Two axis motion for any vehicle

  • Context: Undergrad 
  • Thread starter Thread starter Anand Sivaram
  • Start date Start date
  • Tags Tags
    Axis Motion Vehicle
Click For Summary
SUMMARY

This discussion focuses on the motion capabilities of various vehicles, specifically examining two-axis motion combinations such as Yaw and Pitch, Yaw and Roll, and Roll and Pitch. It establishes that while aircraft like the Citabria can perform complex maneuvers involving these axes, ground vehicles such as cars and boats also exhibit these motions, albeit less noticeably. The conversation highlights that all vehicles experience rotational motions influenced by external forces, and emphasizes the importance of understanding these dynamics in vehicle design and operation.

PREREQUISITES
  • Understanding of vehicle dynamics and motion types (Yaw, Pitch, Roll)
  • Familiarity with aerodynamics and flight mechanics
  • Knowledge of vehicle control systems and suspension dynamics
  • Basic principles of physics related to motion and forces
NEXT STEPS
  • Research the dynamics of aerobatic maneuvers in aircraft, focusing on Yaw and Roll combinations.
  • Explore the principles of vehicle stability and control in ground vehicles.
  • Study the effects of external forces on vehicle motion, particularly in different environments (e.g., ice, water).
  • Investigate advanced vehicle designs that enhance multi-axis motion capabilities.
USEFUL FOR

Aeronautical engineers, automotive designers, pilots, and anyone interested in the physics of vehicle motion and control systems.

Anand Sivaram
Messages
90
Reaction score
43
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)
 
Physics news on Phys.org
Anand Sivaram said:
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.
 
  • Like
Likes   Reactions: Anand Sivaram and Lnewqban
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.
 
Last edited:
  • Like
Likes   Reactions: Anand Sivaram
Anand Sivaram said:
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 rollThis 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.
 
  • Like
Likes   Reactions: Anand Sivaram and Lnewqban

Similar threads

  • · Replies 20 ·
Replies
20
Views
4K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 18 ·
Replies
18
Views
3K
Replies
2
Views
6K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K