Matt,
As everyone has pointed out, no 2 RV's will have the same IAS for any condition unless they are built and configured identically, and have the same static source pressure error. The reason you can jump from one Piper Archer to another Piper Archer and fly the same speed is because those airplanes are built identically, have the same plumbing, same instrumentation and same pitot/static configuration. Not true for an EAB.
Good plan to fly the EAA flight test program! The only way to derive accurate information for
your EAB is to flight test
your EAB. We don't always think of it this way, but we're all experimental test pilots in the RV world, all the time
. Not all POH's are created equally, and a POH isn't even required for an EAB. If you buy an RV with a POH or detailed checklist, the only way you can verify the numbers are correct are to either look at the initial flight test data used to derive them, or run the test yourself.
I fly an RV-4 that has four airspeed indicators in the cockpit using various combinations of the primary pitot/static system and sensors, a boom-mounted Keil probe mounted on the wing providing a separate pitot/static source as well as two angle of attack systems that also compute airspeed. Interestingly, when I look at the data, none of the six that are recorded ever marry up until everything is corrected to calibrated airspeed; and even then I'm lucky if I can get 3 out of 6 to line up
. I'm not sure, but I think there is Voodoo (definitely smoke and mirrors!) involved in pitot/static rigging...
Another point to ponder is that airspeed is just a surrogate for angle of attack. Unlike IAS, AOA is constant from one airplane to another (of the same type, say RV-6/RV-6) for a given condition. The angle of attack for L/Dmax is the "fundamental" AOA for the airplane--it's designed in. Once you know L/Dmax (max range/max range glide), you can also determine an on speed AOA (Vref/neutral energy/max endurance glide) and Carson's (best efficiency) AOA. On speed is also Vx and L/Dmax is close enough to Vy during initial climb segment for gov't work. That's a lot of performance SA from a couple of fixed angles that don't care what attitude the airplane is in or what the G load is. As a matter of fact, you don't even need an airspeed indicator in an experimental airplane for day, VFR if you can accurately measure AOA:
https://youtu.be/r8XcXDHLIIM
Drop a line or PM if you have any questions. I'll send you a data reduction tool that can compute your static source pressure error and provide CAS corrections from GPS horseshoe runs if you'd like.
Fly safe,
Vac
FlyONSPEED.org