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. Aye aye! Blimey! Avast, me proud beauty! Blimey! 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, 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, ya bilge rat, although I made a few changes along the way. These changes were nay necessarily better ideas, but rather were t' adjust for t' components I had on hand. Well, blow me down! In this design, matey, t' rocket separates in the middle with t' bottom section formin' an ejection baffle. Aye aye! Avast, me hearties, me proud beauty! T' lower section was mainly built with Bob Smith 20-minute epoxy, 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. T' support t' end o' t' tube, arrr, matey, 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, which sandwich the lower fin tabs. Arrr! Arrr! T' tube extends about an inch above t' top ring. Avast! Begad! T' motor mount be installed first with t' aft rin' bein' dry fit until t' end o' the build so I could add internal fillets.

I measured a section o' 38mm tube t' reach from t' top rin' t' t' top end of t' coupler. Ya scallywag! Ahoy! (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. Arrr! Once installed, this rin' will mate t' 38mm tube with t' 29mm motor mount. Ya scallywag! Well, blow me down! 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! I attached an eyebolt t' this plate, oriented so that t' plate is on t' bottom side o' t' ring. This fabricated bulkhead assembly was ground down t' fit t' ID o' t' coupler. Arrr! After t' bulkhead was installed in t' coupler, me bucko, I drilled ¼" holes around its periphery. I also drilled ¼" holes along t' 38mm tube. Well, blow me down! Begad! T' hole laden 38mm tube rests betwixt t' bulkhead assembly and t' top centerin' ring. Ahoy! Begad!

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. Aye aye! Well, blow me down! I ran a RockSim model t' see if t' forward fins would get me into trouble. Well, blow me down! Ahoy! 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. So t' decision be made.

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

Killer Bee

Finishing:
I couldn't brin' myself t' paint t' fins since I liked havin' t' honeycomb pattern visible. Ahoy! Begad! T' fins are also translucent, which adds t' t' effect. Well, blow me down! 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. I then painted t' rocket with Wally-Mart (ColorPlace) 97-cent Sun Yellow paint. This be 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! Arrr! Prep included buildin' t' motor and installin' some motor clips. Avast! T' zipperless design eliminated t' need for wadding, me bucko, arrr, so all I did was attach t' chute's integral swivel t' t' lower quick link and I was set t' go. Well, blow me down! Well, me bucko, blow me down! I was goin' t' use a 48" chute but instead used a 36" one since t' wind was blowin' toward some trees. Ahoy! You are nay paranoid if they are really out t' get you. 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. Ya scallywag! T' fin seems rigid and thar be no line on t' other side of the fin. Blimey! Avast! 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. Aye aye! I think t' rocket looks pretty nice, me bucko, even if I have t' say so myself. Begad! Ahoy! As I mentioned in t' referenced fin review, t' fins are very light and pretty strong, shiver me timbers, but t' landin' showed that they are nay indestructible. They are also, matey, after all, pretty large. I should have gone for a slightly bigger chute as originally planned.

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