Projectile Sim

A terminal-based projectile simulator built with Ratatui. Run multiple force-model scenarios side by side and compare their trajectories and energy curves — all inside your terminal.

Features

• 4 launch parameters — angle, speed, mass, initial height
• 5 force-model scenarios — toggle each one on or off independently
  • Vacuum (gravity only)
  • Linear drag — Stokes law F = −b·v
  • Quadratic drag — realistic air resistance F = −½ρCdA|v|v
  • Quadratic drag + headwind
  • Moon gravity (g = 1.62 m/s²)
• RK4 numerical integrator — 4th-order Runge-Kutta, far more accurate than Euler
• ASCII trajectory chart — all enabled scenarios overlaid in one view
• Results table — range, max height, flight time, energy change per scenario
• Energy chart — E/E₀ vs normalised flight time; flat = conserved, dropping = dissipated

Build & Run

cargo run --release

For a debug build:

cargo run

Key Bindings

Key	Action
↑ / ↓ / Tab / Shift+Tab	Move between fields and scenarios
Enter on a parameter field	Edit the value
Enter / Space on a scenario	Toggle it on or off
Enter on Run button	Run all enabled scenarios
r	Run immediately from anywhere
PgUp / PgDn	Scroll the results panel
q	Quit

While editing a value:

Key	Action
Enter	Confirm and run
Esc	Cancel edit
← / → / Home / End	Move cursor
Backspace / Delete	Delete character

Physics

The equations of motion are:

dr/dt = v(t)
dv/dt = F_net(r, v, t) / m

Solved at each time step with a 4th-order Runge-Kutta scheme (local error O(h⁵)):

k1 = f(t,       y          )
k2 = f(t + h/2, y + h/2·k1)
k3 = f(t + h/2, y + h/2·k2)
k4 = f(t + h,   y + h·k3  )
y(t+h) = y(t) + h/6 · (k1 + 2k2 + 2k3 + k4)

Force models:

Scenario	Force law
Vacuum	F = m·g downward
Linear drag	F_drag = −b·v
Quadratic drag	F_drag = −½ρCdA·|v|·v (baseball params)
Drag + headwind	Quadratic drag + F_wind = k·(v_wind − v)
Moon gravity	F = m·1.62 downward