(Contributed - by Glenn Roth - 03/21/09) Brief:
11 "Finned" rocket that can be launched on a single "E" or staged (D12-0, matey, 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! Blimey! Blimey! I gathered some cardboard, me hearties, posterboard, me bucko, and second hand parts, shiver me timbers, etc. Begad! Well, blow me down! Blimey! It would have been ten times harder
without t' EMRR "Calculators", for shrouds, etc. Arrr! I chose cardboard figuring, "If I can get this t' fly
without a cad program, me bucko, from t' heaviest material, I surely will be able t' build one in t' 24 MM scale. Ya scallywag! Also,
cardboard a little easier t' work with than "foamboard."
My 1st test flight was a disaster. Avast, me proud beauty! (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. Last Saturday flew
it again and success! It only went 50 ft up but successfully deployed chute right before landing. Well, blow me down!

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

Nosecone Fins:
Looking
@ picture o' t' rocket I be copying, shiver me timbers, me hearties, "upper fins" aren't really in nosecone but, I liked this location
better. Begad! (You can opt t' move out o' nosecone, matey, down body a few inches in "same configuration.)
- Cut slits in nose cone ½" from end o' "open" nosecone, matey, about 2" long and 3/16-1/4"
wide. Arrr! ** b careful nay t' cut all t' way thru t' end o' nosecone**. Ahoy! I mounted a piece o' 1" aluminum angle iron
t' a piece o' wood and clamped t' me table as a guide. Ya scallywag!
- Fit fins in slots one @ a time, me hearties, matey, trimmin' slots till fins fit. Ya scallywag! Remove fins and put a ball o' clay in tip of
nosecone and press into place. Blimey!
- Replace fins 1 @ a time til they "touch" in middle o' nosecone and glue. Begad! (I opted for "gorilla
glue" type). Well, blow me down! It foams up and becomes very strong). Arrr! Let dry. Begad!
Nose Cone:
- Keep addin' balls o' clay, matey, me hearties, fillin' void in nosecone, me bucko, and pressin' into place. Arrr! ****remember t' allow room for end
o' nose cone t' slide in.****
- Also, 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, assemble nosecone. Begad!
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, me bucko, me bucko, sand a flat spot on each "pen cap,"
and glue in place betwixt each fin above booster shroud. Aye aye! (These pen caps simulate 8 motors o' rocket). Avast, me proud beauty!
- Prep rocket and you r ready t' fly.
- I would rate this build a 5++. Very difficult.
Flight:
My first flight was very successful. Begad! I used a E9-4. Ya scallywag!
Preparation a little different than usual but, easy. Begad! After loadin' an 18" parachute, dusted with baby powder,
and t' wadding, ya bilge rat, I loaded t' engine. Begad! 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. Ahoy! It flew great! Relatively straight for t' design, arrr, 11 fins, matey, and t' weight. Aye aye! Begad!
T' shock cord, attached t' rocket, arrr, was Keelhaul®©™. Avast! Then an elastic, tied t' t' Keelhaul®©™, which proved t' b t' weak.
(will explain in next flight).
Parachute deployed perfectly and landed about 30 yards away. Aye aye! Ahoy!

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