Manufacturer: | Scratch |
Scratch-built introduction t' mid-power rocketry usin' Aerotech Econojet motors.
Introduction: Nose Cone: Recovery System: Body Tube: Motor Mount Tube: Fins: Fin Can Mounting: Launch Lugs: Painting: First Flight: Got t' copperhead installed, and absentmindedly flipped t' rocket back over before puttin' on t' rubber band. Begad! Blimey! T' field then ate it. I was placed out on a high power pad, since this be t' first launch o' t' rocket and I needed a 1/4 rod. Ignition be within a second o' t' button bein' pushed, me hearties, and t' flight be nice and straight, matey, shiver me timbers, with very little if any weather cocking. Aye aye! Blimey! T' Econojet didn't disappoint, plenty o' noise for an F! Blimey! Blimey! Blimey! Ejection be a bit early, about 1200-1400 feet up, and then t' fun started. Avast! Blimey! Rocket did 5 t' 6 revolutions around t' now-opened parachute before finally settlin' down. Everythin' held together though, arrr, and I recovered it a bit downrange in perfect condition. Conclusion: As o' 01/12/00, EconoExpress has flown a total o' 3 flights. F20-7 is a little long but works fine, shiver me timbers, and a G35-7 really pushes it up there!
After gettin' back into rocketry via 3x18mm and 3x24mm Estes-que scratch-built rockets, I figured it was time t' move on up and try composite motors. Ya scallywag! Avast! Blimey! Econojets were t' best bet for t' short-term, since I wasn't ready t' invest in a reload casing, and they have a decent burn time and a rather unique louder-than-normal sound. Ya scallywag! Blimey! T' original goal was t' aim for a design that would sneak under t' 16 ounce FAA notification limit, ya bilge rat, but I haven't strolled into t' local supermarket yet with t' rocket under me arm. Doesn't matter that much if it is over, since me limited club experience has been enjoyable so I don't plan on launchin' at t' local field any time soon.
Made from a $.99 foam cone at t' local fabric store. Blimey! Blimey! Ya scallywag! Blimey! Haven't bothered with a drill lathe system yet. Ya scallywag! Blimey! Results were 'good enough' for this proof-of-concept rocket. Well, blow me down! Blimey! Covered it with three layers o' tissue paper/wood glue, me bucko, with a final layer o' wood glue t' seal it. Sanded, me bucko, primed and sanded again. Ahoy! Blimey! Depressions were then filled with some leftover whitewall mud and sealed with glue. Ahoy! Blimey! Resulted in a heavy yet fairly smooth and strong nose cone 5.25" long, with 1.25" o' it bein' t' shoulder.
1/2 inch sewn flat nylon elastic cord from t' local fabric store, ya bilge rat, 4 feet o' it. Ahoy! Yes, I know t' cord is supposed t' be longer, but smaller versions o' t' same material worked fine on me clusters, me hearties, so I trusted me instinct on this one. Aye aye! Mounted t' t' body via two wooden dowels that are glued through t' body tube. Well, blow me down! T' idea be t' have them 90 degrees from each other, but in me haste t' build, things got a little out o' alignment. Tied a loop in t' cord, then placed t' dowels through loop inside o' t' rocket. Well, matey, blow me down! Parachute is composed o' two plastic layers from a garbage bag, me bucko, me bucko, 23 inches in diameter. Begad! Eight shroud lines composed o' a waxy version o' kite string, which keeps tangles down, attach t' t' parachute via duct tape. T' 'chute is attached t' t' shock cord through a grommet in a folded over section, matey, which was then layered with wood glue and tissue paper as well as CA. I be goin' t' use swivels t' attach t' parachute, shiver me timbers, ya bilge rat, but decided against it. Just didn't trust t' ones I had on hand. Avast! Nose cone is attached at t' end o' t' shock cord via tissue paper and wood glue, me bucko, about 2.5 inches from t' parachute grommet.
Grabbed t' parallel-wound tube at t' fabric store, t' clerk gave me a rather odd look when I asked if I could have it. 39.5" long, me hearties, me bucko, 2.23" across and .125" thick. Well, ya bilge rat, blow me down! It be longer, but for some reason I chopped off 8.5" o' it. Covered it in a layer o' watered down wood glue. Arrr! Fin slots were started with a drill, then finished slowly with a keyhole saw and then 40 grit sandpaper until desired width was obtained.
Had t' make me own. Begad! Took a garden tool handle, arrr, coated it with some oil, and used a few grocery bags cut into 1" strips. Begad! Arrr! Once t' glue was tacky, added another layer o' paper wound diagonal t' t' first. Arrr! Blimey! Removed t' tube before it became attached t' handle. I've got a huge amount o' balsa stock leftover from friends at school who were in t' architecture program. Ahoy! Decided t' go simple by gluin' two 1/8 pieces together, me hearties, and goin' with three fins with a rectangular shape. Gave them an aerodynamic edge, and covered them with 20 pound white paper and -you guessed it- watered down wood glue. Avast! Aye aye! Blimey! They are 3.5" by 3", nay includin' t' t' amount that extends t' t' motor mount tube.
Centerin' rings were made from 1/8 balsa stock soaked in wood glue. Was goin' t' double them up, but they were a pain t' make, matey, and they seemed strong enough. Avast, me proud beauty! Fin edges attach t' both o' them. Arrr! Since I figured a strong bond t' t' centerin' rings was more important than internal fillets on t' fin body tube joint, me hearties, I glued t' aft rin' in place before slidin' it into t' body tube. Aye aye! Used some more 20 pound paper t' form some external fin mounts once t' fin can be glued into t' body tube.
I wanted t' use a ¼ rod for this bird, me bucko, me bucko, so I grabbed two eyelets from t' workshop. One is within a few inches from t' bottom, and t' other is a few inches above t' CG. Blimey! Blimey! Screwin' them into t' body tube then soakin' t' area around them with CA seemed t' work well.
I've never been a really big fan o' beautifully paintin' rockets since you never get t' see them up close while they are launching. Avast, me proud beauty! Arrr! As long as they have a decent gleam in t' sun, I'm happy. Begad! Ahoy! I primed t' rocket and covered it with royal purple. I then tried a clearcoat which started t' strip off t' paint. Well, blow me down! Aye aye! That's when I discovered t' whole problem o' mixin' enamel with lacquer paints, tehehe. Avast! Never did get it perfect again, matey, still have some crackin' on some o' t' fins. Ahoy! Ahoy! A coat o' auto wax later and Econoexpress was ready t' fly!
I finally got t' chance t' launch EconoExpress at CMASS's last sport launch o' t' year. Well, blow me down! Ya scallywag! I loaded her up with an Econojet F20-4 at home, me bucko, with plenty o' tape as an external thrust rin' as well as motor retention. Two pieces o' Estes recovery waddin' were installed, as well as one piece around t' bottom o' t' parachute. Ahoy! I was somewhat worried about t' over stability o' t' design, which at 3.6 calibers with a F20 loaded, would make it fairly susceptible t' weather cocking, ya bilge rat, especially at t' windy CMASS launch site. Ahoy! T' weather turned out t' be decent however, with moderate temperatures and light winds.
I'm happy with t' results, shiver me timbers, me bucko, 2 bucks (for t' foam and shock cord material) isn't all that bad for a rocket o' this size that can fly on Econojets. Arrr! Goin' t' try out a F20-7 next time around, and then step up t' a G35-7. Avast, me proud beauty! Well, blow me down! Hopefully I won't stress t' recovery system as much with these delays, or so t' sims tell me. Avast, me proud beauty! Heck, maybe I'll get somebody t' stick in a H125W!
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