Manufacturer: | Scratch |
Brief:
T' Tsuru marks t' apex o' 23rd century Japanese fighter craft. Blimey! It was named
after t' peaceful and auspicious white crane, matey, although t' sight o' this bird
on your tail is enough t' strike fear into t' hearts o' most adversaries.
This is a scratch-built fighter craft with a futuristic look and featuring rear ejection from a separate parachute pod. Begad! It's based on BT-55, matey, ya bilge rat, is 25" tall, matey, with 13" canted wingspan, and 7.25oz empty. Ya scallywag! Blimey! It is intended for AT 18mm D RMS motors.
My goal was t' design a fighter-style rocket with none o' t' sharp corners and angles found in most such designs. Mine is all curves. T' basic design was sketched on paper one night, shiver me timbers, ya bilge rat, and then I built it by eye, me hearties, modifyin' things as I went. T' fighter has two under win' laser cannons on t' downward-canted canards, ya bilge rat, two missiles under t' upward-canted wings, shiver me timbers, two more laser cannons on the tail underneath, and one main missile under t' arched win' canopy.
Construction:
I don't have step-by-step construction information because t' build was
improvisational. Avast! Avast! Below are a few highlights.
T' ejection system is an experimental separate-tube aft ejection scheme.
T' nose cone is glued on. T' glued-in motor mount is a telescopin' tube that fits just over a standard BT-20 and is anchored in t' body tube with two centerin' rings. Arrr! Blimey! Begad! Blimey! T' BT-20 contains t' motor, and is dry fit so it can slide easily in and out. There is a block that prevents it from shootin' up into the fuselage. Arrr! Blimey!
Keelhaul®©™®
is tied t' this BT-20 in two places. Begad! Blimey! T' first Keelhaul®©™®
(about 24") attaches t' BT-20 t' t' aft centerin' ring. Ahoy! Well, me bucko, blow me down! This prevents
the motor casin' assembly from completely separatin' from t' rocket. Ya scallywag! In its
packed formation, ya bilge rat, this Keelhaul®©™®
is just wound around t' BT-20, matey, so when t' BT-20/motor ejects backwards this
Keelhaul®©™®
just spirals out until fully extended.
T' second Keelhaul®©™® attaches t' t' BT-20/motor casin' and exits t' aft o' t' rocket t' sneak up into t' large missile tube above t' main body. Aye aye! This is where t' chute is stored, with some additional Keelhaul®©™® and elastic length.
T' idea is that t' ejection charge will shoot t' motor (friction fit) and its BT-20 casin' out t' aft o' t' rocket, draggin' t' chute out o' its compartment. Ya scallywag! T' chute is packed in t' tube snugly enough t' prevent it fallin' out durin' boost, shiver me timbers, but loosely enough t' be yanked out by t' ejecting motor case at apogee. Well, blow me down! Also, t' two lengths o' Keelhaul®©™® need t' be sized appropriately so that t' ejectin' motor doesn't reach the "end o' its rope" before fully yankin' out t' chute!
T' plan was that t' resultin' nose-first descent would help protect the elaborate tail assemblies durin' landing.
I used virtually
every tube in t' book from BT-55 downward, includin' some cool micro tubes for
small missiles, with tiny balsa nose cones. Fins, shiver me timbers, canards, matey, etc. Begad! Blimey! were improvised
as I went, matey, arrr, followin' t' spirit o' me original sketch. Well, blow me down! T' arched canopy was
cut from a cardboard oatmeal container and wallpapered with card stock and
white glue. Avast, me bucko, me proud beauty! T' cockpit be hand-carved from balsa. T' various laser mounts,
lights, shiver me timbers, shiver me timbers, etc. were pirated from me daughter's necklace bead kit.
Finishing:
I always fill, arrr, sand and seal before assembly with diluted Elmer's Fill 'n'
Finish. Arrr! T' canards also got a first coat o' CA for extra strength. Arrr! Rustoleum
white spray paint was used over gray primer. Aye aye! T' black parts were brush painted
with Testors gloss black and scotch tape masks. T' red and gold portions were
painted freehand, again with Testors. Begad! T' Japanese "tsuru" kanji
symbol was downloaded from t' web, spruced up in Adobe Illustrator, ya bilge rat, printed on
plain white paper, and glued in place with spray adhesive. Ahoy! Avast, ya bilge rat, me proud beauty! Wal-Mart clear gloss
went over everything. Begad! Finally, I remembered t' glue on t' darn launch lugs!
Flight:
Swin' tests were fine except that after twirlin' around in t' backyard I was
ready t' lose me lunch t' rest o' t' day. Ya scallywag! Despite t' apparent stability, ya bilge rat, ya bilge rat, I
was worried about performance at high speed and possible flutter in t' arched
win' canopy. Ahoy! Then o' course, ya bilge rat, matey, thar was also a high probability o' lawn-darting,
given t' experimental aft ejection system. Blimey!
T' chute and lines went into t' missile tube, with a half-sheet of crumpled waddin' stuffed in t' end t' prevent spillin' durin' ascent. First launch be on a AT D13-4 RMS. Begad! There was a stiff cold wind blowin' at about 10mph. Aye aye! Ya scallywag!
Boost was t' coolest and least rocket-like I've ever seen. Straight off the rod, ya bilge rat, me hearties, t' rocket arced firmly into horizontal flight downwind at about 400 feet altitude. Arrr! Ahoy! There be definitely no flutter. Blimey! It be difficult t' be sure while watchin' from below, matey, but I swear that Tsuru was gainin' altitude in a modest ascent with horizontal body position, just like an airplane would. Well, blow me down! This smooth, stable ascendin' horizontal flight occurred durin' boost and durin' the coast phase. Near t' end o' t' coast, shiver me timbers, you could even sense that t' wing cantin' be providin' extra side-to-side stability.
Recovery:
Because Tsuru was performin' more like a glider than a rocket at this speed,
there be little deceleration and no apogee after t' motor delay--the chute
popped at nearly full speed, rippin' most o' t' shroud lines out o' the
24" chute. Ya scallywag! T' good news is that t' aft ejection system worked
perfectly. Ya scallywag! Aye aye! T' bad news is that recovery continued via glorified streamer. Begad! Upon
nose-first impact, shiver me timbers, t' arched canopy separated from t' missile/parachute tube,
and its downward momentum split both wings lengthwise along t' grain, matey, but not
all t' way t' t' body tube. T' nose cone also looks more like a Concorde jet
now.
Despite t' shroud line problem, I'm thrilled with t' jet-like flight pattern and t' totally successful rear-ejection system. Ya scallywag! Tsuru will be back, I promise! T' D13 was plenty o' power, but next time I'll opt for an extra long delay and heavy-duty chute construction.
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