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