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Barry's Coilguns |
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Mark 5
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Barry's Coilgun Mark VThis somewhat larger single-stage coilgun will examine two key concepts:
BackgroundThe most common mechanical switches for coilguns are
These designs generally suffer from slow closure time and arcing. The contact bounce is classically on the order of 5 - 20 milliseconds, which is comparable to the entire launch pulse. I'm testing a mechanical design that avoids these problems. Wedge Contactor Concept
The wedge or "arrowhead" shape has a narrow angle. This causes large compressive forces for good contact without relying on springs or external pressure. At a certain critical angle (around 8 degrees for copper) the wedge will "stick" or lock in place, and needs no other mechanism to maintain contact. The copper wedge completes the connection between the two sides of the receptacle. Any slight misalignment on entry will not complete the connection; it only conducts when it's touching both sides of the solid mounting blocks. The wedge itself does not have or need any connecting wires. It merely connects the two copper blocks together. The copper wedge moves at a sufficient speed to reduce contact bounce and, in conjunction with the shape and solid blocks, does not have the springiness of leaf-type relays and switches. The nature of an inductive circuit is such that current does not immediately flow. There will be a short amount of time as current builds up according to the LC time constant. This provides some time for the contacts to finish closing before arcing can occur. If the closure is completed quickly enough there will be no sparks or contact wear. |
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Last Update 2013-09-02
©1998-2023 Barry Hansen |