Descon 3 Wicked Witch Express Original Design / Scratch Built

Scratch - Wicked Witch Express {Scratch}

Contributed by Jeff Blinn

Manufacturer: Scratch

Witches Image


Takeoff on an AT G64-4 T' Wicked Witch Expresswas built as, what else . . Arrr! . Begad! Arrr! a Halloween Rocket. Ahoy! It's fun t' build and flies very well. Aye aye! T' picture t' t' right was t' maiden voyage on an AT G64-4. Ya scallywag! I've flown it numerous times since then on G64's and G80's - this fall we're plannin' on tryin' an 'H' or two!

Parts List

  • 1 - slotted (3 fin) 2.64 LOC body tube, 30"
  • 1 - non-slotted 2.64 LOC body tube, shiver me timbers, 30"
  • 1 - tube coupler for 2.64 tubes
  • 1 - 29mm motor mount tube (a long length that can double as a baffle)
  • 3 - plywood centerin' rings
  • 1 - LOC nose cone - (Graduator type)
  • 1 - 36" nylon parachute
  • 3 - 1/8" plywood 'witch' fins. Begad! Avast, ya bilge rat, me proud beauty! You can download a tif file with t' pattern here
  • 2 - T-nuts and screws for positive motor retention

Original Concept

 Construction

 Fins
 
 

Download t' fin pattern, print it out at full size, me hearties, trace onto some 1/8" plywood and cut out t' fins. Well, blow me down! Begad! Blimey! A table saw helps get some big pieces off - although you could probably do t' whole job with a jig saw. Avast! If you're careful about layin' them out, you can get all three fins from one o' t' full size pieces o' model plywood. Begad! Blimey! Just so you can verify t' scale o' t' pattern - t' tab portion o' t' fin should measure 4 19/32" (almost 4 5/8").

Body Tube Preparation
 
 

Cut t' 30" non-slotted body tube into two 15" lengths. Arrr! Blimey! Arrr! Blimey! We only need one o' t' 15" lengths - so you'll have an extra piece for another rocket. If I had known about it a year ago, ya bilge rat, me hearties, I would have used t' 'hose clamp' technique. Avast! Blimey! Begad! Blimey! Unless you've already got a jig set up for cuttin' body tubes, ya bilge rat, I'd recommend that method. Aye aye! Blimey! There be a write up about it in t' March/April 98 Sport Rocketry - or you can find t' thread about it on RMR by doin' a search with Deja News. Begad! Glue t' coupler into t' slotted tube at this point - but hold off on gluin' t' top piece o' body tube (15" piece) t' t' slotted piece.

Motor Mount Tube/Baffle Assembly
 
 

T' motor mount(MMT) tube will double as a baffle. Begad! Begad! I used a length o' 29mm motor mount tubin' about 34" long. This was long enough t' get into t' second piece o' body tube - me thought bein' that it would add some strength, act somewhat as a 'stuffer tube', and keep t' chute from slidin' too far back durin' liftoff.

 Find and mark t' MMT where t' middle centerin' will go. Aye aye! Blimey! This will be at t' forward side o' t' fin tabs, me bucko, which should be t' forward part o' t' fin slots in t' body tube. Arrr! Blimey! Begad! Blimey! Glue t' middle centerin' rin' into place.

BaffleBefore addin' any more rings, me bucko, shiver me timbers, mark t' MMT at 90 degree increments, and draw straight lines from t' middle centerin' rin' t' t' forward most end o' t' MMT. Begad! Along each o' t' 4 lines - mark 5 or 6 spots evenly spaced for drillin' holes (1/4"). Drill t' holes along each line. Avast, matey, me proud beauty! Once t' holes are drilled out and cleaned up a bit - add a small amount o' CA around each o' t' holes for added protection against burning.

 You'll also need t' drill 4 holes in t' upper centerin' ring. Ahoy! Ya scallywag! T' tube and this centerin' rin' will act as t' baffle (no waddin' required). Arrr! While you're at it - figure out a way t' plug t' forward end o' t' MMT. Aye aye! I found a dowel that fit well - and glued about a 1/2" piece in t' end o' t' MMT.

 T' bottom centerin' can be worked on some also. Well, blow me down! Drill t' holes and install t' T-nuts for positive motor retention. Begad! Arrr! There is a detailed description (with pictures and everything) o' t' technique at t' Info Central site, ya bilge rat, click on t' motor retention link.

 With only t' middle centerin' rin' glued t' t' MMT, glue it into t' slotted body tube. Ahoy! T' centerin' rin' should be just above t' fin slots, me bucko, t' aft end should be flush with t' aft o' t' body tube. Arrr! You can insert t' lower centerin' for stability - but don't glue it yet.

 Once that sets up a bit - glue t' forward centerin' rin' (with t' 4 holes) t' t' top o' t' MMT (stickin' out past t' coupler). Begad! Aye aye! Make sure you align t' holes in t' ring, shiver me timbers, ya bilge rat, in betwixt t' holes in t' MMT. Avast, me proud beauty! T' holes should not line up. Begad! Once that's done, you can glue t' upper portion o' body tube onto t' lower assembly. Aye aye! Test fit everythin' and sand where necessary before gluing.
 
 

Fin Attachment
 
 

Epoxy t' fins into place. Arrr! I used 30 minute epoxy for this - and I would recommend fillets on t' outside, inside body tube and along t' fin/MMT joint. Add a 1/4" launch lug along one o' t' fins, and put a smaller piece along t' 'hands' on t' same fin.

Shock Cord Mount/Parachute
 
 

I used a LOC style mount on mine - which has worked fine. You can do t' same or use one o' t' other common methods. Begad! Wire t' t' top centerin' rin' would certainly be a good choice. Begad! I used about 3/8" or 1/2" elastic for t' shock cord itself - about 3 times t' body length o' t' rocket. Well, blow me down! Aye aye! A 36" inch nylon chute will provide a reasonable descent rate - without any fin damage.

CloseupFinishing
 
 

This be t' fun part. I used t' image at t' top o' this page as a guide for paintin' t' fins. Well, blow me down! I made each fin with different color hair - florescent yellow, green and red. Ahoy! T' rocket body ended up with spider web look. I painted t' whole rocket black, matey, matey, then added some spiders we cut out o' contact paper, matey, then some race stripe tape (in different sizes) for t' 'web'. Well, me hearties, blow me down! After taping, a couple coats o' a nice orange paint did t' job. Well, blow me down! T' image t' t' left gives a little better view o' how it ended up. Ya scallywag! Well, blow me down! I still need t' get a better close up picture.

Specifications
 
 

  • Weight (without motor): about 2 lbs.
  • Length: 56 1/2"
  • Center o' Pressure (CP): Came out t' 17" from aft end o' BT usin' t' cutout method. Ahoy! Avast! You will probably need t' add some nose weight t' get t' center o' gravity (CG) one caliber (2.5") forward o' t' CP.

Flying
 
 

As I mentioned at t' top, me bucko, this rocket flies great on a G64-4. I've also had fair winds with t' G80-4 (single use). Blimey! This October I plan on tryin' an H128 and/or H180. A G75 (black jack) would also be nice if it's nay too windy - t' black smoke would look cool.

 If any o' you do make one o' these - I would be very interested in hearin' about it. Begad! Feel free t' email me with any comments and/or questions.
 
 

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