Reference / Paper · 2012
Peak of Flight #317: Make A 18mm Engine Retainer From A Water Bottle
Apogee Components' Peak of Flight newsletter, issue 317 (2012-07-17).
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- apogee-components
- model-rocketry
Reference / Paper · 2012
Apogee Components' Peak of Flight newsletter, issue 317 (2012-07-17).
Apogee Components' Peak of Flight newsletter, issue 317 (2012-07-17).
In This Issue Make A 18mm Engine Retainer From A Water Bottle Cover Photo: US Rockets Piston Stager Rocket Kit. Get one at: www.ApogeeRockets.com//Rocket_Kits/Skill_Level_5_Kits/Piston_Stager Apogee Components, Inc. — Your Source For Rocket Supplies That Will Take You To The “Peak-of-Flight” 3355 Fillmore Ridge Heights Colorado Springs, Colorado 80907-9024 USA www.ApogeeRockets.com e-mail: [email protected] Phone: 719-535-9335 Fax: 719-534-9050 I S S U E 3 1 7 J U LY 1 7 , 2 0 1 2 Make A 18mm Engine Retainer From A Water Bottle By Chris Michielssen Are you looking for a way to save money on your rocketry projects? How about recycling a plastic bottle and turn it into an engine retainer. In a recent online post, Geoffrey Dean Johnson developed a very inexpensive 29mm motor retainer. He made it with a screw on Gatorade bottle cap. This is a brilliant idea. Now the wheels start turning . . . While Geoff made a retainer for 29mm, I searched for a way to make a motor retainer for 18mm model rockets. I’ve got a few pint size water bottles in the recycle bin. Why not? It was apparent that this size of bottle cap wouldn’t fit on a BT-20 or BT-50 sized tube because it would stick outside the airframe of the rocket. But, a BT-55 and larger size rocket might work fine. My damaged Semroc Centurion would be a good candidate for the retainer. If it didn’t work out, I wouldn’t be out much. The Centurion recently crashed into a tree after a bad staging separation in high winds. This simple retainer replaces an engine hook in a BT55 or BT-60 mainframe sized rocket. This is very similar to what some mid power rockets use for engine retention, but on a smaller scale. We’ll be using the screw cap and threaded nozzle from a 1 pint plastic water bottle. When installed on the rear of a model rocket: You unscrew the cap, drop in an 18MM engine and screw back on the cap - DONE! No engine hook, no friction fit or tape wraps. The engine will not eject out the back! This simple retainer can be found on the top of 1 pint water bottles. Look for the water bottles with the short white cap. They do this so they can claim the the bottles use less plastic than an ordinary bottle. The good thing is the cap is just under ½” long including the narrow retainer ring. Picture 2: This pintsize bottle can be turned into a 18mm engine retainer. Picture 1: Geoffrey Dean Johnson created this 29mm motor retainer using a Gatorade bottle cap. About this Newsletter Newsletter Staff You can subscribe to receive this e-zine FREE at the Apogee Components web site (www.ApogeeRockets.com), or by sending an e-mail to: [email protected] with “SUBSCRIBE” as the subject line of the message. Page 2 Continued on page 3 ISSUE 317 Writer: Tim Van Milligan Layout / Cover Artist: Tim Van Milligan Proofreader: Michelle Mason J U LY 1 7 , 2 0 1 2 Continued from page 2 Make A Water Bottle Engine Retainer Your next step is to sand the cut smooth on 220 grit sandpaper. As it is now, clear the nozzle piece is too large to fit on the 18mm motor mount tube. We’ll shim it up with cardstock wraps. Cut a two strips of 110 lb. cardstock ½” wide X 11” long. You can use a glue stick to adhere it to the motor mount tube. Wrap the entire strip tightly. When you reach the end, check the fit of the clear threaded nozzle piece. You’ll have to add about five inches more to the strip you just layed down. Picture 3: Cut off the nozzle below the raised bead with a razor saw. With a razor saw, cut off the threaded nozzle end behind the raised band as shown in picture 3. Use the raised band as a guide for the saw. Remove the narrow retainer ring with your hobby knife as shown in Picture 4 to the left. Picture 4: Remove the security seal ring. Picture 5: On the engine mount tube, build up the thickness using thick paper wrapped and glued around the tube. Continued on page 4 Think of the convenience of getting everything to professionally install your dual-deployment or other electronic payload into a e-bay of your rocket! Includes: nylon standoffs, screws & nuts, wire, push-switch, drill & tap, ejection charge cannisters, barrier strips, wire ties, and step-bystep DVD instructions. www.apogeerockets.com/electronic_mounting_kit.asp ISSUE 317 J U LY 1 7 , 2 0 1 2 www.ApogeeRockets.com Electronics Hardware Installation Kit Page 3 Continued from page 3 Make A Water Bottle Engine Retainer Check the fit of the nozzle again and adjust the cardstock wraps until you get a tight slip fit. Install the centering rings as you normally would, butt the lower ring up against the cardstock wrap Picture 6: Butt aft centering ring of and apply glue the engine mount against the paper fillets. strips. For a cutting guide, trace around a BT-5 and cut a hole in the center of the cap. In the end the hole should be round and a little wider than ½” in diameter. For the best fit of the cap against the engine, trim down the inside ridge of the cap as shown in Picture 8 to the right. Install the engine block as normal so the engine casing extends out the back by 1/4”. Remove the casing and allow Picture 8: Carefully trim down the ridge inside the cap. This will allow the motor to be closer to the rear edge. the glued engine block to dry. After the engine block glue is dry, slide an engine casing into the motor mount tube up to and against the engine block. Screw the white cap onto the clear threaded nozzle. Picture 7: Cut a hole in the plastic cap. Use a 13mm tube as a size guide. Slide both the nozzle Picture 9: Slide the cap over the end of the tube. Continued on page 5 Your Cool Rocket Designs Look So Much Better In RockSim Version 9! Design It. Launch It. v9 www.RockSim.com Space Foundation certified as an excellent teaching aid. Page 4 For further information, call Apogee Components at: 719-535-9335. ISSUE 317 J U LY 1 7 , 2 0 1 2 Continued from page 4 Make A Water Bottle Engine Retainer and cap over the extended casing and onto the cardstock wrapped tube. Press the cap and threaded nozzle forward until it stops when the cap touches the rear end of the motor sticking out of the tube. If you did it right, the inside of the cap should be against the rear of the casing. Carefully remove the cap, leaving the threaded nozzle in place on the cardstock wraps. Apply medium CA glue to the joint between the cardstock wrap and the inside of the threaded nozzle. Let dry. At this point, the 18mm retainer is done! All you have to do is complete the construction of the model. Then just slide in an engine, screw on the cap, install an igniter and fly! Picture 11 show how the retainer looks in my well-worn Semroc Centurion. Picture 11: Remember to leave the engine mount sticking out a little, so you can unscrew the cap. The plastic cap doesn’t melt, but may have a little black soot on it after a flight. The water bottle retainer looks like a ridged nozzle out the back of your rocket. It may not be as easy to install as a standard engine hook, but it’s a great change from the ordinary. About the Author Picture 10: Apply medium viscosity CA glue to the joint where the engine tube and threaded portion meet. Chris Michielssen is a master model builder. He is trained as a graphic designer, but currently is a full-time musical entertainer living in Orlando, Florida. He also has a passion for rocketry, and is currently producing kits as Odd’l Rockets (www.oddlrockets.com). In addition, Chris offers a blog on building rockets at: http://modelrocketbuilding.blogspot.com/ We’re Paying Cash For Great Articles for This Newsletter Are you a writer looking for some serious pocket change? We’re paying up to $350 for good how-to articles for this newsletter. If you’re interested, see our submission guidelines on the Apogee web site. www.ApogeeRockets.com/Newsletter/Newsletter_Guidelines ISSUE 317 J U LY 1 7 , 2 0 1 2 Page 5