1. Add parts from the left rail. They stack bottom→top: engine → tanks → pod → nose. Click or drag to add; click any part in the 3D view to remove it. Hover a part to see what it does and where it goes.
2. Read the numbers. TWR must be ≥ 1.0 to leave the pad (thrust beats weight). Δv is your speed budget — it must beat the mission requirement (the bar fills green).
3. Stage it. A DECOUPLER splits the rocket — everything below drops away when that stage burns out, so you fly further. Build engine + tanks above each decoupler.
4. Boost it. Drag an SRB or strap-on booster onto the side of a stage to attach it radially for extra liftoff thrust.
5. Launch. Pick a mission and hit LAUNCH. A bad rocket failing is the lesson — iterate.
PART ROLES
- Engines — push the rocket; mount at the bottom of a stage.
- Fuel tanks — feed the engine below; more tank = more Δv.
- Command pod — the core that flies the rocket; every build needs one.
- Nose / fairing — caps the top and cuts drag.
- Decoupler — separates stages.
- Boosters / RCS — radial-mount thrust and control.
Δv = Isp · g₀ · ln(m_wet / m_dry) · TWR = thrust / (mass · g₀)