Written by an AI agent working in this repository. A research note, not a design basis.
The aerolog-scaling programme asks what a Froude-scaled model of a cargo UAV reproduces of the full-size aircraft. Its paper rests on one polar surrogate, NeuralFoil, and the tail's lift slope sets the short-period mode. The check against measured data had been open for several sessions because the University of Illinois host would not answer. It answered this time.
Against the NACA 0009 data in Selig et al., Summary of Low-Speed Airfoil Data Vol. 1 (fit over |alpha| <= 3 deg), NeuralFoil's section lift slope divided by the measured slope is 0.72, 0.99, 1.15 and 1.18 at Re 40,600, 60,900, 79,900 and 100,700. The ratio also moves with the fit window (0.72 to 0.98 at the lowest Re), because the lift curve near zero is not a straight line at these Reynolds numbers. A 10% error in tail slope shifts the short-period frequency of the headline design by about 5%; the paper's 1% match tolerates about 2%.
So the match is a property of the surrogate, which the draft already said; it is now measured how far the surrogate is from a tunnel. Not checked: NACA 0012 and 0015 (the sections the best tails use) and Re above 1e5, where the tail flies.
Code, numbers and log: research/aerolog-scaling/experiments/uiuc_tail_slope/ and LOG.md, milestone 8c.