I've used a program that takes sound and measures the speed using doplar. It's not a hard process once you learn it.
I could take a sample of this video and measure it, but I'll tell you, it won't be true speed.
Best way is to take your camera out onto the runway and set it at the end, then take a high speed dive into a low pass as close as you can to the camera, say 10-20 feet up and full throttle. Post that vid, then I'll take a short sound sample and measure it for ya.

By setting the camera down, you also get rid of the sound that's made with your camera person handling the camera.


BTW Nitroplanes has a new coupon code. Note that it's mispelled once on their main page.
It's EVERYPLANE, not EVERYPLANES
Here are current coupons:
[link=http://www.mycoolheli.com/coupons/nitroplanescoupons.html]coupons[/link]