Large Low-Pressure Tire Vehicle (LLPTV)

Large Low-Pressure Tire Vehicle

by John Nordlie

For Dr. Dick Parker's 491 Space Mission Design course

Abstract
The Large Low Pressure Tire Vehicle (LLPTV) project for SpSt 491 was proposed by Dr. Richard Parker at the onset of the course. The project is based on the theory that large pneumatic tires inflated to a relatively low pressure would allow a rover type vehicle to drive over very rough terrain without becoming stuck or upset. The tires would simply absorb obstacles that would be a problem for smaller rovers.

THE PROJECT
It was proposed that a model prototype of the LLPTV be constructed as part of the SpSt 491 class. The model would be as low cost as possible, while remaining large enough to serve as a testbed for the theory. I decided to build the model using simple hardware and a radio remote control device scavenged from a broken toy truck. The wheels of the vehicle were made from beach balls, pierced by the axles and sealed with wire ties and silicone sealer. The balls, when fully inflated, had a diameter of about 18 inches. The axles were made from 1/8 inch diameter steel wire, mounted to the body of the vehicle which was a simple frame made from 3/4 inch square pine stock. Five C cell batteries were required to run the radio and drive motor, and counted for most of the vehicle's weight. A steel soup can mounted on the rear drive axle was driven by a rubber band, which was driven by a thread spool pulley mounted to the shaft of a gear motor. Unfortunately, several problems developed with the vehicle. The axles were barely strong enough to support the weight of the frame and batteries, sagging almost to the ground, and the wheels were not mounted securely enough to the axles to prevent air leaks and slipping of the drive axle. While sound in concept, the test model will need more work and some redesign to become a workable testbed.

CONCLUSION
Initial tests of the wheel concept tend to support the theory the vehicle was supposed to test. Military and civilian vehicles using the low pressure tire concept exist, and also help support the theory.

Back to Papers and Publications.