SPEAR COILGUN

The SPEAR, a recent development in coilgun technology, passively launc hes a projectile with a solenoidally wound armature. This paper descri bes the SPEAR, its electromagnetic operation, its construction, and th e tests performed to prove its principle, It describes the composite s tator sections and the glass reinforced armature coils. It describes h ow engineers at GEM-UT overcame the problem of keeping solid state swi tch volume low by employing a modular switch design with a unique snub bing circuit that reduces required volume. Results of test #5, describ ed in the paper, show how well the operation of the SPEAR matches the computer simulation predictions. Conceptually, the proximity of the ap proaching armature electromagnetically drives a stator coil's current through zero. At zero crossing the stator freewheel switch turns off, preventing reestablishment of stator current as the armature moves awa y. As originally designed, the gun was to accelerate a 2 kg package to 2,000 m/s. The part built is expected to achieve,1,000 m/s with a 0.7 5 kg package, ARDEC sponsored the work under contracts DAAA21-91-C-008 7 and DAAA21-90-C-0011,