Scratch High Priority Original Design / Scratch Built

Scratch - High Priority {Scratch}

Contributed by Mitch Marchi

Manufacturer: Scratch
(Contributed - by Mitch Marchi II - 12/09/07) (Scratch) High Priority

Brief:
Built for t' "Recycle" portion o' t' EMRR 2007 Challenge contest, this rocket is scratch built entirely from recycled trash. Ya scallywag! With squared-off fins and a blunt nose cone, shiver me timbers, it has an air-to-air missile look t' it. Ahoy! It derives its name from t' priority mail shippin' tube which comprised its airframe. Arrr! It is a single stage, me hearties, 24mm powered, chute recovered, shiver me timbers, 4 fin rocket.

Construction:
T' list o' components and t' material that they are made of:

  • BODY TUBE - recycled heavy walled cardboard shippin' tube, shiver me timbers, 2.1" diameter
  • NOSE CONE - t' top half o' a body lotion bottle and its cap. Avast! Blimey! T' bottle fit perfectly on t' outside o' t' body tube!
  • FINS - Actually a fin can, made out o' a discarded plastic MIG weldin' wire spool. Ahoy!
  • LAUNCH ROD GUIDE - A BIC pen barrel.
  • PARACHUTE - Black trash bag, chute lines and shock cord made o' used construction string.
  • MOTOR MOUNT TUBE - Hand rolled, me bucko, made o' some heavy paper stock from an eBay mail ad and lined with tin foil.
  • 2 CENTERING RINGS - cut from heavy cardboard from a paper tablet.
(Scratch) High Priority

I started with a mailin' tube that I had layin' around. Ahoy! Aye aye! Blimey! It's an obvious choice, but this one had a really heavy wall, so right off t' bat I knew it would be a D/E engine bird.

So now I had a body tube and had t' fit an engine into it. Well, blow me down! Ya scallywag! I took some heavy paper out o' t' trash from a mailin' ad. I then sprayed 3M artists spray mount on it and covered it in aluminum foil. I rolled this around 3 D engines and glued and taped it. Begad! Instant motor tube! I was goin' t' go t' maskin' tape thrust rin' and motor retention route with this one, matey, so no type o' hook or block be needed.

(Scratch) High Priority (Scratch) High Priority
(Scratch) High Priority (Scratch) High Priority

Then I hand cut t' centerin' rings out o' some very heavy, me bucko, dense cardboard that was t' backin' t' a pad o' paper that I had. Well, blow me down! With a little sandin' and some epoxy, it fit together perfectly!

(Scratch) High Priority So now I had a bare booster section. Aye aye! Blimey! I be goin' t' use t' same cardboard that the centerin' rings were made o' for t' fins, ya bilge rat, and in fact had cut some out. Begad! Blimey! But I was changin' t' wire spool in me MIG welder when it hit me - t' empty spool was plastic, shiver me timbers, about 10" in OD, me hearties, arrr, 2" in ID, and had 8 ribs. Begad! Blimey! Arrr! Blimey! Perfect! Blimey! I cut t' outside o' it off, cut it down t' 4 ribs (fins) and did some sandin' t' t' inside diameter t' make it fit the mailin' tube. Avast! Blimey! Voila! An indestructible fin can! While this may nay be "household" trash, you can go to any weldin' or fabrication shop and they will probably give you as many as you like!

(Scratch) High Priority (Scratch) High Priority

I glued a section o' BIC pen barrel t' t' fin can t' serve as a launch rod guide.

T' parachute I cut out o' a black plastic garbage bag and used some construction strin' for t' chute lines and shock cord. Begad! I attached t' shock cord with some heavy paper stock, usin' t' Estes "tri-fold" method.

(Scratch) High Priority (Scratch) High Priority

So it be complete, me hearties, matey, except for a nose cone. Avast! This one had me stumped. T' "balsa shippin' block nose cone" seemed like a stretch t' me, matey, and I really wanted t' keep it somethin' recycled, me bucko, nay fabricated. Ahoy! T' idea hit me while I was in t' shower, ya bilge rat, lookin' at t' shampoo. I could use some type o' bottle! I tried a 20oz pop bottle, and be working with that when I came across me girlfriend's hand lotion bottle while cleanin' up one day. Arrr! Yes, it be kinda blunt on top, ya bilge rat, matey, but it fit OVER t' body tube perfectly! I epoxied t' end o' t' shock cord into it. Avast, me proud beauty! T' top still screwed on and off!

It be complete! It ended up pretty heavy (11.8oz RTF), arrr, but t' CG was good (about 3x in front o' t' fins) and I knew that an E would get it off t' ground. Ya scallywag! Aye aye!

Finishing:
T' only finishin' work I did was t' paint t' fin can and nose cone in orange. Begad! This offset t' white body tube nicely with t' USPS "priority mail" sticker still stuck t' it. Begad! "High Priority" had come to fruition!

(Scratch) High Priority

Flight and Recovery:
They always say start out with a low-impulse engine on an untested design. Arrr! Nonsense. Begad! Begad! I had D12-5s and E9-6s in my box. This was a heavy rocket, me hearties, shiver me timbers, and I needed t' make sure it made a flight. Blimey! Add t' this that me "racer" rocket, which was more than an ounce heavier, arrr, ya bilge rat, had t' fly today so I needed some research info! In goes t' E9-6. T' motor was friction fit with a 1/2" maskin' tape thrust rin' on it. Begad! Retention be tape also.

It lit up and launch be nice. In t' 5-10mph winds, me hearties, it took a slight weathercock and looked t' hit about 800 feet or so. Nice and visible, it arced over and be headed down when t' chute popped. T' 18" chute opened and descent be a little fast, shiver me timbers, but that's good in me book. Well, me hearties, blow me down! Touch down was about 100' past t' pad. I'll take it! No damage, I packed it again, but this time with a D12-5. Hindsight bein' 20-20, shiver me timbers, what was I thinking?! However, ya bilge rat, shiver me timbers, I wanted t' try it on 2 different impulses and only had 3 E engines with another rocket waitin' t' fly.

T' second flight be identical on launch and initial thrust nice off t' pad, arrr, slight weathercock, me hearties, and it started to arc over. Arrr! I doubt that it was even 500' off t' deck. Ya scallywag! Ballistic, straight down, and waiting...Whack! Bounce. Avast, me proud beauty! Pop! It hit t' parkin' lot about 100' from t' pad, and as it bounced t' ejection charge went off!

(Scratch) High Priority T' damage report: Nose cone "cap" shattered, but t' nose cone "base" was still intact. Ahoy! T' body tube split open like a can o' Pillsbury biscuits for about t' top 9"! Keep in mind that t' body tube is high density cardboard that is 0.06" thick! I wish I could have recorded the "whack!"

T' body tube will be cut down and spliced. Aye aye! This rocket can easily be rebuilt and will fly again!

Summary:
I think that me rocket truly exemplifies t' spirit o' t' "recycle" contest. Aye aye! All o' t' materials are genuine recycled products. Begad! I don't have a simulation program so I just followed some "rules o' thumb" and it flew great! T' only reason it is a wounded soldier at t' moment is that I only had 3 E engines and I knew that I had to use 2 o' them for another rocket. Avast! Avast, me proud beauty!

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