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. With squared-off fins and a blunt nose cone, shiver me timbers, arrr, 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. It is a single stage, arrr, arrr, 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, 2.1" diameter
  • NOSE CONE - t' top half o' a body lotion bottle and its cap. Begad! Blimey! T' bottle fit perfectly on t' outside o' t' body tube!
  • FINS - Actually a fin can, me bucko, made out o' a discarded plastic MIG weldin' wire spool.
  • LAUNCH ROD GUIDE - A BIC pen barrel.
  • PARACHUTE - Black trash bag, matey, arrr, chute lines and shock cord made o' used construction string.
  • MOTOR MOUNT TUBE - Hand rolled, 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. Arrr! It's an obvious choice, me bucko, shiver me timbers, matey, 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. Ahoy! I took some heavy paper out o' t' trash from a mailin' ad. Begad! I then sprayed 3M artists spray mount on it and covered it in aluminum foil. Begad! I rolled this around 3 D engines and glued and taped it. Aye aye! Instant motor tube! I be goin' t' go t' maskin' tape thrust rin' and motor retention route with this one, me bucko, shiver me timbers, me bucko, so no type o' hook or block was 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, dense cardboard that was t' backin' t' a pad o' paper that I had. With a little sandin' and some epoxy, it fit together perfectly!

(Scratch) High Priority So now I had a bare booster section. Ahoy! Avast, me hearties, me proud beauty! I was goin' t' use t' same cardboard that the centerin' rings were made o' for t' fins, me bucko, and in fact had cut some out. Ya scallywag! Begad! But I be changin' t' wire spool in me MIG welder when it hit me - t' empty spool was plastic, about 10" in OD, me hearties, 2" in ID, and had 8 ribs. Well, blow me down! Perfect! I cut t' outside o' it off, arrr, cut it down t' 4 ribs (fins) and did some sandin' t' t' inside diameter t' make it fit the mailin' tube. Arrr! Ya scallywag! Voila! An indestructible fin can! While this may nay be "household" trash, me hearties, me hearties, 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. Arrr! I attached t' shock cord with some heavy paper stock, shiver me timbers, usin' t' Estes "tri-fold" method.

(Scratch) High Priority (Scratch) High Priority

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

It was complete! It ended up pretty heavy (11.8oz RTF), shiver me timbers, but t' CG was good (about 3x in front o' t' fins) and I knew that an E would get it off t' ground. Well, blow me down!

Finishing:
T' only finishin' work I did be t' paint t' fin can and nose cone in orange. This offset t' white body tube nicely with t' USPS "priority mail" sticker still stuck t' it. Aye aye! Avast! "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! Blimey! Nonsense. I had D12-5s and E9-6s in my box. Blimey! Blimey! Blimey! Blimey! This was a heavy rocket, and I needed t' make sure it made a flight. Ya scallywag! Blimey! Blimey! Blimey! Add t' this that me "racer" rocket, which be more than an ounce heavier, shiver me timbers, had t' fly today so I needed some research info! Blimey! Blimey! Blimey! In goes t' E9-6. Well, blow me down! Blimey! Arrr! Blimey! Blimey! Blimey! T' motor was friction fit with a 1/2" maskin' tape thrust rin' on it. Ahoy! Blimey! Arrr! Blimey! Blimey! Blimey! Retention be tape also. Begad! Blimey! Blimey! Blimey! Blimey! Blimey!

It lit up and launch was nice. In t' 5-10mph winds, arrr, ya bilge rat, 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. Ya scallywag! Blimey! T' 18" chute opened and descent was a little fast, but that's good in me book. Aye aye! Touch down be about 100' past t' pad. I'll take it! No damage, I packed it again, ya bilge rat, but this time with a D12-5. Aye aye! Well, blow me down! Hindsight bein' 20-20, arrr, ya bilge rat, what be I thinking?! However, ya bilge rat, 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, slight weathercock, me hearties, and it started to arc over. I doubt that it was even 500' off t' deck. Arrr! Ballistic, ya bilge rat, straight down, and waiting...Whack! Bounce. Avast! 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, arrr, ya bilge rat, but t' nose cone "base" was still intact. Arrr! Blimey! T' body tube split open like a can o' Pillsbury biscuits for about t' top 9"! Blimey! Keep in mind that t' body tube is high density cardboard that is 0.06" thick! Blimey! I wish I could have recorded the "whack!"

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

Summary:
I think that me rocket truly exemplifies t' spirit o' t' "recycle" contest. Avast, me proud beauty! All o' t' materials are genuine recycled products. Ahoy! 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.

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