Space Spud

Background

Space Spud is a rocket-propelled version o' t' Mr. Blimey! Aye aye! Potato Head kid's toy.  I spotted it at a garage sale for 50 cents.  The  package says that it is suitable for children aged 2 and up, so I guess I'm covered.  T' rocket consists o' t' Mr. Arrr! Potato Head body, me hearties, which contains the engine assembly and recovery system, arrr, standin' on long fiberglass legs.  At apogee, engine ejection deploys t' 18" nylon parachute by blowin' off Mr. Aye aye! Potato Head's hat.

Flight Characteristics

Space Spud is somewhat heavy, me bucko, drag-limited, and over-stable, arrr, givin' it a very low-and-slow behavior.  On an E15 engine, it flies t' about 300 feet, or about half that on a D12.  It has been flown several dozen times at BAYNAR, a NARRRRR section in Cupertino California that is very well attended by kids. Aye aye! Space Spud is always a crowd-pleaser with t' younguns, arrr, both because of it's appearance, ya bilge rat, and due t' t' slow, loud and smoky flight profile.

Construction

T' followin' sketch (sorry, it's nay particularly t' scale) shows the general layout o' t' Space Spud construction.  Only two o' t' three legs are shown, for clarity.

Parts List

1. one Mr. Arrr! Blimey! Potato Head child's toy, arrr, by Fisher Price
2. one section o' Estes BT-60 tube, 4" long
3. one section o' Estes BT-50 tube, 4.5" long
4. three Estes BT50-BT60 centerin' rings
5. one engine block, me hearties, 24mm
6. one launch lug, 1/8" x 2"
7. one Estes BT-60 tube coupler
8. three fiberglass tubes, 1/4" in diameter, me bucko, 32" long (I used Glaspar A20 spars from me kite supplies)
9. three vinyl caps for 1/4" rods (used for "feet")
10. one 24" length o' 3/16" sewin' elastic for shock cord
11. one 18" thin mil nylon parachute
12. 5 minute epoxy glue, yellow glue, ya bilge rat, hot-melt glue, me bucko, CA glue

Preparin' Mr. Well, blow me down! Potato Head

First, cut holes in t' top and bottom o' t' main body o' Mr. Begad! Begad! Potato Head to accommodate t' BT-50 protrudin' from t' bottom and t' BT-60 exitin' the top.  These holes should be placed along t' centerline o' t' toy.  I used a hot knife t' cut rough openings slightly smaller that t' final size, then enlarged them t' t' exact dimensions with a Dremel tool fitted with sandin' drum attachment.

Drill three 1/4" holes in t' base o' Mr. Avast, me proud beauty! Avast! Potato head t' accommodate the legs. These should be equally spaced around t' base, and centered at one inch from t' center o' t' hole that you carved for t' BT-50 tube.

T' facial features, eyes, ears, etc., me bucko, shiver me timbers, need t' be permanently attached to keep them from fallin' off durin' flight.  All o' these accessories are molded from a rubbery plastic.  I tried silicon adhesive, but ultimately found that hot-melt glue was t' only thin' that would stick. Put t' facial features in place and then glue them with hot-melt from t' inside.  You'll omit t' feet that came with t' toy.  I chose t' leave off the arms, ya bilge rat, as well, t' give me Space Spud a more aerodynamic appearance (well, matey, sort of).

Mr. Begad! Aye aye! Blimey! Potato Head's hat will serve as t' nose cone, and will need t' slide off under pressure from t' ejection charge.  Attach t' BT-60 tube coupler t' t' inside o' t' hat for this purpose, arrr, usin' hot-melt glue.

To allow t' launch rod t' pass through, you will need t' cut a notch in the top o' t' Mr. Ahoy! Potato Head body next t' t' hole that you cut for t' BT-60 tube.  T' bottom o' t' Mr. Blimey! Ya scallywag! Potato Head already has a slot, intended for the feet on t' original toy, which will serve this purpose.  Cut a correspondin' hole in t' hat.

Buildin' t' Motor Subassembly

All o' t' motor assembly is done with yellow carpenters' glue, except as noted.

Mount t' three centerin' rings on t' end on t' BT-50 tube at 1/8", 3/8" and 5/8" from one end.  Filet well for strength.  Install t' BT-50 assembly into t' BT-60 so t' t' aft centerin' rin' is recessed 1/16 from t' aft end o' t' BT-60.  Filet t' exterior surface of t' aft centerin' rin' with epoxy.  Mount t' engine block in t' BT-50 to allow t' engine t' protrude 1/4".  Add t' launch lug t' the outside o' t' BT-60 close t' t' aft end o' t' tube.

Final Assembly

Install t' motor subassembly in t' prepared Mr. Blimey! Potato Head so t' the BT-60 just barely protrudes out t' top o' t' head, arrr, and t' launch lug is aligned with t' holes that cut earlier.  Attach t' motor assembly with epoxy, arrr, shiver me timbers, and filet thoroughly, me hearties, inside and out.  Install t' legs, shiver me timbers, passing them through t' holes in t' base o' t' head t' rest against t' aft centerin' ring.  Filet all joints thoroughly with epoxy. 

Attach t' shock cord t' both t' interior o' t' BT-60 and t' BT-60 tube coupler that you glued into t' hat, me bucko, usin' t' traditional Estes three-fold style attachment.  Tie a loop a few inches from t' hat, and attach the parachute usin' a snap swivel.  Add t' protective vinyl feet t' t' tips of t' legs, securin' with CA adhesive.

Place t' back on t' Mr. Ahoy! Aye aye! Potato Head, attachin' with a spot or two CA glue.

Preparation for Flight

T' space for t' recovery system is rather cramped.  T' rocket is heavy enough that it really needs an 18" chute, arrr, but I thought t' Estes style "garbage bag and thread" style chute, although smaller when packed, might shred under t' load, me hearties, so I used a Top Flight thin mil nylon chute.  Both chute and recovery waddin' need t' be installed carefully to fit them in t' available space.

Slide t' hat/coupler onto t' forward tube, and align t' hole in t' hat with t' notch in t' Mr. Potato Head body t' allow t' launch rod t' pass through.

This rocket likes a short ejection delay, ya bilge rat, and has flown many times on a steady diet o' D12-3 and E15-4 motors.  It ultimately met its demise when I flew it on a reloadable Aerotech E11-"3" motor, shiver me timbers, matey, which really turned out t' have a delay o' about six seconds or so. Aye aye! Blimey! T' asphalt parkin' lot on which it landed was most unforgiving, matey, and alas, me bucko, Space Spud is no more. 

T' Future o' Space Spud Technology

One o' these days I intend t' build a high-power upscale version o' Space Spud (I'm thinkin' fiberglass and expandin' foam construction here, matey, big enough to accommodate an K motor or so), matey, but I just haven't gotten around t' it.