CO2 Ejection System

[b o]

Hi everyone,

I'm working on a recovery system for a mid-altitude rocket, and I’m looking to design a CO₂-based ejection mechanism to avoid using explosive materials. My goal is to create a safe and reliable release system by using a cam mechanism controlled by a servo motor.

Concept Overview:​

Cam Mechanism: The idea is to use a cam to hold back springs that are compressed and ready to push the CO₂ cartridge forward. At a certain point in the cam’s rotation, the springs would be released, rapidly driving the CO₂ cartridge into a puncture pin to trigger the ejection.

Servo Motor: The cam will be rotated by a servo motor, which will allow me to control the release point precisely. By adjusting the cam’s profile, I’m aiming for a controlled release of the stored energy in the springs, resulting in a quick and effective deployment.

Questions and Advice Needed:​

How can I optimize the cam profile to ensure a reliable lock and smooth release for the springs?
Any advice on servo torque requirements for this type of system? I want to avoid straining the servo while compressing the springs.

If anyone has experience with CO₂ ejection systems or has used cam mechanisms in similar setups, I’d really appreciate your insights. Thanks in advance for any tips or feedback you can offer!

 

[Cameron Tinder]

Fruity Chutes has such a device. Not designed for rockets and I do not know if it would be/could be made suitable for rockets.
https://shop.fruitychutes.com/products/hawk-co2-system-kit-16-to-45-gram

 

[lr64]

Maybe hold things back with a string that gets melted through by a hot wire.

Alternatively, instead of a servo you could just use a tiny motor with a threaded shaft.

 

[cls]

Although these are pyrotechnic, ematch and a few grains of bp, Rouse Tech CD3 system

https://www.apogeerockets.com/index.php?main_page=product_info&cPath=198_133&products_id=267

Apogee sells a few other types, too.

 

[Azamiryou]

I want to avoid straining the servo while compressing the springs.

Have a latch hold the main spring, and the cam operate the latch (e.g., with a rocker).

 

[Cameron Tinder]

Although these are pyrotechnic, ematch and a few grains of bp, Rouse Tech CD3 system

https://www.apogeerockets.com/index.php?main_page=product_info&cPath=198_133&products_id=267

Apogee sells a few other types, too.

The "Few other types" would be the Peregrine, the RAPTOR and the Eagle CO2 ejection systems from Tinder Rocketry. At this point, Apogee sells the Peregrine only which uses commonly found 8 and 12gm CO2 cartridges.

https://www.apogeerockets.com/Eject..._Systems/Peregrine_CO2_Ejection_Device_8g_12g

https://www.tinderrocketry.com/co2-ejection

As CLS said, these pyro based devices use very little pyro, in the case of all the Tinder Rocketry CO2 ejection devices which are sealed, they use a minuscule amount of BP (.3cc). While I have considered such a non-pyro device for rocketry, honestly with the acceleration forces that you may have with a high altitude flight this does not make sense to me as it adds another layer of possible failure. In addition, consider the space that would be required for such a device. Look at the device from Fruity Chutes. It is a relatively good looking device and by all accounts, it seems to work in the large UAV's that it was designed for. Now try to imagine using it or a modified version of it in a 3 or 4 inch rocket. Seriously, unless you have some aversion to pyro, like the UAV crowd does, sorry but a servo fired CO2 system does not really make sense.

And lastly, since the OP of this discussion is from Turkey, he can purchase these CO2 ejection systems from Euro Space Tech in the Netherlands.

https://eurospacetechnology.eu/index.php?id_category=375&controller=category

Hope this is helpful!