Saturday, June 23, 2007
Video: Ground test #2
Here are some more test runs of my project "X2" speed run car. You can see that I am still having stability issues and oversteer problems. At the end of this video I almost run into John who was filming the run.
This is a test prototype of the body and wing. The body is made from fiberglass. The body attaches to the chassis with button head screws on the sides. The wing is a NACA 9509 airfoil section. I made this wing in college for wind tunnel testing.
The weather held out for John and I to do some testing. There are a couple changes I made since the first ground test. I made a longer chassis out of carbon fiber instead of G10. The G10 chassis was my prototype chassis. I used it to place my components and see if the layout was correct. I found that the car has too much over steer. I have been trying to remedy this problem with much stiffer springs in front. This did help a bit, but I found that carbon fiber has a much better resistance to a torsional load than G10. This means that the chassis bends less and the suspension can do its job more effectively.
The tests didn't prove as promising as I would have liked. I still cannot get my speed up above 30 mph. The steering is way too sensitive and it makes the car spin out. It feels like significant over steer. You can see this in the video. Right at the end my car wanders towards John and I almost hit him.
My new Futaba 3PM 2.4GHZ radio does not have nearly as much range as my very old Futaba 3PK PCM system. The 3PM gave me only about 400' of range. Very disappointing. I was hoping for much more.
After my disappointing testing on Saturday, I also didn't have a very good day today (Sunday). I was testing different front camber/caster settings to help remedy the over steer problem. I go and test a camber change, stop the car, make another camber adjustment, then I go to turn the car on and now my speed control wont arm my motor. I am not sure what the problem is at all. I tried to recalibrate the radio, I tried my old radio and I still cant get it to arm the motor. So at this point I am out of commission until I fix the speed control.