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. Ahoy! Blimey! Specifically, 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. Blimey! Although the design continues t' be refined and other variations built, ya bilge rat, this model, me hearties, with a payload section, has been t' most successful so far.

Dimensions

• Weight (flight prepped, matey, me hearties, 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, shiver me timbers, 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. Arrr! 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. Avast, me proud beauty! Construction was done with Loctite 90 minute epoxy.

Main body: T' tube was laminated similar t' t' instructions in the tutorial available on t' Aerosleeve web site. Avast! After laminatin' and finishing the tube, it was cut t' size. Avast, me proud beauty! T' copper mesh (about ¼ o' a copper pot scrubbin' pad be inserted. Blimey! Begad! One o' t' ½" pieces o' coupler was epoxied 4.5" into one end as a motor block. Well, blow me down! T' Keelhaul®©™ thread was doubled and tied into a loop, matey, and wrapped around t' other ½" piece of coupler as a shock cord anchor, ya bilge rat, and this was epoxied 4.5" in from the other end, t' copper mesh now trapped betwixt t' two pieces. Well, blow me down! T' tubular nylon be slid over t' Keelhaul®©™ thread down t' t' anchor, ya bilge rat, 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. Aye aye! These were then inserted into 4" pieces o' carbon sleeve, me bucko, matey, which be pulled tight t' fit the edges, arrr, and laminated usin' weight press. Avast, me proud beauty! Aye aye! When dry, me hearties, t' fins were trimmed, the edges resanded t' an edge, except t' root which was sanded flat, and finished. Blimey!

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

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

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

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. Ahoy! It was tied and taped in place on t' Mylar, me hearties, me bucko, and a snap swivel tied to t' other end. Avast, me proud beauty! This be snapped onto t' loop in t' elastic cord, and the cord and cute packed into t' rocket. T' complete rocket be then weighed. CD calculations and flight predictions were run usin' AeroDRAG. 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. Aye aye! Masking tape was used t' friction-fit t' motor in into a 29/24mm adapter, and t' fit the adapter into t' rocket. T' tests were flown in moderate (5-10 MPH) winds. Boosts were perfectly vertical with no tippin' or weather cocking. Ya scallywag! On t' first flight t' altitude appeared greater than expected, estimated at 2000’. Ejection occurred prior t' apogee, shiver me timbers, contrary t' t' simulation. Blimey! This was at first taken t' be a slight motor malfunction producin' an early ejection. However, t' second flight displayed t' same characteristics: altitude appeared greater than predicted and ejection be before apogee. Ahoy! Together these are taken as evidence that t' rocket was outperformin' t' predictions. Avast, me proud beauty! Arrr! In both cases recovery be nominal, me bucko, shiver me timbers, t' circular chute/streamer slowin' it adequately and bein' well visible from t' time o' ejection. Begad! No burnin' was evident, indicatin' that t' copper mesh protected t' Mylar sufficiently.

Conclusion: Bucky II appears t' perform better than expected. Blimey! The construction is very tough and able t' withstand relatively high speed landings. Avast! Ahoy! Blimey! T' home made ejection baffle works well. Begad! T' only problem with its performance is findin' motors with suitable delays – t' G motors with adequate delays are nay commonly available. 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. Begad! Blimey! Blimey! A second build o' this design will be done t' attempt t' replicate t' results.