Two axis motion for any vehicle

  • #1
Anand Sivaram
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This question I have been thinking for some time.
1. For an Aircraft we have 4 types of motion. Yaw, Pitch, Roll and Forward Velocity.

2. For a Locomotive, we can say there are only Forward Velocity. No other axis of motion.

3. For a Car, we have the Forward Velocity and Yaw motion (steering control). For a boat also it would be similar.

Now, the question is do we have any vehicle which could do Two axis motion like (Yaw, Pitch), (Yaw, Roll), (Roll Pitch)
 

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  • #2
gleem
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3. For a Car, we have the Forward Velocity and Yaw motion (steering control). For a boat also it would be similar.

Actually, cars and boats have all three rotational motions maybe not as noticeable. Car roll in turns and pitch during acceleration and braking. Boats especially sailboats roll and pitch depending on the seaway.

You refer to yawing as related to steering but planes can fly in a direction they are not pointed. Car yaw while skidding.
 
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  • #3
Lnewqban
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All those axes and directions are imaginary and pre-made conventions.
Please, see:
https://en.m.wikipedia.org/wiki/Degrees_of_freedom_(mechanics)

Like any other body subjected to external forces, a vehicle moves and rotates in one instaneous unique way, which we like to divide into axes components.

A vehicle lacking sprung suspension and moving on a perfectly flat surface, like a frozen lake, could only have freedom to yaw.
 
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  • #4
.Scott
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Now, the question is do we have any vehicle which could do Two axis motion like (Yaw, Pitch), (Yaw, Roll), (Roll Pitch)
When an airplane (hopefully an aerobatic plane) does a snap roll or spin, it is doing these kind of combinations. At the start of the spin, the nose of the aircraft drops down and to the side with a definite yaw component. But once fully developed, the axis of rotation is primarily up and to the rear - so it is a yaw/roll combination.

Spin demonstration (video).

I looked at several snap roll videos, looking for one where the rotation axis is clearly not just a roll. As it turns out, the Citabria, the plane that I practiced in, demonstrates this better than the others. It seems to hold the yaw component for the the full duration of the snap roll instead of spending a lot of time transitioning into and out of a regular roll.

Citabria snap roll


This next one shows a 10-minute "aerobatic workout" with the Citabria - there are no snap rolls.
It shows simple "clearing turns" (used as a safety check), some "ballistic rolls", and some maneuvers that start out as pitch changes. Notice that even with the clearing turns, the plane rolls into the turn - so there is both a yaw and roll component even with that simple maneuver. It's actually difficult to do a pure roll in the Citabria.

Citabria Aerobatic Workout

Finally, I have never "tumbled" a plane, but some aerobatic planes are rated for them.
Entry to this maneuver is most often with a vertical climb - allowing the plane to loose air speed without stalling. As the plane nears zero vertical velocity, some combination of abrupt control inputs are applied (rudder, pitch, and/or aileron) - but typically with a plan to avoid a tail slide. One plane that's rated for this is the Pitts Special - the closest thing to a bumble bee in human transportation.

Pitts Special Tumble

Another Pitts Special tumble - this time from the spectators view.

Ground view of Pitts Special tumble.
 
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