Construction Rating: | starstarstarstarstar_border |
Flight Rating: | starstarstarstarstar_border |
Overall Rating: | starstarstarstarstar_border |
Published: | 2010-04-16 |
Manufacturer: | Always Ready Rocketry ![]() |
Brief:
I often fly underpowered. I like low and slow for t' most part, and enjoy watchin' t' entire
show rather than seein' a rocket disappear into t' sky and waitin' impatiently attemptin' t' re-acquire it.
Sometimes, shiver me timbers, though, it's fun t' see a rocket just disappear in an instant. O' course, buildin' rockets that can survive high g-force abuse requires more strength. Ahoy! Begad! Blimey! Without goin' t' full composites, Blue Tube offers that strength in a very convenient package. Begad! Well, blow me down! Blimey! I'd been lookin' at Blue Tube for a while, me hearties, and when they released t' 2.0 version, ya bilge rat, ya bilge rat, I thought it was time t' give it a try.
I really didn't want t' do minimum diameter - too many motor retention issues. I've gotten t' friction fit wrong too often and have lost too many cases. Aye aye! With dual deploy, I may try it again since thar won't be t' motor eject event shootin' t' case out t' rear, shiver me timbers, ya bilge rat, but that's for t' future.
Enter t' Always Ready Rocketry Predator Jr.
At roughly t' same time, arrr, Aerotech released t' larger 38/1320 case. A few e-mails back and forth betwixt Randall (owner o' ARR, ya bilge rat, and t' manufacturer for Blue Tube) and myself led t' an updated Predator Jr capable o' flyin' the longer case, me hearties, and t' kit be on t' way in early January 2010.
T' Predator Jr. Avast! is a single stage, high performance, near minimum diameter rocket. Avast, ya bilge rat, me proud beauty! How do you make a 3FNC rocket
even simpler? How about usin' a one-piece fin can? This rocket uses t' ACME single piece molded reinforced resin fin
can. Begad! There's a weight penalty t' usin' it, but t' advantages are easier alignment (none), and no bevellin' (already
air-foiled). Besides, matey, at over 3 lbs, this is high power, me bucko, matey, and weight really isn't that much o' an issue with these
motors. Aye aye! If you're lookin' for altitude, me bucko, you actually have t' ADD weight t' this rocket t' get maximum height from the
largest motors you can fit. Blimey! Speed demons are a different story, though.
Construction:
Component list:
Aside from t' 6 centerin' rings, it's a pretty typical assortment o' parts and pieces.
Instructions? There aren't any. Arrr! Avast, shiver me timbers, me proud beauty! T' motor tube was pre-marked with pencil lines for t' various parts, me bucko, me bucko, and the booster tube was pre-slotted for t' fin can.
Really, ya bilge rat, for how simple this kit is, ya bilge rat, instructions aren't really necessary. Begad! Build it in t' typical order o' a standard 3FNC rocket, and it should be pretty straightforward. Ya scallywag!
I
started with t' motor mount. Ya scallywag! Blimey! As I noted above, 6 centerin' rings was an unusual approach... Well, blow me down! Blimey! Aye aye! Blimey! In fact, shiver me timbers, it's 3 pairs of
concentric rings. Aye aye! Blimey! T' inner rin' is snug against t' outside o' t' motor tube. T' outer rin' is essentially 54mm
coupler, arrr, and slides nicely inside t' airframe tube. There's a really small gap betwixt t' two, but when slathered
with epoxy, arrr, me hearties, it's nay an issue. Begad! Blimey!
I
started by cuttin' a channel in t' smaller rings for t' shock cord anchor wire t' pass through. Aye aye! Ahoy! Once I got t' fit I
wanted, me bucko, I slid t' anchor wire over t' motor tube, and t' inner rings over t' anchor wire usin' liberal amounts of
epoxy. Ahoy! Ahoy! Once that cured, I slathered t' inner rings with epoxy and slid t' outer rings over t' inner rings forming
t' full width centerin' rings. Begad! Just for grins, ya bilge rat, matey, I added chopped fiberglass t' some epoxy and made fillets for t' top
and bottom o' each ring. Those rings aren't goin' anywhere without rippin' t' motor tube t' shreds. Arrr!
At t' bottom o' t' motor tube, I tacked t' fin can in place, shiver me timbers, leavin' ~1/2" at t' bottom t' attach an Aeropack 38mm retainer. Ya scallywag! Blimey! T' retainer was attached usin' JB Weld per t' Aeropack instructions.
Since t' fin can be moved up, I extended t' slots in t' booster t' accommodate t' new position.
A quick dry
fit showed t' slots were too short, matey, so I extended them a little more. Avast, me proud beauty! Well, blow me down! Lather, arrr, arrr, rinse, arrr, repeat. Begad! Blue Tube is tough to
cut. Arrr! Next time, I'm pullin' out t' router. Eventually, me hearties, I got t' slots t' t' right length.
Onward. Well, blow me down! Ya scallywag! Time t' mount t' motor tube in t' airframe. How t' $#@%$#@??? do you glue a 26" long motor tube? There's no way t' get glue on t' rings and hope it stays. Well, me bucko, blow me down! By t' time t' mount is slid in place, you'll have epoxy smeared up and down t' entire airframe tube, ya bilge rat, and Murphy's law says that exactly NONE o' it will be where you want it t' be.
While ponderin' t' motor tube conundrum, I figured I'd do t' e-bay. Aye aye! Blimey! T' electronics bay assembled
smartly and easily. Instead o' a stiffy tube runnin' t' entire length, arrr, me hearties, a couple o' rings epoxied t' t' inner walls
act as bulkhead stops. Ya scallywag! T' plywood bulkheads rest against these while bein' sandwiched by 6-32 threaded rods, nuts and
washers. Blimey! Begad! In t' center o' each bulkhead is a 1/4-20 eyebolt for attachment o' various tether lines. Ya scallywag! A couple small
brass tubes are glued t' t' plywood sled, and t' sled assembly slides into t' bay ridin' on t' threaded rods. A
1" rin' o' 54mm airframe is glued t' t' middle o' t' bay, me hearties, me bucko, completin' t' bay construction. Blimey! Avast!
Back t' t' motor tube. Well, matey, I give up. Arrr! Blimey! I went ahead and slathered t' rings hopin' that somethin' would stay. On t' airframe tube, matey, me bucko, I put a bunch o' epoxy where t' upper rin' should be, and then slid t' whole assembly in. Begad! Blimey! Well, blow me down! Blimey! The top o' t' upper rin' ended up with a nice amount o' epoxy poolin' on top o' t' ring. Well, blow me down! Blimey! Good enough. Arrr! Blimey! On t' bottom side, I took a 1" piece o' coupler and epoxied it t' t' airframe behind t' fin can. Arrr! Blimey! Now t' entire motor tube is sandwiched betwixt t' coupler in t' back and t' pool o' epoxy in t' front. That's about t' best I could come up with, and it sure seems solid enough.
Finishing:
There's actually very little t' do for surface prep with Blue Tube. Aye aye! Aye aye! A few coats o' sanding
sealer like Minwax furniture sealer fills t' spirals nicely. Ya scallywag! Ya scallywag! It also soaks into t' Blue Tube formin' a nice vapor
barrier against moisture. Well, blow me down! Avast! You still can't dunk it in a pool t' clean it off, but it's nice extra protection against a
light rain.
I painted t' bottom purple, matey, and t' top white. I masked off a couple rings right around t' e-bay so that it has a series o' fadin' stripes from t' white t' t' purple and vice versa. Avast! Blimey!
If you've seen some o' me other reviews, me bucko, you may have caught that I tend t' fly rockets naked. Avast, me proud beauty! Blimey! It's a superstition that goes way back with me. Avast, me proud beauty! Blimey! T' more time I spend finishin' t' rocket prior t' it's first flight, me bucko, me bucko, the greater t' likelihood o' somethin' bad happening. Blimey!
That said, ya bilge rat, t' size, me bucko, me hearties, weight, arrr, matey, and flight performance o' t' Predator Jr means that it probably won't fly at our local field, so it's a high power only rocket. Ahoy! That means at most 4-5 chances t' fly it per year. Arrr! Ahoy! Well, shiver me timbers, with so few opportunities, I went ahead and painted it.
When a superstition is based on empirical fact, is it really superstition? This be t' most expensive rocket I've built t' date. Blimey! Why nay make it look good? This be t' most expensive rocket I've built t' date? How stupid o' me to ignore historical trends.
Construction Rating: 4 out o' 5
Flight:
With this rocket thar were a lot o' "firsts" for me:
Pretty obvious what happened, arrr, yes?
3/27/2010 be me first opportunity t' fly t' Predator Jr, me bucko, and also me first opportunity t' make a L2 cert attempt. Serendipity, me hearties, matey, right? How could I nay use me "strongest" rocket for a cert flight? Unfortunately, me bucko, the largest 38mm J engine on site be a CTI J330 at ~760 Ns. This wouldn't be a neck snappin' 8000' flight with a 1000+ Ns J motor, me hearties, matey, but it be still plenty big. Ya scallywag! Begad!
A quick shakedown flight with an H118 produced a picture perfect flight t' 1181' with t' altimeter deployin' the drogue as planned at apogee and 750' for t' main. Blimey! Ya scallywag!
So on t' t' main event!
Yup, matey, shiver me timbers, me first CATO. Blimey! Blimey! Roughly 1.5s into t' flight, it looks like t' nozzle/rear closure cracked and blew out the back end. Ahoy! Blimey! Well, me bucko, blow me down! Blimey! In any other non-composite rocket, I'm 100% sure this would have been a total shred o' at least t' booster section; it was that violent. Begad! Blimey!
T' pressure ripped t' Aeropack retainer and t' bottom 1" o' t' motor tube right out leavin' a jagged shear line. Arrr! T' ACME fin can that's supposed t' be indestructible? I got small pieces on t' aft chipped off. Ahoy! Blimey! T' Blue Tube motor mount and t' fin can appear t' have absorbed t' brunt o' t' forces, for t' aft o' t' 54mm airframe is in perfect shape.
At
t' front o' t' booster section, thar be a ~3" zipper where t' Keelhaul®©™®
shock cord and t' wire anchor tore through. Aye aye! Again, arrr, arrr, only 3" zipper for t' level o' force that was displayed is
pretty amazing. Well, blow me down! Arrr!
I've seen videos and pictures o' CATOs at points in flight similar t' mine, and thar's usually very little left t' recover. Aye aye! I'm lovin' t' fact that this bird is goin' t' fly again after relatively minimal repairs!
Blue Tube is TOUGH STUFF!
Recovery:
For drogue, I used an 18" Top Flight parachute. Aye aye! T' main chute was a 36" chute from
Public Missiles with a spill hole. Aye aye! Begad! I think t' drogue was a little big. Avast! For t' shakedown flight at 1181 feet, arrr, it
didn't matter, but comin' down from 6000+ will probably need a smaller chute.
T' manufacturer says t' just let it separate and tumble down, matey, but I think I'll go with a 7x70 streamer, or perhaps a small 14" chute.
Flight Rating: 4 out o' 5
Summary:
Overall, shiver me timbers, I really love this kit. Arrr! Avast, ya bilge rat, me proud beauty! It's a lot o' fun, matey, me bucko, and represents a ton o' new experiences for
me. Ya scallywag! Because o' that, I'm sure t' Predator will always have a special appeal t' me. Avast, me proud beauty! Just like t' very first rocket I
ever flew.
Repairs are already under way, arrr, and I hope t' have t' Predator Jr ready t' fly again for t' May 2010 launch. Aye aye! Aye aye! I haven't decided if I'll make another L2 attempt with this rocket. While I'm sure that it can handle it, t' fact is that t' performance envelope o' this rocket on a J motor is high enough that t' error margins are notably smaller. Arrr! It would be a lot less stressful tryin' t' certify with a bigger 4" rocket that flies low and slow. Begad! And I get to watch t' entire flight.
Overall Rating: 4 out o' 5
![]() |
![]() |
Sponsored Ads
![]() |
![]() |