This is the motor that started it all. We got our name at this event, and this motor was the first motor to be fired with the “TDK Propulsion” branding on the flight card. Joe Cox, Charlie Cox, and SpartaChris (aka Chris Williams) built this 12″ Talon, and Todd and I provided the power plant:

The motor worked well, although the rough deployment at apogee caused the casing to be kicked and subsequently damaged upon landing. A new one is ready to go on the lathe, though, so no worries.Lessons learned:

• Use a stronger motor retainer — 6″ hardware is heavy, no matter what Todd says.
• Forward insulation is a good thing — the bulkhead of the motor got a little toasty and actually melted in one spot. It’s now in the BURP bin. Apparently the larger hardware produces more heat than can be carried away (volume goes up by the cube, surface area by the square…) so this makes sense, as we haven’t seen this on smaller motors, and the aluminum content of this propellant wasn’t inordinately high (5%).
• Aft insulation disks work great — we used 1/16″ G10 on top of the nozzle carrier to protect it from the same fate the bulkhead suffered.
• Nozzle carriers work great, too — this motor had a nozzle made from a 3.75″ diameter chunk of graphite for the nozzle insert, held in place by an aluminum nozzle carrier. We expanded the exit cone into the nozzle carrier a bit, which surprisingly wasn’t harmed by the exhaust flame one bit. I still don’t understand why it doesn’t melt — maybe the flow velocity is so high that it doesn’t have time to heat soak the part. Either way, carriers work. Save a graphite tree and use them. CAD drawings forthcoming.

Posted December 26, 2007 in Media, Tests & Flights. Add Comment / Trackback