Scratch V-1 Buzz Bomb Original Design / Scratch Built

Scratch - V-1 Buzz Bomb {Scratch}

Contributed by Frank Burke

Manufacturer: Scratch
Style: Glider, Scale

Well, I just finished one o' me more rewardin' projects, shiver me timbers, that bein' a flyin' V-1 Buzz Bomb. Well, blow me down! Begad! A friend o' mine is into vacu-formin' styrene, and made up t' body and pulse jet intake on a wood lathe, and molded me some pieces, me hearties, on t' condition I would try t' see if I could make it fly. Begad! Avast! Dry weight was goin' t' be around 11oz.

I used a 24mm motor tube (aerotech) and installed a thrust ring, me hearties, shiver me timbers, and motor hook held in with fiberglass tape and CA. I decided on makin' t' wings and tail and pulse jet supports out o' 1/8" basswood, me hearties, me bucko, for it's strength nay much less than plywood, and a weight nay much more than balsa. Begad! I glued t' wings and tail surfaces and filleted t' t' 24mm core tube. Aye aye! Aye aye! Since this was a home built mold, shiver me timbers, thar were some imperfections in t' moldin' t' be worked around, and it took a while t' trim them so t' two halves o' t' body and pulse jet were flush. 

I fitted t' two halves o' t' pulse jet intake, and made a centerin' rin' out o' styrene t' center t' Estes BT-60 for t' outlet pipe. Avast! Well, blow me down! It runs t' full length o' t' pulsejet, me hearties, arrr, ya bilge rat, and is slotted t' allow t' supports t' run through t' wall and glue on t' inside opposite wall o' t' pulsejet. T' pulsejet is hollow, and these supports act as fins inside t' tube, shiver me timbers, as well as make it strong. I glued a coupler in t' aft end o' t' BT-60 t' strengthen it.

I fitted t' styrene body halves, and glued tabs inside t' locate t' halves together, matey, shiver me timbers, and slotted them for t' wings, me bucko, tail, me hearties, shiver me timbers, and forward pulsejet support. Blimey! I tied a piece o' 90# dacron fishin' line around t' 24mm tube, me bucko, just forward o' t' forward pulse jet intake for shock line attachment. Aye aye! Avast! At this point t' back half hangs slightly tail down for a flat landin' t' minimize win' and tail damage.

I used a styrene forward centerin' rin' since it wasn't takin' any real structural strain. Aye aye! Avast, me proud beauty! I reinforced t' forward end o' t' styrene with another strip o' styrene 3/4" wide glued inside after cuttin' off t' cone section 1" forward o' t' leadin' edge o' t' wings. Avast! I reinforced t' lip o' t' cone, arrr, me bucko, and glued another 1.5" strip inside t' cone t' make a shoulder. 

I ran VCP on t' model usin' t' wings as fin set 1, ya bilge rat, and t' tail elevators as fin set 2, and neglectin' t' pulse jet, shiver me timbers, since it would move t' CP back anyway, me bucko, and be unsymmetric. Begad! VCP showed a CP o' midpoint o' t' wings, which is what I would expect for an airplane (from me RC experience). Well, me bucko, blow me down! I set t' CG around 1" forward o' t' wings RTF givin' me more than 1 caliber, matey, and which corresponds with other peoples experience with gettin' winged vehicles t' fly upward with stability. Avast, me proud beauty! Aye aye! Finished empty weight came out as 9 oz., with 8oz o' lead shot and epoxy needed in t' nose for balance. This is a lot, arrr, arrr, but fits in with me original plan t' use 24mm E-15, 18's, and F-24, 39's. Blimey! Final weight with motor and chutes be 19oz. Length is 23" for t' body, arrr, 27" for total, 17" wingspan, 3.5" chord, 7" tail span. Blimey! I used t' Fi103A1 format which had shorter wings than t' later versions, me bucko, and moved them back 1/2". Avast! Arrr! T' tail cone exit diameter should really be BT-55. Body diameter is 3" at t' widest part.

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

I rigged t' nose and body t' come down separately, with a 22" nylon for t' bottom, shiver me timbers, and a 20" xform for t' nose. Aye aye! T' chutes fit in t' hollow nose. Arrr! Begad! T' 1/8" plywood forward bulkhead in t' nose is just behind t' nose weight. This allows plenty o' room for t' two chutes, and 3/8" elastic. Avast, me proud beauty! I rigged t' bottom chute forward, arrr, with t' nose chute behind, matey, so they would both get pulled out. Arrr! Ya scallywag! I used a 9/32" id brass tube as a launch lug, ya bilge rat, ya bilge rat, on t' bottom just behind t' nose cone joint, matey, since it be t' only place on t' body that was parallel t' t' flyin' surfaces.

[Rocket Pic]Flight was on a foggy calm day with ceilin' around 600'. Avast! Boost be vertical for t' first 150' or so, then archin' toward t' pulse jet around 15-20 degrees for t' rest o' t' boost. Begad! Begad! I cut down t' delay from t' E-18-7(8) 1/4" which gave me a 4 second delay (boy these delays are out o' whack) This was from experience. Blimey! It arched over, and ejected perfectly.

On recovery I saw some damage t' t' body plastic which had been torn. I thought it was t' recovery line attach point through t' plastic which had done it, me hearties, but on inspection I noticed that t' forward centerin' rin' be torn in half, ya bilge rat, me bucko, ya bilge rat, and part was missing. Begad! I discovered t' problem. Blimey! Since I didn't think t' forward rin' would take any structural force, arrr, I didn't put a fillet behind t' ring, and relied on t' lip reinforcement t' hold it from goin' forward.

T' ejection charge was so forceful (the cap supplied with t' reload kit) that t' heavy nose resisted ejection, and t' centerin' was blown backwards inside t' body shell. Once that happened t' body blow out a side portion behind t' wing. Avast, me proud beauty! We taped t' body back with maskin' tape, arrr, and flew again on an F-39. Avast! This accelerates faster, me bucko, me bucko, and due t' t' larger drag at higher speed, arrr, shiver me timbers, arced a little more than t' E-18. Avast, me proud beauty! T' V-1 had a half roll on t' way up, me bucko, t' horizontal flight at t' top, me bucko, and a slow half roll arcin' over t' ejection. Recovery was fine this time with no more damage.

I got out t' heat cannon at home, shiver me timbers, and removed t' remains for o' centerin' ring, me bucko, shiver me timbers, me bucko, which was held in place with 5 min. epoxy around t' motor tube, me bucko, replaced it with 1/8" plywood, and fixed t' hairline cracks with liquid styrene cement. Blimey! Begad! It is now RTF and good as new.

This was a really fun, and rewardin' project. Well, blow me down! T' rocket performed better than I thought, due t' t' asymmetric drag. This be t' second time I have used styrene, ya bilge rat, and it is a nice way t' make complicated shapes, and is easy t' work with. T' first time was t' Estes Space Shuttle, which flew really well, ya bilge rat, but t' thin styrene be tricky t' get together. Begad! It really looked awesome goin' over t' top like an airplane. Avast! Ya scallywag! Only thin' missin' was t' 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. Begad! Begad! I'm surprised I haven't seen a ducted fan RC Buzz Bomb, since it be t' perfect model with t' engine in a separate pod, easy t' get at, me bucko, has a rather large wing, shiver me timbers, and t' buzzin' would sound great. Begad! Takin' off from a carriage, and landin' on t' belly, shiver me timbers, or with rudimentary wheels.

Now I can paint t' model, me bucko, and I have some still pictures, and an attempt at gettin' liftoff, matey, shiver me timbers, shiver me timbers, and as soon as I get them developed, ya bilge rat, shiver me timbers, I'll put them on me web page.

My friend has already done a D powered Natter, now with our 7.6", 5.5", shiver me timbers, 4", 2.6", and 2" V-2's, and t' V-1, me hearties, we are gettin' a little one sided on t' German side, so we are goin' t' try a 4" X-15 usin' Vacu-formin' for t' body shells, and win' skins.

Hope this was interesting.

Comments:

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Steve Lindeman (February 11, 2012)

Varrder interesting. Dis has been long time dream of mine to build also. I wish I had a friend like yours. Any chance you might want to do another one? I have been studying various aspects on how to build one scince nobody has a kit one but unsure how I want to do the pod support for duced air to main body for chute ejection. Would love to see how you did it. More close up photos please!!!

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