Foil Design Comparer

Pick a preset foil and stab, compare setups, or just experiment with design parameters.

Section root

Front:
Stab:
The rest:

The scores come from simple lifting-line and section formulas, not from a tank test. Treat them as a way to feel the trade-offs, not as a prediction of what a real wing will do.

Drag is built up part by part: the front wing (skin friction from the Reynolds number, a form factor for thickness, and induced drag from the lift), the stabiliser (its own profile drag plus the induced drag of the download it carries to balance the wing's nose-down moment), the mast (both faces plus spray at the surface) and the fuselage. Top speed is where that total meets the drive slider, or the cavitation limit if that comes first. Downturned tips cost projected area but earn back span efficiency as a non-planar wing. Pitch stability is the tail volume coefficient scaled by the tail and wing lift slopes.

Axis name their wings by span in millimetres rather than area. The Fireball areas up to 1070 are Axis's own numbers; the larger Fireballs and every other Axis family are worked back from the aspect ratio each range runs, so treat them as close rather than exact.

In the Armstrong list, only area and span come from Armstrong's published figures. For every family except the HA v1, everything else, including thickness, camber and sweep, is my estimate of what that family is doing, so the scores show its character rather than a measurement of the real wing.

The HA v1 shape is measured. It comes from a 3D scan of a real HA1125, cleaned up against Armstrong's own plan-view photo. The other sizes use the same shape scaled to each one's span and area, which assumes Armstrong scaled the range rather than redesigning each size. Its drawings show the measured wing until you move a shape slider.

Sweep is modelled on the actual swept-wing relations rather than a single made-up exponent: the flow component crossing the leading edge falls off as the cosine of the sweep angle, and that is what the section feels for lift purposes, so thickness and camber effectively shrink by that cosine while the physical section stays fat. The benefit against drag rise and cavitation is real but milder \u2014 based on measured swept-hydrofoil data (Hefazi & Besnard), it fades only about a quarter as fast as the pure cosine would suggest. Sweep also makes lift itself fall very slightly, matching the classical result that a swept wing lifts a bit less than an unswept one at the same angle.