Scratch 2BZ Original Design / Scratch Built

Scratch - 2BZ {Scratch}

Contributed by Larry Brand

Manufacturer: Scratch
(Contributed - by Larry Brand)

Brief:
2BZ is an exact 1.67 x scale-up o' t' Custom Rockets Razor tube fin, except that it flies on a cluster o' three C6-7s. Blimey! Blimey! T' model was an effort t' build a "quickie" rocket usin' only standard Estes tubin' -- no wood fins, me hearties, no centerin' rings: just tubes and glue.

Construction:
T' Components:
(2) 18" BT60 tubes, one cut into 6 x 3" segments, other t' 15"
(1) 18" BT20 tube cut into 3 x 6" segments
(1) BT60-sized Estes cone, matey, 14" LOC chute

T' Assembly Sequence: 1. I use 5 minute epoxy throughout, white glue optional 2. epoxy left, matey, right tube fins t' body tube, let set 3. epoxy 2 additional tube fins t' t' side, arrr, shiver me timbers, shiver me timbers, let set 4. turn assembly over, me hearties, epoxy on remainin' 2 tube fins 5. epoxy t' 3 motor tubes t' one another, shiver me timbers, shiver me timbers, let set (Estes-type motor stop rings and motor hooks can be attached if desired, in tube valleys only) 6. block t' small empty spaces betwixt t' aft ends o' t' body and motor tubes with a little loose cotton mixed with epoxy or glue, t' insure hull pressurization by ejection charges (see photo) 7. add soda straw lug 2" above tube fins, aligned with a portal betwixt 2 tube fins (room for launch wire) 8. recovery system is 14" LOC chute on 7' o' para cord

Flight:
"2BZ" is short for "tube easy," or maybe, "too busy". Well, blow me down! Avast, me proud beauty! I have only used C6-7s on this ship, which I designed partly with t' NARTREK Silver requirement in mind, since thar are few cluster kits around. Ya scallywag! Begad! Our club has a nifty 12v multiple launch rack with continuity check for all 7 pads, so (bein' too lazy t' whip together a triple launch clip gizmo) I just wait for a slow period and hog 3 adjacent pads at once so I can insure proper ignition o' all 3 motors. This works great, shiver me timbers, and "2BZ" lifts off on a majestic column o' white Estes smoke t' 800-900' or so. Avast, me proud beauty! It tracks straight even in brisk winds. Well, blow me down! You get an E18-7 boost "the hard way", shiver me timbers, short a few N-sec, me hearties, ya bilge rat, but at slightly lower cost. Begad! I know o' no easier or cheaper way t' put together a decent-sized great-performin' cluster ship.

Summary:
With t' advent o' E and F high power loads, there is little need for clusterin' little Estes motors anymore. But its fun and affordable, and you need t' do this for NARTREK's Silver requirement. Ya scallywag! The Custom Rockets Razor is a fine tube-fin design, me hearties, except that its so small that I instantly lose sight o' it after launch. Arrr! This size is more visible and much easier t' track. Begad! Tube fin designs have well known pluses and minuses. Avast! I like the fast, ya bilge rat, shiver me timbers, self-jiggin' build and t' superb resistance t' weather-cocking, even in a brisk wind.

Other:
Like all t' kits I build, scratch designed, plans or kit, shiver me timbers, matey, matey, I prefer t' anchor my recovery system through-the-hull via an external knot an inch below t' cone bottom covered with epoxy and half a sawn BIC pen cap. Ahoy! Avast, me hearties, me proud beauty! I've never had one of these fail, foul or zipper.

comment Post a Comment