With the redesign work of Stratos II+ nearly finished, the propulsion and capsule teams are working hard to prepare two upcoming test campaigns. Both teams will conduct their test at the facilities of TNO, the leading Dutch organization in the field of applied physics research.
The capsule team will start the test phase with vibration tests of the capsule, electronics and recovery system at the shaker table facilities of TNO in Delft. Two days of testing, the 25th and 26th of May, are planned during which the capsule assembly will be subjected to a wide range of axial and lateral accelerations. This is done in order to validate that the separation mechanism and the electronics stacks are able to cope with the violent vibrations accompanying the launch of the rocket. In order to make sure that the test will be representative for the actual launch loads, vibration profiles where obtained from the NASA Handbook for Sounding Rocket Projects. The load profiles presented in this handbook are based on the Terrier Orion solid sounding rockets and will most likely be more aggressive than the actual loads generated by the DHX-200 Aurora hybrid engine. This way, we can be sure that if the capsule and electronics successfully pass the vibration test they will have successfully function during their journey halfway into space in October 2015.
Two weeks later it is the turn of the propulsion team to put their system to the test. Previously a total of ten hot fire test where performed with the propulsion system, resulting in the tweaking of the feedsystem and combustion chamber layout. More importantly two failure modes, (cracking of the solid fuel grain and failure of the pre-combustion chamber) where identified and mitigated. Unfortunately the team ran out of time before a full characterization of the thrust and total impulse of the engine could be obtained. This will be the main goal of the upcoming test campaign. The DHX-200 Aurora hybrid engine will be mounted at the Prins Maurits Laboratory of TNO in Rijswijk and will be unleashing her metric ton roar during two days in June. The exact dates will be slightly depended on the weather in order to comply with noise emission regulations. Three tests are planned to fully characterize the engine performance over the nominal burn time. If the initial tests are successful, the last test will be conducted using a mixer fabricated from glassfibre reinforced composite in order to increase the combustion efficiency of the motor during the last phase of the burn.
The capsule and propulsion system test campaigns will prove invaluable means to increase both the technical experience of the team and the technical confidence in the Stratos II+ sounding rocket. As such they are important milestones on our way, half way into space.