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Doing the same thing with attaching the carbonfiber rots to the wheels and measure the front and back to make it equal
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skunkwurk (11-04-2020)
Old 11-03-2020, 09:52 PM
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Originally Posted by CARS II View Post
I go straight, it gets a bit of toe in from the struts/wheels when they flex in on the run, has worked perfectly for me.
1. What about when the wheel is on the outside of the leg?
2. Electron and other quality TL legs have almost no free play, the old tubular leg with a sliding pin/screw needed the wheel twisting to take up the free play, then the leg setting.

Dave
Old 11-04-2020, 04:00 AM
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I use a 90 degree builders square, and keep the wheels straight. If using toe in on a tail dragger, then only 1/2-1 degree toe in.
Old 11-04-2020, 10:35 AM
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Originally Posted by ravill View Post
Toe out is no good. It actually increases straight line instability. You can look up all the car racing set ups. Toe in is what you want.
Actually, I use tow out on narrow track planes like the cougar and the F86, especifically to improve cross wind handling. And guess who recommended it (and actually helped me win top gun with that tip?) Juan Pablo Montoya and Peter goldsmith

He told me race cars are toe in in front, and to out on the rears.

What toe out does for you on narrow track, cross wind conditions is that when the outer wheel gets loaded, it does not bite, so the plane does not tip over and bounce back. it is a lot more forgiving. On my current sabre, I have too much toe in (it was factory set, and a pita to correct, but i will fix it) and you cant even touch the brakes cause it starts wingdancing on the ground

I don't know if the airplane becomes a bit more sensitive, but nothing a nosewheel gyro does not solve (i have nose wheel gyros in 100% of my planes). But what you gain on cross wind stability on the ground is priceless....


Old 11-04-2020, 11:05 AM
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Hi Jack,

Very interesting point, thanks for sharing it with us. I suppose we could classify this (toe-in/out) as tuning, and there probably isn't a perfect or right answer for all setups. I used to race motocross and tuning my gearing and suspension was paramount, but it changed constantly based on the track. So I kept close notes of what worked and replicated it every time I would revisit the track and the conditions. But I had a baseline to work from. I think toe-in/out, as it relates to race cars and jets could probably be used to tune/solve different problems. Example, for a race car steering behavior is more important than straight line stability(F1 not a drag-car), so toe-out (negative toe) is potentially preferred over a passenger car. Where a passenger car would tune for straight line stability, rather then steering behavior. Both right or correct, but specific to the use case. I suppose for our jets we probably want to determine what we want to solve for first, then adjust accordingly. In my case, I am looking for straight line stability and a heavier nose wheel presence, to aid in steering. Similar to pulling up on tail-daggers (up elevator) to place weight on the tail-wheel for steering. Your example sounds like a good solution as well.

I think the moral of the story is, if you think through the physics at play and implement a repeatable process you can use as a baseline, you're ahead of the game. It should help you determine what works or what doesn't work, more importantly, how to adjust. I have been eyeballing toe-in until now. I plan to set up new planes per Dave's suggestion as a starting point. Now I'll be able to test and add or remove toe-in per plane. I never had a baseline to work from, this is why I turn to RCU! You guys rock!

Last edited by skunkwurk; 11-04-2020 at 12:43 PM.
Old 11-04-2020, 11:41 AM
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Yup. What I am solving is for cross wind controlability on narrow track planes. And toe out happened to be a HUGE improvement. But as you say, depends on what you are solving for...

For straight line stability, a gyro is your best friend
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Old 11-04-2020, 12:09 PM
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Originally Posted by Dave Wilshere View Post
1. What about when the wheel is on the outside of the leg?
2. Electron and other quality TL legs have almost no free play, the old tubular leg with a sliding pin/screw needed the wheel twisting to take up the free play, then the leg setting.

Dave
Mmmmmm, good point Dave, I supposed all the struts/wheel combos that I have installed in the last few years have had some kind of play and setting them up straight has worked, I have not had the opportunity to play with gear sets like the Electron ones and have not work with wheels on the outside of the struts, in that case then a bit toe in is preferable.

Last edited by CARS II; 11-04-2020 at 03:46 PM.
Old 11-04-2020, 04:37 PM
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Hi

If you adjust with toe out you get more stability in straights, including cross winds. If you adjust with toe in you will have more incisive turns (more twitchy on steering and prone to zig zag). Actually, adding toe in/out, to the set-up, both will shift the center mass of the plane as it rolls on takeoff/landing. Both set-ups add drag and make the nose prone to lower AoA.

Airplanes do not have 4 wheels nor power on these, so we can't just import set-ups used on cars

Any way in racing cars that run on a track (not starights or oval), to have more rear grip you close the rear (add toe in), to have more steering you open the front (toe out), or play with both, depending on grip, tire shore, camber, springs, shock oils, differential, etc.. All set ups have to tune in a band. JackD - its the otherway arround ("He told me race cars are toe in in front, and to out on the rears.")

For those who care, here's a nice article

https://www.competitionx.com/rc-tuning-toe-in-toe-out/


Have fun ;-)

Nuno

Last edited by jetnuno; 11-04-2020 at 05:05 PM.
Old 11-04-2020, 05:21 PM
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I think the net result of what you and I are recommending is the same. Toe out to minimize bite and avoid zigzag/wingdance, specially on cross wind.

Regarding toe in/toe out on race cars, I kinda trust JP Montoya on his explanation

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