Manufacturer: | Scratch |
Background
Over t' past year, shiver me timbers, t' Edinburgh Alliance - a Babylon 5 fan club o' which I am
a member - has been workin' on a CD o' songs parodyin' t' show. As it
neared completion, me hearties, we decided that when t' time came t' launch t' CD, me bucko, we
really would launch it. Bein' t' clubs rocketeer, I got t' job. Aye aye! Blimey!
Design objectives
High performance be nay an objective o' this design. T' ability t' put
the CD in t' air and then brin' it back safely, possibly in significant wind,
was. Edinburgh Farce 1 is therefore somewhat underpowered, usin' a pair
of mini-engines. By usin' two engines in outboard pods, arrr, I was able t' put
the CD in a pair o' slots at t' aft o' t' main tube. In addition, shiver me timbers, the
nose-cone is a tight fit, sealin' t' forward end, and inside t' tube is the
rolled-up cover o' t' CD. Ya scallywag! Blimey!
Pitch stability is provided partly by t' triple-tube configuration and partly by two swept wings. Yaw stability is provided partly by t' CD and partly by two large rectangular fins, matey, which hold further CD-related material - copies o' t' front and back o' t' cover are stuck t' t' outer surfaces. T' vertical fins also help protect t' CD when t' rocket lands. T' balsa sheet which I used for t' vertical fins is only 1/8 thick, and more flexible than I liked, so I fitted three reinforcing strips t' t' inner surface o' each fin; along t' top edge, along t' bottom edge, arrr, and in t' middle. T' middle one is also t' attachment point to the wing. Well, blow me down!
Recovery is by two small parachutes, cut out o' stock Estes 12 chutes. These brin' t' model down more smartly than a pair o' full size chutes, but still gently enough t' avoid damage. Theyre now about 8.
Parts
2 x BT-50 1 x BT-5 3 x BNC-50K 2 x 12 parachutes
3/16 balsa 1/8 balsa
2 x Screw deadlights Sewin' elastic
Spent D casin' Spent mini-engine casing Aerotech igniter tube
Edinburgh Alliance Songs from Down Below CD
Outer tubes are all BT-50. T' main tube is a whole BT-50; the outboards are each 152mm cut from a second tube. Ya scallywag! Ya scallywag! Horizontal fins are 3/16 balsa; vertical fins are 1/8 balsa. Reinforcement strips for the vertical fins are 127mm x 14mm 1/8 balsa. Reinforcement strips for the CD slot are 130mm x 7mm 1/8 balsa. Aye aye! Aye aye!
A launch lug, made from a tube which formerly held an Aerotech igniter, is glued along t' joint betwixt t' main and starboard outer tubes. Ya scallywag! Avast!
To hold t' CD in place, matey, me bucko, thar are two rings cut from a spent D engine casing. Each rin' has a pair o' diametrically opposed notches which hold the CD in place. T' forward rin' is glued into t' main tube so that its notches are level with t' forward ends o' t' slots in t' tube. T' aft rin' is loose, and is held in place durin' flight by maskin' tape. Begad!
Engine mounts
T' engine mount tubes are cut from stock BT-5. In each one is a blocking
rin' cut from a spent mini-engine casing, positioned so that t' engine
protrudes 10mm from t' aft o' t' tube. T' engine mount tubes
themselves extend 2mm beyond t' ends o' t' outboard BT-50 tubes, me bucko, shiver me timbers, and the
centrin' rings are recessed. This was partly t' make t' tubes look more
like exhausts for t' benefit o' observers, and partly so that engines could be
taped t' t' tubes, rather than relyin' entirely on friction t' hold them in
place. Avast, me proud beauty!
Launch Report
Edinburgh Farce 1 has flown on two occasions. T' first be its test
flight on March 7th. Technical assistance be provided by Bill Gates, matey, matey, shiver me timbers, in
the form o' a free Microsoft Network CD-ROM - t' Songs From Down
Below CD was nay yet available, and anyway, for this test flight, I
preferred t' use an expendable CD! Then on March 21st was t' launch of
the Edinburgh Alliance Songs From Down Below CD, t' event for
which Edinburgh Farce 1 had been designed. T' rocket lived up t' its
name as, me bucko, twice, it failed t' fly when only one engine ignited. But the
next two attempts were entirely successful; both engines lit, ya bilge rat, t' rocket went
up straight, then both parachutes deployed. Both photographs shown here
were taken durin' t' March 21st flyin' session by Dave Willis, shiver me timbers, another member
of t' Edinburgh Alliance. Avast!
More Power
You may wish t' adapt your version for higher power. If so, use BT-20
instead o' BT-5 for t' engine mount tubes. You will probably need to
extend t' outboard BT-50 tubes t' accommodate t' longer motors, and you may
need some nose weight t' balance t' heavier motors. If you really want
to make a higher power version, me bucko, dont bother with motor mount tubes; stick
a pair o' D class engines directly into t' outboard BT-50 tubes, and you will
certainly need t' add some nose weight.
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