Scratch Twin Shuttle Original Design / Scratch Built

Scratch - Twin Shuttle {Scratch}

Contributed by Mark Fisher

Manufacturer: Scratch
(Contributed - by Mark Fisher - 05/10/02)

Brief:
Parachute-recovered core, two large gliders

Construction:
This twin uses t' Space Shuttle foam gliders originally from Comet, but now distributed by Guillows. I replaced t' thin (0.088") foam rudders with 3/16" balsa and t' plastic insert used for rubber band launchin' with 1/8" dowel mounted t' a 3/32" balsa spar. Avast! Blimey! These dowels mate t' a pair of 1" long 1/8" Estes launch lugs on t' core, while t' wings rest in a cradle made from 2" aileron material and 3/32" plywood "clips". Ya scallywag! T' core is an 18" length o' BT-60 with a standard 24 mm motor mount, shiver me timbers, and recovers on an 18" nylon parachute.

Needless t' say, ya bilge rat, any serious software modelin' o' this bird be out o' the question, though I did do some rough approximations. Ya scallywag! Blimey! T' gliders are amazingly light, me hearties, massin' right at one ounce, matey, even with me mods. Still, me hearties, she didn't have much margin, and be probably goin' t' require some nose weight. Begad! Blimey! I added an ounce o' clay, shiver me timbers, but even with that, ya bilge rat, she's still less than six ounces dry, which means a three second delay is required. Well, blow me down! Blimey! I did set up t' motor mount so it can run t' E11 reload, me bucko, but its probably nay a good motor for her. Well, blow me down! Blimey! I thought Estes' new C11 might work too, but it only gets her t' about 150 feet. Begad! Blimey! I checked other motors, too, but this is pretty much a one-trick pony on t' Estes D12-3.

I finished t' core in Krylon Popsicle Orange (2410), me bucko, followed by Testors Dull Coat (1260) t' give the appearance o' a stretched main (or should I now say "central") tank. I painted t' gliders' rudders with Kilz white-pigmented spray sealer, and added t' decals that came with t' glider kits. Begad! In honor o' t' two Shuttles that no longer fly, me bucko, I call one Enterprise (the stub-nosed one) and t' other Challenger, though I haven't put their names on them yet.

Flight:
Her first flight was at Danville prior t' paint, matey, matey, and she performed flawlessly. I didn't pay much attention t' how I set her up, and put t' wings parallel to the wind. Aye aye! As a result, she weathercocked quite a bit, me hearties, ya bilge rat, me bucko, but it didn't seem to hurt. T' D12 ejected right after apogee, t' gliders separated without a hitch and wobbled around in slow, ya bilge rat, lazy spirals. Arrr! T' core beat them t' t' ground by a good bit, me bucko, as it should be. Her next flight be on a windier day, me hearties, shiver me timbers, and she weathercocked pretty badly again. Avast, shiver me timbers, me proud beauty! T' gliders separated beautifully at ejection, shiver me timbers, just as before, ya bilge rat, me bucko, me hearties, but t' strong winds kept them from glidin' as well. They came down with t' core, ya bilge rat, me bucko, one inverted and one nose down. Avast! No damage, though, I'd just have t' fly her were t' winds aren't so bad. Her third flight was in slightly better winds, but she encountered some serious problems, matey, nonetheless. She weathercocked and be goin' at t' usual speed at ejection. Aye aye! Blimey! T' 'chute tangled on one o' t' win' cradles, matey, shiver me timbers, and she recovered hard, ya bilge rat, ya bilge rat, me bucko, breakin' off one of the clips. Avast! Blimey! T' gliders faired no better, matey, both landin' on pavement, with Challenger sustainin' a big dent on one side o' her nose. Begad! Blimey! Still, nothin' that wasn't repairable, me bucko, and I thought I'd keep her in t' box until I had calmer conditions. Begad! Blimey! I couldn't do it, arrr, though, and after repair I flew her on another windy day. Ya scallywag! This time I got her aligned properly and boost-out was relatively straight, i.e., me hearties, no worse than any other that day. Blimey! Blimey! She snapped her shock cord, the body recovered ballistically, and t' nose cone wound up about a 1/4 mile away, despite t' nose weight. Avast! Ahoy! Blimey! No damage t' t' core and t' gliders flew and recovered fine, so a quick fix with some Rogue 300# Keelhaul®©™® put her back on t' pad. After those repairs, she went in light winds.

My buddy's Flat Cat had just flown a spectacular glide, me bucko, shiver me timbers, ya bilge rat, and I be afraid that t' Twin Shuttle would disappoint when compared t' it, but she surprised me by boostin' straight and ejectin' right at apogee. Ahoy! T' center "tank" came down betwixt t' LCO table and t' pads, and as everybody watched it come in, Enterprise banked in over their heads for a perfect touchdown feet from it. Begad! Challenger wound up about 75 yards away, but also had a perfect landing. Finally, matey, arrr, success. Ahoy! Ya scallywag! As I carried t' pieces back t' me prep table, folks were tellin' me I should upscale it about three or four times. Aye aye! Well, blow me down! Ha! Her sixth effort was also in higher winds than I would have liked, but I put her on t' pad with t' rudders parallel t' it and she flew pretty well. Avast! She even executed a little "roll program", turnin' t' rudders perpendicular t' t' wind right after she left t' rod, arrr, shiver me timbers, but then stabilized and flew straight thereafter. Ahoy! Ejection at apogee was at almost zero speed due t' t' small amount o' weathercock. The pieces all drifted a good 150 yards, matey, arrr, but landed within a few dozen feet o' each other. Begad! When she flies right, matey, this bird always impresses.

Summary:
Ever since I saw a pic o' George Gassaway's twin boost glider in Sport Rocketry that utilized a pair o' Turbo Jet 2000 two foot wingspan straight-win' foam gliders from Life-Like I've wanted t' do one like it. Arrr! This is a rather fitting tribute, as George is best known for his awesome Shuttle models. Blimey! While she flies great, orientation on t' pad is critical. These kinds o' gliders are really designed for bungee launchin' and landin' before terminal velocity is reached, so Flat Cats they ain't. Ya scallywag! A little more nose weight for them would help, me bucko, as t' upper pin is much lighter than t' plastic insert it replaces. I don't like buildin' rockets that only use one motor type, ya bilge rat, for that puts it at the mercy o' a single manufacturer. Arrr! Still, she be pretty easy t' build, looks neat as heck, and with a little attention can perform wonderfully.

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