Rex is the second Kinetic Sculpture vehicle that I have built. While it was a vast improvement over the first, there are several things I would do differently if I built a third. At the same time, there are several feature I would not want to lose.

The Good

• Two pilots. The two pilots can talk easily since they are sitting side-by-side. A tandem arrangement can work, but communication is more difficult.
• Disk brakes. The brakes are pretty good, but better integration into the frame would make them more reliable.
• Differential brakes controlled by a joystick. Until you've driven Rex down a steep dirt road you won't know why I praise this system.
• Prop drive.
• Small. Easy to store and park. Easy to transport.
• Fun to drive on the road. Taking it out for a spin is not a major undertaking.
• Either pilot can fully control the vehicle. If one get's tired, the other drives. Minor repairs can happen without stopping.
• Inflatable pontoons are light weight, robust, and store nicely.
• Extremely wide gear range. In lowest gear a full pedal rotation moves the vehicle forward 3 inches. This is valuable to protect the pilots knees when slogging thru thick mud and climbing soft sand.
• The custom hubs are wide, so that there is probably no danger of tacoing them. However, they are so wide that the spokes are bent and tend to break. A compromise might be better.
• Luggage rack over the heads provides a sunscreen. A downside is raising the CG.

The Bad

• Front wheel drive with no rear power. When you need maximum traction is when you are climbing a hill. But with front wheel drive that is when you have minimum traction.
• Water conversion is too complex and requires too much force.
• CrMo frame is prone to rust.
• The complexity of the water/sand conversions has made Rex heavy.
• Adjusting for different size pilots could be much better.

Other Potential Improvements

• Integrate the steering and brake system so it is all controlled by a single joystick.
• Drive by wire for brakes and steering. The advantage is non-linear steering. When driving straight the controls can be less sensitive than during hard turns.
• A suspension could bring 4 benefits. Better control over bumps since the wheels would stay in contact with the ground more. Water conversion with less energy. Less stress on the wheels. Improved creature comforts.
• Continuously variable transmission similar to Lutefisk.