DESIGN AND DEVELOPMENT OF AN ACTIVE GUIDANCE, NAVIGATION, AND CONTROL FLIGHT COMPUTER FOR MODEL ROCKETS

Recovery in amateur and student-built model rocketry has traditionally relied on a passive altimeter: a device that does little more than detect apogee, by tracking a barometric pressure peak or an acceleration threshold, and firing a single pyrotechnic or CO₂ charge to release a parachute. This approach is inexpensive and dependable, but it exerts no influence whatsoever over the vehicle's ascent, so any trajectory error introduced by wind shear, motor-to-motor thrust variance, mass mis-estimation, or airframe asymmetry propagates unopposed all the way to apogee. This paper presents the design of an active flight computer that upgrades a conventional altimeter into a closed-loop guidance, navigation, and control (GNC) system capable of correcting the rocket's flight in real time. The proposed architecture fuses inertial and barometric measurements through a navigation filter, derives a guidance command during both the powered and coasting phases of flight, and actuates either a thrust-vectoring gimbal/canard set or a deployable airbrake through a proportional–integral–derivative (PID) control law. A simplified one-dimensional ascent-and-coast simulation, exercised both as a single deterministic run and as a 500-trial Monte Carlo sweep over motor thrust, mass, and drag uncertainty, is used to compare the proposed system against a passive baseline, showing close to an order-of-magnitude reduction in apogee-error dispersion. Hardware selection, failure-mode considerations, and directions for flight-test validation are also discussed.