Well, I just finished one of my more rewarding projects, that being a flying V-1 Buzz Bomb. A friend of mine is into vacu-forming styrene, and made up the body and pulse jet intake on a wood lathe, and molded me some pieces, on the condition I would try to see if I could make it fly. Dry weight was going to be around 11oz.

I used a 24mm motor tube (aerotech) and installed a thrust ring, and motor hook held in with fiberglass tape and CA. I decided on making the wings and tail and pulse jet supports out of 1/8" basswood, for it's strength not much less than plywood, and a weight not much more than balsa. I glued the wings and tail surfaces and filleted to the 24mm core tube. Since this was a home built mold, there were some imperfections in the molding to be worked around, and it took a while to trim them so the two halves of the body and pulse jet were flush. 

I fitted the two halves of the pulse jet intake, and made a centering ring out of styrene to center the Estes BT-60 for the outlet pipe. It runs the full length of the pulsejet, and is slotted to allow the supports to run through the wall and glue on the inside opposite wall of the pulsejet. The pulsejet is hollow, and these supports act as fins inside the tube, as well as make it strong. I glued a coupler in the aft end of the BT-60 to strengthen it.

I fitted the styrene body halves, and glued tabs inside to locate the halves together, and slotted them for the wings, tail, and forward pulsejet support. I tied a piece of 90# dacron fishing line around the 24mm tube, just forward of the forward pulse jet intake for shock line attachment. At this point the back half hangs slightly tail down for a flat landing to minimize wing and tail damage.

I used a styrene forward centering ring since it wasn't taking any real structural strain. I reinforced the forward end of the styrene with another strip of styrene 3/4" wide glued inside after cutting off the cone section 1" forward of the leading edge of the wings. I reinforced the lip of the cone, and glued another 1.5" strip inside the cone to make a shoulder. 

I ran VCP on the model using the wings as fin set 1, and the tail elevators as fin set 2, and neglecting the pulse jet, since it would move the CP back anyway, and was unsymmetric. VCP showed a CP of midpoint of the wings, which is what I would expect for an airplane (from my RC experience). I set the CG around 1" forward of the wings RTF giving me more than 1 caliber, and which corresponds with other peoples experience with getting winged vehicles to fly upward with stability. Finished empty weight came out as 9 oz., with 8oz of lead shot and epoxy needed in the nose for balance. This is a lot, but fits in with my original plan to use 24mm E-15, 18's, and F-24, 39's. Final weight with motor and chutes was 19oz. Length is 23" for the body, 27" for total, 17" wingspan, 3.5" chord, 7" tail span. I used the Fi103A1 format which had shorter wings than the later versions, and moved them back 1/2". The tail cone exit diameter should really be BT-55. Body diameter is 3" at the widest part.

I decided to cut off the back end of the body and have the motor tube stick out the  back, so I wouldn't have to fight asymmetric thrust as well as drag, and It is hard to tell the difference when you look at the model.

I rigged the nose and body to come down separately, with a 22" nylon for the bottom, and a 20" xform for the nose. The chutes fit in the hollow nose. The 1/8" plywood forward bulkhead in the nose is just behind the nose weight. This allows plenty of room for the two chutes, and 3/8" elastic. I rigged the bottom chute forward, with the nose chute behind, so they would both get pulled out. I used a 9/32" id brass tube as a launch lug, on the bottom just behind the nose cone joint, since it was the only place on the body that was parallel to the flying surfaces.

Flight was on a foggy calm day with ceiling around 600'. Boost was vertical for the first 150' or so, then arching toward the pulse jet around 15-20 degrees for the rest of the boost. I cut down the delay from the E-18-7(8) 1/4" which gave me a 4 second delay (boy these delays are out of whack) This was from experience. It arched over, and ejected perfectly.

On recovery I saw some damage to the body plastic which had been torn. I thought it was the recovery line attach point through the plastic which had done it, but on inspection I noticed that the forward centering ring was torn in half, and part was missing. I discovered the problem. Since I didn't think the forward ring would take any structural force, I didn't put a fillet behind the ring, and relied on the lip reinforcement to hold it from going forward.

The ejection charge was so forceful (the cap supplied with the reload kit) that the heavy nose resisted ejection, and the centering was blown backwards inside the body shell. Once that happened the body blow out a side portion behind the wing. We taped the body back with masking tape, and flew again on an F-39. This accelerates faster, and due to the larger drag at higher speed, arced a little more than the E-18. The V-1 had a half roll on the way up, to horizontal flight at the top, and a slow half roll arcing over to ejection. Recovery was fine this time with no more damage.

I got out the heat gun at home, and removed the remains for of centering ring, which was held in place with 5 min. epoxy around the motor tube, replaced it with 1/8" plywood, and fixed the hairline cracks with liquid styrene cement. It is now RTF and good as new.

This was a really fun, and rewarding project. The rocket performed better than I thought, due to the asymmetric drag. This is the second time I have used styrene, and it is a nice way to make complicated shapes, and is easy to work with. The first time was the Estes Space Shuttle, which flew really well, but the thin styrene was tricky to get together. It really looked awesome going over the top like an airplane. Only thing missing was the buzzing. A larger version with a Hypertek hybrid would sound about right:) A little bit larger, and I think an RC version could be worked out with micro servos. I'm surprised I haven't seen a ducted fan RC Buzz Bomb, since it is the perfect model with the engine in a separate pod, easy to get at, has a rather large wing, and the buzzing would sound great. Taking off from a carriage, and landing on the belly, or with rudimentary wheels.

Now I can paint the model, and I have some still pictures, and an attempt at getting liftoff, and as soon as I get them developed, I'll put them on my web page.

My friend has already done a D powered Natter, now with our 7.6", 5.5", 4", 2.6", and 2" V-2's, and the V-1, we are getting a little one sided on the German side, so we are going to try a 4" X-15 using Vacu-forming for the body shells, and wing skins.

Hope this was interesting.