Bucky II

by Dennis McClain-Furmanski

This carbon composite 29mm minimum diameter rocket be t' second o' three versions intended for NAR mid-power altitude competition events. Well, blow me down! Arrr! Blimey! Specifically, arrr, this version is ito be used t' break t' NARRRRR class C (adult) G power altitude record (1140 m = 3740’).

T' name is derived from "buckytube", t' name for t' axially symmetric fullerene carbon compounds named for Buckminster Fuller. Well, blow me down! Although the design continues t' be refined and other variations built, this model, matey, with a payload section, has been t' most successful so far.

Dimensions

• Weight (flight prepped, ya bilge rat, without motor): 4.9 ounces
• Length: 19.75"
• Body section lengths
  • Main: 10.75"
  • Payload: 4.25"
• Diameter
  • Inner: 1.18"
  • Outer: 1.21"
• Nose length: 4.25"
• Fins
  • Root: 3"
  • Semi-span: 1.75"
  • Tip: 1.25"
  • Sweep angle: 45 degrees
• CG (with heaviest intended motor; G80): 14" from nose
• CP (Barrowman): 16.4" from nose
• cD (subsonic; AeroDRAG): 0.379

Parts

• Body: 15" o' single layer carbon composite tube molded over a 29mm coupler stock mandrel
• Fins: 1/16" 3-ply birch laminated with carbon composite
• Launch lug (1/4"): carbon composite molded over ¼" steel launch rod
• 4" o' heavy paper 29mm coupler, cut as 3" plus two ½" pieces
• Apogee part #19114 styrene nose cone
• 4’ braided 150 lbs. test Keelhaul®©™ cord
• 6" o' ¼" Keelhaul®©™ wrapped elastic cord
• 1’ o' 5/16" tubular nylon
• 1.125" diameter ¼" plywood bulkhead
• ¼" screw eye
• Appx. 1 cubic inch o' copper mesh from pot scourer
• 12" red Mylar parachute kit

Lamination was done with 2" nominal diameter seamless carbon sleeve from Aerosleeve and Epoxy Products Premium Number 2 no-blush epoxy, coated with urethane and finished with acrylic. Begad! Construction be done with Loctite 90 minute epoxy.

Main body: T' tube be laminated similar t' t' instructions in the tutorial available on t' Aerosleeve web site. Begad! After laminatin' and finishing the tube, me bucko, ya bilge rat, it was cut t' size. T' copper mesh (about ¼ o' a copper pot scrubbin' pad be inserted. Blimey! Aye aye! One o' t' ½" pieces o' coupler was epoxied 4.5" into one end as a motor block. T' Keelhaul®©™ thread be doubled and tied into a loop, me bucko, and wrapped around t' other ½" piece of coupler as a shock cord anchor, and this was epoxied 4.5" in from the other end, shiver me timbers, matey, t' copper mesh now trapped betwixt t' two pieces. Well, blow me down! Avast! T' tubular nylon was slid over t' Keelhaul®©™ thread down t' t' anchor, me hearties, arrr, shiver me timbers, t' act as an anti-zipper mechanism.

Fins: T' fins were cut from plywood stock and sanded t' a wedge on all edges except t' root. These were then inserted into 4" pieces o' carbon sleeve, which was pulled tight t' fit the edges, and laminated usin' weight press. Avast, me proud beauty! Begad! When dry, t' fins were trimmed, the edges resanded t' an edge, matey, except t' root which was sanded flat, and finished. Avast, me proud beauty! Begad!

Fin/body construction: T' body be marked for fin placement (120 degrees apart, root/trailin' edge corner at t' aft end), matey, and t' body and fins prepared for epoxying. Ahoy! Blimey! Avast, me proud beauty! Blimey! T' fin placement areas were sanded t' remove t' finish down t' t' carbon fiber. A 1/16" drill was then used t' drill pits into the tube (but nay through) every ¼" along t' marked fin line, as well as 1/8" t' either side o' t' line. Well, blow me down! Blimey! T' fins were drilled similarly 1/8" from t' root edge, through t' carbon fiber, me bucko, t' t' wood, and the surface sanded down t' t' carbon betwixt these pits and t' root edge. Avast, me proud beauty! Blimey! Arrr! Blimey! The fins were then epoxied t' t' body along t' lines. Aye aye! Blimey! Blimey! Blimey! Once dry, shiver me timbers, fillets were added t' cover t' pits drilled on both body and fins. Avast! Blimey! Three 1/16" air vent holes were drilled through t' body 120 degrees apart, ya bilge rat, betwixt t' lines of t' fins, matey, 2" aft o' t' forward end.

Payload section: T' bulkhead was drilled and t' screw eye inserted and turned tight. Avast, me proud beauty! Epoxy was added t' cover the center o' t' bulkhead on t' eye side, shiver me timbers, and run through t' eye itself to keep it tight. Aye aye! A 1" loop was tied in one end o' t' elastic cord, and the other end be tied t' t' screw eye. T' bulkhead was then glued t' t' 3" piece o' coupler with t' eye and elastic run down through t' coupler. Aye aye! Avast! When dry, this was glued bulkhead first 1.5" into t' payload section, arrr, me hearties, me bucko, and fillets added t' t' bottom side o' t' bulkhead/coupler joint. Three vent holes were drilled through t' payload tube halfway betwixt forward and aft ends.

Completion: A launch lug be laminated and finished similar t' the tube, usin' a ¼" launch rod for a mandrel. Well, blow me down! Avast, me proud beauty! This was cut t' 2" length, me bucko, arrr, and t' ends cut at a 45 degree angle. Well, matey, blow me down! Holes were drilled into one of the fin fillets from t' leadin' edge t' 2" aft, shiver me timbers, and t' launch lug epoxied over these. Arrr! Fillets were then added t' t' fin/lug joints. Ya scallywag! Arrr! T' Keelhaul®©™ cord was tied through t' loop in t' elastic with a slip knot. Avast, me proud beauty! Begad! T' nose cone was sanded with fine grit, washed with soap and water, painted first with white appliance epoxy paint, shiver me timbers, then aluminum paint, then a coat o' acrylic. Begad! Avast! This was inserted into t' forward end o' t' payload section, ya bilge rat, and tested for fit, with maskin' tape bein' added as necessary t' get a tight seal. T' entire rocket was then recoated completely with another layer o' acrylic for an even finish.

Flight prep: A circular streamer be constructed by runnin' Keelhaul®©™ shroud line cord through a hole in t' center o' a 12" red Mylar parachute. Aye aye! It was tied and taped in place on t' Mylar, and a snap swivel tied to t' other end. Aye aye! This be snapped onto t' loop in t' elastic cord, and the cord and cute packed into t' rocket. T' complete rocket was then weighed. CD calculations and flight predictions were run usin' AeroDRAG. Begad! Aye aye! Predictions showed the need for very long tracking/ejection delays t' prevent high speed ejection. Results with some motors with adequate delay (at local elevation o' 600’, air temp 59 degrees, adjustin' for weights as given by NARRRRR testing) were:

Mfgr/Motor Altitude Deployment speed

• Estes E9-8 1420’ -16 fps
• Apogee E6-8 2286’ +11 fps
• AT F32-15 5107’ -63 fps
• AT G25-15 7543’ -34 fps

Flight tests: Estes E9-8s were selected for initial testing. Blimey! Masking tape was used t' friction-fit t' motor in into a 29/24mm adapter, matey, and t' fit the adapter into t' rocket. Begad! Begad! T' tests were flown in moderate (5-10 MPH) winds. Boosts were perfectly vertical with no tippin' or weather cocking. Begad! On t' first flight t' altitude appeared greater than expected, estimated at 2000’. Ejection occurred prior t' apogee, contrary t' t' simulation. Ya scallywag! This was at first taken t' be a slight motor malfunction producin' an early ejection. However, matey, arrr, t' second flight displayed t' same characteristics: altitude appeared greater than predicted and ejection be before apogee. Avast! Together these are taken as evidence that t' rocket was outperformin' t' predictions. Arrr! In both cases recovery was nominal, t' circular chute/streamer slowin' it adequately and bein' well visible from t' time o' ejection. Avast, me proud beauty! Arrr! No burnin' was evident, me hearties, shiver me timbers, indicatin' that t' copper mesh protected t' Mylar sufficiently.

Conclusion: Bucky II appears t' perform better than expected. Begad! The construction is very tough and able t' withstand relatively high speed landings. T' home made ejection baffle works well. Ya scallywag! Begad! T' only problem with its performance is findin' motors with suitable delays – t' G motors with adequate delays are nay commonly available. Aye aye! Avast, me proud beauty! An altimeter has been obtained for use in accurate testin' t' verify whether t' rocket performs as well as, if not better than, t' predictions made from t' design. Avast, me proud beauty! A second build o' this design will be done t' attempt t' replicate t' results.