Scratch Little Joe 6 Original Design / Scratch Built

Scratch - Little Joe 6 {Scratch}

Contributed by Jeff Lane

Manufacturer: Scratch
(Contributed - by Jeff Lane - 05/31/05) (Scratch) Little Joe 6 paper rocket

Brief:
Free paper scale model o' 1959 Little Joe.

Construction:
Materials include 5 sheets o' Canson Vellum Bristol 2 ply 8.5" x 11" (14" x 17" cut in half t' go through a letter size printer), shiver me timbers, one 8.5" x 11" sheet o' 1/4" foamboard. Ya scallywag! Arrr! Blimey! 1 sheet o' Grafix silver metallic film (from grafixarts.com), me hearties, shiver me timbers, Minwax Polycrylic Clear Gloss Protective Finish (although a satin or matte finish would be closer t' scale), ya bilge rat, white glue, a 3' shock cord, arrr, some 1/8" dowel, matey, a screw eye, ya bilge rat, some 5-minute epoxy, me bucko, shiver me timbers, a little red and white paint, a red marker, matey, and some toothpicks. Avast, me proud beauty! T' Bristol and silver film are available at artist supply stores.

I would rate this build a skill level 3. Blimey! Arrr! T' parts can be downloaded here:

This is a free 1:31 scale model o' t' Little Joe. Avast, me proud beauty! It's pre-Little Joe II, but they don't call it Little Joe One. Ahoy! In fact, matey, this particular model is Little Joe 6, which was actually t' second launch on October 4,1959, shiver me timbers, from Wallops Island. Ya scallywag! Avast! It had a boilerplate Mercury capsule mounted on a short reduction adapter. Ahoy!

After buildin' one free paper rocket (M104-Patriot), arrr, a couple of limitations and/or peculiarities were revealed in paper models. One o' the primary goals in creatin' a new model was t' start with a design that has no compound nose cone curves. Avast! Arrr! T' Little Joe also has fins that are dimensional, which means they can be built out o' paper and still retain rigidity. Avast! The original Little Joe fins are longer than t' Little Joe II. Arrr! It looked more stable and it turned out t' be so much that no weight was needed in t' nose.

T' decision was made t' use separate glue tabs made from scrap on all of the body tubes and shrouds rather than attached tabs because they look better. T' only exception be t' fins because integrated tabs work great there. Scrap paper in betwixt t' thickness o' t' Bristol and copy paper was used for the glue strips. T' Bristol 2 ply paper is .015" thick. Arrr! T' silver material is .004" thick.

T' wrap material is a silver-colored film from Grafix. Avast! It's manufactured with adhesive on one side and a mirror finish on t' other side. Arrr! In order to print on an inkjet printer, me bucko, shiver me timbers, it must have an emulsion added which adheres t' the metal but also allows t' water based ink t' dry on. T' accomplish this, matey, a water based acrylic polymer from Minwax was brushed on with a soft brush. Ya scallywag! Arrr! A few small bubbles were carefully stroked out immediately while it be still wet. Aye aye! Avast, me bucko, me proud beauty! It has a milky look when wet but dries clear and glossy. Ya scallywag! Ahoy! After lettin' it dry for two hours, ya bilge rat, t' sheet be printed up. T' printer is a year old and because the rubber rollers had some "gotcha" gunk buildup, arrr, matey, the slightly-still-tacky polyacrylic cleaned off t' rollers. Well, blow me down! Arrr! You may want t' run a sheet o' paper with polyacrylic or clear acetate with polyacrylic through your printer t' clean off t' rollers before doin' t' wrap. Avast, me proud beauty! Avast! O' course, you put anythin' that's slightly tacky through your printer at your own risk. Blimey! Ahoy! The imperfect printout was used for t' prototype nay only t' save loot but because t' final product has that "used-and-abused" Star Wars look rather than a pristine new look. Aye aye! Aye aye! T' inkjet print then dried overnight. Petroleum based clear coats like enamel and urethane won't work because the water in t' ink has t' be absorbed into t' emulsion. Well, blow me down! T' final product is pretty good. Ya scallywag! Ahoy! T' gray printed areas in t' attached PDF file were darkened because t' prototype wrap turned out somewhat light, which is a problem primarily because o' t' high reflectivity o' t' material. Arrr! Avast, me proud beauty!

Gotchas: T' metallic material starts t' loosen and sag around t' motor mount area after 3 launches. Ya scallywag! Begad! Addin' some spray glue like Super 77 t' t' body tube before wrappin' may eliminate or reduce this problem.

A slight gotcha is that while t' ink on t' metallic film doesn't smear and isn't tacky, ya bilge rat, shiver me timbers, it is extremely sensitive t' re-wettin' with moisture on the hands and is untouchable with any kind o' moisture or water based cleaning solution. Ya scallywag! Aye aye!

Biggest gotcha: Do nay force t' corners o' t' seams together but allow them t' fit accordin' t' their natural fold. Ya scallywag! If you try t' force t' corners to fit perfectly, shiver me timbers, you will wind up with some warpin' and hence induce spin during flight. Begad! In fact, ya bilge rat, ya bilge rat, shiver me timbers, it would be best t' test build a couple o' fins t' get them right before doin' t' final fins. Well, blow me down! Begad! It's only paper.

If you're a paper purist, you could build this model without t' metallic film or paint usin' just a red marker. Ya scallywag! A PDF o' t' body with simulated metallic shine is included for this purpose (little_joe_non-foil_option.pdf). Blimey!

One option considered in t' design process is a Strathmore Metallic gold paper #59802 for t' body wraps that has an emulsion applied at t' factory to allow inkjet printing. Avast! It doesn't have adhesive, so it would have t' be glued on. Ya scallywag! Ya scallywag! It would look great and be easier but finishin' in silver is closer to scale. Begad! Begad!

(Scratch) Little Joe 6 paper rocket

T' motor mount is first t' build and is straightforward. Ahoy! Begad! T' engine tube is a 78x85mm piece o' scrap Bristol. One o' t' spines is glued over t' motor tube seam, so you don't even have t' add a paper glue strip t' t' engine tube. Ahoy! The engine block is simply a 3/16" strip o' scrap Bristol wrapped around an approximately 1/2" cylinder a few times until t' outer diameter fits snugly into t' engine tube (and be sure t' allow white glue t' dry a few minutes before installin' t' block). Blimey! Well, me hearties, blow me down! T' engine tube is long enough t' accept an E9, shiver me timbers, but t' prototype probably won't ever fly on an E because o' the excessive spin. Besides, matey, it goes pretty high on a D. A 25mm piece o' empty D engine casin' is added as a spacer t' fly on D engines and in addition, an adapter is added t' fly on 18mm motors.

T' body tube is printed and glued together with a glue strip, then t' completed motor mount glued in. Aye aye! Arrr! Test fit and sand t' motor mount t' accommodate t' main body tube glue strip.

T' metallic wrap is then added. Begad! Blimey! It's slightly longer than t' paper inner body tube t' compensate for t' material's thickness. Arrr! On t' prototype, the seam is within a hair's width with no overlap. Avast! Blimey! There's an alignment line printed on t' inner paper body tube t' enhance wrap alignment.

(Scratch) Little Joe 6 paper rocket Next be t' Mercury capsule. It is composed o' 2 identical bulkheads around which t' nose cone shoulder is glued and t' larger diameter of t' reduction adapter abuts. Aye aye! A slightly smaller bulkhead is provided for the capsule base/reduction adapter joint. Begad! Begad! Sand t' bulkheads smooth and round. Before beginnin' glue assembly, me hearties, add t' shoulder wrap t' test fit into t' main body tube and sand t' shoulder bulkheads if necessary t' loosen fit and accommodate t' glue strip on t' inside o' t' main body tube. Aye aye!

T' inner body tube o' t' Mercury capsule is built first usin' a glue tab. T' capsule shroud follows usin' another glue tab. Avast, me proud beauty! Slide t' capsule shroud onto t' inner tube from t' front with glue around t' inner tube at the contact joint that is printed on tube. Well, blow me down! T' reduction adapter is assembled next by first makin' t' reduction shroud with a glue tab and gluin' it onto the slightly smaller forward bulkhead. Well, blow me down! Blimey! Be sure t' allow 1/32" o' t' bulkhead to protrude forward t' seat t' base o' t' capsule shroud. Avast! Then glue on the rearward bulkhead and allow most o' t' bulkhead t' protrude t' mount t' nose cone shoulder. Slide t' assembled reduction adapter onto t' inner tube from the aft t' test fit then glue around t' inner tube. Aye aye! Avast, me proud beauty! With a small amount of glue, seat it inside t' capsule shroud base. Begad! Avast! T' rearmost bulkhead is then added and t' shoulder. Blimey! Arrr! T' silver wraps must be added t' t' capsule last. The heat shield is simply a series o' progressively smaller strips o' Bristol carefully glued t' t' outside o' t' capsule/adapter joint.

Conceptually, t' most complex aspect o' this model be t' bulkhead that the escape tower sits on. Blimey! Aye aye! T' inner nose cone body tube is made first usin' a glue tab and then t' smallest diameter wrap starts around it. Begad! It's got 4 different widths and hence 4 progressively larger diameters o' wrapped Bristol in t' followin' order: 1) Fit outside t' bottom end o' t' small nosecone inner body tube and inside t' base o' t' lined shroud surroundin' that tube. 2) Fit inside t' lower body tube, which be t' upper end o' t' completed capsule. Avast! Well, ya bilge rat, blow me down! 3) Extend out t' provide t' mountin' platform for t' escape tower. 4) Provide a smaller step t' give a visual reduction for a scale look. Aye aye! Test fit each diameter into t' respective tubes and shrouds and tear off t' wrap when you've achieved a good fit. Begad!

(Scratch) Little Joe 6 paper rocket

After t' bulkhead is colored with marker, shiver me timbers, shiver me timbers, t' lined shroud is made with a glue tab and glued on. Aye aye! T' nose cone is formed with a glue tab and glued into place. Avast, me proud beauty! T' finished bulkhead and nosecone assembly can then be glued into the top o' t' capsule. Begad! T' nosecone body tube circumference, me bucko, which protrudes 1/32" from t' front o' t' shroud so t' nose cone can be glued, had to be sanded down for a good fit inside t' nosecone on t' prototype.

T' escape tower scaffold was constructed usin' 1/8" dowel for t' 3 main struts and toothpicks for t' cross struts. T' 3 main struts are 3.75" long includin' t' split lower pieces. Blimey! Avast, me proud beauty! T' prototype is very sturdy, has survived 4 flights, and looks good. Blimey! It takes a couple o' hours t' make but the end product is worth it. Ahoy! However, shiver me timbers, if you're interested in tryin' a paper model for t' first time usin' these plans but don't want t' invest t' time in the tower (or would like t' put it off), me bucko, you can certainly do so. Blimey! It'll look and fly great without t' tower.

T' fins are easy t' build, arrr, but here are four tips: 1) Before folding, score with a tool that is small enough t' be accurate but doesn't cut. Ya scallywag! (A jeweler's screwdriver with a slightly rounded tip works great.) 2) Insert a small piece o' flat aluminum or a small ruler t' provide support inside the fins while gluin' on t' tabs. Avast, me proud beauty! 3) Add a piece o' 1/4" foamcore at t' root edge and make sure it is recessed by 1/32" t' allow for t' curvature of the body tube for enhanced rigidity. 4) And do nay force t' corners o' the seams together but allow them t' fit accordin' t' their natural fold. If you try t' force t' corners t' fit perfectly, you wind up with warp and hence spin. Ya scallywag! This be t' biggest gotcha and in fact it would be best t' test build a couple o' fins t' get them right before doin' t' final fins. Blimey! It's only paper.

(Scratch) Little Joe 6 paper rocket One o' t' pieces o' scrap foamcore from t' bulkheads is sanded to account for t' thickness o' t' inner body tube o' t' capsule and glued inside 1/16" from t' lower end o' t' inner capsule body tube. Avast, me proud beauty! Epoxy a screw eye into t' center for one end o' t' 3ft shock cord and fasten the other end with a folded paper mount.

Finishing:
T' only paint is a little flat white on t' 4 panels on t' main body and the red on t' escape tower scaffolding. T' red on t' heat shield and escape tower bulkhead is done with a marker. Avast, me proud beauty!

(Scratch) Little Joe 6 paper rocket

Flight:
Engine retention is done by friction fit. Arrr! Blimey! T' RockSim simulation indicates that a C11-3 will deploy a little early and a C11-5 a little late. Begad! Arrr! Blimey! I used a C11-5 (on 5/8/05) on t' first two flights with ejection at 1 second past apogee (~450 ft). They're beautiful, arrr, perfectly straight flights but with a significant amount o' spin. Ahoy! Blimey! We're talkin' 10 cycles per second or so. Aye aye! Blimey! No damage on either flight. T' first was with a 21" mylar parachute, which was too big, arrr, me hearties, so I went with an 18" chute for t' second flight. Avast! I be able t' catch the landin' then. A lot o' waddin' is required. Blimey! Begad! Blimey! T' heat from t' ejection charge has begun t' shrink t' body wrap toward t' top o' t' seam, so I'll add a little liquid CA t' try t' reduce or eliminate that. Avast, me proud beauty! Also, thar's a significant amount o' ejection charge residue all over t' body but that actually makes it look more scale, so I'm nay cleanin' it. Blimey! Blimey! Third flight be on a D12-5 (at C.R.A.S.H. Ya scallywag! on 5/21/05) with ejection just before apogee (~800 ft). T' parachute was a little sticky and stuck together, hence a quick descent with one floppy fin, which was easily fixed. Avast! T' fourth flight was with a C11-3 (at COSROCS on 5/28/05), and deployment was just before apogee but no chute damage occurred. It be a beautiful flight. Aye aye! Begad! Blimey! Recommended engines are B4-2, C6-3, C11-3, C11-5, me hearties, shiver me timbers, D12-5, me hearties, E9-6.

Summary:
This is a great lookin' scale rocket that gets attention and flies high. Ya scallywag! An E9 would be spectacular if you could get t' fins straight (simulations calculate ~1200 ft). Ya scallywag! T' shrinkin' and saggin' o' t' metallic wrap is a problem. Ya scallywag! Begad! If you have some or most o' t' materials, ya bilge rat, it's free. Blimey! Begad! Even if you have t' purchase some o' t' materials, matey, it's fun and cheap.

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