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| If you're looking for a way to safely
recover that bird in one piece (or as many pieces as you intend to) from
75,000 ft, you've come to the right place. Here, we have
information direct from past research projects. Check back often
to keep up with all the new data that will continue to be posted here. |
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| Extreme
Altitude Recovery |
Although there are probably several ways to accomplish recovery from 50,000+ ft, we have developed a relatively simple method that only has a few basic requirements/"comfort elements" that will need to be fulfilled.
- You must be comfortable with the use of Pyrodex™
instead of black powder.
- The rocket must have a relatively large diameter. (I'll leave it as "relatively" because some people can manage to stuff more things into a body tube than most other people.)
- Expect to conduct a lot of ground testing to ensure proper operation of the recovery system.
- And the fourth and major requirement is... you'll need to be comfortable working with metal and using some in the design of your rocket.
The basic principle of our extreme altitude recovery mechanism is that of a three stage recovery system with a set of pistons (resembling shotgun barrels) inducing ejection, and the ejected section deploying a drogue parachute. Once this drogue parachute has been deployed, the rocket continues down to an altitude greater than 1,000 ft and a pilot chute is deployed, and the drogue chute is shed from the vehicle along with the nosecone. The pilot chute then deploys the main chute(s) via trigger of a pyrotechnic release device and your bird touches down softly as a feather.
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| In the two stage recovery system, the pistons are
pressurized with Pyrodex™ ejection charges, blowing off the upper
airframe and deploying the drogue chute. At a predetermined altitude, the
main parachute is then deployed by a release mechanism. |
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In the three stage recovery system, the pistons perform in the same manner as the two-stage system. Instead of deploying a main chute after the drogue, a pilot chute is deployed at an altitude of above 1000 feet. Immediately afterwards, the nosecone with the drogue chute is shed from the airframe. Then, a PRM fires, allowing the main
chute(s) to deploy with the aid of the pilot chute. The main parachute or pilot chute deployment is best controlled by a manually activated device, such as Tom Farrand's "Radio Flyer."
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Although the system is shown in a
two-dimensional format, The system is obviously in a three-dimensional
space. On very large rockets, it is imperative to use multiple pistons
around the radius of the airframe. They must all be wired in parallel to
ensure even and optimal deployment of the recovery system. Although
we have never utilized the simpler two-stage extreme altitude recovery
system on any of our rockets, we have utilized the three-stage extreme
altitude recovery system. We have never lost a rocket due to a
recovery failure with the three-stage recovery system. The only time
that we lost a rocket equipped with the system was due to a massive motor
CATO that obliterated the entire booster, avionics bay, and recovery
section. The only part that was left undamaged was the payload
section. Ultimately, with any recovery system designed to function
at very high altitudes, a black powder substitute will be necessary. Black
powder is simply too inefficient and too unpredictable in the low pressure
environment of such high altitudes.
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Hints:
- Use a drogue chute no bigger than 18 inches.
- Use a pilot chute of no less than 24 inches but
no larger than 84 inches for the most heavy rockets.
- Do not use too much Pyrodex™ as it can sever
the drogue chute from the recovery system.
- If the drogue chute does become severed
prematurely, immediately fire the pilot chute and drogue release
charges. Allow the main chute to deploy at its normal altitude.
Recovery will behave like a two stage system.
- Use either a tower or rail, ensuring that it is
at least three times the length of the rocket, to ensure a straight
trajectory.
- Triple check everything on your checklist before
launch.
- Use dual or triple redundancy on all possible
systems, including ignition for clusters (a.k.a. onboard ignition
system).
- Ensure that you establish a larger than necessary
perimeter around the launch site for spectator safety.
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