Rouse-Tech CD3 Recovery System

High-Altitude Applications

In high-altitude flights, in other words greater than 20,000ft, the chances for pyrogen to ignite in its entireity and thus produce enough gas to expel the recovery system drops dramatically.  If, at this altitude, your drogue chute fails to eject, it will mean disaster for your rocket.  As your rocket is tumbling or ballistically diving towards the ground, your main chute may eject, but the speed of the descent would be so great that it's likely that recovery system will fail in some way as well.

With CO2, there is only a small amount of pyrogen and it's packed in such a way that it will ignite fully and the system will work as it should at any altitude.  The gas that ejects the recovery system is compressed CO2, so you're not trying to rely on large amounts of black powder to produce enough gas to expel the parachute.

Safety increase, particularly for large diameter rockets.

The larger the recovery compartment, the more gas pressure is needed to expel your recovery system.  In most rockets, the ejection charge is a black powder contained within a vessel, whether that be, in smaller motors, the actual motor or in the case of dual deployment and larger motors, a separate ejection canister.  As the scale of your rocket goes up, so does the amount of BP that you need, as does the risk of premature ignition.  With the CO2 system, you can seriously scale back on the amount of BP needed to eject the recovery system in large rockets, increasing the safety of your rocket and set-up many-fold. 

Cleanliness

The relatively miniscule amount of BP/pyrogen in your rocket will nearly eliminate the burnt smell and residue inside of your rocket*, as well as keep your parachutes from burning.  The CO2 in the canisters is clean and odorless, resulting in less cleanup time for future launches.

*Well, it won't add to it.  Whatever smells were in the tubes before you used the CD3 are not our responsibility. 

It's just cool.

While this product is primarily aimed at larger, high-altitude rockets, once you've got your kit, you'll want to use it on all your low-altitude rockets too!  Yeah, everyone can pour some powder pyrogen into a canister with some tape, but you'll be ejecting your parachutes with class.

Disadvantages

• It weighs more than your standard ejection canister.  It's all aluminum, so it's relatively light, but it still adds weight.
• It's more complicated to assemble than a standard ejection canister.
• It's more costly than an ejection canister & pyrogen (?)  It's got a higher initial cost than an ejection canister & pyrogen (?)
• It won't fit in small rockets - minimum diameter is 2" (50mm).

A small amount of pyrogen is ignited within a closed container and those gasses push a piston down, puncturing a pressurized CO2 cartridge.  The pressurized air then flows out of holes in the piston casing, filling the recovery compartment quickly to eject your recovery system.  The same tiny amount of pyrogen is used no matter the size of the cartridge.

There are a couple methods to determine which size CO2 Cartridge you need.

First, you can look at the table below for an approximation.  The table is dependent on 2 factors, recovery compartment length and diameter.  This table is only for typical sizes of typical rockets. It is best to use this as a step off point for ground testing and refine your system as needed for your specific rocket.

Method Two involves calculating a black powder equivalency.  This method is often preferred by those who are experienced flyers and who are comfortable with a black powder "ejection charge calculator" or other technique. 

More on this method and using the table above can be found in the CD3 Manual.

CO2 Cartridges - 12gram, 16gram, 25gram and 38gram.  The HPR kit comes with all of them, whereas the Jupiter kit comes only with the 25 and 38 gram sizes. 

The size cartridge you need depends on the size of your recovery compartment.  See the table above for a quick estimate.

Q. What is the minimum rocket diameter required to use the CD3 kit?

A. The red (25g) and yellow (12g/16g) flanges are 1.7 inches in diameter. That is the base-plate that you'd use to mount it to a bulkhead. So it should fit in the 54mm tube diameter easily, such as in an e-bay. But if you wanted to mount it next to a engine mount tube in the bottom of the rocket, I don't think it would fit there. But with a little ingenuity, I'm sure you can make it fit.