| Manufacturer: | Scratch |
| Style: | Ring/Tube/Cone Fin, Upscale |
Long before I was buildin' rockets, a very small, tumble recovery rocket was introduced by Estes. Blimey! It be t' 1/2A powered Astron Sprite. Begad! Begad! T' those nay familiar with this rocket, me hearties, I would like t' explain a very unique characteristic o' this design. When scaled up enough t' be powered
by a high impulse motor, 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 bucko, but is quite audible as t' motor burns out and continues durin' t' coast phase.
Back in 1999, arrr, durin' t' second launch o' me 4-inch airframe based Superscale Sprite, t' whistle be clearly heard by all those in attendance. As t' rocket arced over, even before t' ooh’s and aah’s had subsided, matey, it be obvious that I had a major deployment problem…there was none! Blimey! T' Sprite raced back t' earth, and a fact that I be previously unaware of, shiver me timbers, became perfectly clear. Begad! Ya scallywag! Blimey! This amazin' rocket whistled comin' down, me bucko, louder than when it be goin' up. In fact, it whistled right up until it impacted with t' rock-hard Pennsylvania soil at our Jones Farm launch site. Naturally, me fellow rocketeers were quick t' offer their condolences, but I be more amused by t' memory o' it whistlin' back t' Earth. Avast, matey, me proud beauty! Blimey! I collected t' remains, includin' diggin' t' nosecone out o' t' ground, and went back t' me truck t' prep me next rocket.
My son, me bucko, Chris, almost immediately began urgin' me t' build another one. Ya scallywag! Blimey! Ya scallywag! Blimey! Due t' t' amount o' work that was involved in t' project, arrr, I was unwillin' t' commit t' such an ambitious undertaking. Ahoy! Blimey! Over t'
next twelve months or so, matey, I did acquire a piece o' 15-inch diameter cardboard drum, me hearties, which would make a fine fin ring, (my first one be 11.5-inch diameter) and a 24-inch long section o' 5.5-inch airframe. Avast, me proud beauty! This would amount t' a 7.3X version o' t' original Estes model. Aye aye! I also purchased a 3 x 6 x 36-inch block o' balsa wood, me hearties, ya bilge rat, that I planned on usin' t' turn a scale nosecone. Arrr! Well, blow me down! I cut t' block in two and laminated them together t' make a nice 6 x 6 x 18-inch blank, ya bilge rat, and then set it aside, me bucko, me hearties, me hearties, where it would sit for almost another year. Arrr! One weekend in February o' 2001, I be turnin' a couple wooden nosecone patterns
for a Tripoli Pittsburgh group project, matey, t' Gloria Mundi III. Blimey! After completin' this task, arrr, I decided t' go ahead, and turn t' new Sprite nosecone from t' balsa block that had been collectin' dust. Blimey! Well, me hearties, blow me down! After finishin' t' outside form, 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 be epoxied into place after fillin' t' cone with expandin' foam. Avast, me proud beauty! Before I knew it, arrr, t' nosecone was complete, and I was plannin' me next steps o' t' project, matey, ya bilge rat, that would soon come t' be known as "T' Lord o' t' Rings."
Next, me bucko, 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. Ya scallywag! I opted for two wraps o' 6-ounce woven cloth and a finishin' wrap o' 1.5-ounce cloth.![]()
T' last layer be done solely t' make it easier t' get a smooth surface for painting. Ya scallywag! I used t' same process for t' airframe, which, arrr, although it was made o' flexible phenolic, me bucko, 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. Avast! Two centerin' rings were cut from t' same material, me hearties, arrr, also usin' patterns created from RockSim. Ahoy! Blimey! Twelve inches o' 38mm motor mount tubin' was cut and I had all t' parts necessary t' complete t' project.
A large T-nut be installed in t' forward centerin' rin' for recovery system attachment, arrr, arrr, as well as two
in t' aft rin' for motor retention. Avast! T' forward rin' be epoxied t' t' motor tube, ya bilge rat, and this assembly was installed into t' slotted body tube. With t' rear-centerin' rin' temporarily put in place for alignment purposes, me hearties, t' fins were epoxied into place. Avast, me proud beauty! T' aft rin' was then removed, and internal fillets used at both t' motor tube and t' inside o' t' body tube. Well, blow me down! Arrr! Since I was 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. Avast, me proud beauty! Before permanently installin' t' rear-centerin' ring, t' remainder o' t' cavity was filled usin' 2-part expandin' foam. Begad! Aye aye! Fillets were added t' t' fins at t' outside o' t' airframe for added strength, me bucko, usin' a combination o' epoxy and micro-balloons.
It was now time t' attach t' fin rin' and fin caps. Begad! Careful attention be paid t' t' alignment o' t' caps so that minimal fillin' o' gaps be necessary. Well, blow me down! Well, blow me down! When t' assembly was completely dried, shiver me timbers, shiver me timbers, ya bilge rat, 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. I used grain filler on t' plywood fins, and after some extensive sanding, was finally ready t' prime t' entire rocket. Avast! More sanding, matey, me bucko, fillin' and primin' followed, o' course, matey, until I was ready t' paint. Avast, me proud beauty! Aye aye! After addin' an 18-foot, arrr, 5/8-inch tubular nylon shock cord and a Sky-Angle 52-inch parachute with Nomex protector, 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, April 7th, 2001. Well, blow me down! Blimey! 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, matey, t' whistlin' only occurred on t' way up.
![]() |
![]() |