\u00a0Article: 1355
\nBy: David Randall, Nov 2009<\/p>\n
So, you opened up your spiffy new kit, bought\u00a0your epoxy and paint, and you’re reading the instructions… “Requires motor retention (not included)”.\u00a0\u00a0 ACK!\u00a0 So, now you’re trying to figure out what type of motor retention you need…\u00a0 For those of you who’ve built a zillion rockets and have your favorite retention method, don’t expect to learn something completely new.\u00a0 For those of you getting started, read on…<\/p>\n
For\u00a0purposes of this article, there are basically two types of rockets.\u00a0 Those that are built and don’t have motor retention (yet) and those that haven’t yet been built.\u00a0\u00a0\u00a0 This short article is going to sound a bit like an advertisement, but rest assured, I have no stock in Aeropack.\u00a0\u00a0<\/p>\n
Link to Aeropack’s motor retention information is here<\/a>.\u00a0 You can find them from a number of vendors.\u00a0 Take a look on our links page <\/a>for vendors.<\/p>\n If your rocket is not yet built – get the Aeropack retainer for your motor mount tube type.\u00a0 If you’re rocket is built already, you may be able to use the Aeropack Universal retainers.\u00a0 These bolt on to your centering ring and give you the same great quick change ability.\u00a0<\/p>\n Yep, you’ll probably wince a bit at the price.\u00a0 Save a few pennies if you need to wait to buy the retainer, but buy the retainer for your motor mount size and tubing type.\u00a0\u00a0 It’s worth it.\u00a0\u00a0 When you get your retainer, install, admire and be glad you made the right choice…<\/p>\n That’s it.\u00a0\u00a0\u00a0 Not particularly exciting, but that’s my story and I’m sticking to it.\u00a0\u00a0<\/p>\n Here’s why I like them.\u00a0 1)\u00a0 They are very easily installed on your rocket.\u00a0 2)\u00a0It takes all of 3 seconds to secure your motor. 3) They wipe off cleanly and easily in the field – both from dirt and from exhaust gases.\u00a0 4) They fully adhere to the KISS principle.\u00a0 5) You can easily step down in size with Aeropack’s adapters.<\/p>\n While I don’t have first hand knowledge of using the “Slimline Kwik-Lok”, it\u00a0appears functionally equivalent to the Aeropack – although it has finer threading.<\/p>\n Ok, Ok, Ok… you’re craving more information – after all, this is an article… Here’s my experience<\/em> with various types of motor retention, and for the most part, why I don’t like them.\u00a0 I’m not going to call out specific products here, or post links.\u00a0 If you spend some time looking at other\u00a0rockets at your next launch, or perusing the internet, you’ll run across most of these methods or devices.\u00a0 And, I’m not saying that these other methods don’t work, I’m simply saying that for me<\/em>, they don’t work nearly as well as the Aeropack retainers do.<\/p>\n 1. Snap-ring based retention rings.<\/strong>\u00a0 These are similar to the Aeropack – its\u00a0 a section of aluminum tubing with a groove machined out.\u00a0\u00a0You epoxy it\u00a0onto your motor tube and use a snap ring that fits in\u00a0the groove to hold the motor in.\u00a0 Why don’t I like them?\u00a0 A) Snap rings are easier to lose.\u00a0 B) Snap rings require a tool to remove.\u00a0\u00a0\u00a0 I’ve also had experience with one type that was a basic aluminum retention tube and it got eaten up by the exhaust gases and corroded within a few days of not cleaning the retention ring.<\/p>\n 2. Internally threaded retention ring<\/strong>.\u00a0 Yet another tool required, a nifty little –specialty<\/em>– spanner wrench.\u00a0 While the snap ring solution requires a screwdriver to get my snap ring out, I just don’t want to worry about losing my single-purpose tool and then trying to jury-rig something to get the ring in\/out or find one from another flyer at the launch.<\/p>\n 3. Bolts, Washers and Blind nuts<\/strong>.\u00a0 This method is the quick and easy way to get motor retention done – all at a low, low price from your local hardware store.\u00a0 And, I’m guilty of indulging in this method on several of my rockets.\u00a0 Here’s why I don’t like it long term.\u00a0 1) Inevitably the washers get re-used for another project, and I’ll be missing one – the critical one – while trying to get my rocket prepped.\u00a0 2) Especially on larger motors, it’s easy to bend the bolt on a hard landing.\u00a0 That may render the blind nut useless depending on how hard it hits by popping out the blind nut inside your fin can assembly space.\u00a0\u00a0 3) Probably the biggest problem – you can’t always get the washers to hold the motor in place.\u00a0<\/p>\n 4.\u00a0 Screw-in clips<\/strong> – These are small pieces of steel or aluminum, usually in a “Z”, “C” or “S” shape.\u00a0 One end is bolted or screwed to the aft centering ring, the other end hangs over the edge of the motor.\u00a0\u00a0 They are usually good for retrofitting on a rocket, but I wouldn’t recommend them for any rocket you’re building from the start.\u00a0\u00a0 Here’s why\u00a0– 1) They often bend under stress and eventually require replacement.\u00a0 2) They can easily swing to the side and flop around, having no retention benefit at all.\u00a0<\/p>\n 5. Screw on retention plate<\/strong>.\u00a0 This is a piece of aluminum or steel that has a couple of holes in it around the sides.\u00a0 You use threaded inserts in your aft centering ring or possibly use blind nuts, and hold the entire motor in place with the retention plate.\u00a0\u00a0 I had one of these on my very first 29mm rocket – and it was cool.\u00a0 Until 1) It took forever to screw in the fine threaded screws, 2) I couldn’t find the one screwdriver in my toolbox that fit the screws best, 3) the screws got bent and I couldn’t retain the motor with only 2 of the three.<\/p>\n 6. Spring Clips or Wires<\/strong> – While I’ve never used these beyond Estes kits, I’ve seen some that have been put together, especially on minimum diameter rockets.\u00a0 These work reasonable well for 18, 24 and 29mm rockets, but above that, I wouldn’t trust the strength.\u00a0<\/p>\n 7.\u00a0 Blue Tape (aka Friction Fit).<\/strong>\u00a0 Wrap your motor in tape, stick it in, twist, press, twist some more, tape some more and voila! … motor retention and its simplest.\u00a0\u00a0 Works great for your 18, 24 and 29mm motors.\u00a0 Personally, I would only do this for single use motors.\u00a0<\/p>\n So, there you go.\u00a0 I hope this helps you get on your way to great success in flying mid and high power rockets!<\/p>\n – Dave Randall<\/p>\n NAR 84939 L3<\/p>\n","protected":false},"excerpt":{"rendered":" \u00a0Article: 1355 By: David Randall, Nov 2009 Motor Retention – getting started … So, you opened up your spiffy new kit, bought\u00a0your epoxy and paint, and you’re reading the instructions… “Requires motor retention (not included)”.\u00a0\u00a0 ACK!\u00a0 So, now you’re trying to figure out what type of motor retention you need…\u00a0 For those of you who’ve […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":848,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","meta":{"ngg_post_thumbnail":0},"_links":{"self":[{"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=\/wp\/v2\/pages\/1355"}],"collection":[{"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1355"}],"version-history":[{"count":10,"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=\/wp\/v2\/pages\/1355\/revisions"}],"predecessor-version":[{"id":1417,"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=\/wp\/v2\/pages\/1355\/revisions\/1417"}],"up":[{"embeddable":true,"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=\/wp\/v2\/pages\/848"}],"wp:attachment":[{"href":"https:\/\/northwestrocketry.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1355"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}