Tuesday, December 28, 2010

Review: The Whole Enchilada

The Whole Enchilada
"The rocket that is the meal!"

The idea for The Whole Enchilada came into being one Sunday afternoon while cleaning out the frig. We had leftover tortillas that had been in the freezer way too long. Then the idea to use the stale tortillas hit me.....



Ingredients

1. Three stale flour tortillas, ~12" in diameter, for body tube and fins. (sure fresh ones would work better, but then they wouldn't quite as "flounder") ["flounder" was the DesCon 8 term for "found parts"]
2. One leftover, medium-sized jalapeño pepper for the nose cone.
3. Sections of BT-50 tubing from a dead rocket, for the engine mount and nose cone shoulder.
4. Section of spent engine for the engine block.
5. Computer paper for the shock cord mount.
6. 3' of Kevlar cord from stock.
7. Slightly charred plastic chute.
8. Section of soda straw for launch lug.
9. Home-made taco sauce and a sprinkle of grated cheese for decoration.
10. As required: carpenter's glue, Liquid Nails, clear polyurethane liquid (as a preservative), Pam spray

Recipe

After some thought, I decided that I wanted to base the rocket approximately on a BT-50 sized tube. BT-20 seemed too small in diameter to sucessfully wrap my tortilla tube and I thought 29mm would require more engine mount components, etc. So, I grabbed a section of BT-50 as a mandrel. I sprayed on a light coating of Pam to make sure it wouldn't stick to the tortillas. Since this is a glassine covered tube, the Pam didn't seem to have any lasting effect.

Next came preparation of the tortillas. (I know enchiladas are classically made with corn tortillas, but I had more of 'em and they were larger.) Since they were stale, I nuked them for ~10 sec. each. For the body tube, I immediately formed them around my mandrel, spreading a thin layer of carpenter's glue as I went. The body tube took two tortillas. For the fins, I cut them out while the tortilla was still flexible and then placed them under a heavy pot to straighten them out. I chose a simple fin Nike Smoke-style fin. I like the design, they were easy to cut out, and most importantly they are swept forward to minimize the chance of breakage upon landing. (Note on the pic: this shows corn tortillas, which didn't work out - later replaced with flour.)


After the body tube had dried for a few hours, I slid the mandrel part way out, and glued in the engine tube with the block already installed. I also coated the ends with CA, as I would a cardboard tube. The resulting tube and fins were dried for a day and then the fins were glued to the body tube with Liquid Nails. Despite flattening the fins for several hours the day before, they warped big time anyway.

To prep the nose cone, I cut the end off of the jalapeño and glued in a small section of BT-50 tube, cut longways. Before gluing the tube in, I first tied the Kevlar line around the tube and tied it off.

The final construction steps included mounting the shock cord to the inside of the body tube and gluing on the soda straw.

Garnish

I spread some of my home-made, world-famous, gourmet taco sauce on the body tube. A small sprinkling of cheese was added to make The Whole Enchilada complete. After the sauce dried, the final step was a coat of clear polyurethane over the nose cone, body tube, and fins.


Presentation

For its maden flight, I decided that I wanted as low an impulse engine as possible. After entering the design on RockSim, I found a 'B' engine would be just about right. The sim said an Apogee 10.5mm 'B' didn't have enough impulse to get it going, so I went out and bought a package of B6-2's (to be used with a 18-24mm adapter from my Pratt Tomahawk). The Whole Enchilada flew on 03/10/2001 at the NARHAMS' Middletown Park (MD) sport launch. Because of the 'questionable' construction, I had to wait until most people went to lunch. With the rod pointed slightly downrange and relatively high winds, the rocket proceeded on a low trajectory and ejection was too late to prevent a core sample. To my amazement, it was undamaged! I then acquired a C5-3 and tried again. More altitude but still a low arcing trajectory. This time the chute snagged. I would have tried it on a 'D', but the front part of the body tube was broken and the jalapeño was mush.



Final Thoughts

I want to thank the folks at NARHAMS for hosting the launch, and Khim Bittle for both providing the C5-3 motor and for taking the on-the-pad pic.

The tortilla's seemed to work OK for the body tube, although the cardboard tube industry doesn't have anything to worry about. However, despite a couple of tries, lots of pressing and drying, the tortilla fins still warped quite a bit. Maybe I should have used pre-dried taco shells?

So what's next? Guacamole wadding? Maybe a flying sub with pizza fins? Nah, probably not - I just hope I get a vote this time around! ;-)

EGADS! Look what popped up...