# Two axis motion for any vehicle

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• Anand Sivaram
In summary, vehicles such as airplanes, cars, and boats have different types of motion including yaw, pitch, and roll. However, there are some aerobatic planes, such as the Citabria and Pitts Special, that can perform two-axis motion combinations such as yaw and roll or yaw and pitch. These maneuvers require precise control inputs and can be seen in videos of snap rolls, aerobatic workouts, and tumbles.
Anand Sivaram
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)

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.

Anand Sivaram and Lnewqban
All those axes and directions are imaginary and pre-made conventions.
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:
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.

Anand Sivaram and Lnewqban

## 1. What is two axis motion for a vehicle?

Two axis motion for a vehicle refers to the movement of a vehicle along two perpendicular axes, typically the x-axis and y-axis. This allows the vehicle to move in any direction within a two-dimensional space.

## 2. How is two axis motion achieved in a vehicle?

Two axis motion can be achieved through various mechanisms, such as a steering wheel and pedals in a car, a joystick in a plane, or a remote control in a drone. These mechanisms control the vehicle's movement along the x-axis and y-axis.

## 3. What are the advantages of two axis motion for a vehicle?

Two axis motion allows for greater maneuverability and flexibility in a vehicle's movement. It also allows for more precise control and the ability to navigate through tight spaces or obstacles.

## 4. Are there any limitations to two axis motion for a vehicle?

One limitation of two axis motion is that it is limited to movement in a two-dimensional space. This means that the vehicle cannot move vertically, which may be necessary in certain situations.

## 5. How is two axis motion used in different types of vehicles?

Two axis motion is used in various types of vehicles, such as cars, planes, boats, and drones. Each vehicle may have different mechanisms for achieving two axis motion, but the concept remains the same.

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