Rex Features: Good and Bad
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.
- 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.
- 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
Copyright 2007 C. Allen Brown