Test 2017-13

8 grain 75mm sorbitol motor with pyrodex pellet ignition in 4-inch Wildman rebuilt airframe at Tripoli Colorado Hartsel.

CTI Pro75 6xl case, Loki #52 (long) nozzle with 2 o-rings, CTI forward and aft closure rings, forward bulkhead from Terry's pile machined to have 0.5" inside snap ring plus 0.25" inside liner, with two o-rings, one pushing against liner.
Liner 37" long with just under 36" available for fuel load.

Original simulation says this should be a a 26% M-2291 with 6138 Ns total impulse, 869 psi max, 75% volume loading, and about 2.3 seconds burn time. After casting and weighing the grains, the adjusted simulation says this will be a 5% M-1785, 699 psi, 67% volume loading, and about 2.7secs burn.

Results

Flown at last Tripoli Colorado launch of 2017 at the Hartsel launch site. Perfect flight, no damage. Mach 1.1 on the way to 13711 ft AGL by GPS, with a 2.8 sec burn time. Winds at ground level 5-7mph, used Terry's launch trailer (20 ft 1515 rail), landing was 1 mile to the SSE, across the creek on state owned land south of the road. Crowd response was very positive. Largest sugar motor known to have been flown in Colorado to date. Spectacular!

Flight data logged as sn 3121, flight 4 on 2017-10-22.

Used a Chinese e-match with 2 pyrodex pellets on a 1/8" dowel inserted so the aft end of the pellets was 36" from the aft end of the case. The time from button press to smoke and then to acceleration was surprisingly short!

Terry Lee captured launch video.

I captured high-speed still of the launch.

The acceleration plot looks pretty clean, with some bumps near burn-out that strike me as maybe being related to propellant flaking off the inside of the casting tubes?