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

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

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

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