I borrowed heavily from the last two vehicles for inspiration, but the air stair chassis was created new this week. Unlike the luggage conveyor, I used the Subdivision Surface modifier on the chassis for the air stair which helped the model look cleaner, particularly around the wheel wells. Normally, I start from the ground up. This time, I got the stair extension/retraction mechanism working first before attaching it to a vehicle.
To the right is a view of the stairs extended. The four support feet are also extended out and down to the ground. I initially used a driven key for one of the four support feet and tried to use constraints to make the four units animate together. That proved to be problematic when the vehicle moved and changed the global orientation. Eventually, I used three driven keys for the support feet, all tied to the first foot which was also controlled by a driven key.
- Mirror and Array Modifiers are great for speeding up the modeling process. They will mess up the Constraining and Animating process, however. My current Rule of Thumb is to create a complete copy when I am done modeling but before rigging. Then I will apply most Modifiers before beginning the rigging.
- I discovered that 'Distance' can be an input to a driven key. I used that to animate the tire rotation. As long as items are moving in relatively straight lines, that seems to work adequately.