Static pressure will be "by far" the most challenging measurement to get from any onboard data acquisition system without a professionally designed pitot-static probe. To derive air speed you need to measure "freestream" total and "freestream" staic pressure. Freestream referes to a non disturbed pressure(out of the influence of local accelerated flow due to things such as wings, fuselages, etc). Search Pitot-staic probe manufactures and you will find a variety of "off the shelf" probes wich will give you say 2-3% type air speed data. In general, a pitot probe will have both a total and static pressure taps. As Michael stated, the total(or ram) pressure is not real sensitive due to influences of the wings or fuselages, however the static pressure is. Most Pitot probes will have the static pressure orifices 6 to 10 probe diameters downstream of the total pressure port to reduce probe tip influences and also 8 to 10 probe diameters ahead of any mounting/attach structure. Trying to use a fuselage cavity pressure for a airspeed calculation is a crap shoot. Any static pressure measurement in the fuselage is not a "freestream" staic pressure but actually a measurement of the static pressure associated with a "local" fuselage velocity(higher velocity, lower static pressure). I would bet for 20 to 30 bucks you could pictup a 0.125 inch diameter pitot static probe that would get you 2-3% type data(staright and level flight only). Both total and static pressure measurements are Angle-of-attack sensitive. At 10º AOA you start introducing another pressure measurement uncertainty that increases as AOA increases. To minimize AOA sensitivity you can purchase a shielded(more expensive) pitot probe which is less sensitive to AOA effects. Boring, I feel like I'm at work.

MaxQ

Tom Hegland
37c