Hi Matt,
Your comments about static/dynamic is spot on of course. I have done many hours of datalogging on a current RPV project where we use GPS and airspeed extensively. The autopilot we used unbeknown to us actually used different sensors for alt(static) and dynamic. After finding discrepancies and dismantling the autopilot we found the dynamic sensor to pick up static from within the unit..... At different aircraft pitches the airspeed would vary quite a lot from GPS during level flight, probably due to ram/venturi effects on the various retract wells etc. Also GPS would give wild errors on anything more than 30 deg from vertical orientation of the antenna. I base this on a few MB of datafiles we collected.
If the speed limiters are to be of any value a proper dynamic/static pitot tube is absolutely a requirement.
As an example, if a fuselage picked up static pressure from a forward facing hole of some sort the airspeed could seriously under-read. The opposite could also happen when picking up static within the fuselage.
Cheers
Andre Baird