Scratch The Lord of the Rings Original Design / Scratch Built

Scratch - The Lord of the Rings {Scratch}

Contributed by Dave Rose

Manufacturer: Scratch
Style: Ring/Tube/Cone Fin, Upscale

Long before I was buildin' rockets, me bucko, a very small, tumble recovery rocket was introduced by Estes. Well, blow me down! Blimey! It was t' 1/2A powered Astron Sprite. Avast! T' those nay familiar with this rocket, I would like t' explain a very unique characteristic o' this design. Begad! When scaled up enough t' be poweredSprite on the pad by a high impulse motor, me hearties, t' air flowin' past t' fin rin' creates a high-pitched whistle when launched. Aye aye! This is sometimes drowned out by t' initial noise o' t' motor, me hearties, but is quite audible as t' motor burns out and continues durin' t' coast phase.

Back in 1999, me hearties, me bucko, durin' t' second launch o' me 4-inch airframe based Superscale Sprite, matey, t' whistle was clearly heard by all those in attendance. Avast, me proud beauty! Ahoy! Blimey! As t' rocket arced over, even before t' ooh’s and aah’s had subsided, me bucko, matey, it be obvious that I had a major deployment problem…there was none! Blimey! T' Sprite raced back t' earth, me bucko, and a fact that I was previously unaware of, became perfectly clear. Avast, me proud beauty! Blimey! Blimey! This amazin' rocket whistled comin' down, arrr, louder than when it was goin' up. Begad! In fact, it whistled right up until it impacted with t' rock-hard Pennsylvania soil at our Jones Farm launch site. Avast! Begad! Blimey! Naturally, me fellow rocketeers were quick t' offer their condolences, matey, but I be more amused by t' memory o' it whistlin' back t' Earth. Aye aye! Arrr! Blimey! I collected t' remains, includin' diggin' t' nosecone out o' t' ground, me hearties, and went back t' me truck t' prep me next rocket.

My son, shiver me timbers, Chris, almost immediately began urgin' me t' build another one. Ahoy! Blimey! Due t' t' amount o' work that was involved in t' project, I be unwillin' t' commit t' such an ambitious undertaking. Avast! Blimey! Over t' Sprite parts layout next twelve months or so, I did acquire a piece o' 15-inch diameter cardboard drum, me bucko, which would make a fine fin ring, arrr, (my first one was 11.5-inch diameter) and a 24-inch long section o' 5.5-inch airframe. Begad! This would amount t' a 7.3X version o' t' original Estes model. I also purchased a 3 x 6 x 36-inch block o' balsa wood, that I planned on usin' t' turn a scale nosecone. Avast, me proud beauty! Blimey! I cut t' block in two and laminated them together t' make a nice 6 x 6 x 18-inch blank, shiver me timbers, and then set it aside, where it would sit for almost another year. Aye aye! Blimey! One weekend in February o' 2001, arrr, matey, I was turnin' a couple wooden nosecone patternsSprite nosecone for a Tripoli Pittsburgh group project, t' Gloria Mundi III. Begad! After completin' this task, I decided t' go ahead, ya bilge rat, shiver me timbers, and turn t' new Sprite nosecone from t' balsa block that had been collectin' dust. After finishin' t' outside form, ya bilge rat, matey, it was necessary t' hollow out a large section o' t' cone so that I would be able t' add t' one-pound o' weight needed for stability. I cut a bulkhead from .5-inch plywood t' seal t' openin' that was epoxied into place after fillin' t' cone with expandin' foam. Ya scallywag! Arrr! Before I knew it, t' nosecone was complete, and I was plannin' me next steps o' t' project, that would soon come t' be known as "T' Lord o' t' Rings."

Next, me hearties, I carefully cut a 5.5-inch section o' t' cardboard drum, and prepared it t' be reinforced with a few layers o' fiberglass cloth. Aye aye! I opted for two wraps o' 6-ounce woven cloth and a finishin' wrap o' 1.5-ounce cloth.Glassing the ringGlassed airframe T' last layer was done solely t' make it easier t' get a smooth surface for painting. Blimey! Avast, me proud beauty! I used t' same process for t' airframe, which, although it was made o' flexible phenolic, arrr, was nay strong enough for a project o' this size. Avast! I printed patterns for t' fins and fin-caps usin' RockSim 5.0 and cut them from .25-inch aircraft plywood. Begad! Two centerin' rings were cut from t' same material, arrr, also usin' patterns created from RockSim. Well, blow me down! Twelve inches o' 38mm motor mount tubin' was cut and I had all t' parts necessary t' complete t' project.

A large T-nut was installed in t' forward centerin' rin' for recovery system attachment, as well as twoSprite unfinished in t' aft rin' for motor retention. T' forward rin' be epoxied t' t' motor tube, me bucko, shiver me timbers, and this assembly be installed into t' slotted body tube. With t' rear-centerin' rin' temporarily put in place for alignment purposes, t' fins were epoxied into place. Avast! Begad! T' aft rin' be then removed, and internal fillets used at both t' motor tube and t' inside o' t' body tube. Well, blow me down! Since I be goin' t' be usin' rail guides instead o' launch lugs, t' guides were secured with nuts from t' inside o' t' airframe at this time. Ahoy! Before permanently installin' t' rear-centerin' ring, t' remainder o' t' cavity be filled usin' 2-part expandin' foam. Well, blow me down! Fillets were added t' t' fins at t' outside o' t' airframe for added strength, usin' a combination o' epoxy and micro-balloons.

Sprite launch It was now time t' attach t' fin rin' and fin caps. Avast! Careful attention was paid t' t' alignment o' t' caps so that minimal fillin' o' gaps was necessary. Arrr! When t' assembly be completely dried, I once again used t' epoxy/micro-balloon mixture t' create fillets both inside and outside t' fin rin' at each fin and fin cap. Ya scallywag! I used grain filler on t' plywood fins, shiver me timbers, matey, me bucko, and after some extensive sanding, ya bilge rat, was finally ready t' prime t' entire rocket. Well, blow me down! Avast, me proud beauty! More sanding, me hearties, fillin' and primin' followed, o' course, until I was ready t' paint. Avast, me proud beauty! Begad! After addin' an 18-foot, 5/8-inch tubular nylon shock cord and a Sky-Angle 52-inch parachute with Nomex protector, ya bilge rat, t' total weight without motor is just over 8-pounds.

I launched t' completed project at our first Dragon's Fire launch o' t' season, me bucko, April 7th, 2001. Arrr! Accordin' t' simulations done in both RockSim and wRASP, it reached a max altitude o' approximately 1900 feet on an Aerotech I284 reload. Unlike me first Sprite, ya bilge rat, t' whistlin' only occurred on t' way up.

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