featured sponsor:

Turbo Creeper

Race Order	Entry #	Driver Name	Car Name	Mass (grams)	Length (inches)	Width (inches)	Height (inches)	Distance Traveled (feet)	Running Time (seconds)
7	21	Terry Scharton	Turbo Creeper	80	11	6.75	9	0.17	0.50

Balloon car designer Terry Scharton writes:

• Design approach taken - explain how it worked.

  A water impulse turbine is most efficient when the turbine blade circumferential velocity is one-half of the jet velocity. Since the balloon jet velocity is ~200 ft./sec., this implies that the turbine velocity should be ~100 ft./sec. Therefore a 10:1 reduction gear is required to reduce the turbine speed of 100 ft./sec. down to a car speed of say 10 ft./sec., which is very optimistic. (This assumes that the turbine and car wheel diameters are the same.)

• Unique or clever features embodied

  Plastic reduction gear obtained from hobby store for approximately $10. Electric motor replaced by small turbine wheel.

• Materials of construction (mention unique parts you used or fabricated)

  Turbine wheel made from wife's sewing bobbin and straw blade segments. Remainder same as Turbo Dasher.

• Reasons behind any significant design choices you had to make

  Turbine thought to make energy extraction more efficient for reasons stated above.

• Lessons learned (what you'd do differently next time)

  Friction in the turbine was too great. Car wouldn't move under its own power. (Hence the nickname, "ISO 9000".)

• Anything else you'd like to add

  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.

MB 1/9/99