SunTiger IV

SunTiger IV left Washington D.C. on June 20th for Sunrayce 99. Despite cloudy weather most of the next 10 days, it still managed to come in 3rd on day 5, 2nd on day 9 and place 6th in the overall competition.

Many of the designs of SunTiger III were reused in SunTiger IV. The same symmetrical teardrop airfoil design was used for the body of the car. A new solar array was constructed using refinements in the method developed for the previous car. The new array put out over 1200 watts, head and shoulders above all the other arrays at the race, and won an award for Best Array Design.

Some of the changes between SunTiger III and SunTiger IV were due to Sunrayce rule changes. The most obvious of these was the addition of an extra wheel in the back for a total of four wheels. The frame of the car was also drastically reduced in size and the canopy was moved up. The new frame design allowed another battery to be added, for a total of 9 lead-acid batteries.

Great changes were made to the design of SunTiger IV in order to improve the car's aerodynamics. A new, sleeker canopy was added. Instead of the shell just sitting over the frame, camlocks were added to firmly secure the bellypan to the shell at fifteen different points. Farings were also added and were attached to the car's steering system so as to allow them to be even slimmer and more aerodynamic. Besides required ventilation, all this together created a virtually airtight seal between the road and the inside of the car. (Just ask the drivers how hot it got.)

SunTiger IV Specs

Final standing: 6th place
Weight with driver: 842 lbs.
Motor: NGM axial flux 3-phase AC, wheel hub mount
Battery: 9 Lead-acid deep-cycle
Frame: Chromoly steel tubing
Body: Carbon fiber/nomex honeycomb composite
Wheels: Four NGM 6061 Al rims with Bridgestone/Ecopia tires at 114 psi
Wheel configuration: 2 front, 2 rear - standard car configuration

Improved 2001 SunTiger IV Specs

Final standing: 11th place
Average speed: 31 mph
Weight with driver: 632 lbs
Motor: NGM axial flux 3-phase AC, wheel hub mount
Battery: 640+ LG-Chemical Li-ion cells
Frame: Chromoly steel
Body: Carbon fiber and nomex honeycomb
Wheels: New Generations rims with Bridgestone electric vehicle tires at 120 psi
Configuration: 2 front, 2 rear - standard car configuration