A fellow blogger , Dick Stafford over at the Rocket Dungeon, made a suggestion that recovery devices include the terminology of sensor, initiator, and actuator. I thought this was a great idea and will use this terminology.
In my previous post I went over some old ideas in indirect recovery ejection. This week I will explore some of the most common modern methods along with a few new ideas. The most popular method used in indirect recovery ejection is the altimeter( a sensor). The altimeter sensing a pre-determined altitude completes a circuit that actuates a recovery ejection. Altimeters are a reliable and inexpensive sensor for ejection recovery. The Perfectflite Altimeter is a good example of these devices.
Another modern method relies on a device that can monitor multiple sensors. The device is the flight computer( a sensor). A flight computer is an advanced and more costly means of determining the correct conditions for deployment. Here is a great paper on explaining the flight computer(PDF file). One of the most popular flight computers is made by G-Wiz.
We are currently facing a great deal of scrutiny from the BATF and this has started discussions on devices that do not use Black powder to actuate the recovery ejection
A new concept device for deployment is the Rouse CO2 deployment device. This device uses a CO2 cartridge to actuate the deployment. The device needs a sensor like an altimeter and an e-match as the initiator.
There has been some talk of using springs as actuating devices. These devices have been used by NASA to release satellites. The X-Prize Lander contender Armadillo Aerospace has been experimenting with spring devices for their chute deployment.
“We put together a drogue spring cannon as a possible alternate to pneumatic ejection. We aren’t sure how we want to go with this, so we built a proof-of-concept to feel out the issues. Pneumatic requires a tank and a big solenoid of some kind, and requires a good piston seal. Spring ejection requires a longer tube to hold the compressed spring, and requires a Sea-Catch to release the spring. “
The spring concept is already being experimented on by rocketeers. See here.
There will need to be a great deal of R&D on the spring issue but I’m sure that the rocketry community will find ways to make it work along with new concepts not yet addressed.