Re: Open-source / community certification-like analysis of homebuilt air

Jay Scheevel

Hi Brad,

Given that QAC, and virtually all kit manufacturers of that era would routinely report the most optimistic numbers they were able acquire (or imagine). These were rarely measured in a way that certified aircraft are required to do. For example, landing and cruise speeds were done flying way below the gross weight for the QAC planes. This is understandable, they were selling dreams, not airplanes.  But certified A/C have to report demonstrated performance at gross weight. True, these tests are at sea level with a crack test pilot, but at least they are standardized.

As an example of numbers QAC may have acquired if rigorous flight testing was done, I have computed the following numbers from my models for minimum level flight airspeed in ground effect (my model was calibrated to match the QAC Q-200 prototype, at sea level).

weight (lbs.)        Vmin (mph CAS)
900                    66.6
1000                  70.21
1100                  73.64
1200                  76.9
1300                  80.5

From my modeling, other flight numbers are similarly affected. So, I don't think it would be useful to publish fixed numbers for an aircraft like the Q-200 that is significantly impacted by weight. That would be more of an academic exercise.

My intention is to create realistic charts for my plane that include effects of density altitude and weight, once it is flying. For now, I am using my models to give me a feel for what to expect. I will calibrate them to match my performance as I do my flight testing.

Jay Scheevel, Tri-Q, still building

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