Rocket Fly-away Rail Guide V1 (DEPRECATED)

thingiverse

**EDIT 22 June 2019** - After more testing I found the hinge on this version may shatter from the impulse of G and H motors (the rockets themselves launched fine / just the rail guide ended in pieces). A new stronger version is at https://www.thingiverse.com/thing:3706482 **Instructions** This is a fly-away rail guide for medium power and high power model rocketry. It's used to launch sport rockets as an alternative to gluing on launch lugs or screwing rail buttons directly onto the rocket body. The guide fits around the rocket with two sets of rail buttons that engage in the launch rail (rails are usually 1010 extruded aluminium). On launch, the guide provides stability as the rocket travels up the rail - as soon as the rocket clears the launch rail the flyaway guide springs open and detaches from the rocket body to reduce drag in-flight. **MILEAGE VARIES - READ THE INSTRUCTIONS CAREFULLY** - you're on your own to ensure this rail guide is OK for your rocket and launch rail - we all want safe launches - please do follow the high-power safety code for your country (e.g. https://rocketry.org.au/safety-information/high-power-rocket-safety-code/ ) There are two versions here: - 2.1" / 59mm ID that's a snug fit for a PML Callisto - 1.6" / 42mm ID for smaller diameter rockets Both are slightly over-size to allow for a little shrinkage when printing - use some electrical tape, foam or similar on the inside to fit the guide securely to your rocket, making sure it's tight enough so that it won't slide down the rocket body when launching, but not so tight that it causes the rail buttons to bind. If the guide doesn't readily spring open, try adding another rubber band and testing it in your launch rail until you have the tension right for your setup. I'd be happy to adjust the .stl model for other diameters if you'd put the exact dimensions of your rocket body and carbon fibre rod in the comments. All i ask is that afterwards please post a photo of your launch! Parts you'll need are: - print out two sets of the STL files for top and bottom - 3 x 8.3mm OD x 300mm long carbon fibre rods - 4 x rail buttons ( https://ausrocketry.com.au/hardware/launch-lugs-rail-buttons/rail-buttons-small-1010-pair.html) - 4 x M4 x 15mm screws with M4 nuts to secure the rail buttons - 8 x M3 x 12mm countersunk screws with M3 nuts to secure the outside carbon fibre rods - 2 x M3 screws to physically secure the centre carbon fibre rod (optional / just-in-case) - 4 x 80mm rubber bands (2 each for top and bottom for redundancy) Assembly is: - first add 4 x rail buttons secured by M4 x 15mm screws with M4 nuts - slide the three carbon rods into the holes each end to create the rail guide assembly - as the rods slide in, pass the rubber bands around each rod as shown in the photo to create a spring - secure the rods with 8 x M3 x 12mm countersunk screws and M3 nuts - drill or tap a small hole into the central carbon fibre rod at the top and bottom (you'll see a small countersunk hole in the .stl file to line up where the hole should go). Screw in an M2 or M3 fastener to prevent the centre pivot from coming apart. - add a thin layer of electrical tape or similar on the inside of the rail guide to provide grip on the rocket body and to protect your paintwork. - its ESSENTIAL that the two halves open freely - if there is any sticking or binding disassemble and sand or file away any rough spots / add a lubricant such as dry graphite to ensure the assembly opens with minimal friction A word on filament: - we've been printing test versions in PLA and had successful launches so far... - settings were 1.75mm PLA, 0.2mm layers, 30% infill, support is required, no brim or raft. - fully assembled weight was around 120 to 150 grams, however, the guide is discarded immediately after the rocket clears the rail - through testing it seems a thicker wall is the key to higher strength prints The finished product is quite strong .... BUT.... - our experience is that PLA is very poor for long term use as it is quite hygroscopic and becomes brittle after a few months - for long term use, definitely use one of the newer high strength filaments that are stable even in high humidity and provide greater shock resistance - even using polycarbonate we've shattered the hinges on launch - take some spares