|Entry #||Driver Name||Car Name||Mass
|6||38||Terry Scharton||Turbo Dasher||80||12.5||12||6||22.67||19.74|
Balloon car designer Terry Scharton writes:
Turbines are a conventional method of taking energy from a jet. However, for a balloon, with 0.37 psi of internal pressure, the pressure ratio (14.7 psi /(14.7 + 0.37) psi = 0.975) and associated jet velocity (~200 ft/sec.) are very small, and a turbine is not very efficient.
Turbo Dasher featured a direct drive, with the turbine incorporated into the front wheel.
The turbine wheel was fabricated from an empty ribbon dispenser with plastic straw segments used for the turbine blades. The car frame is piano wire soldered together. The jet nozzles are plastic syringes use for feeding small animals.
I had to add a second jet, in parallel with the first, to get the car to move.
I wouldn't use a turbine -- too inefficient. (See notes on my other entry Turbo Creeper.)
The calculations on the energy available from a balloon may be of interest to someone. As the calculated energy, 44 ft-lb., seems too high, I would appreciate comments, or corrections, anyone might offer. Email them to Terry Scharton.