Balcony Shoot #27 - Rockets with Payloads

Date: 2003-11-07


Two 9.5 mm ID, 50 mm long motors were prepared. Each using RP as the propellant. The wax treated cat litter bulkhead was rammed first, on the nipple until the case bulged slightly to ensure good lock-in. Then the motor was filled with RP until about 5 mm from the top. The final 5 mm filled with wax treated cat litter. A case extender was very useful for the final charge of RP and clay.

The nozzle and core was bored out using a 2.5 mm drill, stopping 10 mm short of the bulkhead. A 1.8 mm passfire hole was drilled off-centre through the bulkhead and slightly into the RP to complete the motor.

The first payload was a Titanium Hummer, prepared in an identical manner as the 2003-11-04 device. The blackmatch fuse was cut to about 20 mm in length, folded over and dipped into meal-NC paste. A small quantity of -20+40 mesh pulverone was placed into the recess at the top of the motor casing. A bead of hot-melt glue was used to attach the hummer to the motor. Additional glue was added to make a good seal in the hope that the relatively small ejection charge would break the hummer cleanly from the motor not just ignite it in place.

The second payload consisted of a Kinder Suprise Egg, filled with D1 Glitter stars and about 2 teaspoons of -20+40 mesh pulverone. A piece of lance tube ran through the larger half's bottom and in to near the centre of the assembled egg. Two sticks of blackmatch made the passfire from the motor to the shell core. The shell was attached to the motor in a similar manner as the hummer, pulverone in the motor bulkhead recess and hot-melt glue. The two shell halves were taped together as I did not have a suitable solvent for the plastic on hand to melt them together.

Both motors were fused with Zn effects blackmatch glued in place with meal-NC paste. A standard bamboo stick stabilizer was glued on.


Good performances!

Both rockets were launched from the balcony, which is a little unusual for experimental devices, but someone was sitting in the fall-out zone of our usual testing site.

The launch rail was placed at a fairly shallow angle to ensure the effects broke over the ocean, not land. This caused a few problems for the somewhat unstable shell carrying rocket. I must find longer bamboo sticks for these larger devices. The problem isn't really CP/CM stability in normal flight but the low aerodynamic pressures at the slow speeds just after launch, the CM has greater effect and causes rotation of the rocket towards the ground before it picks up enough speed to fly straight, if launched almost straight up there is no such problem.

The hummer payload seperated cleanly and functioned perfectly. I was concerned that the glue join would resist the seperation charge too much and the hummer function while still attached to the rocket. The rocket remains can be seen falling behind the hummer on the video, the seperation charge slowing the rocket body significantly. The hummer spun up to around 700 Hz, or 42 kRPM.

The shell payload was a little disappointing. The break was weak, and I believe a fair quantity of the stars either blew blind or stayed in the bottom half of the shell. The crackle as it hit the water may be due to these trapped stars in the bottom shell half. If the shell seam was fused rather than just taped the break may have been better. It would also have looked better if the shell was vertical rather than horizontal (and pitched slightly down) at the time. The glitter was very beautiful in effect, the flashes reflecting off the ocean surface. The glitter was much more orange that I recall in the stargun tests, less than the Winokur 24 glitter of the 30 mm shell though.


title type size
Rocket with Hummer Video video/x-msvideo 642.670 kbytes
Rocket with D1 Glitter Shell video/x-msvideo 819.904 kbytes
Pre-Test Picture image/jpeg 64.954 kbytes
Construction Picture image/jpeg 66.061 kbytes
Shell Assembly image/jpeg 44.729 kbytes
Hummer Rocket Spectrogram image/gif 141.569 kbytes