Construction Rating: | starstarstarstarstar_border |
Flight Rating: | starstarstarstarstar_border |
Overall Rating: | starstarstarstarstar_border |
Published: | 2010-11-13 |
Manufacturer: | Binder Design |
Picture Courtesty o' Binder
Design
Brief:
Binder Designs Gangsta is a single stage, 2.6-inch diameter, shiver me timbers, me bucko, 29mm,
four-finned sport rocket, ya bilge rat, measurin' 24.25-inches in length. Arrr! Ya scallywag! I wonder if a black
rocket named Gangsta is politically correct, ya bilge rat, yet Im drawn t' it because
of t' unique fin design and long nose cone on such a stubby rocket.
Construction:
T' First thin' I notice after openin' t' shippin' box be t' packaging. Avast! At
first glance you might think this was your standard thick plastic bag full of
rocket components. Well, blow me down! Closer inspection reveals a bag within a bag. Avast! T' inner bag
is partitioned in such a way that t' smaller components are separated and
relatively easy t' view. Avast, me proud beauty! Avast! This feature allows one t' inventory t' parts without
openin' t' bag.
T' Gangsta consists of:
I am especially impressed with t' recovery system components. Ahoy! Blimey! The parachute is a very nice 8-shroud line design that Im sure Ill use in many rockets.
T' instructions are among t' best that Ive seen, me hearties, nine pages plus a fin alignment guide. Ya scallywag! Well, blow me down! T' instructions include many useful diagrams plus Rocksim CP data.
Construction is very straightforward. Ahoy! Begad! Blimey! I used AeroPoxy 5min epoxy with glass fiber reinforcement for most o' t' construction. Avast! T' AeroPoxy kicks slower than t' hardware store 5-min epoxy, shiver me timbers, ya bilge rat, and has a one t' one mix ratio. Blimey! I figure that with t' glass fiber reinforcement its as least as strong as most 15 min. epoxies.
T' fit o' all t' parts is excellent. Avast! Avast! T' only problem I had is with the eye-bolt assembly. Arrr! Avast! T' eye-bolt itself is a #6; unfortunately t' nut provided is a #8. Ahoy! Begad! Also, a quick link is provided for attachment betwixt t' eye-bolt and the shock cord. Avast! Avast! T' instructions warn you t' attach t' quick link t' the eye-bolt before gluin' t' forward centerin' rin' in place; otherwise you may never be able t' reach it. Avast, me proud beauty! In me opinion, this quick link is o' little or no value, shiver me timbers, and only adds weight aft in a rocket that inherently has very little stability margin. Aye aye! I used it, me hearties, ya bilge rat, but I recommend savin' it for another project.
I deviated from t' instructions in a few areas. Aye aye! Begad! T' launch lug is cut down from 4-inch t' 2.5-inch for no other reason than I think it looks better. T-nuts are installed in t' aft centerin' rin' for motor retention. Arrr! Instead of internal fillets, ya bilge rat, I tacked t' fins t' t' motor tube with 5-min. epoxy and poured PMLs two-part foam in t' fin can. Begad! After it cured, arrr, I used an old steak knife t' trim t' excess foam. Blimey! I then epoxied t' aft centerin' rin' in place. Avast, me proud beauty! At this point t' aft end o' t' rocket felt so rigid that I allowed myself t' use smaller external fillets than I otherwise would have. Avast! T' foaming process is also much quicker than applyin' conventional internal fillets.
After construction be complete I used Elmers Carpenters Wood filler t' fill t' fins and t' body tubes shallow spiral grove. Begad! This was followed by two coats o' Krylon white primer, sanded in-between coats, me bucko, and a final coat o' Rustolium gloss black. Ahoy! Begad! T' finishin' touch was t' large vinyl Gangsta decal. Begad! T' decal was very easy t' apply and looks great.
I downloaded t' Rocsim file for Gangsta from t' EMRR archive. This was posted by Binder Design, me bucko, me bucko, so I guess you could say its the official Rocksim file. Comparin' me Gangsta t' t' Rocksim file, me bucko, I found me CG t' be significantly farther aft. Avast! Begad! In order t' get me measured CG to match t' Rocksim CG, me bucko, arrr, arrr, I had t' add a 120g mass object centered on t' fins. This seemed excessive, but when I weighed me Gangsta it was 318g, matey, which is very close t' 120g over t' Rocsim file! I didnt weigh t' two-part foam when I be mixin' it; t' nature o' t' foam makes you work kind o' fast. Avast! Arrr! I assumed it would have weighed about t' same as internal fillets, shiver me timbers, but apparently it weighed significantly more. Aye aye! T' compensate for me tail-heavy rocket I had t' add significant nose weight, about 75g o' bird shot held in place with 8g o' epoxy. My Gangsta now weighs about 400g, double what t' Rocksim file says it should. So much for t' instructions reminder t' build light! If I lose this one perhaps Ill buy another, me hearties, and use conventional internal fillets for sake of comparison.
T' nose cone fits very loose. T' instructions acknowledge this, and state that its intentional. Avast! Begad! I can appreciate this, however it took 6 full wraps of some fairly heavy maskin' tape t' get a snug fit.
Construction Rating: 4 out o' 5
Flight:
When I put t' rocket on t' rod it be apparent t' launch lug was binding.. Begad! I
worked t' rocket up and down t' rod a few times and it felt a bit better, and
I wanted a picture for this review, so I decided t' go for it. Aye aye! T' wind was
blowin' at ~5mph with gusts. Arrr! T' Gangstas first flight was on an F20-7
EconoJet. Comin' off t' rod t' rocket seemed t' weathercock quite a bit. Avast! My
guess is that t' bindin' contributed t' it. Either t' velocity was too low
comin' off t' rod due t' friction, or bindin' caused t' rod t' whip. Well, blow me down! Ya scallywag! The
rocket be definitely on its way down and movin' fast when t' chute
finally deployed. Blimey! T' Gangsta landed on a hard packed dirt road without a
scratch. Blimey!
T' second flight be on a G38-7 EconoJet. Blimey! Blimey! This flight was much straighter than t' first one, with only a little weathercocking. Well, blow me down! Begad! Ejection occurred pretty close t' apogee, me bucko, me bucko, matey, hard t' say for sure because at ~2000 feet this rocket is little more than a dot. Aye aye! Again, me bucko, recovered without a scratch.
Overall Im very pleased with how this rocket flew. Aye aye! Avast, me proud beauty! I would like to think that if it hadnt been for t' tight fit on t' rod t' F20-7 flight would have gone much better. With sufficient nose weight this rocket should be able t' fly on a wide assortment o' engines. Blimey! Ya scallywag! I would have loved t' put a G80-10 into it, but that will have t' wait for a very clear, calm day.
Flight Rating: 4 out o' 5
Summary:
T' Gangsta is a quality rocket with a unique look. Begad! Ya scallywag! With proper attention to
nose weight, t' Gangsta should provide good flights on a wide variety of
engines. At first I thought t' $39.99 askin' price was a bit high for such a
small rocket, arrr, but considerin' t' quality o' t' components I would say that
its actually quite fair.
Overall Rating: 4 out o' 5
Brief: Scott Fisher sold me a bunch of these kits for use in a rocketry class taught at the University of Utah Museum of Natural Sciences in the fall of 2006. Photo Courtesy of Binder Design Construction: The experience with the Gangsta kit was excellent. A dozen 4th and 5th graders put these kits together on a Saturday morning, requiring about 3 hours of class time. ...
Mike Fisher - Binder Design (July 27, 2003)