Scratch The Emporer's New Rocket Original Design / Scratch Built

Scratch - The Emporer's New Rocket {Scratch}

Contributed by Lance Alligood

Manufacturer: Scratch

Brief:

I'd been reading about spool rockets & decided to build one for myself. After my Estes Stormcaster lawndarted itself into destruction, I decided to salvage what I could. I'd forgotten that there was a rather long MMT tube in there & it proved to be a perfect fit for what I had in mind... A spool rocket looks like such an incomplete rocket that I had to give it an unusual name. I decided upon "The Emperor's New Rocket" (TENR) because much like the emperor's new clothes, it looked only like the ugly insides of what should have been a nice outfit.

Construction:

A spool rocket looks like a MMT tube with centering rings & that's it! No fins, no nose cone, & no body tube.

 

I used parts I had laying around:

  • A6 3/8" piece of BT-50 MMT tubing
  • 2 CDs that I no longer had a need for (AOL CDs work great except I believe in the higher cause of sending my AOL CDs here: http://www.nomoreaolcds.com/)
  • A carefully sliced 1/4" thick piece sliced off a used Estes D12 motor casing to act as a thrust ring (there is no motor retainer clip so that I can use the longer Estes E9s or run into any problems with Aerotech SU E15s or F21s!)
  • A 1" paddle drill bit
  • A5/32" standard drill bit
  • 5 or 12 minute epoxy
  1. Draw a single line running the length of the BT-50. This it to aid in lining up the launch rod holes.
  2. I strongly recommend the assistance of another person or some clamps to hold the CDs against a scrap piece of wood. (Having access to a drill press would make this even easier.) Use the 1" paddle bit to widen the hole in the center of the disc. Or you can be like me & waste 7 or 8 CDs before getting two that look decent...
  3. Use a knife to score the discs with a point 1/4" from the newly widened inside edge. Now with the 5/32" drill bit, drill a single hole in each disc. This should leave less than 1/8" from the edge of the center hole to the edge of the launch rod hole.
  4. Mix up some epoxy & attach one disc at one end of the BT-50 (this is now the "top". Attach the other disc 3/8-1/2" from the other end, aka the "bottom". BE SURE TO LINE UP THE LAUNCH ROD HOLES!! Add fillets too.
  5. Use a popcicle stick or chopstick to put a small ring of epoxy about 2" inside the BT-50 from the bottom. Put the thrust ring inside the tube & push the ring inside with an empty D12 casing until ~1/4" of the casing is sticking out. Quickly remove the empty casing.

I chose epoxy because I figure I'd rather have too much strength holding the CDs on than too little. With so little materials, weight was not an issue.

Painting is completely optional...I considered it downright unnecessary in this case & chose to leave everything 'au naturale'.

Flight:

With this being an atypical design & my first real scratchbuilt rocket of any kind, I chose to fly this in an open field by myself...away from any potential ridicule should there happen to be any failure in the launch of this rocket, not to mention for safety reasons.

I loaded it up with a D12-3 & let 'er rip! Much like my Art Applewhite Delta Saucers, it provided a draggy flight to about 300ft straight up before beginning its glide back down. It didn't really tumble but the CDs caused it to drift maybe 50ft from the pad, landing softly in the surrounding grass. The ejection charge went off about 25ft from the ground.

Thankfully I had another D12-3 with me & had it loaded up in no time flat. It zipped right up again! Similar height & trajectory, this time however it began to quickly spin end over end on recovery. Fluttering to the ground like a butterfly, it landed a few feet closer to the pad & even softer than the first flight

Summary:

There really aren't any CONs to this rocket. I was resourceful in using parts that I already had (so it was done with a negligible cost to me) & found it to be an enjoyable experiment if nothing else. I'd like to put it up with an Estes E9 or even Aerotech SU E15W or F21W. I found that a spool rocket while draggy, fun to watch & easy recovery of a saucer, it doesn't have the violent takeoff I like. (I still get weak in the knees when I think of my Art Applewhite 7.5"/29mm Delta Saucer ripping off the pad with a G35w!!) This design could be easily scaled up or down but will always be a small field flier thanks to it's oh-so-non-aerodynamic design!

Comments:

avatar
Steve Lindeman (March 24, 2012)

I like this article so much that I went and built one myself. I call mine Disc-A-Soarus because it fits the style of the rocket. I  also chose to finish mine by covering the top sides of the CD's and the motor tube with red prism wrapping paper to give it more flash. The other thing I did was to measure for the motor stop ring distance so that I can load D's in one end or E's in the other end. I also plan on trying a few flights with an 18mm adaptor.

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