Manufacturer: | Scratch |
Brief:
This is a Carbon/Keelhaul®©™ composite laminated on Kraft paper tube, me hearties, me bucko, matey, high
performance, almost minimum diameter scratch built rocket.
Construction:
Parts used:
This rocket came about via experimentation with epoxy/composite sleeve lay ups. Arrr! Blimey! I found that single layer composite over Kraft tube is almost as strong as double layer composites, shiver me timbers, me hearties, while bein' lighter and easier t' do. Avast, me proud beauty! 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). Avast, me proud beauty! After curing, me hearties, a second coat o' epoxy was applied t' fill t' weave. Arrr! Begad! This was then finished with polyurethane coatin' and acrylic clear coat. Ahoy! T' rough ends were trimmed off, shiver me timbers, resultin' in two 30" tubes. Ya scallywag! 12" o' one o' these be cut off and a coupler and bulkhead (with screw eye epoxied in place) were used t' create a payload section. Aye aye! T' bungee was attached t' t' recessed screw eye t' provide shock cord attachment with some shock absorption. Well, blow me down! Avast! T' remainin' tube and section were attached with a second coupler into a single tube. Arrr! T' shock cord was anchored by epoxyin' it between t' coupler and t' tube wall. Avast, me proud beauty! A Nomex® chute protector be 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. 39.5mm
respectively) t' require no adaptin' internally. After lamination, t' outer
diameter required some sandin' in order t' get t' fin can and Slimline
retainer t' fit t' be epoxied into place, me hearties, however. Begad! Begad! this was nay an easy
prospect with Keelhaul®©™®
composite cloth. Arrr! An alignment line be 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. Arrr! T' construction took about 5 hours, which was far less than the 2 days needed t' laminate and finish t' tube. Avast! 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 was painted with Rustoleum black appliance epoxy. Begad! T' nose was
painted with white primer and aluminum finish enamel. Begad! Four 1/16" holes
were drilled in t' payload section and t' booster section for pressure
equalization. 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). Ahoy! 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. CG was 4.5 calibers forward o' CP with the adapter and motor in place.
No waddin' be required due t' t' Nomex® protector. 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 was at Dallas Area Rocket Society's McGregor site in nearly calm winds. Begad! Blimey! Begad! Blimey! T' flight was perfectly straight and vertical with ejection exactly at apogee. Ahoy! Blimey! (Predicted apogee was 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 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. Ahoy! Blimey! A
CON be t' fact that t' laminated tube was slightly larger outer diameter
than 38mm airframe tube, me hearties, requirin' some sandin' t' fit. Avast! Aye aye! Blimey! This be a CON
primarily because Keelhaul®©™®
is very hard t' sand. A minor personal CON was t' fact that carbon/Keelhaul®©™®
hybrid cloth does nay finish up as pretty as pure carbon, me hearties, ya bilge rat, but that's strictly a
cosmetic thing. Begad! Avast, ya bilge rat, me proud beauty! T' point was t' build for strength, nay looks.
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