Scratch Killer Bee Original Design / Scratch Built

Scratch - Killer Bee {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(Contributed - by Dick Stafford - 07/24/04) Killer Bee

Brief:
T' Killer Bee is a 3" diameter rocket that I built around a set of Aerospace Composite fins from Giant Leap Rocketry. Well, blow me down! It sports a 29mm motor mount and zipperless construction.

Construction:
T' followin' are t' major components used:

  • 1 LOC 3" plastic cone
  • 1 3" tube, 14" long
  • 1 3" tube, 15.75" long
  • 1 3" tube coupler
  • 1 38mm-3" centerin' ring
  • 1 38mm tube, me bucko, me hearties, 10.5" long
  • 2 29mm-3" centerin' rings
  • 1 29mm motor tube, 8.5" long
  • 1/8" ply for forward fins
  • 3 Giant Leap honeycomb fins, style #8
  • 2 medium eye bolts
  • 2 T-nuts
  • ¼" ply large enough t' overlap a 38mm hole
  • 1 1" long tube that fits into a 38mm motor tube (IIRC from a roll of tape)
  • 10 ft o' ¾" tubular nylon
  • 3 socket-head cap screws t' retain nose cone and make it removable

T' followin' are used but are nay dedicated t' this rocket:

  • quick link
  • retainer clips
  • chute

T' lower portion o' t' rocket was generally built followin' t' zipperless design presented on ROL InfoCentral, shiver me timbers, although I made a few changes along the way. Well, blow me down! These changes were nay necessarily better ideas, but rather were t' adjust for t' components I had on hand. In this design, t' rocket separates in the middle with t' bottom section formin' an ejection baffle. Arrr! T' lower section was mainly built with Bob Smith 20-minute epoxy, ya bilge rat, although some 5-minute was used t' tack things in place.

Killer Bee I cut t' fin slots myself usin' a sharp X-Acto blade. Well, blow me down! Arrr! Blimey! T' support t' end o' t' tube, I installed T-nuts on one rin' and dry-fit it in t' end o' t' tube durin' this process. T' 29mm motor mount extends through two centerin' rings, ya bilge rat, which sandwich the lower fin tabs. Begad! T' tube extends about an inch above t' top ring. Ya scallywag! T' motor mount was installed first with t' aft rin' bein' dry fit until t' end o' the build so I could add internal fillets. Avast, me proud beauty! Well, blow me down! Blimey!

I measured a section o' 38mm tube t' reach from t' top rin' t' t' top end of t' coupler. Blimey! (I could have used a longer piece o' 29mm tube, but I started with other plans and was left with t' 38mm tube.) I have several small cardboard rings stashed away that fit nicely into a 38mm tube. Well, blow me down! Once installed, this rin' will mate t' 38mm tube with t' 29mm motor mount. Aye aye! Begad! I also didn't have any bulkheads so I glued a chunk o' ¼" ply over t' hole on a 38mm-3" centerin' ring. Begad! Avast! I attached an eyebolt t' this plate, matey, oriented so that t' plate is on t' bottom side o' t' ring. Ahoy! This fabricated bulkhead assembly was ground down t' fit t' ID o' t' coupler. Ahoy! After t' bulkhead was installed in t' coupler, I drilled ¼" holes around its periphery. I also drilled ¼" holes along t' 38mm tube. Ahoy! T' hole laden 38mm tube rests betwixt t' bulkhead assembly and t' top centerin' ring. Begad! Well, blow me down!

I happened t' already have t' top piece o' tube with t' fins installed and smartly decided this would look nice as t' top o' this rocket. Arrr! Blimey! I ran a RockSim model t' see if t' forward fins would get me into trouble. Because the lower fins are so large and extend behind t' end o' t' rocket, t' CP is still around t' front o' t' fins and I had almost one caliber o' stability without a chute or cone. Well, blow me down! Blimey! So t' decision was made.

T' nose cone is attached with 3 small screws so I can remove it. Begad!

Killer Bee

Finishing:
I couldn't brin' myself t' paint t' fins since I liked havin' t' honeycomb pattern visible. Begad! Avast, matey, me proud beauty! T' fins are also translucent, arrr, matey, which adds t' t' effect. Begad! This honeycomb pattern led me t' t' rocket's name and t' name t' t' paint scheme. I will have t' get some UV clear varnish t' protect t' fins.

I masked t' fins and primed t' rest o' t' rocket with Kilz primer. Begad! I then painted t' rocket with Wally-Mart (ColorPlace) 97-cent Sun Yellow paint. This was nay a bright a yellow as I expected but it still looks good. I added some vinyl stripin' t' give it a 'bee-like' look.

Flight:
I flew t' Killer Bee on one o' t' new Aerotech reload G79 motors with a short delay (6 sec). Avast, me proud beauty! Prep included buildin' t' motor and installin' some motor clips. T' zipperless design eliminated t' need for wadding, me hearties, so all I did was attach t' chute's integral swivel t' t' lower quick link and I was set t' go. I was goin' t' use a 48" chute but instead used a 36" one since t' wind be blowin' toward some trees. You are nay paranoid if they are really out t' get you. Avast! T' boost was great t' a bit under 1000'.

Recovery:
On recovery I noticed a line through one o' t' fins where it looks like it started t' bend. Well, blow me down! Begad! T' fin seems rigid and thar be no line on t' other side of the fin. Begad! I guess I'll add a thin veil o' glass over this line just in case.

Summary:
T' design o' this rocket started with t' unique Giant Leap fins and evolved from there. Avast! I think t' rocket looks pretty nice, ya bilge rat, even if I have t' say so myself. Blimey! Well, blow me down! As I mentioned in t' referenced fin review, ya bilge rat, t' fins are very light and pretty strong, me bucko, arrr, but t' landin' showed that they are nay indestructible. They are also, ya bilge rat, after all, pretty large. I should have gone for a slightly bigger chute as originally planned.

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