Freefly Glide

Steady flight

Fall rate-

Horizontal speed-

Path below the horizon-

Horizontal per meter fallen-

At 3000 m, body held at the angle above long enough to settle.

The jump

Distance-

Freefall time-

Time to settle-

Side view, to scale. Starts from no speed at exit; the plane's forward throw is left out.

Distance against angle

Only angles the CFD runs can reach are drawn. Dot: current angle.

CFD runs

Each run holds the body still in a vertical wind, as in a tunnel; its angle is the body's to the horizon there. L / D: push across the wind per unit of drag. Dots: CFD. Line: interpolation.

How it's computed

Formulas and assumptions

The CFD holds the body still in a vertical wind at several angles and measures:

D (drag): along the wind.
L (lift): across the wind, towards the chest.

You hold your body at an angle to the horizon. Once you move forward, the air comes partly from the front: the path tilts away from vertical by the glide angle, and the air meets the body as in a tunnel run at a steeper angle.

Tunnel angle the air sees = body angle + glide.
Steady when the air force is straight up: tan(glide) = L / D at that angle.
The weight sets the speed: m g = 1/2 rho V^2 sqrt(ClA^2 + CdA^2).
Fall rate w = V cos(glide); forward speed u = V sin(glide).

Distance over the jump:

Steady, forward per meter fallen = tan(glide): the height times that, whatever the speed.
Faster forward only helps if the fall rate rises less.
The path is stepped in time from exit: speed builds, the air swings from below to the front, and air density changes with altitude.

Between CFD runs, ClA and CdA are interpolated linearly in the angle. Outside them the nearest run is held; the page says when. Ticks on the angle slider: where a run is exactly the steady flight.

Limits:

Rigid body holding one angle the whole way; no suit flapping.
No wind; distances are through the air.
Steady RANS CFD: lift is likely high and drag low (whitepaper 6.4).