Canyon side view, (angle, angular velocity) phase portrait and the landing-position-versus-release-angle map.
Two checks without drag: simulated range against the closed-form projectile range over release angles, and measured period against the elliptic-integral value at 60 degrees.
Not run yet.
The science
Large-angle pendulum. With the rope taut and the pivot fixed, the rider obeys θ'' = −(g/L) sinθ − (ρ CdA L / 2m) |θ'| θ' (θ from straight down, quadratic air drag). The page integrates it with RK4 and the same module as the 3D lab. Energy without drag: θ'² = (2g/L)(cosθ − cosθ0), which is the closed curve in the phase portrait.
Tension. The rope force is T = m (Lθ'² + g cosθ); at the bottom T = m g (3 − 2 cosθ0), so a swing started at 90° loads the rope with 3 mg. If T exceeds the rated tension the rope breaks and the rider is released at that point.
Period. The exact period is T = 4√(L/g) K(sin(θ0/2)) with K the complete elliptic integral (computed with the arithmetic-geometric mean), which grows from the small-angle 2π√(L/g) by about 7 % at 60° and 18 % at 90°.
Release. After release the rider flies as a projectile (drag-affected RK4). Without drag the range from the pivot has a maximum release angle found by scanning; with drag it shifts. The lower-left graph is the landing position against release angle for your parameters (solid) and without air (dashed); the white dashed line marks the far edge. Releasing at the right moment, not just swinging harder, decides whether the platform is reached.
Honest simplifications. Rigid massless rope, point-mass rider with a fixed centre of mass, constant drag area, no rider body rotation, no rope stretch, instantaneous release, flat ledge and platform, no landing impact injury model. This is a physics lesson, not safety guidance for real rope swings.