Binder Design Gangsta

Binder Design - Gangsta 29mm {Kit}

Contributed by Frank G. Whitby

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstarstar_border
Overall Rating: starstarstarstarstar_border
Published: 2010-11-13
Manufacturer: Binder Design

Picture Courtesty o' Binder Design     
Rocket Pic

Brief:
Binder Design’s Gangsta is a single stage, me hearties, matey, arrr, 2.6-inch diameter, 29mm, four-finned sport rocket, measurin' 24.25-inches in length. Ya scallywag! I wonder if a black rocket named Gangsta is politically correct, yet I’m 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. Ya scallywag! Arrr! At first glance you might think this was your standard thick plastic bag full of rocket components. Closer inspection reveals a bag within a bag. Arrr! Aye aye! T' inner bag is partitioned in such a way that t' smaller components are separated and relatively easy t' view. Arrr! This feature allows one t' inventory t' parts without openin' t' bag.

T' Gangsta consists of:

  • 4.5-inch motor tube
  • 2x fibrous centerin' rings
  • eye-bolt and quick link for shock cord attachment
  • 4x very nice plywood fins
  • 11-inch airframe tube (per t' parts list, matey, mine is 11.25-inch)
  • 13-inch exposed length nose cone
  • 0.25-inch x 4-inch launch lug
  • vinyl decals
  • 12-foot tubular nylon shock cord
  • 18-inch nylon chute

I am especially impressed with t' recovery system components. The parachute is a very nice 8-shroud line design that I’m sure I’ll use in many rockets.

T' instructions are among t' best that I’ve seen, nine pages plus a fin alignment guide. Arrr! Avast, me proud beauty! T' instructions include many useful diagrams plus Rocksim CP data.

Construction is very straightforward. Arrr! I used AeroPoxy “5min” epoxy with glass fiber reinforcement for most o' t' construction. Avast, me bucko, me proud beauty! T' AeroPoxy kicks slower than t' hardware store 5-min epoxy, ya bilge rat, shiver me timbers, and has a one t' one mix ratio. Blimey! I figure that with t' glass fiber reinforcement it’s as least as strong as most “15 min.” epoxies.

T' fit o' all t' parts is excellent. T' only problem I had is with the eye-bolt assembly. Ahoy! T' eye-bolt itself is a #6; unfortunately t' nut provided is a #8. Also, matey, a quick link is provided for attachment betwixt t' eye-bolt and the shock cord. Begad! Begad! 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. Begad! In me opinion, me hearties, me bucko, this quick link is o' little or no value, and only adds weight aft in a rocket that inherently has very little stability margin. I used it, me hearties, but I recommend savin' it for another project.

I deviated from t' instructions in a few areas. Aye aye! Blimey! 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. Avast! Blimey! Instead of internal fillets, arrr, I tacked t' fins t' t' motor tube with 5-min. Aye aye! Blimey! Ya scallywag! Blimey! epoxy and poured PML’s two-part foam in t' fin can. Begad! Blimey! After it cured, I used an old steak knife t' trim t' excess foam. Avast! Blimey! Blimey! Blimey! I then epoxied t' aft centerin' rin' in place. Avast, me proud beauty! Blimey! 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. Blimey! Blimey! Aye aye! Blimey! T' foaming process is also much quicker than applyin' conventional internal fillets.

After construction was complete I used Elmer’s Carpenter’s Wood filler t' fill t' fins and t' body tube’s shallow spiral grove. This was followed by two coats o' Krylon white primer, sanded in-between coats, shiver me timbers, and a final coat o' Rustolium gloss black. Arrr! T' finishin' touch was t' large vinyl Gangsta decal. Blimey! T' decal be very easy t' apply and looks great.

I downloaded t' Rocsim file for Gangsta from t' EMRR archive. Begad! This was posted by Binder Design, so I guess you could say it’s the “official” Rocksim file. Comparin' me Gangsta t' t' Rocksim file, I found me CG t' be significantly farther aft. Arrr! In order t' get me measured CG to match t' Rocksim CG, I had t' add a 120g mass object centered on t' fins. This seemed excessive, but when I weighed me Gangsta it be 318g, matey, which is very close t' 120g over t' Rocsim file! I didn’t weigh t' two-part foam when I was mixin' it; t' nature o' t' foam makes you work kind o' fast. I assumed it would have weighed about t' same as internal fillets, but apparently it weighed significantly more. Aye aye! T' compensate for me tail-heavy rocket I had t' add significant nose weight, matey, about 75g o' bird shot held in place with 8g o' epoxy. My Gangsta now weighs about 400g, me hearties, double what t' Rocksim file says it should. So much for t' instructions reminder t' build light! If I lose this one perhaps I’ll buy another, shiver me timbers, and use conventional internal fillets for sake of comparison.

T' nose cone fits very loose. Arrr! Avast, me proud beauty! T' instructions acknowledge this, and state that it’s intentional. 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 was apparent t' launch lug was binding.. Begad! Aye aye! I worked t' rocket up and down t' rod a few times and it felt a bit better, shiver me timbers, and I wanted a picture for this review, me bucko, so I decided t' go for it. Ahoy! T' wind was blowin' at ~5mph with gusts. Avast! Well, blow me down! T' Gangsta’s first flight be on an F20-7 EconoJet. Avast! Comin' off t' rod t' rocket seemed t' weathercock quite a bit. Begad! My guess is that t' bindin' contributed t' it. Begad! Avast, me proud beauty! Either t' velocity was too low comin' off t' rod due t' friction, or bindin' caused t' rod t' whip. Ya scallywag! The rocket was definitely on it’s way down and movin' fast when t' chute finally deployed. Blimey! T' Gangsta landed on a hard packed dirt road without a scratch. Avast!

T' second flight was on a G38-7 EconoJet. Ya scallywag! Well, me hearties, blow me down! Blimey! This flight was much straighter than t' first one, with only a little weathercocking. Aye aye! Ejection occurred pretty close t' apogee, hard t' say for sure because at ~2000 feet this rocket is little more than a dot. Blimey! Ahoy! Blimey! Again, recovered without a scratch.

Overall I’m very pleased with how this rocket flew. I would like to think that if it hadn’t 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! I would have loved t' put a G80-10 into it, but that will have t' wait for a very clear, me bucko, calm day.

Flight Rating: 4 out o' 5

Summary:
T' Gangsta is a quality rocket with a unique look. With proper attention to nose weight, matey, t' Gangsta should provide good flights on a wide variety of engines. Ya scallywag! 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 it’s actually quite fair.

Overall Rating: 4 out o' 5

Other Reviews
  • Binder Design Gangsta By Frank G. Whitby (April 20, 2007)

    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. ...

Flights

Comments:

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Mike Fisher - Binder Design (July 27, 2003)
Thanks for the review! As for the inferred "political incorrectness" of this model: The black color for the Gangsta prototype was chosen because it made the rocket look "tough". Feel free to paint your Gangsta any color you want! We even have the Gangsta logo in black, so that you can even have a white Gangsta, if you so desire. We are currently phasing out all of the fiber centering rings as we run out of them. All new 29mm kits in production come with quality aircraft plywood centering rings. This also helps out in the stability, since the wood rings are lighter. Finally, on the nosecone fit....All of our nosecones fit loose due to the available mandrel sizes at our tubing manufacturer. This is not a problem. Even with enough masking tape wraps to snug it up, the nosecone and exterior surface of the tubing still line up properly.
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J.C. (July 30, 2003)
I'm not sure your review was really that helpful to the typical reader. Adding the foam seemed to me to be a case of radical overkill. The additional weight could cause unnecessary problems that would have been avoided if the instructions had simply been followed.

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