Doppler shift might come into play if the rocket went much faster, but Mach 1 just isn't that fast compared to the speed of light. A quick calculation suggests that a 2.4GHz signal would get shifted by ~3kHz. Wifi isn't that sensitive.
> Why bother with a TCP/IP link, though? Seems like a less verbose protocol would be a better choice to use to get a simple data stream from your rocket to ground control.
We used UDP/IP for telemetry data (and had almost no packet loss). TCP/IP did allow us to SSH to the (Linux-powered) rocket for debugging, though.
Also, being able to SSH into a rocket is pretty fucking awesome on it's own. :)