3D Printed CO2 Canister Rockets and Launchpad

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Introduction: 3D Printed CO2 Canister Rockets and Launchpad

About: I am a Hobbyist, Maker and Designer and love to spend my free time getting creative and building new things!

For a long time I have been interested in getting started with model rocketry, but there seems to be a bit of a barrier to entry, with the cost of kits and rocket motors and the general danger of pyrotechnics and projectiles that fly several hundred feet in the air. So I decided to design a more compact, affordable and less dangerous way of experimenting with model rockets. I wanted to design a modular system so I could change the length of the rocket, the design of the nose cone, and the design/size of the fins. I decided to make my rocket system based off of 12g CO2 cartridges as they are cheaper, easier to replace in the field and would produce a more manageable amount of thrust for the experiments I wanted to do.

This then involved two separate builds, a safe method to puncture the CO2 canister, preferably from a distance, and a rocket system with the CO2 cartridge at its center.

Supplies

A 3D Printer

Spool of Filament

12gm Co2 Cartridges

2 9.1x34.9mm Compression Springs

1 5.6x17.5mm Compression Spring

1 2.4x14mm O Ring

(Optional) 1 2.4x20mm O Ring

1 2.6x50mm Nail

4 6x150mm Nails

Super Glue

String/ Fishing Line

Step 1: Parts

Start by printing out the attached files, some of them have a few versions depending on the design you want to create. I, like most people who are used to 3D printing avoid support material in my designs as much as possible. Therefore, all of the attached files can be printed without supports apart from the "Launch Pad Top' file. As I am still an amateur when it comes to rocket design, I don't claim to know what is most aerodynamic or how to balance center of drag and center of mass, which is part of the reason I have designed the system in this way. I have made a pointed nose cone and a slightly rounded nose cone design. There is currently only one version of the fins however, I will continue to make different fins and nose cone designs to allow mixing and matching and see which combinations work the best.

I have this set of springs, which includes both of the sizes used in this design, however you can buy the springs individually or find similar springs to use. https://www.amazon.co.uk/gp/product/B00IJYC1DI/ref...

I also own this set of O rings so have used two sizes within this set, however the same applies as the springs. https://www.amazon.co.uk/gp/product/B07ZRC4FXJ/ref...

These are the 12gm CO2 cartridges I used. https://www.amazon.co.uk/gp/product/B00345AQNY/ref...

Step 2: Remove Support Material

The support material is fairly easy to remove as it is only on this one part. Be gentle while removing the supports to ensure you don't damage the part or the threads in the model.

Step 3: Assembling the Launch Mechanism

Start by sliding the 5.6x17.5mm spring onto the trigger part, this may require you bending the PLA of the part slightly to put the spring in place.

Compress the spring then place the trigger mechanism in the launch pad base as shown.

Once the internal components are assembled, place the launch pad top on top of the assembly and use the launch pad nuts to secure the assembly together. This will hold everything tightly in place. Be careful not to overtighten these parts as it is easy to split the layers of the threads.

Step 4: Installing the Firing Pin

In order to actually puncture the canister, place a small bit of super glue in the Launch Firing Pin piece and then slide the nail through. This may be a tight fit, so a bit of sandpaper can help, and also help to remove any excess glue that could clog the mechanism once the nail is in place.

Then, take the two larger 9.1x34.9mm springs and place them in the base. I have found one spring is not strong enough to piece the aluminium seal of the canister consistently however two works just right. then place the Launch Sled in the Launch Pad Rocket Holder then begin to thread this piece into the base, ensuring the springs slide into the hole properly.

Once these pieces have been successfully assembled, the launch pad mechanism is complete. It works by compressing the firing pin while pulling on the launch trigger. Then release the launch trigger so that it engages in the slot in the firing pin. I find that the head of a 150mm nail works great to safely compress the firing pin assembly while arming the system.This will make the launch mechanism armed, and pulling the trigger will release the spring loaded firing pin. There is a hole in the end of the launch trigger to allow a piece of string or fishing line to be attached to allow the mechanism to be triggered from a distance.

On the base part, there are three holes on the outside of the assembly that are used to securely mount the launch pad to hold it in place. I did this by placing 3 150mm nails through the holes and pressing them into the ground. However, you could also use these mounting holes to screw the piece into a sheet of plywood or other surface to keep it secured while the trigger is pulled.

Step 5: Installing the Rocket Guide

Once the launch pad is assembled, a 8mm wooden dowel can be placed in the remaining hole in the assembly. this will guide the rocket so it fires straight up as opposed to spinning out of control (hopefully).

Step 6: Installing the CO2 Canister

Once you have the rocket fins off the printer, install the smaller O ring on the base of the rocket to create a good seal on the base.

Then slide the CO2 canister into the opening of the part and if the canister is loose in the part (depending on your printer tolerances, you can place a larger O ring to secure it in place.

Step 7: Finish Assembling the Rocket

Screw the domed connector screw into the nose cone with the dome facing outwards. This domed surface will press flush against the CO2 canister and hold it in place when the nose cone and fins are screwed together.

Step 8: Your CO2 Rocket and Launch Pad Is Finished!

Now that the mechanism is finished it is time to test it.

Step 9: Blast Off!

Now i'm going to be honest, these rockets were extremely fun to make but did not fly the highest or straightest. But then again, I am still only an amateur rocket scientist.

They are a great alternative to pyrotechnic propelled rockets and the launch pad mechanism will work with any CO2 canister rocket design with the appropriate base to fit in the launch pad. I am therefore going to keep experimenting with different fin and nose cone designs, as well as playing with the weight and dimensions of the rocket as a whole.

Step 10: Design Your Own!

This kit will be a great starting point for your own amateur rocketry experiments and I will keep releasing new parts to try or you can design your own parts to use in this system.

The threads used to connect the two halves of the rockets are M22x3, you can use this to design your own fins and nose cones around my current system. I have also attached two blank files to this step. One is the fin part of the rocket without fins or connector, and the other is a model of the CO2 canister. I hope these files help you build your own unique model rockets!

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    26 Comments

    0
    gldgrobler
    gldgrobler

    9 months ago on Step 9

    Hi. Thank you very much for the launch pad plans. I will adapt them for CO2 Car racing for young children. I have been trying to figure 1 out myself. no luck so far.

    0
    kjellgnilsson.kn
    kjellgnilsson.kn

    Question 1 year ago on Step 9

    I have now printed three nose cones with various infill percentage and layer height.
    No one of them have any threads but in the Cura program it look that there are threads.
    They come out very thin and empty. What can the problem be? Do you have recomended setting. I use an Ender 3 Pro. Thanks for an answer. Kjell

    0
    cdavenport
    cdavenport

    1 year ago

    Not fussin, jus' discussin' it appears to me that your rocket instability is due to its short length with a heavy cylinder at the tail end which puts the center of pressure too close to the center of gravity. Ideally, for a stable rocket without active guidance, the center of pressure should be well aft of the center of gravity. Concerning the altitude....the 3D printed stuff is just too heavy for the specific impulse of the CO2 cartridge. Thus, to improve stability, you have to make the rocket body longer or increase the size of the fins which makes the model even heavier. Perhaps the answer is to make a CO2 adapter that fits commercially available paper rocket tubes & nose cones with balsa wood fins. Another really cheap option is to make a screw-on CO2 adapter for 2 litre soda bottles!

    0
    RefiningDesigning
    RefiningDesigning

    Reply 1 year ago

    These are some great ideas! I knew that using 3D printed parts would have some restrictions due to the weight of the parts, but for my purposes, I am just really enjoying the accessibility and ease of customisation that 3D printing offers. I definitely agree with what you were saying about needing the body of the rocket to be longer, so I will try to incorporate that in version 2 and will focus on having the weight down as much as I can by making the walls thinner and trying to keep the Infill of the printed parts low. I was thinking of making an adapter to launch paper rockets as well actually but was struggling with how to direct the airflow after puncturing the canister, but I will let you know if I manage to revisit that point!

    0
    cdavenport
    cdavenport

    Reply 1 year ago

    Across the void of the internet, it seems to me that you need to design a 3D printed "booster insert" that fits into a paper rocket body in the same manner than a propellant rocket engine does. In your case, the CO2 cartridge would fit inside this insert which also includes a nozzle section. Then, the whole shebang fits into the rocket body. NOW, if you design the booster insert with a loose fit, you can design a parachute section into the booster so that some spring action in the rocket body forces the heavy booster section out. My Inventor design package is down right now or I would work up a quick design for you. Your whole idea is really fun, but is constricted by the heavy weight of the cartridge at the exact point where the center of pressure is greatest. You know, the other option is to move that cylinder up into the rocket body! Put an exhaust nozzle at the end of the rocket and let the cartridge pressurize the aft end of the rocket body. Those rocket bodies are designed to withstand the pressure generated by the parachute ejection charges of propellant rocket engines. I'm looking forward to seeing how you solve this problem! Good luck!

    0
    cdavenport
    cdavenport

    Reply 1 year ago

    Just thought of another idea. Treat the cylinder as if it were an aerodynamic payload and mount it on "top" of the rocket with the rounded end of the cylinder acting as the nose cone! Then, use the idea that other fellow cited: a spring-loaded plunger can puncture the cap in the cylinder from the bottom of the rocket. You'll need to play with some exhaust nozzle designs, but YOU CAN DO IT!

    0
    banman11
    banman11

    1 year ago

    I love it! Can you post some videos please...

    Keep up the awesome designs.

    0
    UnknownPro
    UnknownPro

    1 year ago

    Very cool idea - an easy way to get straighter flights is to get the weight closer to the tip (having the centre of gravity well forward of the centre of pressure). The weight of the cartridge is a challenge there but easy to simulate. Have a try with http://openrocket.info/

    0
    cdavenport
    cdavenport

    Reply 1 year ago

    Hope our rocket designer is reading our comments.

    0
    RefiningDesigning
    RefiningDesigning

    Reply 1 year ago

    Yeah the cartridge is a bit of a difficulty to work around but I may have a play with how the weight is distributed!

    0
    fstedie
    fstedie

    1 year ago

    I 3D print little rocket cars, so I know these canisters can pack a punch. My thoughts:
    1)You probably don't really need the o-ring, it will likely just cause unnecessary friction
    2)Definitely use the 3-vertical post launch guide idea
    3)You can move the canister up into the body and use a longer nail to access it
    4)Others have launched rockets by dropping them into one end of a 5-ft pvc tube with a nail at the bottom. Only problem is that you would need to find a way to "activate" the fins once launched since the rockets don't fit in the tube w fins.
    5)Parachute?

    Thumbs up!

    2020-02-19 10.05.18.jpg
    0
    RefiningDesigning
    RefiningDesigning

    Reply 1 year ago

    This is some great feedback! Thanks for your input! You made several good points, so allow me to address them each.
    1. I wasn't sure if the O ring was necessary or not, but I found that it held the rocket in place and allowed the pin to puncture the canisters seal, as if it was just left loose that the rocket would more likely just pop out without rupturing the canister. If I changed the design to something more similar to your suggestion in point 4, then that may get rid of the resistance the O ring provided and make the rocket fly better.
    2.I think I am going to do a V2 with those new launch guides and see what improvements it makes to the flight.
    3. I had actually been considering the last 3 points when designing, and might try to make a few changes and see how it affects things. As for moving the canister up into the body and using a longer nail, that would be a pretty easy change to make in my original fusion 360 file, I just did not know if that would effect where the thrust was being generated and make the rocket more unstable, but I will give it a try because I honestly am not sure the science of how that may effect things.
    4. I may play around with a rocket design with some spring loaded fins that deploy and see if using this method is more efficient.
    5. This is the one aspect I am struggling with a bit, as normal model rockets have a secondary charge included in the rocket motor to blow off the nose cone and release a parachute, since I am using the CO2 canisters I will have to find a mechanical alternative, maybe rigging some way to put a time delay spring loaded ejector, but it will take a fair amount of trial and error to determine the right time delay as Id like to wait for the canister to run out to get the most flight time, since the ejection charge and the rocket motor in traditional motors are linked together, it is easier to control the timing of the parachute release. So this is definitely something I am going to try and tackle but at this point its a bit tricky until I arrive at a flight design I am happy with.

    P.s. Those rocket cars look awesome! How do you go about puncturing the CO2 canisters if you use a similar principle? I might have to try my hand at a rocket car now. We could start our own racing league.

    0
    drinklifeup
    drinklifeup

    1 year ago

    This is so awesome. Love the idea that you could just print a new one if the old one was lost too. Couple of thoughts on the design but without seeing a video of the launch these are just spitballs.

    I'd imagine that the little ring that holds the rocket to the rod is enough to cause the rocket to pull to one side. What if you used three dowels, one between each fin spaced evenly around the rocket, about as close as you have the one dowel to the rocket. I think that might negate the need for the little ring.

    Also, you can buy metal dowels for pretty cheap from stores that sell RepRap parts (self built 3d printers). They might add some stiffness and you could even lube them before flight.

    0
    RefiningDesigning
    RefiningDesigning

    Reply 1 year ago

    That’s very true! It’s possible the way I’m guiding the rocket is making the centre of mass off centre. I may try a different way to guide the rocket, either the rods as you’d mentioned or maybe a way of having the fins pass in slots that hold them in their orientation until they leave the launch pad.

    0
    BerenV
    BerenV

    1 year ago

    Wow, nice project! I’m going to have to try building one of these sometime.

    On a side note, did you mean M3x22mm instead of “M22x3”? That would be a very strange size!

    0
    NirL
    NirL

    1 year ago

    awesome :) I've never seen a tiny rocket before!

    0
    seerena
    seerena

    1 year ago

    it is really amazing