Giant Leap Rocketry Motor Retainer (38mm)

Giant Leap Rocketry - Motor Retainer (38mm)

Contributed by Dick Stafford

Manufacturer: Giant Leap Rocketry
Rating
(Contributed - by Dick Stafford)

Brief:Rocket Pic
This is a brief review of Giant Leap Rocketry's 38mm snap-ring style SLIMLINE Motor Retainer. SLIMLINE retainers are also available for 29mm, 54mm, 76, and 98mm motor tubes. There are also motor adapters, boat-tail retainers, and a newly released threaded SLIMLINE retainer system.

Construction:
The SLIMLINE retainer system includes a sleeve, a snap ring, and a spacer washer. The instructions come on a single 5" x 8" sheet and include diagrams. The sleeve is black anodized aircraft-grade aluminum (6061-T6), and the two rings are stainless steel.

The main feature is the snap ring that pops into a groove on the inside of the sleeve. This ring is easily visible in the attached photo. Unlike the typical snap rings used on the Kosdon style motor hardware, no special tools are required to install or remove this ring. One end is notched and a small screwdriver is all that's required. This internally mounted ring allows the outer diameter to be thinner than other quick-release retainers do, which is important to reduce aerodynamic drag on minimum diameter rockets.

To install the SLIMLINE, you mount the motor tube so that its protruding behind the aft centering ring. The sleeve is made to fit all motor tubes and should be test-fit for both tightness and spacing. If you don't test fit it with your motor hardware, you may not have enough room between the motor tube and the snap ring to accommodate the motor's thrust ring - this would be a show-stopper! If it's too tight, you sand the tube a bit. If it's too loose, you add small slivers of tape 120 degrees apart. It fit my LOC motor mount tubing just right. As with most bonding applications, the tube should be roughed up. No processing is required on the inside of the sleeve since it is grooved. To glue it on, you slather some heat resistant epoxy such as JB-Weld onto the exposed tube, and twist the retainer on.

The retainer is advertised to work with AT, Kosdon, Ellis, and hybrid motors. For motors with integral retaining rings, you just slide them in, insert the notched end of the snap ring, and then press it in with a circular motion. For motors that don't have a rear thrust ring, the instructions say to glue in a section of coupler tubing at the depth of the longest motor, and then cut additional sections of coupler to form spacers when using shorter motors. You then insert the motor and spacer washer (really more of a retaining ring), followed by the snap ring.

A note on spacing: I was concerned that I might mess up and make it so the snap ring wouldn't fit once there was a motor installed. In addition to checking and double-checking my work, I also inserted the spacer washer, which isn't required for AT hardware. This provided provide a small safety margin.

Construction Rating: 4 out of 5

Flight:
I used this retainer on my Upscale Big Brute. Although I have only flown it once, I have inserted and removed AT casings several times and have formed my opinion: this retainer is pretty neat, but I like the screw type (i.e. Aero Pack) retainers better. The SLIMLINE is a easier to use than "Kaplow" style retainers (I re-use a couple of sets from rocket to rocket, so I have to install and reinstall these every time). The snap ring is very easy to remove, but I'm all thumbs and have to work at getting it on. I don't mean to imply this is really tough, but is not as easy as screwing on a cap. Maybe I will improve with more practice.

Flight Rating: 4 out of 5

Summary:
In summary, the SLIMLINE is a just a tad more difficult to install and use than an Aero Pack retainer. Still, if you're building a minimum diameter model and want to minimize drag, this is the way to go. The final factor is cost. The SLIMLINE currently goes for $20, with its competitor costing $28. However, you can reuse the latter's cap and buy additional housings for $15. You can do the math for your application and needs. I probably will not buy many of any of these machined units, as they are all more expensive than my homegrown or reused clips. But, those boat tail adapters sure look cool...

Overall Rating: 4 out of 5

Comments:

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J.F.D. (August 20, 2002)
I currently use the AEROPACK units on my 29/38/54mm ships. I find them basically foolproof and easy to use with the larger screw on cap. Their multi range adapters (38/29) are real nice. As an aside, you can also have the screw on caps laser engraved with your name, NAR/TRA numbers, etc. Expensive...initially yes. However, as mentioned in the review, after you buy the initial unit (body and cap) you only then need to buy the body for additional ships. I have not used the Giant Leap unit however I did use a similar unit from Binder Design. I found it somewhat harder to use (you need some type of tool to start the snap ring open) and appeared less hearty than the AEROPACK. The small size of the snap ring make it harder to find on a crowed table with the "W" blowing. One caveat when installing either retainer...know what range of motors you intend to use. I measured the Binder unit for an RMS 29mm Hobby Motor and it worked fine. I later wanted to use my 29mm Hi Power hardware and...uh, oh...the aft closure was much thicker and I can't install the snap ring. Measure three times....etc. Finally, the AEROPACK units will not work on AEROTECH motor tubes without a lot of sanding that makes the end of the tube "very thin". I have two ships modified this way and they both have flown OK for several flights.
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J.C. (October 13, 2003)
I had the 29mm motor retainer on a Hawk Mountain Raptor and found that a Dr. Rocket 29/180 aft closure was too big for this retainer. Those who have Dr. Rocket casings should avoid purchasing the 29mm retainer.
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R.H.H. (October 24, 2003)
I have the 54mm X 38mm on a Rocketman Firefly. Installation was pretty easy (during rocket build). The boat-tail look of the black anodized tailcone on the red airframe is spectacular. Motor installation is quick and easy once you get the hang of the Spiralock ring. A very cool product, I'll use it again on future builds.
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A.G. (October 22, 2004)
I installed the 38mm slimline retainer on my Thunderbolt 38 and my AT 38/720 and Pro38 motors fit perfect. I also have the 38/29mm adapter and my AT 29mm lineup of motor casings fit perfect as well. I used my dremel tool to lightly sand the internal surface of the plastic boat tail on my PML Black Brant X to accept the Giant Leap 54mm slimline retainer and this allowed me to keep the rocket looking exactly as designed. The motor retainer is completely hidden and I don't have any hardware protruding out from the bottom to hold my motors in place and it looks and works great.

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