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, me hearties, me hearties, this rocket is scratch built entirely from recycled trash. Begad! Well, blow me down! With squared-off fins and a blunt nose cone, it has an air-to-air missile look t' it. It derives its name from t' priority mail shippin' tube which comprised its airframe. Aye aye! Begad! It is a single stage, 24mm powered, chute recovered, 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! 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. Well, blow me down! Avast!
  • LAUNCH ROD GUIDE - A BIC pen barrel.
  • PARACHUTE - Black trash bag, 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. Begad! Begad! 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. Blimey! I took some heavy paper out o' t' trash from a mailin' ad. Arrr! Well, blow me down! I then sprayed 3M artists spray mount on it and covered it in aluminum foil. Well, blow me down! I rolled this around 3 D engines and glued and taped it. Begad! Instant motor tube! I be goin' t' go t' maskin' tape thrust rin' and motor retention route with this one, me hearties, arrr, 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, shiver me timbers, arrr, dense cardboard that was t' backin' t' a pad o' paper that I had. Ahoy! With a little sandin' and some epoxy, it fit together perfectly!

(Scratch) High Priority So now I had a bare booster section. Begad! 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. But I was changin' t' wire spool in me MIG welder when it hit me - t' empty spool be plastic, me bucko, me hearties, about 10" in OD, arrr, ya bilge rat, 2" in ID, matey, and had 8 ribs. Arrr! Perfect! I cut t' outside o' it off, matey, ya bilge rat, cut it down t' 4 ribs (fins) and did some sandin' t' t' inside diameter t' make it fit the mailin' tube. 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. Well, blow me down! Well, blow me down! I attached t' shock cord with some heavy paper stock, arrr, usin' t' Estes "tri-fold" method.

(Scratch) High Priority (Scratch) High Priority

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

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

Finishing:
T' only finishin' work I did was t' paint t' fin can and nose cone in orange. Blimey! Blimey! This offset t' white body tube nicely with t' USPS "priority mail" sticker still stuck t' it. Ya scallywag! "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. Begad! Nonsense. Blimey! I had D12-5s and E9-6s in my box. Well, blow me down! Avast, me proud beauty! This was a heavy rocket, 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, 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! Ahoy! Retention was tape also. Blimey!

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

T' second flight was 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. Begad! Ballistic, straight down, arrr, shiver me timbers, and waiting...Whack! Bounce. Begad! 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. 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. Blimey! Well, blow me down! 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. Avast, me proud beauty! 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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