Brief:
A spool rocket made entirely out of household rubbish built for the EMRR 2007 Challenge. Performs well on any Estes 24mm motors, both Ds and Es. Spools are always interesting because they look like the least aerodynamic rocket at any launch. Called it ED as it takes E and D motors.

Construction:
The parts list:

• 1 tube from the center of a cling film roll
• Two CD-ROMs
• Glue. I used Bostik, although epoxy would be better.
• Drill with hole cutter bit
• File
• Hack saw

The tube needs to be cut down to 6 inches. For the tube I was using this meant cutting it in half.

Next fashion an engine block out of a bit of card tube. I used a cut off from the cling film tube, cut out a few mm, and then glued it back together. Next glue it into place by adding glue to the ring and then pushing it into place with an empty D motor. Remove the D motor immediately. The motor block will now be in place so that either side of the tube can be used--one side for D motors and one side for the longer E motors.

Next find a drill bit that cuts a 1 inch hole.

After clamping the CD securely, drill out the center of the CD. Make sure to wear goggles. With a smaller drill bit, drill out a launch lug hole a few mm from the central hole. Repeat for the second CD. (It's best to make several CDs at this stage).

Glue each CD to either end of the tube and make sure that the launch lug holes match up.

Finishing:
I didn't do anything in terms of painting for the first few flights although I eventually painted the whole thing a maroon color.

Flight and Recovery:
Since this was the first spool rocket that I had ever built or seen fly, I headed out to my flying field with just the rocket, motors, and a friend. I was a bit nervous, but not as nervous as my friend who bravely sent the next twenty minutes positioning himself behind me away from the rocket.

The first flight was on a D12-0. It went straight but entered into a unstable wobble towards the end of the flight. It recovered tumbling end over end. On landing, one of the CD cracked.

The second flight was on an E9-4. The spool rocket was reversed and prepped as normal.

Take off was fast, but the spool arched into the 20mph winds but only slightly. Height was significantly higher than the D12 motor with a good long burn from the motor. Tumble recovery again, this time landing on both edges of the CDs and the spool rolled off with the wind-–no further damage to the cracked CD.

Third flight was also on an E9-4, although the winds had dropped a bit. Flight was as before. On recovery, the spool landed on the cracked CD and more damage was sustained. The CD had to be striped and a new CD added-–this is why it is good to make a few spare CDs while you have a drill out.

Summary:
Well, it costs nothing to make, except a bit of glue. It flies well, even in winds where you would not want to fly a normal 3FNC rocket. It's a bit unusual. I wish I'd made one years ago.

On the down side the CDs do break quite easily. I think it would be best to spend a few quid (dollars) on some thin plastic to use for the disks.