Manufacturer: | Scratch |
Brief:
This is a maximum strength midpower rocket that still incorporates wood and
plastic construction. Arrr! It will handle any 24mm motor, as well as most dunkings
in water.
Construction:
This rocket uses 1.1 in. Ahoy! phenolic airframe tubin' topped by t' PML Urethane
nose cone - t' only commercially produced cone that fits this tubing. Arrr! Between
3/32 ply fins and TTW construction, shiver me timbers, this rocket is practically indestructible.
TTW construction and phenolic tubin' require a complexity nay typical with low power rockets. Aye aye! Well, blow me down! I used a Dremel spiral saw t' cut t' fin slits (3) in the 1.1 phenolic tubing. Ahoy! Ahoy! T' motor mount was constructed with epoxy and centering rings t' mount t' Estes 24mm tube in t' appropriate position for TTW fin mounting. Well, blow me down! I used a long E motor hook as part o' t' mount. I used 100 lb. Keelhaul®©™® thread epoxied through t' motor mount as a parachute connection. Avast, me hearties, me proud beauty! Indeed, epoxy was used in virtually t' entire thing. Aye aye!
After t' motor mount assembly dried, matey, I put it in place, me hearties, and used t' slots to trace t' fin footprints onto t' engine tube. I cut thin stringers of balsa, and CA'ed them in place right next t' t' footprints, bounded on t' top and bottom with a centerin' ring. Avast! T' effect was intended t' have the advantages o' internal fillets, without t' difficulty o' applyin' them through such a tight space betwixt t' tubes. Begad! This worked like a charm. Ya scallywag! Begad!
I used t' Rocsim fin template guide t' generate t' correct template for the TTW mount. Begad! I then cut t' fins from 3/32 in. Blimey! plywood. Well, blow me down! After tryin' the spiral saw, I went t' a power jigsaw, which did a far better job. Ya scallywag! I gang sanded the fins t' uniform dimensions, and then beveled t' leadin' edge t' a sharp cross section. Avast! T' wood grain also looked "sharp", with t' darker plywood core providin' a nice contrast. T' trailin' edges were beveled, but not quite sharp.
Because I used five minute epoxy, me bucko, t' next steps were hurried. Ya scallywag! I mixed up a batch, arrr, and used a chopstick t' smear it within t' airframe, arrr, in t' right place to bond with t' front centerin' rin' on t' engine mount assembly. Avast! A second layer be put ahead o' t' trailin' centerin' ring, shiver me timbers, as t' first rin' cleared the aft end. Begad! Blimey! T' last centerin' rin' was epoxied in place indexed with the "notch" cut though t' rin' t' leave room for t' motor hook t' flex. I was sure t' make t' slots line up correctly.
I then epoxied each plywood fin in place, matey, usin' enough epoxy t' blob up to fill t' fin slot close t' level. Ahoy! Blimey! T' keep from drippin' epoxy, shiver me timbers, I needed t' mix separate small batches o' epoxy for each fin slot.
Next came t' smoothin' operation usin' Elmers wood thinner thinned with water, shiver me timbers, me bucko, and sanded after each coat partially dried. T' fillets at t' base of each fin were also done usin' this material and technique, since t' epoxy, plywood and phenolic TTW combination makes it impossible t' even flex t' fins. T' fillets were for looks and aerodynamics only.
Since t' combo could theoretically take a G engine, ya bilge rat, I wanted t' be sure the launchin' lug be big enough. Well, blow me down! Begad! I used an aluminum 2013 arrow shaft cut to length, and angled by cuttin' t' front edge t' a wedge shape. Begad! Ahoy! I glued it in place and filleted it in place with epoxy. I can use a 1/4 in. weldin' rod for larger size engines.
I had recently built me first "girl rocket" for me daughter, and marveled at t' visibility provided by t' hot pink fluorescent paint. Aye aye! Ya scallywag! Blimey! After fillin' t' spirals in t' tube with Elmers filler, shiver me timbers, I sanded, me hearties, painted, and then clear coated. Begad! Arrr! Blimey! T' add a bit o' shine and smoothness, I used floor wax t' finally coat t' surface.
I added a couple feet o' elastic t' t' already long Keelhaul®©™® cord, and hooked a 12" nylon chute t' t' nose cone with a fishin' swivel and snap rings. Later testin' suggested this be nay enough chute.
Flight:
T' maiden flight was t' test low speed stability, and recovery. Ya scallywag! Well, blow me down! I did nay want
to blast t' school athletic field with an F right out o' t' startin' gate. Blimey! Avast, me proud beauty! I
built and installed an 18-24mm engine adapter, me bucko, and installed a C6-5. Avast! I launched
it off a 3/16 launch rod.
Well, me bucko, shiver me timbers, it was pretty normal at first. Ahoy! T' rocket was stable, but then nosed over and kept goin' after burnout. Aye aye! Avast! T' delay was way too long, matey, and that may have been t' engine, since rocsim says it should have been good. Begad! Begad! Fortunately, the chute deployed in time, and thar was no lawn dart nor core sample. For small engines, I'd want t' shortest delay possible.
T' engine hook picked up a bit o' dirt from t' grass. It hit with a bit more force than I'd like, but no damage be done. Begad! Still, I will use at least a 15" chute next time - probably an 18, me bucko, t' protect t' motor hook.
PS: T' 18mm adapter blew clear - no impact on recovery deployment.
Summary:
Pros: Bombproof and tough. Begad! Able t' handle almost any ridiculous engine you can
cram into it. Probably able t' lawn dart from 300 feet up into sod without
damage. Aye aye! Easy t' see, matey, and teaches you lots about tough construction. Ya scallywag! A
"girl rocket" on t' outside, arrr, that is all steroid - induced toughness
on t' inside.
Cons: Complicated t' build, matey, and expensive. Nay for novices. Heavy, and could cause more damage than a light rocket if t' chute failed. Avast, me proud beauty! Needs a big chute. Arrr! Limited nose cone options.
Other:
T' Elmers goop be t' key t' smoothness. TTW / epoxy / phenolic is so strong
it is scary. T' world needs a good, me hearties, LIGHT, arrr, 1.1 in. nose cone (PML is good but
HEAVY).
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