Scratch Tube Lifter Original Design / Scratch Built

Scratch - Tube Lifter {Scratch}

Contributed by Peter Stanley

Manufacturer: Scratch
(Contributed - by Peter Stanley - 08/16/09) (Scratch) Tube Lifter

Brief:
T' Tube Lifter is a two-stage fin, arrr, shiver me timbers, me bucko, tube, shiver me timbers, and rin' tail rocket. Ya scallywag! Sustainer is recovered with a 14" parachute, ya bilge rat, and booster via tumble recovery. Ahoy! Well, me hearties, blow me down! It has a clear payload bay.

Construction:
T' parts list:

  • PNC-55AC Nose cone
  • 5" Clear - BT-55 tube, from Semroc
  • 20.0" BT-55 tube
  • 1.28" x 1.0" Balsa Bulkhead
  • 1/16" Staples brand illustration board
  • 4 BT-50 t' BT-55 centerin' rings
  • 20" BT-50 tube
  • 14" nylon chute
  • 2 1/4" pieces o' 4" FedEx tube
  • 15" 400lb Keelhaul®©™® cord
  • 10" x 1/8" elastic
  • 1/8" x 2" launch lug
  • 2 motor hooks
  • 1 small screw eye
  • 0.75oz o' nose weight
  • 24mm t' 18mm motor adapters (optional)

Click t' download fin temples for t' forward fins and aft fins.

(Scratch) Tube Lifter(Scratch) Tube Lifter

T' Tube Lifter is quick and easy t' build. Begad! Ahoy! T' fins are cut from 1/16" presentation board and require no extra finishin' besides for primer and paint. Ya scallywag! T' tube fins for t' sustainer were glued two at a time on a flat surface. Aye aye! The tube rings are cut from 4" diameter FedEx tube. Ya scallywag! That type o' tube fits perfectly around a BT-55 tube fin configuration. Blimey! Arrr! T' method I used t' cut t' 1/4" rings is similar t' how I cut body tube in general. Aye aye! I made a guide with two pieces o' cardstock paper wrapped around t' end o' t' tube, recessed slightly more than 1/4" from the end. Avast, me proud beauty! I used a razor saw and worked me way around in a circular fashion until I cut through t' tube.

(Scratch) Tube Lifter(Scratch) Tube Lifter

T' motor mounts were built as most standard kits, except t' sustainer mount requires t' bottom o' t' lower centerin' rin' be located 3/4" from t' bottom o' t' motor tube. Begad!

I friction fit t' nose cone into t' forward end o' t' clear payload bay usin' tape. Aye aye! Begad! T' lower end has a balsa bulkhead glued in with thin CA.

I used 0.75oz o' lead shot for t' nose weight and fixed in place with 30 minute epoxy. Well, blow me down! When usin' epoxy in nose cones, it is important t' keep t' nose cone cool while t' epoxy cures otherwise it can warp t' nose cone. Well, blow me down! I kept it cool by placin' t' nose cone pointed down in a cup o' water.

T' booster connects t' t' sustainer in two ways. Ahoy! T' motor mounts connect via a sleeve, matey, which is made from BT-50 tube that is cut lengthwise. Begad! T' bottom half is glued t' t' exposed end o' t' booster motor tube. Well, blow me down! T' forward end slides around t' lower part o' t' sustainer motor tube. Well, blow me down! T' protect against exhaust flame, I coated t' inside o' the sleeve with thin CA and t' outside with 30 minute epoxy. This also adds some strength. Well, blow me down! T' second connection point is made by t' booster tube fins. Begad! T' booster tube fins are made from BT-50 tube that slide inside 3 o' t' sustainer tube fins. Arrr! I cut two 1/4" pieces o' BT-55 tube lengthwise and wrapped around t' main booster tube. Avast! This served as a standoff for t' booster's tube fins. Well, blow me down! T' boosters tube fins are aligned by first connectin' t' motor tube sleeve, then placin' t' booster tube fins inside three o' t' sustainer tube fins, shiver me timbers, ya bilge rat, and are held in place against t' booster body tubes standoff sleeves with rubber bands. Well, blow me down! Once everythin' was in place, arrr, I tacked t' booster tubes t' the standoffs with 5-minute epoxy. Avast! After that set I reinforced with more epoxy.

(Scratch) Tube Lifter(Scratch) Tube Lifter

(Scratch) Tube Lifter(Scratch) Tube Lifter

T' shock cord was made from 400lb test Keelhaul®©™® tied t' t' sustainer motor tube with t' other end tied t' a 10" piece o' 1/8" elastic. Begad! Arrr!

(Scratch) Tube Lifter

Finishing:
Most people would probably fill in t' body tube spirals, but I skipped that and just painted everythin' with a coat of white primer. Aye aye! Begad! I then painted t' sustainer body with white paint. Avast! Avast! I hand painted t' sustainer/booster fins and sustainer rings with black acrylic. Begad! Arrr! I used Krylon aluminum for t' nose cone and booster section. Arrr! Begad!

Flight:
T' first flight be perfect. Begad! Begad! I used 24mm t' 18mm adapters and flew it on a B6-0 t' a B6-4. T' stagin' worked great and thar was no damage t' t' booster or sustainer. Begad! Well, blow me down! One major advantage o' this design is it can fly on a wide range of motors. Begad! T' second flight was on a B6-0 t' a B4-4. Begad! That too, was a perfect flight and recovery. I flew it as a single stage on a C6-5 for t' third flight. Arrr! Blimey! It arched over slightly and delay was way too long for that rocket. Ya scallywag! Begad! The chute be deployed about 2.5 t' 3 seconds after apogee. Avast, me proud beauty! A C6-3 would have been better. Well, blow me down! I didn't have any C6-3s, so I tried again but used a B6-0 booster. It arched over again as t' previous flight, arrr, and delay was too long. Well, blow me down! Blimey! I attribute the archin' over t' a too short, flimsy launch rod and moderate wind. Well, matey, blow me down! I plan t' fly this on 2 D motors at t' next launch. Aye aye! Begad!

Recovery:
T' 14" nylon parachute that I used seemed optimal, shiver me timbers, but a smaller chute might be needed in stronger wind, especially when flown t' higher altitudes. Well, me bucko, blow me down! T' last two flights deployed at a high speed and thar was no zippering. One o' t' booster's tube fins did get a little squashed after t' last flight.

Summary:
I wanted t' build a unique lookin' two-stage rocket that would be fairly easy and simple t' build. I was a little concerned about t' stability o' t' design, but after flyin' it, I am mostly pleased with how it performs. Ya scallywag!

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