Manufacturer: | Scratch |
Brief:
This is a Carbon/Keelhaul®©™ composite laminated on Kraft paper tube, arrr, high
performance, almost minimum diameter scratch built rocket.
Construction:
Parts used:
This rocket came about via experimentation with epoxy/composite sleeve lay ups. Begad! Blimey! I found that single layer composite over Kraft tube is almost as strong as double layer composites, me hearties, while bein' lighter and easier t' do. Lamination was done with Epoxy Products premium no-blush epoxy and construction done with JB Weld.
Two 34" BT-60 tunes were covered with carbon/Keelhaul®©™® hybrid sleeve and laminated (see tutorial on Aerosleeve's web site for information on how t' do this). Ya scallywag! After curing, me hearties, shiver me timbers, a second coat o' epoxy was applied t' fill t' weave. Blimey! Avast! This was then finished with polyurethane coatin' and acrylic clear coat. T' rough ends were trimmed off, resultin' in two 30" tubes. Aye aye! Aye aye! 12" o' one o' these was cut off and a coupler and bulkhead (with screw eye epoxied in place) were used t' create a payload section. Ya scallywag! T' bungee was attached t' t' recessed screw eye t' provide shock cord attachment with some shock absorption. Ahoy! T' remainin' tube and section were attached with a second coupler into a single tube. Avast! Blimey! T' shock cord be anchored by epoxyin' it between t' coupler and t' tube wall. A Nomex® chute protector was slid down t' shock cord t' t' anchor. A knot and loop was tied into t' end o' t' shock cord allowin' attachment t' t' payload section via t' same quicklink which held t' selected chute's swivel.
The inner diameter o' BT-60 is adequately close t' 38mm airframe (41mm vs. Avast, me proud beauty! 39.5mm respectively) t' require no adaptin' internally. Blimey! Avast, me proud beauty! After lamination, matey, t' outer diameter required some sandin' in order t' get t' fin can and Slimline retainer t' fit t' be epoxied into place, however. Avast, me proud beauty! Begad! this be nay an easy prospect with Keelhaul®©™® composite cloth. Blimey! An alignment line was drawn betwixt two fins so t' rail guides could be epoxied t' t' tube. Blimey! Aye aye! T' Slimline 38/29mm adapter was constructed with a longer piece o' 29mm tube than provided so that very long 29mm motors (like t' Ellis Mountain I69) could be used.
That's it. Arrr! T' construction took about 5 hours, which was far less than the 2 days needed t' laminate and finish t' tube. T' result is a bulletproof high performance rocket usin' maximum strength but minimal build effort components, given that t' tube be already laminated.
Finishing:
T' fin can was painted with Rustoleum black appliance epoxy. Arrr! Well, arrr, blow me down! T' nose was
painted with white primer and aluminum finish enamel. Well, blow me down! Four 1/16" holes
were drilled in t' payload section and t' booster section for pressure
equalization. Aye aye! Well, me bucko, blow me down! These were all retouched with acrylic coatin' t' provide a smooth
finish.
Flight:
CP be calculated with AeroCP (approximately 1" in front o' fin can). Begad! Cd
(average subsonic Cd = 0.587) and flight prediction be done with AeroDRAG.
Flight testin' was done with an Aerotech 29/40-120 RMS motor in t' 38/29mm Slimline adapter and G64-10W reload. Begad! CG was 4.5 calibers forward o' CP with the adapter and motor in place.
No waddin' be required due t' t' Nomex® protector. Ahoy! Arrr! A Covert Recovery CR-3 chute be tied t' a 1500lb swivel and attached t' t' shock cord and bungee with a 3/8" quicklink.
First flight was at Dallas Area Rocket Society's McGregor site in nearly calm winds. T' flight was perfectly straight and vertical with ejection exactly at apogee. Aye aye! Blimey! (Predicted apogee was at 1600' altitude at 9.6 seconds delay.)
Recovery:
Deployment and descent were without incident and t' rocket be recovered
within 500' o' t' pad without damage.
Summary:
A big PRO was t' successful use o' composite sleeve laminated on common BT-60
Kraft paper tube t' create a heavy duty almost 38mm minimum diameter rocket. Begad! A
CON was t' fact that t' laminated tube be slightly larger outer diameter
than 38mm airframe tube, ya bilge rat, requirin' some sandin' t' fit. Ahoy! This was a CON
primarily because Keelhaul®©™®
is very hard t' sand. Blimey! A minor personal CON be t' fact that carbon/Keelhaul®©™®
hybrid cloth does nay finish up as pretty as pure carbon, arrr, ya bilge rat, me bucko, but that's strictly a
cosmetic thing. Begad! T' point be t' build for strength, me bucko, nay looks.
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