EggLofter

(click t' enlarge image)

Concept

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

Prior t' launch, me bucko, ya bilge rat, put a handful o' wrapped chocolate Easter cackle fruit in t' grass on t' base disk. Aye aye! 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, arrr, approximately 4 1/2" diameter x 8" long, me hearties, $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, shiver me timbers, 24mm x 6 1/2"
Hardboard disk, me hearties, 1/8" thick x 9" diameter, center drilled t' accept the 40mm tube

2 Centerin' rings, matey, cut from hardboard, 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, me bucko, ya bilge rat, and trace around it. Carefully cut out t' traced circle on t' egg. Begad! Drill a dozen 3/32" holes around t' cut out hole, arrr, shiver me timbers, and several more in t' tip o' t' egg. Ahoy! Ahoy! Epoxy "rivets" will fill these holes durin' assembly, addin' t' the strength o' t' assembled rocket. Blimey! Ya scallywag! Sand t' blunt end around t' hole t' create a small flat area for gluin' t' hardboard disk. Sand or scrape t' interior of the egg wherever glue will contact it. Well, blow me down! Wash t' egg with soap, rinse well, and dry. Avast! 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. Avast, me bucko, me proud beauty! Blimey! Set aside, arrr, for later use as a thrust rin' in t' 40 mm tube. Begad! Blimey!

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. Punch two holes in t' forward end o' this tube, ya bilge rat, thread t' nylon cord through one from the inside, then back through t' other, tyin' it securely inside t' tube to anchor t' shock cord. Well, blow me down!

Glue t' two centerin' rings onto t' 24mm motor tube, matey, matey, 1/2" in from each end. Ya scallywag! When dry, ya bilge rat, drill a 3/32" hole through t' forward ring, shiver me timbers, thread the free end o' t' nylon cord through it (Make sure t' cord is threaded through t' 40mm tube first!), me bucko, then tie t' nylon cord around t' 24mm tube. Glue securely. . Avast, matey, 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. Ya scallywag! Avast, me proud beauty! Mark t' position o' the forward end o' t' centerin' rin' inside t' 40mm tube. Ahoy! Blimey! 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, me bucko, and make sure t' central hole fits snugly over t' 40mm tube.

Final Assembly

Test fit t' 40 mm tube into t' egg, centerin' t' forward end (with the nylon cord) in t' pointy egg o' t' egg. Begad! Blimey! Mark a spot on t' egg 1/2" out from t' forward edge o' t' tube, matey, along t' seam. Begad! Blimey! Blimey! This will later be used to drill a hole for t' launch rod. Avast! Aye aye! Blimey! Remove t' tube, slather a couple of tablespoons o' mixed epoxy into t' AFT end o' t' egg, 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. Blimey! Allow t' epoxy t' cure. Begad! Blimey! Blimey!

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

Slide t' hardboard disk over t' central tube. Well, blow me down! 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. Ahoy! Ya scallywag! 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. Begad! Aye aye!

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

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

Attach an 18" parachute t' t' motor mount tube, betwixt t' centering ring. Ya scallywag! I like a mylar chute, ya bilge rat, 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, with half o' t' ejection charge left out - thar be very little headspace for t' ejection charge t' pressurize. Begad! Blimey! Aye aye! Blimey! A shorter delay would be an improvement, if only one were available. Begad! Blimey! 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. Avast! Blimey! Avast! Blimey!

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. Avast! Insert a small amount o' waddin' into the top o' t' motor mount. Aye aye! Paper Easter grass would, o' course, matey, shiver me timbers, be perfect - IF you can find some that is flame retardant. Avast! Mine wasn't, me hearties, so I used treated cellulose insulation. Avast, shiver me timbers, me proud beauty! Gather as much o' t' shock cord as possible and tuck it into t' top o' t' motor mount tube, above t' wadding.

Fold t' chute t' a spike, lay t' shroud lines along side, arrr, and wrap the chute/lines in a spiral around t' motor mount tube betwixt t' centering rings. Ahoy! Well, blow me down! Slide t' motor mount/chute assembly inside t' 40mm central tube. Arrr! Ya scallywag! 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.

At t' pad, shiver me timbers, insert an igniter and slide t' egg over t' launch rod. 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. 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. T' draggy design allowed for a flight that was slow enough t' enjoy. Ahoy! Ya scallywag! T' egg flew through one vertical loop while under power. Aye aye! Avast! This flight behavior was carefully designed into t' airframe, so as t' maximize t' dispersion o' t' chocolate eggs bein' carried aloft. Ya scallywag! Begad! (To those who doubt t' veracity o' this statement, matey, ya bilge rat, ya bilge rat, I can only say "Hey, arrr, 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.

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

Figure 4 shows t' EggLofter after touchdown.