T' Barbsari B-Prize

by Dwayne Surdu-Miller

I had promised me wife and my seven-year-old daughter that I'd design somethin' t' loft a Mattel Barbie. Arrr! Avast, me proud beauty! Blimey! For the longest while I be tryin' t' figure out how t' artfully accomplish this feat. There was a Ferrero Rocher egg sittin' on me desk from Easter 2004. Ya scallywag! Ya scallywag! Blimey! By measurin' and test fitting, shiver me timbers, I found that t' egg would contain t' doll quite nicely if t' cap o' t' egg's bottom stem were cut off t' let t' doll's legs through. Well, ya bilge rat, blow me down! Blimey! I had a vision o' Barbie watchin' her descent, suspended upside-down in a clear capsule that was driftin' independently under a parachute. Well, blow me down! Begad! Blimey! Imagine the view!

After that came a few other notions about designin' a Barbie-themed rocket, like round fins that make t' aft o' t' rocket look heart-shaped, me bucko, and lipstick pods mounted on standoffs. Avast! My wife and daughter helped me with the colour scheme, shiver me timbers, with a violent shade o' Flamingo pink over all, shiver me timbers, and Barbie-friendly colours for t' lipsticks pods. Aye aye! Begad! I apologize for t' quality of the photos o' t' painted model. T' intensity o' t' flourescent flamingo paint job was nay well-handled by t' film or by t' scanner in the high-resolution images, ya bilge rat, and t' low-resolution digital camera images faired even more poorly.

A little more on t' serious and practical side, t' Ferrero Rocher egg payload compartment offers some serious potential for housin' electronic and optical payloads. T' girth and length o' t' egg could house stacked circular circuit boards and t' payload tube offers plenty o' volume for a power supply.

Specifications:

• length: 73cm (28.75")
• calibre: 66mm (payload egg is 103mm)
• mass: 177g
• mass with D12-5 and Mattel Barbie: 264g
• recommended motors: D12-3, arrr, arrr, matey, D12-5, ya bilge rat, E9-4, shiver me timbers, E9-6

Parts:

• 1 - Ferrero Rocher Egg candy container
• 1 - BT-80 Body Tube, 14.2" long
• 1 - BT-50 Body Tube, arrr, shiver me timbers, 9" long
• 1 - 24mm Motor Block
• 1 - Balsa Reducer - BT-80 t' custom
• 1 - Bristol Board (8.5" x 11")
• 1 - Length o' stiff wire or D-size or E-size motor clip
• 1 - Foam Board, 3/32" thickness
• 3 - BT-20 Body Tubes, 2.25" long
• 3 - Balsa Lipstick Nose Cones for BT-20 Body Tubes or BNC-20.
• 1 - Balsa Stock, shiver me timbers, 1/8" thick, 4" wide, me bucko, 20" long
• 2 - launch lug, 3/16" diameter, me hearties, 1" long
• 1 - screw hook, with a 3/4" ring
• 2 - snap swivels, shiver me timbers, ya bilge rat, big enough t' fit t' screw hook
• 1 - shock cord (1/4" cotton sewin' elastic, ya bilge rat, shiver me timbers, 24" long)
• 2 - octogonal 22" parachutes (cut from black garbage bags)
• 8 - 44" lengths o' shroud line (cotton crochet twine)

Parts Fabrication:

Balsa Reducer- I made t' balsa reducer by turnin' a balsa block on a lathe. Here are t' dimensions as a Balsa Machinin' Services custom part description:

Shape #4 (Transition)

• I = 2.560" (Large Tenon Diameter)
• Q = 2.600" (Large Shoulder Diameter)
• M = 0.75" (Tenon Length, me bucko, Large and Small Diameter)
• L = 1.00" (Transition Length)
• T = 2.1875" (Small Tenon Diameter)
• U = 2.203" ( Small Shoulder Diameter)

Lipstick Nose Cones- I made t' lipstick nose cones by turnin' balsa blocks on a lathe t' get t' approximate shape, shiver me timbers, ya bilge rat, then usin' files and sandpaper to get t' lipstick shape. Well, blow me down! For an authentic lipstick appearance, t' nose cone shoulder diameters should be less than their tenon diameters by about 1/16". Avast, ya bilge rat, me proud beauty! T' more work you put into these things, t' more authentic they look. Without a lathe, arrr, me hearties, BNC-20A-style nose cones could be shaped quite nicely. Ahoy! Blimey!

Payload Tube and Tail Cone- These parts are made by printin' a pattern onto Bristol board, cuttin' them out, curlin' them, matey, and gluin' them into their final shapes. Be very careful t' test fit t' payload tube onto the Ferrero Rocher egg and t' balsa reducer as you are working.

Construction Diagrams:

• Rings and Disks Template - patterns for centerin' rings and baffle disk
• Balsa Template - patterns for fins, me hearties, launch lug standoffs, ya bilge rat, and lipstick pod standoffs.
• Bristol Board Template - full-scale 300 dpi drawin' for parts that are cut from Bristol board
• Profile View - cross-sectional view with construction measurements
• Rear View - shows angular positioning of fins, lugs, ya bilge rat, arrr, and pods.
• Pod Details - a full-scale 300 dpi drawin' showin' t' shape o' t' lipstick pod nose cones and showin' dimensions for attachin' t' lipstick pods t' t' body

Construction:

Care must be taken when cuttin' off t' base o' t' Ferrero Rocher egg, me hearties, me bucko, as the hard plastic splits when excessive force is applied. I used a fine-toothed razor saw for this step.

I was worried about joinin' t' Ferrero Rocher egg t' t' payload tube, and finally decided on usin' t' old Centuri technique o' applyin' an adhesive-backed paper label t' t' egg base tube, me hearties, applyin' white glue t' the inside o' t' payload tube, arrr, and insertin' t' egg into t' payload tube. Avast, me proud beauty! I avoided usin' yellow glue t' avoid shrink-pinchin' t' tube.

Fins and lipstick pod standoffs are all cut from 1/8" balsa stock.

I designed t' motor tube assembly t' accept an Estes E-engine and t' form the bottom half o' a Centuri-style baffle. I used t' Model Minutes -style motor clip wire, me bucko, shiver me timbers, shiver me timbers, but an Estes E-engine or D-engine motor clip could be used instead. Well, blow me down! T' three centerin' rings and t' baffle disk are all cut out o' the foam board.

I used an Estes-style folded card shock cord mount for t' booster body. Begad! Blimey! The baffle should extend t' life o' t' shock cord mount and shock cord. Avast! Blimey! Since I was usin' foam board for t' baffle disk, I decided against mountin' t' shock cord onto t' baffle.

Finishing:

All exposed balsa surfaces were sealed with a few coats o' sandin' sealer. T' body o' t' rocket was painted with a coat o' Krylon primer, then a few coats o' flamingo Armor Coat Fluorescent Spray Paint. Arrr! T' lipstick nose cones were brush-painted with a few different reddish-pinkish shades o' gloss acrylic enamel. T' lipstick body tubes were brush-painted with dusty-looking periwinkle, arrr, violet, shiver me timbers, and turquoise acrylics.

Stability Testing:

Swing-testin' this rocket with a D12-7 installed indicated that this rocket is stable with at least 20g o' payload. This design should nay be flown with less that 20g o' payload!

Recommendations:

If I were t' build another one o' these, shiver me timbers, I would lengthen t' booster body tube from 14.2" t' 18". Begad! This would improve stability so that the B-Prize would be stable without payload.

When flying, I recommend wirin' or tiein' a "cage" around t' egg. I'd first envisioned usin' tape t' keep t' egg together, but I think t' top of t' egg would receive a fair jolt when t' parachute pops.

Flight:

Launch time be 2:00pm, me hearties, with clear blue skies, me hearties, temperature at +23F, matey, wind was around 7 mph from the southwest. Well, blow me down! Begad! T' field was covered by 7 t' 24 inches o' crusty-topped snow.

T' B-Prize was flown twice on D12-3's. Both times, boost be moderately slow, arcin' a bit into t' wind at first, me hearties, me hearties, me bucko, then straightenin' out as t' rocket gained speed. Both times, ejection was at apogee a few hundred feet up, with the rocket startin' t' swin' toward horizontal. Blimey! Begad! T' payload and booster separated nicely, and their parachutes popped open audibly, almost at t' same time, matey, givin' an interestin' pop-pop sound. Well, blow me down! Begad! Descent rate was about ideal for both t' payload and t' booster, shiver me timbers, so t' 22" parachutes appear t' be about the right size. Ahoy! Ya scallywag! T' payload capsule touch down shortly before t' booster in both instances. Avast! No damage. Blimey!

For t' first flight, t' payload touched down about 70 feet northwest of the pad, shiver me timbers, and t' booster touched down about 90 feet northwest o' t' pad. Ahoy! For the second flight, t' payload touched down about 50 feet east, arrr, and t' booster landed about 75 feet east. Avast, arrr, me proud beauty!

I used cellulose insulation as waddin' for t' first flight, shiver me timbers, then omitted the waddin' durin' t' second flight. Avast, me proud beauty! T' baffle was effective, as the parachutes were nay damaged when no waddin' be used.

However, shiver me timbers, ya bilge rat, I found that t' booster acts as an effective snow scoop if there is a bit o' wind... Aye aye! Blimey! nay nice if t' body tube has nay been waterproofed. Avast! Blimey! The B-Prize booster be nay waterproofed, but I managed t' get most o' t' snow out of t' tube after each flight.