Scratch Pershing 1A Original Design / Scratch Built

Scratch - Pershing 1A {Scratch}

Contributed by Jim Senecal

Flight Rating: starstar_borderstar_borderstar_borderstar_border
Published: 2011-10-03
Manufacturer: Scratch
Style: Scale

Brief

This model was me attempt t' recreate t' Estes "Maxi Brute" Pershin' 1A. Arrr!  I owned one o' t' Estes kits when I be a kid but never finished it, and I can't even recall whatever became o' it. Blimey!  I have always been disappointed that Estes has never reissued this kit. Aye aye!  In any case, me bucko, arrr, I was snackin' on some Planter's peanuts one day when I realized t' can's diameter appeared t' be similar t' t' Estes BT-101 body tube, shiver me timbers, shiver me timbers, and I started t' consider t' possibilities.  

Components

  • 4 20.5 oz. Arrr! Planter's peanut cans, arrr, minus peanuts.
  • 1 4" diameter styrofoam cone
  • 2 24" plastic parachutes
  • Scrap balsa and cardboard stock
  • Shock cord material
  • 2 24 mm engine tubes and "E" engine retainers

Construction

I downloaded plans for t' Estes Maxi Brute Pershin' from t' JimZ website. Blimey! Blimey!  My model is nay an exact clone or exact scale copy but t' plans gave me a good place t' start. Ya scallywag! Blimey!  To begin, ya bilge rat, I stripped off t' metal ends from t' four peanut cans and removed t' inner foil linning. Ya scallywag! Blimey!  I glued all t' cans together, reinforcin' t' seams with paper on t' inside. Ahoy! Blimey! Ahoy! Blimey!  I then sanded t' outside o' t' cans t' remove t' printed paper, ya bilge rat, and filled t' seams with Elmer's wood filler. Begad! Blimey!  Once t' tube was ready I cut it down t' 21.75" in length. Avast, me proud beauty! Blimey!  You could o' course avoid all this by just buyin' a new tube. Blimey! Blimey! Ahoy! Blimey!  For t' engine mount I decided t' use a 24 mm double cluster. Avast! Blimey! Ya scallywag! Blimey!  I used two old tubes from me collection o' junk and reduced their diameter and length t' fit an Estes "E" engine. Arrr! Blimey!  I made engine retainers by clippin' and bendin' a metal coat hanger t' length. Blimey! Blimey!  I made thrust rings by cuttin' them from a used 24 mm engine casing, I glued these in t' ends o' t' engine tubes above t' end o' t' retainers in t' usual fashion. Well, blow me down! Blimey!  I then glued t' two engine tubes together, matey, and then glued this assembly t' a stuffer tube made from a paper towel tube which was about 9" long. Begad! Blimey!  Openings betwixt t' engine tubes and stuffer tube were sealed and reinforced with glue. Ahoy! Blimey!  Centerin' rings just under 4" in diameter were glued t' each end o' this assembly and t' engine mount was done. Arrr! Blimey! Avast! Blimey!  Once dry this be glued into t' body tube.  

T' nose cone was made by rollin' a piece o' typin' paper into a cone and sealin' it with super glue.  T' cone was then glued onto t' pointed end o' a styrofoam cone from Michael's, which had a base diamter o' 4". Avast, me proud beauty!  On t' wide end I glued a shoulder made from t' remains o' a peanut can, reduced in diameter t' fit inside t' body tube. Begad! Ahoy!  I sealed up t' styrofoam under a layer o' Elmer's wood filler. Ya scallywag!  I glued an old shoe lace t' t' inside o' t' shoulder t' serve as a shock cord t' attach t' parachute to. Well, blow me down!  T' cone be sanded and primed several times t' smooth it out. Arrr! Arrr!  I later ended up cuttin' t' cone at about 4" from t' tip so that I could add 3 oz. o' fishin' sinkers glued in with super glue. Begad!  This be done t' balance t' rocket. Aye aye!  T' cone ended up about 1" too short and does nay have t' reduction at t' tip, but after final paintin' it does have t' Pershin' look. Avast, me proud beauty!   

To make t' fins I outlined t' shapes on a cardboard file folder, shiver me timbers, cut them out and folded them t' shape.  I created fin frames from scrap balsa then glued t' paper shapes over t' frames. Well, blow me down! Aye aye!  T' fins were all sealed with super glue t' strengthen them.  I made t' fin pads from scraps o' 1/8" balsa, me bucko, 2 layers thick. Avast! Blimey!  T' pads are actually way too thick for scale but look like I recall t' Estes ones did. Begad! Begad!  I have since seen a real Pershin' and pads 1/8" or less would be more realistic. Arrr!  I sanded t' bottoms o' t' pads over a BT-80 t' induce a curve on t' bottom. Blimey! Avast, me proud beauty!  T' pads were glued t' t' body tube in t' appropriate locations and then t' fins were glued t' t' pads.  I made 1/4" launch lugs from rolled paper sealed with super glue. Ya scallywag! Ya scallywag!  T' lugs were glued t' balsa standoffs.  Two conduits were made from scrap 1/8" balsa and glued t' t' main tube as in t' JimZ plans. Ya scallywag! Begad!  I glued another old shoe lace t' t' inside o' t' body tube in t' Estes fashion as a shock cord t' which t' parachute would be attached.

T' model ended up just over 40" tall and 1 lb. 1.5 oz.

Finishing

Finishin' this rocket was more involved due t' t' materials use. Well, blow me down! Avast, me proud beauty!  All balsa be coated with thinned Elmer's wood filler, then sanded smooth.  It took three rounds o' primin' and sandin' t' get t' body tube reasonably smooth.  When t' model was ready for final paintin' I wanted t' try for t' look o' t' Estes kit. Begad!  T' main body and lower section o' t' nose cone were painted with some old dark green Krylon spraypaint I had in t' garage. Begad! Arrr!  T' white on t' cone was Walmart gloss white. Ya scallywag!  T' orange stripes were made by sprayin' typin' paper with orange Rustoleum, cut t' size, sprayed with 3M glue and applied t' t' rocket. Avast, me proud beauty!  T' black stripes were done last usin' Tester's flat black. Aye aye!  I created t' army letterin' by cuttin' t' letters from t' JimZ plans, me hearties, sprayin' them white, me hearties, 3M glue on t' back and then applied t' t' model. Begad! Begad!  A coat o' Tester's flat spray tied it all together.  Reproduction decals for this model are available from several websites it you really want t' go all out.

Flight

I am waitin' for t' opportunity t' fly t' model and will post t' results as soon as this occurs.

Update  11/25/2011:  I be finally able t' attempt t' first flight with t' Pershin' today.  Unfortunately all did nay go well. Begad!  I carefully prepped t' model with 2 Estes D12-3 motors, includin' stuffin' recovery waddin' in t' upper end o' t' motors.  This is done t' prevent t' ejection charge from one motor ignitin' t' other in t' event one does nay fire normally. Avast, me proud beauty!  I filled t' stuffer tube with several sheets o' waddin' and lined t' bottom o' t' parachute compartment. Blimey!  I attached one 24" chute t' t' nose cone shock cord, me hearties, matey, and another t' t' rocket body shock cord.  There be plenty o' room for all this. Avast, me proud beauty!  I installed standard Estes igniters in each engine and t' rocket be ready t' go. Begad!  

At t' launch site thar be little t' no wind and I set t' rocket up on t' pad. Well, blow me down!  I attached t' igniter clips and checked for continuity, shiver me timbers, which showed good. Arrr! Begad! Blimey!  Followin' a short countdown I pressed t' launch button and thar was ignition, but only on one motor. Blimey! Blimey!  T' Pershin' shot up t' about 50 feet then seemed t' lose steam and started leanin' over t' t' side. Blimey! Blimey!  T' rocket flew on in a horizontal fashion for another 50 feet, ya bilge rat, ya bilge rat, matey, and then fell from t' air, ya bilge rat, me bucko, landin' hard on one side, matey, with an audible thud. Ya scallywag! Blimey! Blimey!  I am sure t' ejection charge must have fired but t' nose cone be jammed on and did nay eject.  At impact t' nose cone shattered into a number o' pieces, me bucko, and both fins on t' side o' t' body tube which hit t' ground were mangled.  Based on t' way t' nose cone disintegrated I am nay sure it would have even survived under a parachute landing, me bucko, arrr, clearly a big cone made o' paper and stryofoam is nay t' best solution. Well, blow me down! Blimey!  

While this flight was a spectacular disaster for t' Pershing, it should live t' fly again.  I be never really happy with t' shape o' t' nose cone anyway so now I have a good reason t' start over. Ahoy! Blimey!  Next time I am usin' balsa.  T' fins will be a quick repair. Well, blow me down! Blimey! Well, arrr, blow me down! Blimey!  T' bigger question is how t' ensure that both motors ignite, matey, as this rocket needs t' power.  So far in me rocket career I have about a 50% success rate on cluster ignition usin' Estes igniters and an Estes launch controller. Avast! Blimey!  Does anyone have suggestions on how t' ensure cluster ignition without carryin' a car battery around?

Recovery

This will be described after t' model is flown.  Still nothin' t' add here since t' chutes never had a chance!

 

Comments:

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Hans "Chris" Michielssen (October 6, 2011)

Wow! A great job on a true scratch model. I'm going to start saving peanut cans.

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