Sapphu

Sapphu is a projectile and ballistics range lab that turns your phone 📱 into a real physics instrument. Set a projectile's launch speed ⚡, angle, mass, drag ✋ coefficient and cross-sectional area, add a wind vector, choose your gravity and air density, then fire it across a scaled range and watch 👀 the trajectory arc, climb to its apex and fall under gravity and air resistance.

The motion is computed with genuine RK4 numerical integration of two-dimensional projectile flight with quadratic air drag ✋ — not a simplified textbook parabola. You can see 👀 exactly how air resistance bends and shortens a real shot, with live readouts for range, time ⏱️ of flight, apex height, impact speed ⚡ and impact angle.

Key features:
• Range Lab — a live trajectory canvas with a radial launch gauge you drag ✋ to aim; tune every parameter with precise sliders and fire.
• Vacuum-vs-drag ✋ overlay — draw the ideal no-air parabola behind the real drag-bent arc to see 👀 the effect of air resistance at a glance.
• Target 🎯 Solver — enter a target distance and solve for the launch angles that hit it, finding both the low-arc and high-arc solutions, plus the true maximum range when a target is out of reach.
• Trajectory Sweep — sweep the drag ✋ coefficient, air density or launch angle and redraw the whole family of arcs at once, with a range-vs-parameter chart 📊.
• Saved shots — name and store any shot with its full parameter set and results, reopen it to replay the trajectory, and attach a reference photo 📸 to it.
• Adjustable gravity presets (Earth, Moon, Mars), metric or imperial readouts, and a one-tap 👆 reset.

Whether you are a physics student checking how drag ✋ changes the classic 45-degree answer, a hobbyist exploring ballistics, or a teacher demonstrating projectile motion, Sapphu gives you an accurate, hands-on sandbox to experiment in. Every calculation uses real numerical physics, so the results respond faithfully to every change you make.

No accounts and no ads — just a focused instrument for exploring how things fly. Set up a shot, read the numbers 🔢, and discover ✨ Sapphu.