I don't believe your GPS'd speeds!

[redshift]

Wow it's official, Mazda has entered the supercar arena!

I have seen this before, buddy of mine had one stuck to his sled, a Rev 600, and he got I think it was 638 mph.... ya they ain't that fast are they. The sledheads love GPS, because there is so much trackspin (especially un-studded) that the speedo is almost useless........ but they are still prone to error, sometimes significant error!

[BrianG]

Originally Posted by redshift

Wow it's official, Mazda has entered the supercar arena!...

lol, even the 'speed3 doesn't go up to 177 (set to 155 IIRC).

[rabosi]

What was your estimated max speed anyway and do the averages seem right?

[Quattro 83]

I've also watched plenty of people on you tube using their radar guns at the wrong angle, casting some doubt on their actual top speeds.

[BrianG]

Does angle really matter as long as you are pointed in the general right direction? Radar guns use the doppler effect (phenomenon where frequency changes with speed rather than simply using speed = distance/time) to calculate speed and a wrong angle would reduce the speed if anything I would think.

[rabosi]

Angle could be important if the radar is picking up a target other than the intended. Multipath (false targets) could also be a source of errors with radar.

[BrianG]

That would be true for radaring in an environment with multiple moving objects, but when clocking a single R/C car amongs stationary objects, I wouldn't think those would apply.

[Quattro 83]

Not really sure how much of an inaccuracy it causes, but Bushnell make a big deal out of it in the instructions.

"If the target is in a direct line (collision course) with the radar gun the measured speed will be exact. .....The measured speed will decrease as you move off this centre line. This phenomenen is called Cosine Effect, etc, etc.

As I said, not sure how much of an effect it has on Rc cars.