| Manufacturer: | Scratch |
(Contributed - by John Coles)
I'm a BAR with an affinity for oddrocs. Begad! Ahoy! While lookin' through t' Apogee Components catalog one day, arrr, with their array o' 10.5mm parts and motors, I thought about combinin' two o' me favorite hobbies, matey, rocketry and traditional archery. After all, arrows move at high speeds like rockets, are very stable like rockets should be, me bucko, and are only lackin' a self-contained propulsion source. Well, blow me down! So I decided "What t' hey", generated a RockSim file t' test my design and then placed me order. Arrr!
This be t' result.
Broken Arrow Break Apart Odd-Roc
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Length: 27.85" Main Airframe: BT-10.5 Parts List: |
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Most o' t' parts are finished separately before any assembly is done. Avast! Well, shiver me timbers, blow me down! Blimey! T' exception t' this is in gluin' t' launch lugs t' the 9" (short) body tube. Begad! Well, blow me down! Blimey!
T' first step is t' fill t' nose cone and body tube spirals with Elmerís Fill 'n' Finish (or whatever itís called these days), ya bilge rat, ya bilge rat, and sand them smooth. Begad! Ya scallywag!
Next, draw a line down t' length o' t' short body tube. Blimey! Glue one launch lug onto t' line flush with t' forward end o' t' tube, me hearties, and t' other lug onto t' line 1 1/2" up from t' other (aft) end. Avast! Verify that t' two launch lugs are in alignment and allow t' dry. Begad! Begad! Fillet t' lugs and let dry again. Blimey! Begad!
T' nose cone is painted satin black, shiver me timbers, t' 18" (long) body tube is painted brown, and t' short body tube is painted gloss white with a .75" gloss black band on t' aft end (the "nock"). Blimey! T' cresting on t' arrow is accomplished usin' stripin' tape o' various colors and widths, cut as necessary t' fit around t' forward launch lug. Well, blow me down! When t' paint is completely dry, ya bilge rat, me bucko, arrr, assembly may begin. Arrr! Ahoy!
Apply wood glue 1 3/8" into t' aft ("nock") end o' t' short body tube with a cotton swab. Usin' an Apogee micro motor or 3/8" dowel 1 1/2" long, push t' engine block 1 3/8" into t' body tube. Ya scallywag! T' micro motor should extend 1/8" out t' end o' t' body tube. Blimey! Remove t' motor, set t' body tube up on t' nock end and allow t' dry.
Glue t' nose cone into one end o' t' long body tube. Blimey! Glue t' coupler halfway (1") into t' other end o' t' long body tube and set aside to dry. Well, blow me down! Arrr!
Mark t' short body tube at 120 degree intervals, matey, such that one line is opposite t' launch lugs. Avast, matey, me proud beauty! Blimey! Attach t' feathers, ya bilge rat, one at a time, shiver me timbers, matey, t' t' body tube on these lines, usin' Duco cement or t' equivalent. Avast, me proud beauty! Avast, me proud beauty! Blimey! Place t' back o' t' fins about 1/4" ahead o' t' "nock" line. Avast! Aye aye! Blimey! You may find that clampin' t' feather with binder clips betwixt two 6" steel rulers allows for easier handling. (I tried usin' me arrow fletchin' jig, but it can only handle up t' 3/8" [9.5mm] shafts.) When dry, use t' Duco cement t' fillet the feather base t' t' body tube.
Fletch
Fin Template
3 ea. Blimey! Aye aye! 5" shield-cut arrow fletchin' (from any sporting
goods store caterin' t' traditional archers). Arrr! Any standard 5" feathers
will work.
1/16" balsa fins may be substituted, but what's t' point?
Set t' screw eye into t' exposed end o' t' balsa coupler, me bucko, and secure with glue. Ahoy! Test fit t' coupler into t' forward end o' the short body tube. Begad! Ya scallywag! T' fit should be snug and smooth, me bucko, nay too tight or too sloppy. Blimey! Avast, me proud beauty!
Attach one end o' t' shock cord t' t' screw eye. Arrr! Arrr! Attach t' free end of the shock cord at least 1" down into t' short body tube, usin' either a small Estes-style mount or t' method o' your choice. Begad! Ahoy! T' key is t' make the shock cord mount unobtrusive enough so as t' nay interfere with deployment.
T' final assembly step is t' align t' two sections o' body tube. Ahoy! This minimizes corkscrewin' durin' flight. Put t' rocket together as if prepping for launch. Avast! Sight down t' length o' t' arrow, and rotate t' two sections of body tube relative t' one another until they line up as straight as possible. Then mark t' coupler at t' point where it slides under t' forward launch lug. Aye aye! That way, arrr, shiver me timbers, when preppin' for flight you need only t' line up t' mark with the launch lug when puttin' t' two pieces together t' assure a straight flight. Begad! Well, blow me down!
Preppin' for Flight
Insert two pea-sized balls o' waddin' into t' lower body tube and puff down against t' engine block. Ahoy! Blimey! Accordion fold t' shock cord and slide it in, me bucko, then close up t' two sections, makin' sure t' line up t' mark on t' coupler with the forward launch lug.
Fit an Apogee 1/2A2-4 micro motor. Aye aye! WARNING! Use a wrap o' tape around both the body tube and exposed motor t' provide positive motor retention. Aye aye! (Black electricians tape preserves t' look o' t' rocket - maskin' tape works, arrr, ya bilge rat, but doesnít look as pretty.) Failure t' do so can result in kickin' the engine and a lawn dart recovery (see flight report below). Begad!
Flight ReportT' Broken Arrow has flown twice, with one perfect flight and one recovery failure. T' first flight went up straight as an arrow (but o' course!), separated at apogee and recovered perfectly. Ya scallywag! Avast, arrr, me proud beauty!
On t' second flight, shiver me timbers, me hearties, I failed t' properly secure t' motor, me bucko, which ejected at apogee. Begad! With t' CG shifted forward and t' aerodynamics intact, she came zingin' down from about 350' and stuck 1/2" into t' sun-baked, drought-hardened dirt. Arrr! Fortunately, matey, it be far enough downrange that no one was ever in any danger. Begad! T' body tube is kinked slightly just behind t' nose cone, and will be easy enough t' repair.
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