In a message dated 97-12-08 19:54:20 EST, you write: << can't put my hands on the magazine at this time but will try to find it. For now I will try to explain as best I can remember. The theory of operation is that there is a static charge in the atmosphere. The radio active particles keep the sensors from building up any static charge. They used 4 sensors in 2 pairs. one on each wing tip for roll stabilization, and one on the nose and tail for up and down stabilization. The sensor were then input to a op amp and the output from it tied into the radio control servo of the necesary control. >> What are the sensors detecting as a reference field? The ionosphere? Mark A. Corio Rochester MicroSystems, Inc. 200 Buell Road, Suite 9 Rochester, NY 14624 Tel: 716-328-5850 Fax: 716-328-1144 http://www.frontiernet.net/~rmi/ ****** Designing Electronics for Research and Industry ******