Zia Spacemodelers

November 16, 2003 —Mouser Explodo Invitational

Those of us that have been enjoying rocketry for many years have invariably accumulated a collection of old motors that are un-flyable, either because they have lost their certification or because we simply suspect that they are a cato risk to our rockets.

As a special event for this launch, we decided to hold a contest to intentionally cato rocket motors in order to burn off some of our unusable stock. We set up a special static test pad and encouraged those at the launch to attach their old motors to the pad and do something creative in the process.

We figured that people who have problem with motors exploding probably are in need of three things: new motors, new rockets, and glue. So we gave away prizes of crazyglue, an Estes Viking kit, and a pack of C6-5s to those who met the challenge and managed to destroy their old motors.

The following is a photo-documentary of our efforts to rid our range boxes of old motors. (for shots of the normal launch activities for this day, click here.)

  The first experiment of the day involved an old FSI E60-4, a no longer certified motor from Mouser's range box. The idea was to static fire the E60 with the nozzle facing up into the aft end of an Estes Gnome flying on a A10-3T, and have the E60 light the A10.
Photo by Mouser Williams
  Unfortunately, this is about all anyone saw of the launch. The E60 is a really fast burner, and the Gnome was nowhere to be found. Apparently the A10 did light, or we expect the gnome wouldn't have traveled very far. Best guess is that the E60 exhaust caused the gnome to tumble above the pad before the A10 could get up to speed, and it sent the gnome flying off at some low angle. It could be anywhere.
Photo by Nina Lanza
  For the second shot, a tin can with unpopped popcorn was placed above the motor - an FSI E5 from Tom's range box. You can see popcorn flying through the air as well as the motor casing, and most of the propellant is on its way to the ground.
Photo by Tom Beach
  A slightly-late photo of the cato. The bulk of the propellant can be seen burning on the ground to the left of the pad. In the air just over the mountains - that's not a UFO, it's part of the motor casing. Tom's FSI E5 didn't manage to pop any of the popcorn, sadly.
Photo by Nina Lanza
  After the popcorn popping attempt, most of the popcorn was found unpopped on the ground. The remainder was found unpopped still in the can, despite the giant hole burned through the bottom of the can.
Photo by Mouser Williams
  The third shot featured this monstrosity from Mark Hamilton's range box. It's an old FSI E60, with an A8-3 epoxied into the back end. The E60 didn't have an ejection charge, so a younger and less-wise Mark thought that grafting an A8 onto the forward end of the rocket would provide the necessary charge. This, of course, made the motor uncertified for launch. But no reason not to static fire it!
Photo by Mouser Williams
  This static launch event is the only time Mark would admit ownership of this motor.
Photo by Mouser Williams
  Mark fires off the E60 static test. In this shot it looks like it's functioning normally. But moments after this was taken, the motor exploded brilliantly with a great pop and a shower of burning propellant, see below.
Photo by Nina Lanza
  Tom gets the award for best cato picture of the day! Wow.
Photo by Tom Beach
  Robin holds up the split casing next to the static test pad. Notice the sharp bend in the 1/8" launch rod caused by the explosion. The blast deflector is also severly deformed.
Photo by Mouser Williams
  Another shot of the split E60 case and the bent launch rod. Hand model by Robin, Inc.
Photo by Tom Beach
  Shot Four: Here we see the second of Mark's epoxied conjoined motors, this time firing up into the tin can. Tom decided it would be a good idea to fill the can with flour and see if we could create a big flour dust cloud.
Photo by Mouser Williams
  Another view of the same setup, showing the can full of flower.
Photo by Mouser Williams
  The E60 flour shot. The flour can got dislodged from the launch rod, sending flour everywhere.
Photo by Tom Beach
  The E60 flour shot post-mortem. The launch rod got very bent, as did the blast deflector. Last but not least, the explosion broke the Aerotech Mantis launch pad, preventing it from holding the launch rod upright.
Photo by Mouser Williams
  Mark shows off the remains of the E60. Amazingly, the A8 that was epoxied into the forward end was found relatively unscathed and the propellant inside hadn't been lit!
Photo by Mouser Williams
  Shot Five: This motor is an FSI D20-0 from the range box of Tom Beach. It was set up in another attempt to pop popcorn. At this point, the Mantis launch pad was being held together with duct tape.
Photo by Mouser Williams
  Here's Mouser modeling the popcorn used in today's experiments, and a better view of the duct tape job used to repair the Mantis.
Photo by Tom Beach
  The D20 burned successfully, or rather, it failed to cato. In this shot you can see the can of popcorn being dislodged from the launch rod and sending unpopped kernels everywhere. Look at the deflection of the launch rod!
Photo by Tom Beach
  The motor appears to be burning out of the forward end because this is a zero-delay and at the end of its burn it burns out both ends.
Photo by Nina Lanza


Here are some statistics for the Explodo event:
  • 5 motors static fired
  • 3 motor catos
  • 0 kernels of popcorn popped
  • 1 broken launch pad
  • 1 lost rocket
We declared Mark Hamilton to be the "winner" of the "contest" because he had the most catos. He took home the pack of C6-5 motors as his prize.