Martlet 3 launched in September 2017 in the Black Rock Desert, Nevada USA. Martlet 3 was a two-stage boosted dart style rocket designed to reach 11km flying an entirely custom avionics package. Weighing 40kg on the pad, with a rocket motor designed to produce an average thrust of 3.4kN for 6.2 seconds, Martlet 3 reached a max velocity of Mach 1.2. The rocket motor was bought off-the-shelf and unfortunately exploded several seconds into the burn. The 1st stage was destroyed in the explosion, but the dart was able to ride the shockwave of the blast and fly in a stable trajectory to 3.5km. Our avionics went beyond the call of duty, surviving the explosion, and the dart maintained live telemetry throughout the flight and correctly deployed parachutes for a safe recovery.