# Bearing-guided sled / linear carriage ![[Pasted image 20261003031311.png|center|500]] >Small plate/sled that straddles the launcher w/ 3-4 small rollers or bearings - Flat plywood, aluminum, or 3D-printed carriage plate - Bearings ride against the sides/top of the rail so it cannot twist - Simple cradle on top supports the BoilerBird/glider- Spring/cable attachment point is centered underneath - At the end of the track, the carriage hits a **hard stopper**, while the aircraft continues forward from inertia - Add foam/rubber to the stopper to reduce impact loads # PVC slide carriage ![[Pasted image 20261003031341.png|center|500]] - Cut a longitudinal slot so it can fit around brackets/cable attachments - Add UHMW tape, felt, or small plastic pads inside to reduce friction - Mount a lightweight platform/cradle on top - Very few parts and cheap to prototype **Possible issue:** sliding friction & binding if the PVC flexes or the carriage gets slightly misaligned # Notes - Make the aircraft-to-carriage interface passive rather than attaching the aircraft to the carriage - Use shallow V or U-shaped cradle with foam where it contacts the vehicle - Constrains lateral movement during acceleration but lets the vehicle slide/fly out when the carriage stops - For early test rigs, avoid latches/hooks/pins or timed releases unless deemed necessary - Spring attachment should be low & centered on the carriage - If the pulling force is significantly above or beside the rail centerline, it creates a moment, increasing the chance of binding - Keep carriage mass low b/c some of the stored spring energy will accelerate the carriage instead of the aircraft - Design carriage s.t aircraft position is adjustable - Slots/foam blocks?