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