Friday, January 07, 2011

Two reviews: Raygun Gothic Birdhouse and HoJo

These are two reviews of scratch rockets inspired by the Raygun Gothic Rocketship, which debuted at Burning Man 2009 and is now on display in San Francisco's Embarcadero. When I found the rocket-themed birdhouses at Michael's, I couldn't resist. In fact, they were on sale so I couldn't resist three of them. They are about 10" high, 4.25" in diameter that the widest point, and the base is about 3.125".  Proceed below for the reviews or follow the post tag 'Raygun Gothic Rocketship' to see the real thing.  The 'My Project' tags will also lead you to all of the individual posts.

Raygun Gothic Birdhouse

This first review is of a sci-fi themed rocket inspired by, and named for, the Raygun Gothic Rocketship. This one flies on high impulse 24mm motors - the E30 SU, F24 RMS, or F39 RMS.

1. Prepping the raw birdhouse: Removed the top (ie the nose cone); drilled a hole in the base for the 24mm motor tube; and realigned 3 of the four fins.

2. Body: Cut a piece of 2.5" Giant Leap phenolic tubing to fit; mounted a short 24mm motor tube using one centering ring; slid this in from the top; epoxied a Kevlar® leader in the base next to the motor tube; and added a bolt through the base to provide positive motor retention..

3. Nose cone: Made a shoulder from a sectioned piece of the 2.5" tubing; cut two bulkheads using a hole saw; one bulkhead is abutted to the base of the cone; slipped the shoulder over that; added an eye bolt to the second ring; and used it to cap off the shoulder.

4. Nose weight: I drilled a 1/2" hole through both bulkheads and the cone's base. After assembly was complete, I added nose weight (lead shot and fast dry Gorilla Glue) until the desired static margin was achieved.

5. Fins: The Lexan fins are screwed to the sides of the stock fins. They were hand cut with a Dremel diamond cut-off wheel, stacked and sanded to match.

6. Launch lug: This is half of a First Fire igniter tube mounted between the widest point in the body and one fin.

I decided to keep a rough look so I filled only a few deep dings and the rough fin edges. I shot a coat of primer, not to fill the grain but to provide a uniform color base. I then painted the body silver. The ring on the cone and around the open hole are gold. The Raygun Gothic Birdhouse has a Creeple Peeple pilot behind a clear window held on with small nails. The only suitable plastic that I had isn't really that clear, but it is easy to replace later.

I built the rocket with the 24/40 case in mind but had decided to try the F35 in the 24/60 case for its maiden flight. Well, there isn't much room in the body and I couldn't pack the 2 chutes around the longer case. So, I prepped an F39-5. I used a car air bag chute protector and two 18" 'chutes so the heavy nose and body can come down separately.

The boost was fine with some weather cocking. Ejection was a little late and the two shock cords tangled. However, both 'chutes opened and it recovered just fine.

I think these birdhouses are so cool and like how this rocket turned out. Everyone who saw it took note and liked it too. If I did it again, I'd make the shoulder hollow to provide more room for 'chute(s) and add a 29mm mount. This thing got heavy fast.

Raygun Gothic HoJo

This was the second rocket I built around the wooden birdhouses I found at Michael's. I decided the body of the birdhouse reminded me of a squatty version of the Honest John cone. This rocket is based on 3" tubing and flies on a cluster of four 24mm motors.

I found 3" tubing would fit the 'cone' perfectly and decided to use some Giant Leap tubing that I had around. I started construction with the cone. The fins on the birdhouse were held on with both glue and wire brads, but were easy to remove. A bulkhead was glued to the bottom of the birdhouse, the shoulder (Giant Leap coupler) was glued over that, and a 2nd bulkhead was glued to the end. A long eyebolt goes through both bulkheads.

I cut the centering rings and fins from 1/8" luan plywood. The rings were cut on buddy's router and the four 24mm holes with a hole saw. I cut the fins on a table saw. Because the four motor tubes were shorter than the fin root, the through-the-wall tabs had to be notched accordingly.

The shock tether is 1/8" Kevlar® attached to the motor mount. A bolt is attached in the center of the mount for motor retention. I recessed the mount so the rocket could sit flat on its end with the motors installed.

I originally had thought about 'steam punk' styling with metal trim and copper piping for the spin motors, however, the weight was adding up and I wasn't finding suitable 'surplus' parts. So, I went with more of a classical Honest John trim scheme. I added a couple of thin outer tube sections around the body, one at the top and one above the fins. I used a couple of wooden craft spools for the rail button standoffs. The 'spin motors' were formed from scrap balsa.

The cone was left rough but was sealed with a coat of primer. I only filled a couple of spots where the fins had been. Most of the rocket is painted olive drab using Rustoleum paint. The keep a little of the steam punk look, I painted the tip of the cone gold and the raised ring silver. I looked and looked for something to plug the hole in the cone and came up with an emerald colored plastic bottle that fit perfectly.

Flight numero 1:
I used a Nomex® chute protector and a large 40" chute. I added tape thrust rings to four D12-5 motors and held them in with a small washer. The four motors were ignited with Quest Q2/G2 igniters. All four lit but the boost was awfully anemic. Weather cocking resulted in late ejection. The chute opened in plenty of time and the recovery was good.

More power, Scotty!

I decided there were two ways to increase the HoJo's power - cluster composites or add outboard boosters.  I opted for the boosters.  The four motor tubes are scrap, thick walled, semi-24mm-compatible tube that my daughter scrounged for me.  The cones are the ends of plastic termite traps.

Flight numero 2:

The second flight was at MDRA's ESL--146 on 4x EST SU D12-5 + 4x EST SU C11-P. It was an excellent flight with respectable altitude and ejection at apogee.