The FAMU-FSU solar car team was experiencing some problems with their electrical motor. There seems to be some deflection at the strut that holds the electrical motor causing the bearings inside the motor to get prematurely worn. The cost of repairs of this electrical motor can be very high so our team has been commissioned with the task of determining if there is any actual deflection in this strut.

figure of the current spare wheel mount (Click image to enlarge)

In order to determine actual deflection in the strut some tests have to be performed. I the case of the solar car a static and dynamic test are in order. The static test consists of loading the solar car with weight (People) and making accurate measurements on the strut for signs of deflection. The dynamic test consist of towing the car and determining if under loading conditions such as turns, acceleration and breaking any deflection is obtained. The static test has been performed before the problem was assigned to us but there was no deflection observed. The solar car team still believes that the deflection is the cause of the motor failures so a dynamic test will be conducted.

Static test being performed on solar car. No deflection was obtained

To carry a dynamic test the solar car has to be towed speeds close to 70 MPH. In order to achieve this and not damage the electrical motor an whole new wheel mount had to be developed. Once testing is done this wheel mount will be used to tow the car into service. The current set up of the car does not allow mounting the rear wheel unless the electrical motor is placed in position.

The task given to our team was to develop a wheel mount that would best resemble the actual setup in the solar car. This mount would have to be adapted with the current design of the car and could not change any of the characteristics of the wheel such as ride height or position. The wheel mount should be usable for towing purposes later on. The weight of the electrical motor is about 18 Kg and the wheel mount that is replacing it should weigh about the same. This is the only way to determine in dynamic testing if there is any deflection in the mounting strut.

The device that will be used for the testing will be a potentiometer of variable resistance that would be attached to the strut using a cable. If any deflection occurs, the cable will either tighten or loosen causing the potentiometer to change it's resistance. Current will be supplied and readings will monitor any position change in the strut.

Once all testing has been done and the data analyzed we will make recommendations on what should be done to prevent this kind of problem for 2003 solar car. There will be some recommendations as what should be done to correct the problem in the present car.