When people talk about an experimental rocket, they are mostly interested in the propulsion, rocket hardware or the maximum altitude that can be reached. The safe recovery is sometimes disregarded, however, it is equally important.
Today, Christian Plasounig is going to talk about our recovery system and the backups, which will ensure a safe landing of “The Hound”.
“There are two main reasons, why we want to recover the rocket:
First, we want to see if any part of the hardware got damaged during the flight. Second, we want to get high-resolution flight data from our onboard computers. We are using these to proof that we reached the desired altitude. With our telemetry systems, we are only able to transmit some basic status values, which can give us information about possible malfunctions and main flight events. This is why we depend on the onboard data.
We are using a classical two staged recovery system for each stage of the rocket. This means, that we deploy a drogue parachute on apogee, with the goal to stabilize the descent. It will also ensure that we fall fast enough so the wind does not carry us away too far. At a defined altitude of a few kilometers we deploy the main parachute that decelerates the rocket to land safely with a speed below 10 m/s.
The deployment of the drogue is performed with a pyrotechnical device, which separates the rocket. The main chute gets released with a line cutter. For the upper stage we are using a timer to deploy the drogue, because it is difficult to detect the apogee at this high altitude. The booster uses an apogee detection algorithm based on the atmospheric pressure. The main parachutes are deployed based on the atmospheric pressure too.
We are using commercial computers as a backup for our in-house built onboard electronics. Furthermore the pyro-charges are all redundant to ensure a safe recovery.
To find the rocket, we are using 3 independent telemetry devices. Two devices are in-house built transmitters at 433 MHz and at 144 MHz. One device is a commercial satellite-tracking module.”