An automatic flight attitude control system for your free-flight model glider.

In order to amuse his young nephew last summer, the author made a number of model gliders, which were taken to the top of a local hill and then launched. The models were made from balsa wood and were not powered in any way, except by gravity.

Several designs showed some promise, but maintaining level flight with any consistency was a problem. Promising designs were shelved because after 20 meters they showed signs of losing stability, preferring to roll over or stall with the occasional “crump” of deforming balsa wood.

As their glides were observed, it seemed apparent that it must be possible to incorporate an automated flight control system, to give the designs at least a fighting chance. Following a number of prototypes, this article describes how to make and install into a model glider a low cost microcontrolled stabilisation system that helps model gliders to fly a little more straight and level.

Glider flight times have been increased from an average of five to six seconds to over 15 seconds - the limitation now being that the author's local hill is just not big enough! The real power of Freebird is that the flight correction algorithm can be modified by re-programming the PIC16F84A microcontroller, which handles the attitude detection and flight correction, all in real time.