Descon 8 F.T.B.o.D. Original Design / Scratch Built

Scratch - F.T.B.o.D. {Scratch}

Contributed by Mark Simpson

Manufacturer: Scratch

 

Flyin' Traffic Barrel o' Death
F.T.B.o.D.
by Mark Simpson

As part o' me Level 3 project, buildin' and flyin' a full-sized orange traffic barrel, I decided t' make a 1/6th scale flyable traffic barrel t' test its dynamic flight stability.

I started with a 3" section o' garden variety mailin' tube, donated by an office mate. Ya scallywag! Ya scallywag! Blimey! I scrounged a piece o' 6" mailin' tube from another office mate t' use as a larger rin' fin. Well, blow me down! Since t' "real" traffic barrel, matey, purchased for t' L3 project, ya bilge rat, me hearties, me hearties, was sittin' in me garage already, I got out me tape measure and went t' town takin' measurements.

Here's a summary o' t' major dimensions:
Height at top o' barrel (flat surface) : 36"
Diameter at top o' barrel : 18"
Flasher: 6" long, 4" high at top o' battery pack.
Flasher dome: 8" in diameter

Now that I had t' basic dimensions, I went t' work creatin' t' model.

Here's a materials list:

  • 6" o' 3" mailin' tube for t' body
  • 1" o' 6" mailin' tube for t' rin' fin
  • 1 Stainless Steel Fishin' Leader for shock cord anchoring
  • 1 small screw in eyelet for shock cord mount
  • 3' o' nylon shoelace
  • Handful o' politically correct steel bird shot mixed with non-hardenin' modelin' clay scrounged from "the wife"
  • Scraps o' wood cut into 1" x 2/3" _" blocks for flasher base
  • 4 small wooden 1-1/4 convex disks (scrounged from wife's Michael's Craft Store supplies)
  • 1/16" balsa wood scraps for centerin' rings and fin supports.
  • Aluminum foil
  • 4" o' 29mm motor tube
  • Titebond II Wood Glue
  • 3" circle o' basswood for barrel top
  • 3" X _" strip o' basswood for (somethin' or other, ya bilge rat, Mark you left this out - ed.)


Construction:

I started by cuttin' 6" o' 3" mailin' tube on me Miter saw, then cuttin' a 1" rin' off o' a 6" mailin' tube, me bucko, usin' an Exacto knife.

Usin' VCP I printed out a fin alignment guide usin' t' followin' information:
# o' fins: 8
Diameter: 3"
Fin Span: 1.5"
Thickness: 3/32"

I laid t' 3" body tube on t' alignment and positioned t' 6" outer rin' so that t' radiatin' lines from alignment guide were even all t' way around t' ring. This ensures that t' 6" rin' fin is equidistant from all points. Begad! Begad! I then marked t' inside o' t' radiatin' line so that I could measure t' length o' balsa needed t' act as supports for t' rin' fin. Avast, me proud beauty! (It was slightly less that 1.5") I cut out 8 supports from scrap balsa that were roughly 1.5" X 1", arrr, makin' sure that t' grain was perpendicular t' t' body tube. Begad! Avast, me proud beauty! I test fitted t' 8 supports inside t' rin' fin, while sittin' on t' fin alignment guide. Arrr! After some minor adjustments and sanding, me hearties, me bucko, I glued all 8 supports in place. Avast! (Gettin' them straight be easy since I glued them on top o' t' alignment guide.) Once dried, I filletted all joints t' add strength and removed t' assembly from t' guide.

T' motor mount assembly is made from a small piece o' 29mm motor tube ~5" and balsa for centerin' rings. Begad! T' strengthen t' centerin' rings, I made four and glued them in sets o' two with one o' each pair havin' it's grain perpendicular t' t' other for strength. Begad! I glued both ends on and drilled a hole t' pass t' shock cord through.


A basswood sheet cut into a 3" circle forms t' barrel top and a 3" strip o' basswood acts as t' flasher support. Ya scallywag! (see below for details). Well, blow me down! For t' flashers, me hearties, I cut two 1" x 2/3" _" blocks from scrap wood t' serve as t' battery pack (white base). Well, blow me down! Avast, me proud beauty! T' flashers were 1-1/4" one-sided convex "buttons" found in me wife's craft box. Well, blow me down! Gluin' two together gave a nice convex lens assembly. Then I drilled through t' center o' t' lens assembly and t' middle o' t' flasher and inserted a small dowel t' hold t' lens on top o' t' base. Ya scallywag! (T' dowels aren't visible in t' photo, ya bilge rat, but are located at t' glue joint) I glued t' flasher support and both flashers t' t' top o' t' barrel at once so that I could ensure t' support be perpendicular t' t' barrel top.

Now comes t' shock cord attachment and weightin' process. Blimey! I used a small screw eyelet and screwed it into a _" by _" block o' plywood which I glued into t' underside o' t' basswood barrel top (see photo below) Then I added a _ thick plastic spacer from a brown paper roll endcap and punched out a section so that t' launch rod could go through t' rocket. Arrr! I filled t' _" circular gap with a mix o' modelin' clay and steel shot (estimated at ~2-3 oz). Arrr! Attached t' t' eyelet be a stainless steel wire fishin' leader. Avast, me proud beauty! I tied t' other end o' t' leader t' 3' o' heavy duty nylon shoelace.

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T' shoelace is attached t' t' motor tube assembly. T' aluminum foil-covered disk in t' picture below is t' protect t' shockcord and upper portion o' t' barrel's insides. Since this is a aft ejection model t' whole motor assembly should fit loosely in t' body tube. Blimey! Arrr! T' parachute is wrapped around t' motor tube ( like in t' Estes Sizzler). Begad! Care should be taken when test fittin' t' assembly so that holes can be drilled t' allow t' launch rod t' pass through t' rocket.

Since this be t' serve only as a test vehicle for t' real thing, I painted t' rocket usin' water-based acrylics. Aye aye! Blimey! T' completed project is below.

Flight Report:
On Saturday, ya bilge rat, me hearties, March 1st, I loaded up t' rocket with an F50-4 and it flew perfectly t' ~500'. Arrr! Ya scallywag! Ejection be just about right on and t' rocket landed within 50' o' t' pad.

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