# Rigging Landing Gear

The Blender File is attached to this post.

When the first controller object moves down on the local Z axis, I'd like the land gear empty controller object, on both sides of the wings, to rotate along the local y axis.

This way, you can use a single object to rotate the landing gear up and down.

I assume this can be done with constraints, but couldn't figure out how.

If anyone can help, I'd appreciate it. Thanks!

It is quite simple, you put a Transformation constraint on both gear controllers, as Target you choose the "Landing Gear Main Controller" object for both.

Now the important thing is to set the Owner to Local Space to make sure the gears rotate on their local Y axis.

Then you have to choose Map From > Location and set Z values for Min and Max which match the distance you want to move the controller for fully rotating the gear.

In the Map To section you choose Rotation, and since you want to rotate on the Y axis by Z values, you set Y Source Axis to Z and then choose angles you want for the gear rotation. And I forgot to mark it in the image below, but you also could switch the Mix setting from Add to Replace. In this example it does not make a difference, but it depends on if you want to set absolute angles for the gear or add a rotation to an existing angle, for example if you want to copy the constraint without changing it to another object which has a different base rotation.

Very important note here: I've seen the gears have to rotate from 0° to a negative angle (I chose -90°) and you want to move the controller down to get them rotated down (I chose Z values 0 and -0.3). Other than a Map Range node in shaders or Geometry Nodes, the Transformation constraint does not work correctly if you switch Min and Max values in the source, i.e. let's say you want to start the rotation with a Z value of 0 and end it at Z = -0.3, that could lead to thinking you could just use Min for "start" and Max for "end" - but this will result in weird behaviour and the rotation will not work.

By the way, the Min/Max values are clamped, so that moving the controller higher or lower than the range that is given will not rotate the gear more than specified, unless you activate the Extrapolate option in the constraint. And here is the result:

When you parent the gear controllers which have the constraints to the wing, it is important to switch the Mix to After Original:

Another by the way, I left the Target at World Space because the "Landing Gear Main Controller" is not parented to anything, so its Z position is not relative to some other object. But if you parent it to the airplane or what this will become in the end, Local Space makes sense or otherwise the gears will be rotating when you might not want it. Local Space could also make sense if the controller is not parented, if it is somehow rotated and you want to use movement on the local Z position rather than the actual position in the world (however this can be tricky because Z = 0 local might not be the same as before with Z = 0 global).

• Thanks! This all seems to work, however, when I parent the landing gear controller empty to the wing, the rotation is messed up. It seems to rotate on the local Z when its parented to the wing. Changing the target to local space also doesn't fix the issue. Commented Jul 21 at 16:39
• @RyanKingArt Oh, sorry I did not mention that in the answer, I'll edit that in: when you parent the controllers to another object like the wing, you have to change the Mix to After Original. Commented Jul 21 at 17:00
• Thanks so much for your help! Commented Jul 21 at 17:20