Modular Rocket system
This project was inspired by the design by Landru however it is completely reworked and extended. There are now many more components. I will publish add-on components as they are tested however this Thing includes the basic set of components which you will need to fly rockets.
For a more powerful rocket, I have published a booster set add-on at www.thingiverse.com/thing:3608759.
The rocket is designed to use Estes motors which are either 18mm or 24mm in diameter (B, C, D series motors). You can buy the rocket motors on the internet or at good model shops. Information about the motors including safety instructions are available at the Estes website. Download the latest Estes Catalogue which includes a chart of the different rocket motor specifications.
Print your rocket
- Select a Fin_18 or Fin_24 depending on the size of the rocket motor you will use. The fin-cans are stackable so that you can optionally have booster lower stages (suggested booster engines C5-0, C11-0, D12-0). You can print the fin can in LPA but the motor retaining clips are less likely to snap off if you use PETG or ABS.
- Print a top stage with a guide loop. Optionally you can print as many intermediate stages as you wish in which case it is better to have one intermediate stage with a guide loop and print the top stage without a loop.
- Print the nose cone. A simple hemispherical nose cone is included which should be a good shape to start with however I will be publishing a nose cone set shortly with many more designs.
- Print the ejection wad. This is needed to protect an optional (recommend) parachute or streamer and push it out of the rocket at the top of the climb.
- Tie a length of flame resistant cord to the loop inside the top of the fin-can. If you are using booster fin-cans then tie the cord to the top one only, to allow the booster stages to fall away once they are burned.
- Thread the cord through any (optional) intermediate stages and the top stage.
- Assemble the (optional) intermediate stages and the top stage to the fin-can. You may need to trim the stages with a knife to get them to fit if the bottom layer has printed thickly. The stages should be a fairly tight push fit. You do not want them to separate when the motor fires to eject the parachute else it may not deploy. If in doubt apply glue to the joints.
- Thread the cord through the hole in the wad and drop the wad down into the rocket stages. The flat surface of the wad should face upwards with the curved surface over the motor.
- Tie the cord to the underside of the nose cone leaving at least 1 foot (30cm) of loose cord.
- Make a lightweight parachute or streamer. Insert it upside down into the rocket with the strings on top. Tie the strings to the underside of the nose cone.
- Place the nose-cone on top of the rocket. It should be a fairly loose fit so that the parachute can deploy easily.
I have published a printable launch pad suitable for this rocket separately at www.thingiverse.co./thing:3595995.
You will require a launch controller to launch your rocket. You can buy one or there is a printable one here. It consists of 2 crocodile clips to attach to the rocket motor igniter, approximately 10 metres of good quality cable (2 core lamp cable is suitable), a battery supplying between 6 and 12 volts, a push button and an optional safety switch.
- Please check the Estes safety instructions. Take precautions as for fireworks. Children should be supervised by a responsible adult.
- Pre-launch check the integrity of your rocket. I will publish detailed information on weight-and-balance calculations with my additional components. Aerodynamics and stability should not be a problem with these basic components.
- Pick a day when there is little or no wind and a large safe area to launch from. I had underestimated the height to which my first rocket would travel and I have no idea where it landed!
- When outside, push a rocket motor into the fin-can. The engine housing prints with a raft so you will need to cut this in 4 places around the base with scissors in order to insert the engine.
- Cut an igniter from the strip and insert it into the engine so that it touches the gunpowder and secure it in place with a plug. Bend the wires of the igniter to the side of the rocket and put a half bend in them (see image).
- Erect the launch pad and guide rod as level as possible. You can adjust the angle of the legs for uneven ground.
- Clip the launch controller crocodile clips to the half bends in the igniter wires. You should check that the switch on the controller is turned off or that the battery is disconnected. Better still, just assume that the controller is live and never stand over the rocket nor have the motor pointing at your face when attaching the wires.
- Carefully slide the rocket guide loops down the wire on the launch pad. Have a final check that the rocket is level and everything of okay.
- Retreat to a safe distance, check that the safe area is clear of people, animals and anything that could get damaged and press the button!
Suggested 3 top and bottom layers, 3 side layers.
This is a thin- wall model. Print without cooling and a print head temperature 10 degrees higher than normal to ensure good adhesion.
The engine tubes are printed with a raft which needs to be cut with scissors so that you can insert the engines.
The petals which hold the engine in place may snap off easily if printed in PLA without good adhesion. The fin-can is best printed in something more flexible such as PETG, ABS or Nylon.