Introduction
There will be at least three tests, more will be added depending on the results from the previous tests. The first requirement is that the differential do its job, one wheel should be able to spin while the other is not no matter what the rpm. The second test is the speed test, in Appendix A-5 the requirement states that the car will need to reach a speed of 15 mph. This requirement is relevant to the “Slalom-and-Sprint” part of the competition where the car will have to accelerate and reach as high a top speed as possible in order to complete the sprint faster than the other cars. Third and final will require that the motor not reach a temperature of above 50 degrees C after being driven for a certain period of time.
Methods
Differential
For the first test, one of the partners held the RC from the rear with one hand on the chassis while the other held either wheel in place. The other partner then gradually applied full throttle to the motor making sure that the differential had no problem spinning one wheel over the other. Lastly, mid test the partner that held the car released the wheel making sure the differential would then disengage allowing for both wheels to spin together.
The test results were a simple "pass/fail", and it was evident that the car did pass. No issues did arise during testing and the car performed as expected. This was a very important requirement of the entire project so it was added as one of the tests from the beginning. The differential was tested in previous construction videos; however, this test was specifically to see if it would work with the gear up and actually in action on the car.
Acceleration
Two cones were placed on the floor 30ft apart for the sprint test. All partners performed this test to ensure the car reached a speed of 15 mph at least before the cone. To do this, one partner drove, one timed, and the other used a radar gun aimed at the ending cone to record the cars terminal velocity at that point. This test was repeated two more times with each person getting to do each task once.
The test results are presented on the table and are as follows: the car was able to hit the modified requirement of 15mph within the 30ft allowed. There was a crash during the first test but the car was repaired and able to continue testing. The acceleration of the car was very impressive and the gearbox handled it with ease; however, from dead stop 30ft was not enough space to reach 30mph even with a sticky surface like rough concrete. The requirement was changed deeming the test a success.
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Temperature
The requirement was that the motor not reach a temperature of above 50 degrees C. This would be conducted through a series of three ten minute tests where the car is driven at 10-15mph. To complete this, a couple partners would be needed to help film, time and take the temperature of the car before and after. (Please click on and open videos to watch, as they are taken in portrait mode).
Temperature Test Results
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This video shows the disassembly of the differential after the second temperature test. The conclusion was that nothing had gone wrong yet, the plastic was just getting worn out from constant start and stop.