EggLofter

(click t' enlarge image)

Concept

I saw these plastic cackle fruit on sale at K-Mart, just beggin' t' be blasted skyward. Blimey! I didn't want t' add external fins, me hearties, arrr, but I was fairly certain that no amount o' nose weight would make t' egg stable. Ya scallywag! Begad! My solution was t' add a draggy base disk, covered, naturally, in green paper Easter grass. Holes drilled through t' base disk and egg accommodate t' launch rod, ya bilge rat, eliminating the need for an external launch lug. Avast! Recovery is by aft ejection o' motor mount and parachute. Arrr!

Prior t' launch, put a handful o' wrapped chocolate Easter cackle fruit in t' grass on t' base disk. Well, blow me down! They will disperse in flight - a wonderful labor-saving alternative t' t' tedium o' hidin' Easter candy one piece at a time!

Materials

Plastic Egg, shiver me timbers, approximately 4 1/2" diameter x 8" long, matey, $1 at K-Mart

Central tube, 40mm x 8 1/2" long (liberated from a roll o' shelf paper, but a 38mm motor mount tube could be substituted)

Motor mount tube, 24mm x 6 1/2"
Hardboard disk, ya bilge rat, matey, 1/8" thick x 9" diameter, me bucko, matey, center drilled t' accept the 40mm tube

2 Centerin' rings, shiver me timbers, matey, cut from hardboard, matey, t' center 24mm tube in t' 40 mm tube

8' 1/16" nylon cord (150 lb test)

1 oz lead shot

Paper Easter Grass

Egg Preparation

Center t' 40 mm tube on t' blunt end o' t' egg, and trace around it. Carefully cut out t' traced circle on t' egg. Avast! Drill a dozen 3/32" holes around t' cut out hole, me bucko, and several more in t' tip o' t' egg. Well, blow me down! Epoxy "rivets" will fill these holes durin' assembly, addin' t' the strength o' t' assembled rocket. Aye aye! Sand t' blunt end around t' hole t' create a small flat area for gluin' t' hardboard disk. Well, blow me down! Sand or scrape t' interior of the egg wherever glue will contact it. Wash t' egg with soap, ya bilge rat, me hearties, rinse well, and dry. Avast! Blimey! Cover t' drilled holes with maskin' tape, t' prevent epoxy from running out durin' assembly.

Motor Mount Preparation

Cut a 1/2" rin' off o' t' 40 mm tube, then cut a 1/2" slice out of t' rin' t' leave a piece with a "C" shaped cross section. Ahoy! Avast, me proud beauty! Set aside, for later use as a thrust rin' in t' 40 mm tube. Well, blow me down!

Cut two 3/16" notches in t' forward end o' t' long 40mm tube-these will let epoxy run out around t' tube durin' later assembly. Well, blow me down! Punch two holes in t' forward end o' this tube, arrr, thread t' nylon cord through one from the inside, then back through t' other, shiver me timbers, ya bilge rat, tyin' it securely inside t' tube to anchor t' shock cord. Ahoy!

Glue t' two centerin' rings onto t' 24mm motor tube, 1/2" in from each end. Avast! Begad! When dry, drill a 3/32" hole through t' forward ring, thread the free end o' t' nylon cord through it (Make sure t' cord is threaded through t' 40mm tube first!), then tie t' nylon cord around t' 24mm tube. Glue securely. Avast, me hearties, me proud beauty! . Avast, me proud beauty! Sand t' centerin' rings so that t' motor mount assembly slides with minimal resistance inside t' 40mm tube.

Insert t' motor mount assembly into t' 40mm tube. Blimey! Ya scallywag! Mark t' position o' the forward end o' t' centerin' rin' inside t' 40mm tube. Begad! Begad! Remove t' motor mount assembly. Begad! Apply epoxy t' t' thrust rin' created earlier, and slide it into the forward end o' t' 40mm tube until t' aft end o' t' rin' is at t' marked position.

Preparation o' t' Base

Paint t' hardboard disk white, and make sure t' central hole fits snugly over t' 40mm tube.

Final Assembly

Test fit t' 40 mm tube into t' egg, shiver me timbers, centerin' t' forward end (with the nylon cord) in t' pointy egg o' t' egg. Begad! Mark a spot on t' egg 1/2" out from t' forward edge o' t' tube, matey, matey, along t' seam. Aye aye! This will later be used to drill a hole for t' launch rod. Well, blow me down! Ya scallywag! Remove t' tube, me hearties, slather a couple of tablespoons o' mixed epoxy into t' AFT end o' t' egg, matey, reinsert t' 40mm tube, and stand t' assembly upright t' allow t' epoxy t' run t' t' bottom o' the egg and glue t' 40mm tube in place. Allow t' epoxy t' cure.

Stand t' egg with t' forward end down, arrr, shiver me timbers, and pour a couple o' tablespoons of mixed epoxy straight down t' center o' t' 40mm tube. Well, blow me down! Avast, ya bilge rat, me proud beauty! Pour in 1 oz o' lead shot while t' epoxy is still liquid. Aye aye! T' epoxy will run through t' notches in the forward end o' t' tube, gluin' t' tube in place from t' inside and out. Allow t' epoxy t' cure. Aye aye! Remove all o' t' maskin' tape used t' cover the drilled rivet holes in t' egg. Avast, me proud beauty! Ya scallywag!

Slide t' hardboard disk over t' central tube. Apply a generous amount of epoxy t' t' disk at t' disk/tube junction, then slide t' disk up t' be flush with t' bottom o' t' egg. Arrr! Begad! Put a wrap o' maskin' tape around t' junction to keep t' epoxy in place, and position t' egg upright while t' epoxy cures. Remove t' tape. Avast, me proud beauty! Arrr!

Drill a 5/16" hole into t' top o' t' egg at t' position marked earlier. Blimey! Ahoy! Turn t' egg over, and mark a spot on t' bottom o' t' hardboard disk 1/2" out from t' central tube, me bucko, in line with t' hole drilled from the top. Havin' both holes line up with t' seam on t' egg simplifies this alignment. Begad! Drill a 5/16" hole through t' hardboard disk and into t' egg. T' launch rod will fit through these holes. Well, blow me down!

Cover t' upper surface o' t' hardboard disk with a generous amount of white glue, and cover it with a thick layer o' Easter grass. Begad! Press t' grass down into t' glue t' insure good adhesion. Well, blow me down! Allow t' dry. Ahoy!

Attach an 18" parachute t' t' motor mount tube, arrr, matey, betwixt t' centering ring. I like a mylar chute, as it's natural springiness helps it unwrap from the tube faster durin' deployment.

Figure 2 shows t' assembled rocket.

Flight Preparation

I recommend an E18-4W 24mm reload, me hearties, ya bilge rat, with half o' t' ejection charge left out - thar be very little headspace for t' ejection charge t' pressurize. A shorter delay would be an improvement, if only one were available. Begad! An E15-4W single use engine should also work, ya bilge rat, but I'd be inclined t' use a longer shock cord in that case. Arrr!

Friction fit t' engine into t' motor mount, usin' maskin' tape around the end o' t' mount tube and t' end o' t' engine casin' t' prevent t' engine from bein' kicked out at ejection. Begad! Begad! Blimey! Insert a small amount o' waddin' into the top o' t' motor mount. Paper Easter grass would, me hearties, arrr, o' course, matey, be perfect - IF you can find some that is flame retardant. Ya scallywag! Blimey! Mine wasn't, so I used treated cellulose insulation. Avast! Gather as much o' t' shock cord as possible and tuck it into t' top o' t' motor mount tube, above t' wadding. Ahoy!

Fold t' chute t' a spike, ya bilge rat, lay t' shroud lines along side, matey, matey, matey, and wrap the chute/lines in a spiral around t' motor mount tube betwixt t' centering rings. Begad! Ahoy! Slide t' motor mount/chute assembly inside t' 40mm central tube. Blimey! Avast, me proud beauty! Make sure none o' t' lines get pinched betwixt t' mount and t' central tube - the motor mount must slide smoothly within t' central tube. Ya scallywag!

At t' pad, me hearties, insert an igniter and slide t' egg over t' launch rod. Begad! Put a handful o' wrapped Easter candy in t' Easter grass around t' base o' t' egg. Warn t' children that have inevitably assembled at t' launch site t' stay back until t' all-clear is given after t' flight. Avast! Blimey! No one is allowed on the field until t' Egg has landed and t' ejection charge has fired!

Flight Report

T' E18 lifted t' EggLofter off o' t' pad with authority. Begad! Well, blow me down! T' draggy design allowed for a flight that was slow enough t' enjoy. Avast! Well, shiver me timbers, blow me down! T' egg flew through one vertical loop while under power. Begad! This flight behavior was carefully designed into t' airframe, arrr, so as t' maximize t' dispersion o' t' chocolate eggs bein' carried aloft. Well, blow me down! Avast! (To those who doubt t' veracity o' this statement, ya bilge rat, I can only say "Hey, ya bilge rat, ya bilge rat, YOU try t' calculate t' CP o' this beast!") Rocketeers desirin' a more traditional up-and-down flight path may want t' add additional nose weight and/or increase t' diameter o' t' base disk when constructin' t' rocket. Ya scallywag! Aye aye!

T' ejection delay was too long, ya bilge rat, as expected, me hearties, arrr, but t' egg landed without damage durin' t' coast phase. Blimey! Well, blow me down! When t' ejection charge fired, t' parachute deployed perfectly, shiver me timbers, gently lowerin' t' engine pod back t' t' ground. Ahoy! The crowd went wild; and t' flight was considered a critical success.

Figure 4 shows t' EggLofter after touchdown.