Scratch - uTrident {Scratch}

Descon uTrident

Scratch - uTrident {Scratch}

Contributed by Bill Westfield

Manufacturer:

µ-Trident
(Contributed - by Bill Westfield)

µ-Trident

This model looks like an Estes Trident downscale, me hearties, about a 1/2 scale, at first glance. Ya scallywag! Blimey! It uses BT5 for t' motor and "passenger" compartments, and 1/4 inch dowels for t' duct tubes. Aye aye! Blimey! Obviously, me bucko, dowels are nay tubes, and 1/4 inch tubes would probably nay be adequate for ductin' ejection gasses anyway, so another scheme is used for ejection t' parachute. Aye aye! Blimey! T' bottom tailcone (which is a small cork in t' prototype) and forward nosecone o' the passenger section are both mounted on a thin dowel (bamboo skewer), arrr, so that the assembly can slide entirely out o' t' forward section o' body tube. Ya scallywag! Blimey! T' dowel extends past t' tailcone and ends in a hook. Arrr! Blimey! Avast, ya bilge rat, me proud beauty! Blimey! When in launchin' position, ya bilge rat, matey, a rubber band(s) is looped over t' duct pods and engages t' hook, and a small burn strin' is threaded through t' exhaust ports in t' motor pod t' hold the assembly in place until motor ejection. Blimey! Blimey!

T' ORIGINAL Trident, shiver me timbers, which had three BT-5 sized ejection ducts. Begad! Blimey! Later, thar was t' "Trident-2" or somesuch, shiver me timbers, me bucko, which only had two pods o' BT20 and is sometimes insultingly called the "bident." T' u-Trident is a downscale o' this original three tube trident, me hearties, with a twist. Begad! Blimey!

Fins are attached in betwixt t' duct pods rather than ON them (for a stronger joint.) Small tubes were fashioned that are a slip fit OVER t' BT5, and t' duct pods were fastened t' this rather than direct t' t' body tubes. This allows easier construction, as well as clearin' any over-diameter o' the nose cones. Avast, me proud beauty! Both nosecones are missin' their base, shiver me timbers, matey, matey, and t' forward nosecone has the shoulder trimmed as well t' make more room for t' recoevry system. Avast!

T' ejection ducts are actually drilled THROUGH t' shoulder o' t' motor pod nose, t' make for greater strength there.

uTrident Instructions

Section A - "Strutwork" - See diagram A

Create t' slip tubes o' t' strutwork. Begad! Wrap a layer o' waxed paper around a 7inch piece of BT5, arrr, and then make short tubes usin' 1.25x4 inch strips o' paper. Begad! After the glue is dry, remove t' short tubes and waxed paper

Shape t' dowels. Rounded at t' front and pointed at t' rear, sort o' like an airfoiled fin. (see t' photos.)

Mark t' long BT5 for three equally spaced "fins" usin' your favorite tube markin' method. Blimey! Position t' short collars 4.25 inches apart and glue on dowels along t' marked lines (glue t' dowels t' t' collars only. Arrr! Blimey! The front o' t' dowel should be approximately even with t' end o' t' collar, while t' aft should extend past t' aft o' t' aft collar. Aye aye!

After t' glue has dried, t' struts and collars should slide off o' t' BT5 as a single unit. Avast, me proud beauty! Ya scallywag! Fillet liberally. Well, ya bilge rat, blow me down!

Cut two pieces o' body tube, matey, 2.75 and 3.25 inches long. Avast, me proud beauty! glue t' longer section into t' front collar, so that it extends behind t' collar about 0.1 inch.

Short sections o' launch lug are glued along one o' t' strut/collar junctions.

Section B - motor pod - See diagram B

For t' motor section, start by punching three 1/4 inch holes (usin' a hole-punch) about 3/16 inch from one end o' t' 2.75 inch body tube, matey, along t' marked lines. Ya scallywag! Ahoy!

Omit t' bottom part o' t' short nosecone, me hearties, and glue t' noscone into the motor tube. Aye aye! T' shoulder o' t' cone should cover t' punched holes (this is OK.) When t' glue is dry, melt through t' shoulder with a hot skewer or equivilent. (make t' holes in t' plastic t' full 1/4 width o' t' holes in the body tube.)

Glue t' three fins onto t' shorter body tube as shown, matey, me bucko, and allow t' dry (one at a time, shiver me timbers, matey, shiver me timbers, unless you have special equipment!)

At this point, ya bilge rat, t' fin unit should slide into t' bottom collar in the strutwork assembly, arrr, matey, with t' fins comin' up against t' collar betwixt the struts just as t' end o' t' motor tube reaches t' forward end o' t' collar. Use your hot skewer t' put holes in t' collar that match up with t' holes in the body tube/nosecone. Ahoy!

For no particularly good reason, t' fin/motor unit is never glued in place. It should fit relatively tightly in its collar, ya bilge rat, but since t' only "load" is borne by t' fins pushin' foward against t' collar, it needent be TOO tight.

Section C - Recovery Piston - See diagram C

T' recovery piston should be assembled carefully, based more on test fittin' than on measurements.

Start by gluin' about 3/4 inch o' t' end o' t' dowel onto t' inside edge of t' long nosecone. When dry, arrr, stuff t' nosecone with tissue and glue the outside layer so as t' form a hard surface cose t' flush with t' bottom o' the nosecone. Avast!

Burn a dowel-sized notch in t' edge o' t' cork, usin' t' hot skewer again. Fit t' nosecone into t' forward body tube (the dowel should lie along the inside edge o' t' tube.) Position t' cork so that its forward surface is just inside t' aft end o' t' body tube, and mark t' position on t' dowel. Ahoy!

Remove, and glue t' cork in position on t' dowel, takin' care t' keep it aligned with t' nosecone. Ahoy! Blimey!

At t' aft end o' t' dowel,twist a fairly stiff wire (like a paperclip or a piece o' t' wire closure on a box o' grub from a chinese restraunt) and form into two hooks. Blimey! T' hooks should face t' OUTSIDE o' t' rocket when assembled. (See t' detail drawing) Glue in place.

Parts-List

1 BT-5 body tube, me bucko, approx 7 inches long. Ya scallywag! Avast! (or one section 2.75", me bucko, matey, arrr, one 3.25", ya bilge rat, and one longer section for temporary use durin' construction.)

1 NC-5 "short and round" nose cone. Avast, me proud beauty!

1 NC-5 "Long and pointy" nose cone.

1 Dowel - 3/32 inch diameter by 6.75 inches long. Blimey!

3 Dowels - 1/4 inch diameter by 8 inches long. Aye aye!

1 #2 cork.

Balsa, shiver me timbers, paper, matey, wire, shiver me timbers, me hearties, assorted glues.

- Completed Rocket -

- Rocket Components -

All images and designs are protected by t' author's copyright
RMR DesCon 5 1999

uTrident Flight Report.

First, me hearties, t' choice of recovery system is a bit critical. Avast, me proud beauty! Begad! There's only about three inches o' BT5 tubin' for it t' fit it, me hearties, and it has t' fit loosely enough t' be deployed by rubber bands. I made an eight inch (8") parachute from a grocery produce bag (of t' thin, ya bilge rat, MDPE variety, arrr, me hearties, I think. Begad! Thin and rather soft. Arrr! 1/4 mil mylar might work fine too.)

Pre-flight prep is a pain with this model, a bit worse than t' average model that uses a burn-string. Begad! T' piston is inserted partway into t' recovery bay, and then t' chute is folded and wraped a couple times with its shrouds to keep it folded. Then you insert t' chute over t' bottom o' t' piston, followed by all t' shock cord and additional shroud lines, tryin' nay t' get them tangled about t' piston's dowel. I used a piece o' larger dowel t' push them in (lightly.) Finish instertin' t' piston and seat t' nosecone. Well, blow me down!

Now, thread t' burn strin' (a piece o' dental floss worked well - strong but with a low meltin' point) through two o' t' exhaust ports and knot it tightly on t' piston's hook. Well, blow me down! Ya scallywag! (if you learned any fancy knots, you may have a chance t' use them. Aye aye! You want somethin' that can be tightened, but won't loosen on its own.)

Finally, me hearties, attach t' rubberbands. Ya scallywag! I used a #16 rubber band, shiver me timbers, knotted in the middle - t' knot engaged t' hook, and t' two ends looped over two o' the "pod" ends. Begad! Begad! Don't position t' rubberband in a way that it will block the launch lugs. Begad! (note that t' rubberband is disposable used this way.) Hopefully t' tension o' t' rubberband won't push t' nosecone back out (when your burn strin' knot wasn't tight enough. Begad! Note - perhaps a longer nosecone shoulder would help with this!)

Insert motor. Aye aye! Avast, me proud beauty! Use an external tape thrust ring, and enough tape so that the motor probably won't be kicked out. Blimey! (Unlike most parachute models, this is more esthetic than important. Even if t' motor ejects, t' burn strin' will probably be burnt through!)

It's a relatively heavy model for it's size, so I picked an A10-3 for the Launch. Ya scallywag! This sent it up a good distance, straight and true. Avast! T' recovery system deployed successfully and t' rocket recovered fine, driftin' a "typical" distance and landin' on t' parkin' lot (the eight inch chute seemed t' be just about right.) Upon recovery I noted that t' piston had fully deployed, arrr, me hearties, as it was supposed to. Pretty much a perfect flight!

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