Tuesday, December 28, 2010

Reviews: Recycled daiquiri glasses from Las Vegas

If you've ever been to Las Vegas, you couldn't have missed that about a quarter of the people wandering the Strip seem to be sipping on long plastic doohickeys filled with colored liquids. These jumbo, spiked versions of the Slurpee are themed to various casinos and venues.  I'm always looking for rocket parts, and couldn't pass up glasses from the Stratosphere Hotel, Casino and Tower and the Paris Hotel and Casino.  One was acquired in around 2000 and one in 2008.  This post describes the rockets that they became.

Stratosphere (my DesCon 8 entry)

Parts List:
1. one slightly used souvenir daiquiri glass.
2. 29mm mmt tube
3. 12" section of 38mm tube
4. 1 1/4" section of 2" dia. shipping tube
5. masking tape
6. one home grown 3/16" 29mm to ~2.5" centering ring
7. 1/16" G10 stock for fins
8. 3 1/2" section of 38mm tube
9. cardboard core from electrical tape
10. scrap 3/16" plywood for nose cone bulkhead
11. one plastic plug - original use unknown
12. section of styrene tube
13. section of neon green solid plastic tube
14. small section of brass tubing for a launch lug
15. ~4" of kevlar twine
16. eyebolt
17. 12" nylon chute from the rangebox
18. adhesive backed holographic film

The daiquiri glass separates right below the tower's top, making a natural transition between the body and nose cone. I quickly found that 38mm tubing from Giant Leap fit nicely into the body and nose cone sections. So, I cut a 12" section for the body and 3 1/2" section for the nose. The nose was quite snug, but the body wasn't. The solution was a small section of mailing tube inserted into the front of the body, between the 38mm tube and the outer shell. I decided on a 29mm mount since that's what I had on hand (plus it allows the use of 24mm motors with an adapter). I made centering rings out of masking tape soaked in CA (idea borrowed from Aerocon).

I didn't want to have to glue anything to the clear shell of the daiquiri glass, so I decided to make the lower body non-load bearing. I made a plywood ring that was glued to the bottom of the motor tube and rested against the 38mm inner tube, forming a thrust ring. I designed and cut four through-the-wall fins, which were glued to the thrust ring and the 38mm tube. Next, I removed the bottom of the daiquiri glass and cut fin slots. The inner tube asembly, with thrust ring and fins, was then slid into the daiquiri glass from the bottom.

For the nose cone assembly, I made a plywood bulkhead and inserted an eyebolt. I found that the cardboard core from a used roll of electrical tape fit nicely into the 38mm tubing, so that became the nose cone's shoulder. I then needed something to fashion a spire for the top of the tower. After much scrounging, I found a plastic plug that fit tightly into the top of the daiquiri glass. I also grabbed a section of plastic tubing (originally bought as launch lug stock) that fit over the end of the eyebolt. I drilled the plug so the tubing fit through and slid these into the front of the nose. Finally, I cut a hole in the nose cone's shell for the launch rod to pass through.

A section of kevlar string, a chunk of tubing for a launch lug, and the basic construction of the Stratosphere was complete.

I thought and thought about finishing. Should I paint the components and leave the shell clear? Or, should I paint the shell from the inside? While wandering the aisles in a craft store, I noticed some self-adhesive holographic film and decided that was it. I covered all of the inner tubes and the fins with the film and re-inserted them into the clear outer shell.

 As a final touch, I bought a small, neon green, see-thru plastic rod that fit nicely into the end of the plastic tube mentioned above. This is interesting looking stuff. It catches ambient light and its tip appears to be lit up - an effect that is somewhat similar to optical fibers. I think this effect is visible in the pic to the right.

Flight Report:
The Stratosphere first flew on 3/10/2001 at the NARHAMS sport launch in Middletown, MD.  I was nervous about using a 29mm 'G' so I opted for an adapter and an E15-4.  The  flight was under powered but the Stratosphere was recovered in one piece.  I flew it again a few years later on an E30-4.  This was a better motor choice but it snapped a fin.  The final flight was this year.  I supposedly drilled the F24's delay to 7 seconds.  RIP.

Eiffel's Nightmare

Parts list:
* One jumbo sized plastic daiquiri glass
* One BT-60 tube
* One 24mm motor mount for BT-60
* Kevlar® twine, 1/8" tubular Kevlar®, and an elastic shock cord
* Plexiglas stock for fins
* 10.5mm tubing

A BT-60 fits nicely in the upper neck so all I had to do was cut a hole in the bottom. I started the hole with a circle cutter on a hand drill and finished it with a hobby knife. I slopped some 5-minute epoxy around the inside of the glass where the BT-60 was inserted. This pooled and retained the tube. I added a standard 24mm motor mount: 2 rings, a coupler tube and an engine hook. A length of Kevlar® twine was attached for the recovery harness. I also adjusted the upper tab of the hook so I could use 24mm RMS motors.

I picked a spot on the outer edge of the lower section of the tower and ground holes to accommodate a piece of 10.5mm tubing, which works as a 1/4" lug. The location is far enough out so the rod will clear the nose cone. The gap between this tube and the opening was sealed with epoxy clay.

Epoxy clay was also used in the tip of the nose (straw hole) and retains a loop of 1/8" Kevlar®. I tied a long piece of elastic to the Kevlar® leader and then to the loop on the nose cone.

I created a RockSim model early on and spent a lot of time thinking about stability. I applied Bruce Levison's base drag method. This almost convinced me that it could be stable without fins, but subsequent discussions on TRF and comparisons to my Quest DC-Y Space Clipper made me reconsider.

While at a club building session, I cut some fins from clear Plexiglas using a miter saw. This worked well. Plexiglas is not the best choice but it was scrounged from an old screen protector for a big screen. Now that I think of it, I really don't know what the material exactly is. I cut some small through the wall tabs and attached the fins with 5-minute Epoxy.

Flight and Recovery:
I decided to fly the Eiffel's Nightmare on an F24. The sim showed this would give it a nice ride. I adjusted the delay from 7 to 6 seconds to more closely match the simulation. Despite the stiff winds, the boost was fairly straight. The rest of the flight wasn't that good. The rocket stopped quickly due to the high drag design and lawn darted a split second before ejection. RIP.

Despite my limited success, I still like these oddrocs.  I guess it's time for another trip to Vegas!