This weekend, I ran a 480 load of the new blue at a lower pressure (400 psi instead of ~600 like last time). The result:

Aerotech I357

TDK I300

OH YEAH. The one drawback was that this motor was not nearly as loud and generally “nasty” sounding as the higher pressure one. This was down at a Kn of 180, and operation was completely smooth, coming up to pressure and shutting down cleanly. I like this a lot. I have a 54/1050 and two 38/640s of this stuff ready to go next…

For the new blue, I’ve been trying to characterize rate data from motor burns, rather than from strand burn data or burn rate motor testing. (It’s more fun to static test a motor than it is to do a strand burn test.) More on the maths later, but here’s the results so far:

I’ve been working on a new blue formula as of late. Consider this the first “official release”. It was conceived in January, first fired in April, and first fired with data last weekend. It’s a smokeless variant of the typical blue I’ve flown in the past — 1% CuO, 2% Al — with the goal of getting something “Blue Thunder“-like. The story of the first flight is up in a blog post on OurPlanet.

First reactions from the flight were: (1) Not quite as fast as Blue Thunder, but certainly nice nonetheless, and (2) Oh my, look at that flame separation. Data from static testing showed that this burn was only at ~570 PSI, but the flame stands off nicely, even at low chamber pressures. It turns out to be about as fast as Kosdon fast, at least per the data. Here’s a typical curve from a Loki 38/480 firing:

Delivered Isp is somewhere around 200 sec, so nothing too special — just another “knob” propellant to add to the fray. Formula and rate data after the jump.
Read on »

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.