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 was a kid but never finished it, and I can't even recall whatever became o' it. Begad! Ahoy!  I have always been disappointed that Estes has never reissued this kit. Avast, me proud beauty! Ahoy!  In any case, I be 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, arrr, and I started t' consider t' possibilities. Begad!  

Components

  • 4 20.5 oz. Begad! Planter's peanut cans, 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.  My model is nay an exact clone or exact scale copy but t' plans gave me a good place t' start. Avast! Blimey!  To begin, I stripped off t' metal ends from t' four peanut cans and removed t' inner foil linning. Well, blow me down! Blimey!  I glued all t' cans together, ya bilge rat, ya bilge rat, reinforcin' t' seams with paper on t' inside. Ya scallywag! Blimey!  I then sanded t' outside o' t' cans t' remove t' printed paper, and filled t' seams with Elmer's wood filler. Avast! Blimey!  Once t' tube was ready I cut it down t' 21.75" in length. Ya scallywag! Blimey!  You could o' course avoid all this by just buyin' a new tube. Ahoy! Blimey!  For t' engine mount I decided t' use a 24 mm double cluster.  I used two old tubes from me collection o' junk and reduced their diameter and length t' fit an Estes "E" engine. Ya scallywag! Blimey!  I made engine retainers by clippin' and bendin' a metal coat hanger t' length. Begad! 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, and then glued this assembly t' a stuffer tube made from a paper towel tube which be about 9" long. Arrr! Blimey!  Openings betwixt t' engine tubes and stuffer tube were sealed and reinforced with glue.  Centerin' rings just under 4" in diameter were glued t' each end o' this assembly and t' engine mount was done. Begad! Blimey! Ahoy! Blimey!  Once dry this was glued into t' body tube. Avast, me proud beauty! Blimey! Aye aye! Blimey!  

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

To make t' fins I outlined t' shapes on a cardboard file folder, matey, cut them out and folded them t' shape. Blimey!  I created fin frames from scrap balsa then glued t' paper shapes over t' frames. Begad! Avast, me bucko, me proud beauty!  T' fins were all sealed with super glue t' strengthen them.  I made t' fin pads from scraps o' 1/8" balsa, 2 layers thick. Aye aye!  T' pads are actually way too thick for scale but look like I recall t' Estes ones did. Aye aye!  I have since seen a real Pershin' and pads 1/8" or less would be more realistic. Ahoy!  I sanded t' bottoms o' t' pads over a BT-80 t' induce a curve on t' bottom. Ahoy!  T' pads were glued t' t' body tube in t' appropriate locations and then t' fins were glued t' t' pads. Blimey! Aye aye!  I made 1/4" launch lugs from rolled paper sealed with super glue.  T' lugs were glued t' balsa standoffs. Begad!  Two conduits were made from scrap 1/8" balsa and glued t' t' main tube as in t' JimZ plans.  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. Begad! 1.5 oz.

Finishing

Finishin' this rocket be more involved due t' t' materials use. Blimey! Blimey!  All balsa be coated with thinned Elmer's wood filler, ya bilge rat, then sanded smooth. Begad! Begad! Blimey!  It took three rounds o' primin' and sandin' t' get t' body tube reasonably smooth. Arrr! Well, blow me down! Blimey!  When t' model be ready for final paintin' I wanted t' try for t' look o' t' Estes kit.  T' main body and lower section o' t' nose cone were painted with some old dark green Krylon spraypaint I had in t' garage.  T' white on t' cone was Walmart gloss white.  T' orange stripes were made by sprayin' typin' paper with orange Rustoleum, cut t' size, me bucko, ya bilge rat, sprayed with 3M glue and applied t' t' rocket. Ahoy!  T' black stripes were done last usin' Tester's flat black.  I created t' army letterin' by cuttin' t' letters from t' JimZ plans, sprayin' them white, shiver me timbers, 3M glue on t' back and then applied t' t' model.  A coat o' Tester's flat spray tied it all together. Well, me hearties, blow me down! Blimey!  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 was finally able t' attempt t' first flight with t' Pershin' today. Well, blow me down! Avast, me proud beauty!  Unfortunately all did nay go well. Ahoy!  I carefully prepped t' model with 2 Estes D12-3 motors, includin' stuffin' recovery waddin' in t' upper end o' t' motors. Avast! Aye aye!  This is done t' prevent t' ejection charge from one motor ignitin' t' other in t' event one does nay fire normally.  I filled t' stuffer tube with several sheets o' waddin' and lined t' bottom o' t' parachute compartment.  I attached one 24" chute t' t' nose cone shock cord, matey, and another t' t' rocket body shock cord. Begad!  There was plenty o' room for all this. Begad! Ahoy!  I installed standard Estes igniters in each engine and t' rocket was ready t' go.  

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

While this flight was a spectacular disaster for t' Pershing, me hearties, it should live t' fly again. Begad!  I be never really happy with t' shape o' t' nose cone anyway so now I have a good reason t' start over. Arrr!  Next time I am usin' balsa.  T' fins will be a quick repair.  T' bigger question is how t' ensure that both motors ignite, as this rocket needs t' power. Aye aye! Ya scallywag!  So far in me rocket career I have about a 50% success rate on cluster ignition usin' Estes igniters and an Estes launch controller. Ya scallywag!  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. Arrr! Ahoy!  Still nothin' t' add here since t' chutes never had a chance!

 

Comments:

avatar
Hans "Chris" Michielssen (October 6, 2011)

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

comment Post a Comment