| AAMOF, TNT manufactures all of their landing gear (CF & Al) with 2-3° of | toe-in. Toe-out will increase the groundlooping tendency. Don't try to | figure it out rationally 'cuz it won't work. ;-)
Sure it will! It's really quite simple.
Put your hands in front of you, fingers straight, palms parallel to each other.
| | | | | |
(Phear my mad ASCII art skillz!)
This is your landing gear with no to-in or to-out.
Now, add some toe-in --
/ \ | | / \
(The weird bend is just because I can't really show an angle less than
45 degrees with ASCII art very well. Both hands should still be straight, but angled in a little.)
Now picture this going forward, straight ahead (away from you.) You can see that the tires will drag, but just a little, and evenly on both sides, so it won't make it turn either way.
Now picture the plane suddenly turning a bit to the right while the plane itself is still going straight --
/ | ^ / | | direction of travel / | |
This will cause the left wheel to drag more and the right wheel to drag less. This drag will tend to make the plane turn left, counteracting the perturbation that made it turn right in the first place.
If you do toe-out, you can easily see that the drag caused by it not going straight will make it worse rather than better.
| An automotive engineer will explain it clearly if you listen for | about 20 minutes .
You may be right. But it can be explained more simply.
Of course, all of this is needed largely because turning on a tail dragger is an unstable affair. If you're driving your car forward and you turn your wheel to the left and then let go of the wheel, the wheel will tend to turn back to the center. But if you're driving your car backwards and turn and then let go of the wheel, the wheel will tend to turn more and more. Taildraggers, because the steering wheel is in the back, work like a car going backwards.
Tricycle gears, with the steering wheel up front, are more stable.
Regarding cars, this page --
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explains it pretty well. But cars are different too -- where they might want toe-out to make the car more nimble, we just want our tail draggers to go straight as we take off. Nimble is something we want in the air ...