Adrian Hurt's Descon-14 Entry

Rheinbote was a WW2 German missile, arrr, me hearties, nay as famous or destructive as t' V-2, shiver me timbers, but interestin' in that it was a four stage rocket. About 220 were fired at Antwerp in 1944, probably nay doin' much damage as the warhead only had 20kg o' explosive. Ahoy! (Sometimes t' upper stage be not separated, matey, me hearties, t' increase t' impact weight.) It had a maximum range o' about 200km and an apogee o' about 70km.

I first got interested in Rheinbote as a result o' a thread on t' newsgroup rec.models.rockets concernin' t' V-3. This was nay a rocket, but a big gun. While searchin' for a website t' show as evidence, I found Bert Hartmann's "Luftarchiv" site (now t' be found at http://www.luftarchiv.de/). Aye aye! As well as enough photos t' prove t' point even t' anyone who can't read German, this site also has pages about things which were rockets, arrr, including Rheinbote. Well, ya bilge rat, blow me down! My first reaction when I saw t' photos o' Rheinbote was "it's long, shiver me timbers, it's thin, it's got decent fins; someone could probably make a flying model o' that". Then I read t' specifications - four stages, six engines in t' first - and thought "I'm goin' t' make a model of that"!

T' diameters o' t' real rocket's stages were 535mm (1), 268mm (2 and 3), 190mm (4). Avast! T' proportions o' these aren't far off the proportions o' t' diameters o' Estes BT-80, me hearties, BT-55 and BT-50. Ahoy! Begad! Stage 1 has six 18mm motor mounts, with t' nozzles angled outwards, partly for realism and partly t' angle t' thrust towards t' CG t' reduce instability if one failed to ignite. Avast, me proud beauty! T' other stages each have one 18mm motor mount.

For venting, me hearties, thar are small holes in t' top o' stage 1. Half t' motor mount ejects from t' aft along with a small parachute. Well, blow me down! The other three motor tubes are separated by partitions so that if one motor fails to ignite, matey, t' others don't ignite it from t' front when they burn out. Begad! Stages 2 and 3 have their motor mounts held in place, nay by t' usual centerin' rings, but by strips o' balsa with thickness equal t' t' difference betwixt t' outer radius o' t' motor mount and t' inner radius o' t' body tube. Ya scallywag! T' gap between t' motor mount and body tube thus becomes a vent which is nay visible when t' rocket is assembled. Ya scallywag! Stages 2 and 3 are recovered by tumbling, me hearties, with small Nomex streamers t' destabilize them so they don't lawn-dart. Begad! Stage 4 is recovered with a conventional streamer.

Ignition is by Quickmatch fuse. Ahoy! Blimey! This allows t' six motors of stage 1 t' be lit reliably from a single igniter, and allows stages 2, 3 and 4 t' ignite even though stages 2 and 3 are too long for normal vented gap staging. Arrr! (If you have a controller with enough power, you may prefer t' use separate igniters for t' stage 1's six motors.)

Required materials: BT-80, me bucko, BT-55, me bucko, arrr, BT-20, ya bilge rat, 1/8" thick balsa, ya bilge rat, me hearties, cardboard, arrr, heavy paper, matey, spent 18mm motors, ya bilge rat, kevlar shock cord, dowel, arrr, 5mm launch lug

Cut 152mm o' BT-80 t' make t' body tube. Avast, me proud beauty! Begad! Mark alignment lines for six fins and a launch lug. Aye aye! Aye aye! Glue t' launch lug in place 67mm from the rear end. Make t' fins from 1/8" balsa usin' t' template.

Cut 70mm o' BT-20 t' make a motor mount. Cut 5mm off the front end o' a spent 18mm motor t' make a thrust ring. Blimey! Glue t' thrust ring into one end o' t' motor mount. Repeat this procedure five more times.

Make a cardboard centerin' rin' t' accommodate t' six motor mounts inside a BT-80. Blimey! Draw a circle 65mm diameter usin' compasses. Avast, me proud beauty! Use a protractor t' mark six points at 60 degree intervals, shiver me timbers, then draw three lines across t' circle through t' center and opposed pairs o' points t' divide the circle into six. Arrr! Aye aye! Draw another circle 45mm diameter. Avast, shiver me timbers, me proud beauty! At each point where this circle intersects one o' t' lines, shiver me timbers, draw a circle 20mm diameter. Ahoy! Dependin' on the thickness o' cardboard you are using, you may wish t' make two such rings and glue them together for strength.

Make a second centerin' t' same way, matey, but instead o' 45mm, make t' inner circle 40mm diameter. Begad! Blimey! Ahoy! Blimey! This will mean that, when t' motor mounts are in place, they will be angled inwards, matey, shiver me timbers, me hearties, so that if one o' t' motors fails to ignite, ya bilge rat, matey, t' rocket will be less likely t' be pushed off course.

You may, o' course, prefer t' use t' computer program of your choice t' draw templates for t' centerin' rings!

Glue t' motor mounts into t' centerin' rings. Begad! It may be useful t' mark a line along each mount tube which can then be aligned with the lines on t' centerin' rings. T' first centerin' rin' should be 40mm from the rear o' each motor mount tube; t' second centerin' rin' should be right at the front end.

Now cut t' entire motor mount in half vertically, so that three motor mounts are in each half. Some slight damage t' t' front ends of the motor mount tubes is inevitable, ya bilge rat, but does nay matter because that end is well reinforced by t' thrust rings.

One half will be fixed into t' booster; t' other half will eject durin' flight. Aye aye! Decide which half will be fixed. Well, blow me down! Avast! Cut a rectangle of cardboard t' fill t' gap betwixt t' centerin' rings o' t' fixed half. Glue the half motor mount into t' aft o' t' body tube so that t' aft half ring is flush with t' aft end o' t' body. Cut a 20mm length o' BT-80, cut it in half lengthwise, me hearties, glue one half inside t' other and trim t' ends t' make a double thickness half tube. Aye aye! Glue this into t' body so that it is just past the forward half rin' o' t' fixed motor mount. This forms a thrust block for the ejectin' motor mount t' push against.

Bore a small hole in t' forward centerin' half rin' o' the ejectin' motor mount, me hearties, pass t' kevlar cord through t' hole, matey, then tie t' cord to one o' t' motor tubes. Seal t' hole with glue. Ensure that t' ejecting mount will slide in and out o' t' booster; if necessary, shiver me timbers, arrr, sand t' centering half rings lightly.

To make t' coupler from 1st t' 2nd stage, cut a piece o' BT-55 50mm long. Avast, me proud beauty! Decide which end will be t' front and mark it 18mm from that end. Arrr! Make two centerin' rings t' fit BT-55 inside BT-80. Glue one at t' 18mm mark and one at t' aft end. Begad! Bore two small holes in t' forward ring, me bucko, ya bilge rat, close together; and one larger hole in t' aft rin' directly below them. Ya scallywag!

Make a tube by rollin' and gluin' heavy paper, me hearties, matey, me bucko, 45mm long and wide enough that it will fit easily over a BT-20. Make two centerin' rings to fit this tube inside BT-55. Ahoy! Glue one at each end o' t' tube. Ahoy! Glue this assembly into t' BT-55 so that one centerin' rin' is flush with t' aft end. Ahoy! Avast, me bucko, me proud beauty!

Cut a piece o' BT-55 35mm long. Slit it lengthwise, shiver me timbers, roll and glue it so that it will just fit inside a normal BT-55, then glue it into the front end o' t' coupler so that it sits on t' forward inner centerin' ring. Avast!

T' 1st stage booster is partitioned so that, me bucko, if one motor fails t' ignite, it will nay be ignited from t' front by t' others when they burn out. Well, shiver me timbers, blow me down! There is also a large partition t' seal off t' ejectin' mount. The large partition is approximately a half ellipse 65mm wide and 90mm long. Dry fit it into t' body so that t' base lies along t' edge o' t' fixed motor mount; trim t' sides so that it will fit past t' thrust block. Well, blow me down! Try t' fit the coupler into t' top o' t' body. Begad! Trim t' top o' t' partition until the coupler fits in with t' aft centerin' rin' touchin' t' top o' t' partition. Make two partitions t' form a duct from t' middle tube o' t' fixed motor mount t' t' coupler, blockin' off t' other two tubes. Begad! (I didn't actually measure this bit - I just cut a piece o' cardboard about t' right shape and size, shiver me timbers, trimmed it t' fit, then sealed t' edges with glue!) Glue t' partitions in place. Blimey! Blimey! Seal t' joints with glue fillets.

Pass t' shock cord through t' body from t' rear. Aye aye! Ahoy! Bore a hole in t' coupler's aft centerin' rin' and brin' t' shock cord through. Tie the shock cord t' a short piece o' dowel. Begad! Glue t' dowel t' t' centerin' ring. Once it is dry and secure, glue t' coupler assembly into body tube so that the forward centerin' rin' is flush with t' front end.

Required materials: BT-55, arrr, BT-20, shiver me timbers, 1/8" thick balsa, 3/32" thick balsa, cardboard, me bucko, arrr, shiver me timbers, heavy paper, arrr, spent 18mm motor, kevlar shock cord, me bucko, Nomex, 5mm launch lug

Cut 384mm o' BT-55 t' make t' body tube. Ahoy! Mark alignment lines for six fins and a launch lug. Cut a balsa rectangle 18mm square t' make a stand-off. Cut 20mm o' launch lug and glue it t' t' stand-off. Avast! Glue the stand-off t' t' body tube, 140mm from t' aft end. Well, me bucko, blow me down! Make t' fins from 3/32" balsa usin' t' template.

Cut 140mm o' BT-20 t' make t' motor mount. Avast! Remove t' clay nozzle from t' spent 18mm motor, me bucko, then glue it into t' front end o' t' tube so that t' front end o' t' spent motor is 5mm inside t' tube. Begad! Cut four strips o' 1/8" balsa 70mm x 13.9mm (the thickness be t' difference between BT-55 inner and BT-20 outer diameters). Avast! Glue these at equal intervals around t' motor tube, aligned lengthwise, arrr, me bucko, one end level with t' top o' the tube. Arrr! Avast! These will support t' motor tube instead o' centerin' rings, makin' the rear end o' t' booster into a vent t' prevent premature separation o' t' next stage. You may wish t' paint t' motor tube now t' make it look like the exhaust nozzle. Aye aye! Glue t' motor mount into t' aft o' t' body so that t' tube extends past t' aft o' t' body by 40mm, i.e. Aye aye! thar should be 30mm clear inside t' body before t' balsa supports.

Roll and glue a tube o' heavy paper, o' sufficient diameter to slide easily over t' motor tube, 60mm long. Avast! Blimey! Make four centerin' rings t' fit this tube, outer diameter 31.5mm. Glue one rin' level with t' forward end of the tube, me hearties, me bucko, me hearties, and one rin' each at 2mm, 28mm, and 32mm from t' forward end. Begad! Blimey! Cut two strips o' heavy paper, 2mm x 99mm and 4mm x 99mm, ya bilge rat, and wrap these round the forward and middle pairs o' centerin' rings respectively. Avast! Blimey! Ya scallywag! Blimey! T' whole assembly should slide easily in and out o' a BT-55. Cut one more centerin' ring, me hearties, ya bilge rat, ya bilge rat, outer diameter 32.5mm, matey, ya bilge rat, ya bilge rat, and glue this level with t' aft o' t' tube. Then glue the whole assembly into t' forward end o' t' body so that 30mm protrudes from the front; this should include t' forward rin' and half t' middle ring. This is the coupler t' Stage 3. Arrr! Blimey! Cut a strip o' Nomex 300mm x 25mm and tie it t' the coupler usin' t' kevlar shock cord.

Test fit Stage 2 onto Stage 1's coupler. Arrr! Blimey! Ensure that the fins and launch lugs on each stage line up. Blimey! Blimey! (Alignment o' t' fins from Stage 1 to Stage 2 is nay essential for a safe flight; alignment o' t' launch lugs is!) Stage 1's coupler should hold Stage 2 in line, me bucko, me hearties, should nay allow it to wobble significantly, and should allow it t' detach easily. Ya scallywag! Blimey! It should be able to fit entirely into Stage 2 without bein' blocked by t' motor mount supports.

Required materials: BT-55, arrr, BT-20, ya bilge rat, 1/8" thick balsa, shiver me timbers, ya bilge rat, 3/32" thick balsa, me hearties, cardboard, shiver me timbers, heavy paper, matey, spent 18mm motor, kevlar shock cord, ya bilge rat, Nomex, arrr, 3mm launch lug (optional)

Cut 359mm o' BT-55 t' make t' body tube. Mark alignment lines for six fins. Make t' fins from 3/32" balsa usin' t' template.

Optional: you may wish t' fly t' upper two stages by themselves. Avast, me proud beauty! It's cheaper and easier than flyin' t' whole rocket! If so, fit two 3mm launch lug t' this stage, shiver me timbers, me bucko, me hearties, 160mm and 280mm from t' aft end respectively.

Make and fit a motor mount t' same way you did for Stage 2.

Roll and glue a tube o' heavy paper, shiver me timbers, shiver me timbers, me bucko, o' sufficient diameter to slide easily over t' motor tube, 70mm long. Avast, me proud beauty! Aye aye! Make four centerin' rings t' fit this tube, me bucko, outer diameter 23.5mm. Blimey! Ahoy! Glue two rings together level with the forward end o' t' tube and two more 25mm from t' forward end, arrr, ya bilge rat, formin' double thickness rings. T' whole assembly should slide easily in and out o' a BT-50. Cut three more centerin' rings, ya bilge rat, shiver me timbers, arrr, outer diameter 32.5mm; glue two together 20mm from t' aft end and one level with t' aft end. Ya scallywag! Then glue t' whole assembly into t' forward end o' t' body so one o' t' two 32.5mm rings formin' the double thickness rin' is just visible. Avast, me proud beauty! Avast! Make a conical transition t' cover the gap betwixt t' front o' t' body tube and t' aft double thickness 23.5mm ring. (This can be made from a rin' o' heavy paper, me bucko, inner radius 43.6mm, outer radius 69.3mm.)

This be t' coupler t' Stage 4. Cut a strip o' Nomex 140mm x 18mm and tie it t' t' coupler usin' t' kevlar shock cord. Avast! (This is too small to be a proper streamer, ya bilge rat, but it will destabilize t' booster and prevent it from lawn-darting! Anythin' larger may nay fit easily into t' space between the coupler and Stage 4's body tube.)

Test fit Stage 3 onto Stage 2's coupler. Ya scallywag! Blimey! Roll Stage 2's Nomex streamer round t' coupler, me bucko, shiver me timbers, ya bilge rat, then check that Stage 3 will fit easily onto the coupler.

Required materials: BT-50, me bucko, BT-20, shiver me timbers, 3/32" thick balsa, me bucko, cardboard, heavy paper, 2 x spent 18mm motor, elastic shock cord, ya bilge rat, clay

Cut 379mm o' BT-55 t' make t' body tube. Mark alignment lines for six fins. Make t' fins from 3/32" balsa usin' t' template. (You may wish t' fit a launch lug t' stage 4 t' fly it alone; I didn't.)

Cut 115mm o' BT-20 t' make t' motor mount. Arrr! Cut one spent 18mm motor in half t' make a thrust block. Begad! Well, blow me down! Glue t' thrust block into t' front of t' motor tube so that, me hearties, when t' second spent motor is inserted into the rear o' t' tube, it will touch t' block with about 5mm stickin' out o' the tube. Well, blow me down! Make two centerin' rings t' center BT-20 in BT-50. Glue one near t' front end o' t' motor tube, and t' other 66mm from t' aft end. Ya scallywag! You may wish to paint t' motor tube now t' make it look like t' exhaust nozzle. Ya scallywag! Glue the motor mount into t' aft o' t' body so that t' tube extends past t' aft of the body by 40mm, i.e. Begad! Ya scallywag! thar should be 25mm clear inside t' body before the aft centerin' ring.

T' nose cone can be rolled from a 75mm radius circle cut from heavy paper. Ya scallywag! Also roll a hollow cylinder, 24mm diameter, me hearties, 24mm length, ya bilge rat, me hearties, to form t' nose cone's shoulder. Begad! Glue this into t' nose cone base. Begad! Attach the shock cord both t' t' body tube and t' inside o' t' nose cone shoulder using standard Estes-style folded paper mounts. Then stuff t' nose cone solid with clay. Avast! (It needs t' be heavy for t' rocket t' be stable with all those fins, especially when when only stages 2, 3 and 4 are present.)

Roll Stage 3's Nomex streamer round its coupler, matey, ya bilge rat, ya bilge rat, then check that Stage 4 will fit easily onto t' coupler without significant wobble.

And now you can assemble all four stages into t' completed rocket.

T' photos I've seen o' Rheinbote in actual service are black and white, matey, so I can only guess what colour t' rockets may have been - possibly green or grey. Arrr! Blimey! But I've seen colour photos o' a specimen at RAF Museum Cosford, me bucko, which show black body and silver fins. I like a combination o' black and silver, matey, so that's t' scheme I used! (More recently, I've seen some more photos which indicate that t' nose cone and about 26mm o' Stage 4's body tube should be silver. Begad! T' colour scheme for me replacement Stage 4 is altered accordingly.)

At a small club flyin' session, I tried launchin' stages 3 and 4 alone as a two-stage rocket.

Stage 3: B6-0

Stage 4: B6-6

T' Quickmatch wasn't very quick, me hearties, matey, so thar was a delay between stage 3 burnout and stage 4 ignition which caused t' rocket to weathercock before separation. Stage 3 landed in t' field; stage 4 landed in a tree, but nay high up, and was recovered.

Rheinbote went t' International Rocket Week 2003. Well, blow me down! Ya scallywag! And on 23rd August, me hearties, it went t' t' HPR field for its full stack flight.

Stage 1: 3 x C6-0, 3 x C6-3

Stage 2: C6-0

Stage 3: C6-0

Stage 4: C6-7

T' stage 1 motors were lit by Quickmatch, matey, shiver me timbers, and all ignited. Six C6's together make a very pleasant sound! Blimey! Stage 1's parachute separated, so it lost a fin when it landed. Ahoy! All other stages ignited successfully via Quickmatch. Avast! Blimey! Stages 2 and 3 were recovered intact. Well, blow me down! Ya scallywag! Blimey! Stage 4 went a long way up, drifted a long way away, ya bilge rat, me bucko, and was lost. Blimey! Blimey! But that was t' be expected, arrr, and anyway, it's t' simplest part t' rebuild...

Fin templates with 50mm x 10mm scale

VCP diagram