(Contributed - by Glenn Roth - 03/21/09) Brief:
11 "Finned" rocket that can be launched on a single "E" or staged (D12-0, D12-3) with a parachute
recovery.
Prototype:
I built a protoype o' me choice o' rockets for t' EMRR "Rockets o' t' Future." I choose t' t' do an 18mm
version first. Begad! Avast! I gathered some cardboard, ya bilge rat, posterboard, shiver me timbers, and second hand parts, me bucko, etc. It would have been ten times harder
without t' EMRR "Calculators", me hearties, arrr, for shrouds, ya bilge rat, etc. I chose cardboard figuring, ya bilge rat, "If I can get this t' fly
without a cad program, from t' heaviest material, I surely will be able t' build one in t' 24 MM scale. Avast! Also,
cardboard a little easier t' work with than "foamboard."
My 1st test flight was a disaster. (Remember, I have no software t' determine where t' CP & CG Is and if it
will fly.) After givin' it some thought, cut open nosecone and added some clay t' move CG forward. Begad! Last Saturday flew
it again and success! It only went 50 ft up but successfully deployed chute right before landing.

What I've learned is,"use t' material in your prototype, that u intend t' use on your final version."
Mine did fly but, would have saved a lot o' aggravation and speeded up t' build. Begad! Also, shiver me timbers, Highly recommended buildin' a
prototype, especially in me case. Avast, me proud beauty! Blimey! My submission for t' "rocket o' t' future" has 12 fins! Blimey! Never came close
t' design such a complex rocket before. Blimey! Well, blow me down! Blimey!
Construction:
PARTS LIST:
- 24mm engine block
- 1 engine hooks
- 1 sheet o' foam board, arrr, 20x30x1/4"
- 2 sheets o' poster board, shiver me timbers, 20x30"
- 1 (priority mailin' box)
- 2 BT-55's (15" long)
- 1 BT-55 coupler
- 18"x24mm Body tube for "engine Mounts"
- Shock cord; ¼"x 24+"
- 3, 4"x"36"x1/8 balsa sheets/basswood
- 1 "quest" egglofter nosecone
- 1 (18") parachute, me hearties, & shroud line
- "non-hardening" clay
- (8) bic pen caps t' "simulate 8 motors"
- 2 spent "D" engines
- Templates (will be loaded shortly)
Just wanted t' interject for a moment. Hope you find this rocket as much o' a challenge t' build as I found to
design it, without t' help o' any "Cad software." If anyone cares t' "plug" these measurements
into a cad program, I would be very curious as t' t' result. Aye aye! Ya scallywag! I did use EMRR "Calculators" for t' shrouds
and centerin' rings. Well, blow me down! I thank Nick for makin' available because without them, me bucko, couldn't have made this design. Ahoy!
This design is for "Personal use only" and nay for resale, with express permission o' myself, Glenn
Roth. Begad! Blimey!
I stated in "parts" section that t' balsa is very fragile. Begad! Well, me hearties, blow me down! Just discovered Tech Report # 29, me bucko, ya bilge rat, from
www.apogeerockets.com; "Take your rocket t' Supersonic Speeds. Well, matey, blow me down! " This is a compromise t' replacin' entire fin
with basswood or ply. Blimey! You can download this free report and make these large fins MUCH STRONGER! I tried this on 3 of
me fins and they are NOTICEABLY stronger.
ASSEMBLY:
Read thru all instructions before proceeding. Begad! Avast! Blimey! Options exist. Blimey! Blimey!
**Not happy with way main "body shroud" turned out. This "posterboard" is hard t' keep smooth
without "kinking." You might want t' A) shorten t' about half t' length; b) wrap it around a smooth form of
some kind while gluing, shiver me timbers, t' keep smooth.**
- Gather parts, arrr, matey, make templates, and gather followin' tools: sharp razor knife, metal ruler, shiver me timbers, scissors, carpenters
square, 2 "spent D" engines, me hearties, adhesive spray, (worn out windshield wiper. For engine hooks)., ya bilge rat, protractor, me bucko, and
compass. Ya scallywag! Well, blow me down!
- Cut two engine mounts from 24mm body tube. Arrr! Arrr! Main 2 " long and "booster" 3 1/2" long.*****note:
Now that t' rocket is half done, me hearties, t' shroud looks too short. Ya scallywag! I have increased length from 3 t' 3 ½ inches or
longer, in instructions. You'll have increase length o' shroud accordingly.****
- *** OPTION: I've since elected t' use a "friction fit", arrr, instead o' an engine hook, me bucko, arrr, on main motor. Avast, me proud beauty! Ahoy! Blimey! I'm
sure you can use one but, me bucko, have t' "dry fit" b 4 assembly.*** I've discovered that with t' aft "body
panels", extendin' an inch, arrr, it's very difficult t' use an engine hook. Aye aye! Avast! Blimey! I've since elected t' slip "main
motor" into booster engine mount, and tape. Well, blow me down! T' tape will require a "slit" into it, so makes easy
separation.
- Glue 24mm engine block into end o' engine tube w/engine hook stickin' into it. Well, blow me down! Blimey!
- Option*** This designed as a "two stage". Aye aye! If you want an easier conversion t' single stage, you may
want t' insert "booster engine tube" in a section o' BT-55. Begad! Then usin' a BT-55 coupler, fasten t' engine
tubes together. Ya scallywag! Ahoy! (skip 1st /main engine tube.) It is much easier buildin' booster shroud separately.
Main Engine Tube
- Glue t' BT55 centerin' rings on main engine tube. Begad! Let dry. Blimey!
- You'll want t' "dry fit" main engine mount and make sure "spent engine" recessed inside BT55
about ¼".
- Mark Bt55 where "engine Hook" will be, and cut a slot 1/8" x3/8". Ya scallywag!
- Glue main engine mount with engine hook lined up with slot in BT55. Avast, me proud beauty!
Booster Engine Mount
- Take 3" piece o' 24mm BT; then cut 1/8"x 3/8" slot in one end. Avast! Blimey!
- Lay "flat" side o' hook inline with slot and tape. Avast, me proud beauty! *** I used a long piece o' old wiper blade for hook
and cut t' length later. Avast, me hearties, me proud beauty!
- Cut out 3 "rear shroud centerin' rings. Arrr! ***Tip: when I cut out middle o' rings FIRST, matey, I then took a spent
engine and inserted and twisted t' check for a tight fit. Arrr! Then inserted engine in tube for support. Arrr! Well, blow me down!
- Take largest aft rin' and glue over aft engine mount WITHOUT coverin' slot in t' mount. Aye aye! Be careful nay t' get
glue on motor!!
- Glue middle and end centerin' rings and remove spent motor and let dry. Well, blow me down!
- While drying, ya bilge rat, cut out aft shroud. (You will see I include pattern, me hearties, showin' a "saw tooth design" on
inside radius o' shroud. Cut design in shroud. Avast, me proud beauty! Begad! Much easier t' glue.)
- Shape shroud, matey, tape together on inside. Begad!
- Fold "teeth" over t' inside and make a sharp crease. Straighten out. Begad! Begad! Blimey!
- After center rings on engine tube have dried, take some glue and apply t' edges o' rings. Avast! Blimey!
- Take shroud and slip over engine assembly. Be sure t' get completely in. Avast, me proud beauty! Aye aye!
- Spread some glue on smallest centerin' rin' and fold shroud "teeth" down, me hearties, holdin' till set. Aye aye! Blimey! You may
only be able t' do a few @ a time. Let dry Thoroughly. Blimey! Blimey! Avast, ya bilge rat, me proud beauty! Blimey!
- Put a spent engine in "Main and aft " engine mounts. Ya scallywag!
- Slide together, arrr, linin' up "slots" in engine tubes. Avast, me proud beauty! Begad! Blimey! T' aft engine tube should slide over t' Main
engine about ½" and stay in place. ***Make sure aft Booster engine is as far forward as it will go WITHOUT
disengagin' t' booster. Avast! Blimey!
- Mark t' aft engine hook , arrr, cut and bend t' correct size. Begad!
- Cut shock cord mount and glue shock cord t' it. Avast, me proud beauty! Avast! Blimey!
- Slide "loose" end o' shock cord thru a BT55 coupler. Arrr!
- Glue Shock cord mount t' inside o' BT55 containin' engine mount far enough inside t' be able t' glue BT55
coupler. Glue Bt55 coupler and let dry.
- Cut other BT55 t' length so when t' two r put together , arrr, me bucko, you have a rocket body 23" long,
"without" aft shroud. Begad!
- Cut out Main Body centerin' rings. Avast, me proud beauty! Ahoy! (u can take spare piece o' BT55 t' check fit). Arrr!
- Take t' "fin template" and mark 3", me hearties, me bucko, 3.5" rin' where it will engage each fin. Arrr! ****Note: you
can mark 4" rin' but, because o' size, it won't line up with other two rings. Ya scallywag! Ya scallywag! You will have t' do slots on this
rin' once it is mounted. Arrr! Avast!
- Take care, cut a ¼" deep slot x 1/8" wide into each ring. Begad!
- Mark 1st slot on each rin' with a #1 for reference.
- Make a fin from 1/8" "Basewood/plywood" as a guide t' check fit o' fins. Aye aye! Avast! It will also b used t' as
guide for slots, ya bilge rat, and cut initial fin slots in 4" ring.
- ***You may want t' fasten up aft shroud again w/spent motors t' check placement o' centerin' rings and fins.***
Fins and Body:
- Cut out 8 fins, and use sealer if desired.
- Use fine guide and cut slots in each fin: 1" from aft o' fin, 1x1/4 deep. Next one 7" from end. Avast, me proud beauty!
- Last slot is 2.5 " from previous slot and only 5/8" deep.
- These r initial slots. Avast! Ya scallywag! You may have t' widen for proper fit. Aye aye! Blimey!
- Slide center rings on BT one @ a time. Ya scallywag! ***If seems tight or binds, shiver me timbers, me hearties, increase size o' hole slightly. Begad! You can use a
piece o' BT55 t' "shape" hole. Begad! (you want t' maintain a fairly tight fit). Avast! Well, blow me down! Blimey!
- Space rings approximately same distance as slots on fin. Avast, me proud beauty! Blimey!
- "Orientate" all 3 rings with #1's lined up. Begad! Begad!
- Take your "Guide Fin", shiver me timbers, me hearties, ( t' one made from plywood), and check slot lineup for first fin. Ya scallywag!
- You'll have t' cut slots deeper in each ring, matey, checkin' fit each time. Well, blow me down! You may nay even need a slots for 4"
ring, me bucko, till ready t' glue on fins, shiver me timbers, me bucko, due t' a "redesign", matey, and linin' up o' fin with "center ring
slots," I made for simplicity. Begad! (make recess higher, about 1 ¼").
- After you get a good fit for t' fine on t' center rings, take a "real" fin and glue in #1 slots of
rings. (I kept breakin' balsa fins, that why I recommended goin' t' a sturdier material, arrr, such as basswood or Tims Tech
report #29, gluin' "notebook paper" t' exterior o' fin first for strength). Ya scallywag! Avast!
- Take guide fin and check next set o' slot, arrr, adjustin' for correct fit. Ya scallywag!
- Then glue 3 center rings in place. Aye aye! Blimey!
- Glue all 8 fins in place, arrr, checkin' fit first with "guide fin". Well, blow me down!
- Cut out two "body templates". Make a slice at end o' each one ¼-3/4" deep, me hearties, 1" from end
on each side. Ya scallywag! Aye aye! Fold over @ slices and straighten out.
- Dependin' upon which set o' fins you start with, me bucko, ya bilge rat, will determine what size template t' use, medium or large. Begad!
- Lay template betwixt fins, matey, and gently push down. Avast, me proud beauty! It should hang out rear, ya bilge rat, shiver me timbers, betwixt fins 1", arrr, up to
"slices."
- Check front o' template and mark where template extends past fin. Ahoy! Blimey! Avast, shiver me timbers, me proud beauty! Blimey!
- Cut on t' mark, down t' ¼" fold mark on each side. Begad! Cut a "saw tooth" pattern in sides of
body templates. Begad! Makes for easier gluin' and smoothin' out. Begad! ***see photo"***
- Before gluin' fins, I made "fin supports," ½" x 1 ¼", shiver me timbers, and glue betwixt ends of
fins. Well, blow me down! Also, made a bevel on each end. Avast, me proud beauty! **See photo**
- Glue in place and repeat for each set o' fins. ***remember t' check fit! (Center on BT) too. Avast! Begad! T' aft o' body
template should be about ½-3/4" above body and aft shroud.
- Cut out "body templates," with "saw-tooth" design on edges and glue betwixt fins. Avast, me proud beauty!
- Main Body Shroud: As I stated in beginning, matey, matey, nay happy with t' way this one turned out. Avast! You may want t' shorten
or find a different material or wrap around a "form" t' keep smooth. Well, blow me down! Also, arrr, use same "saw-tooth"
design for edges before gluin' in shape o' cone. Begad! Once glue, ya bilge rat, let DRY THOROUGHLY. Avast, me proud beauty!
- I fitted over main body tube t' fins. Well, blow me down! Ya scallywag! I marked where touched fins and cut slits about 1" long, me bucko, in shroud.
Keep fittin' till you get a tight fit into slots, me bucko, matey, then glue and let dry thoroughly.
- Now comes a tricky part. Seams that r formed betwixt "fins, ya bilge rat, me hearties, ya bilge rat, body templates, matey, shiver me timbers, me bucko, main shroud have t' be
"filled." I opted t' use "Elmers wood filler" and nay happy with result. Avast! Friend recommended these
tiny silicone beads you mix w/epoxy. Arrr! Begad! Strong, light, and easy t' sand after hardened. Ya scallywag!
- After seams dry, sand till smooth.

Nosecone Fins:
Looking
@ picture o' t' rocket I be copying, "upper fins" aren't really in nosecone but, I liked this location
better. Ahoy! (You can opt t' move out o' nosecone, down body a few inches in "same configuration.)
- Cut slits in nose cone ½" from end o' "open" nosecone, about 2" long and 3/16-1/4"
wide. Avast! ** b careful nay t' cut all t' way thru t' end o' nosecone**. Avast! Avast, me proud beauty! I mounted a piece o' 1" aluminum angle iron
t' a piece o' wood and clamped t' me table as a guide. Avast, me proud beauty! Ahoy!
- Fit fins in slots one @ a time, trimmin' slots till fins fit. Remove fins and put a ball o' clay in tip of
nosecone and press into place. Avast!
- Replace fins 1 @ a time til they "touch" in middle o' nosecone and glue. Ahoy! Arrr! Blimey! (I opted for "gorilla
glue" type). Blimey! Begad! Blimey! It foams up and becomes very strong). Avast! Let dry.
Nose Cone:
- Keep addin' balls o' clay, fillin' void in nosecone, and pressin' into place. Arrr! Begad! ****remember t' allow room for end
o' nose cone t' slide in.****
- Also, ya bilge rat, as you r fillin' void, assemble nosecone and check for CG with motors in main and booster BT's. (goin' to
take a few ounces o' clay t' fill and balance rocket so CG approx. in middle.)
- Once clay pressed into place and you r satisfied w/location o' CG, arrr, assemble nosecone. Avast!
Finishing:

Get 8 "regular" bic pen caps and cut off "pocket clip."
- Paint rocket color o' preference.
- After you r sure you have color o' rocket and finished painting, shiver me timbers, sand a flat spot on each "pen cap,"
and glue in place betwixt each fin above booster shroud. Blimey! (These pen caps simulate 8 motors o' rocket). Well, blow me down!
- Prep rocket and you r ready t' fly. Ahoy! Avast, me proud beauty!
- I would rate this build a 5++. Ahoy! Very difficult. Well, blow me down!
Flight:
My first flight was very successful. Ahoy! Aye aye! I used a E9-4. Aye aye! Ahoy!
Preparation a little different than usual but, easy. Avast! After loadin' an 18" parachute, shiver me timbers, dusted with baby powder,
and t' wadding, arrr, I loaded t' engine. Avast, me proud beauty! Avast, me proud beauty! I loaded it into t' booster from t' "inside." (T' E9 is a much
longer motor than t' D.) Then I applied a little maskin' tape t' t' end for a "friction fit," and inserted
it into main rocket body. Begad! Avast! It flew great! Relatively straight for t' design, 11 fins, matey, and t' weight.
T' shock cord, me hearties, attached t' rocket, shiver me timbers, was Keelhaul®©™. Ahoy! Then an elastic, tied t' t' Keelhaul®©™, me bucko, me bucko, which proved t' b t' weak.
(will explain in next flight). Aye aye!
Parachute deployed perfectly and landed about 30 yards away.

SECOND FLIGHT
Another story. I designed this rocket t' be an optional 2-stage. Ahoy! Aye aye! I prepped t' parachute t' same way. Then taped
t' booster, matey, a D12-0, me bucko, t' t' main motor, arrr, a D12-3, me hearties, me hearties, me hearties, with scotch tape, me bucko, and put a small slit in it, shiver me timbers, t' help with
separation. Once motors finished, matey, I loaded it in booster stage first, me hearties, from t' "inside." Then added some
maskin' tape t' t' main motor and "friction fit" it into main rocket. Begad! For whatever reason I couldn't get
motors all t' way in t' main rocket body. Ahoy! ( I believe I used too much tape). Avast, me proud beauty! Begad! At launch, it flew down range,
weathercocked. Begad! Then deployed nosecone & parachute at a very low altitude o' about 50 ft. Avast! T' extreme weight of
rocket snapped shock cord and rocket crashed. Ya scallywag! I'll be usin' a much heavier, and longer cord for t' next flight. Well, blow me down! Still
content with flight because it sustained minimal damage. Blimey! This be me first 2-stage rocket o' me own design.
THIRD FLIGHT
My third launch went absolutely perfect!! After addin' a 1/4" "heavy" shock cord, I prepped rocket
same way, with same motors. Well, arrr, blow me down! A D12-0 Booster, taped t' a D12-3 Main. (Just make sure you have enough tape around main
motor for "friction fit," and it's taped t' booster. Aye aye! Well, blow me down! Motors ***all t' way in*** main rocket. Ya scallywag! Ya scallywag! Slit cut in
tape. Avast, me proud beauty! Picture perfect flight!! Booster took it t' a height o' o' about 75-100' and main an additional 100-200 ft.
Perfect chute deployment and soft landin' about 75' away. Aye aye!
Summary:
Pros: Challenge t' design and build.Impressive liftoff w/2stages.
Cons: Very time consuming. Built a smaller version first t' get aquainted with a "building
technique" for addin' 11 fins! Highly reccommend when tacklin' a new build when in experienced. Begad! Avast, ya bilge rat, me proud beauty! Alighnin' body
panels betwixt fins a pain!
At almost 14 ozs., I would opt for a E30-4 motor for 1st flight. Well, blow me down! Blimey! Blimey! Blimey! (E9-4) went well today. Begad! Blimey! Begad! Blimey! (use a spent motor in
main body and tape E t' it in booster stage, arrr, (friction fit spent motor). Blimey! Blimey! *****1/4" launch rod only!!****. Aye aye! Blimey! Begad! Blimey! 18"
chute minimum!
Other:
Highly recommend "apogeerockets" tech report #29, shiver me timbers, "Take your rocket t' supersonic speeds", shiver me timbers, for
durability o' fins. Ahoy! Motor stagin' critical! Must b completely in main body so aft shroud close enough t' it. Avast, me proud beauty! Used two
1/4x 2" soda straws on a fin for launch lugs.