With Summer in our wake and the Holiday season still a couple of months away, we enter our favourite part of the year: The DARE Launch Season. As you may recall, last September/October we travelled to the south of Spain, to the INTA’s El Arenosillo launch base, where we attempted to launch our Stratos II rocket. The rest, as they say, is history. We had a misfire, and returned home. And now, we are going back! We spent the last year redesigning and improving the Stratos II, and we performed additional tests where required. The new rocket, called the Stratos II+, is scheduled to be launched in one of two windows. These windows run from 13 to 16 October and 19 to 20 October, giving us a great six day total.
The crew will leave early in October, and as done last year, we will try to keep everybody back home and across the world up to date of all the things we are doing leading up to the launch. So keep a close eye on the website, our Facebook page (Delft Aerospace Rocket Engineering) and our Twitter account (@DARE_TUDelft) so you don’t miss anything. To kick-off, we have prepared an article on some of our technical upgrades: The new propellant feed and tank heating systems. Enjoy the read!
Propellant Loading Test of the Hybrid Propulsion System
During the failed launch attempt of October 2014, a major problem arose when a part of the feed system was found to be leaking. A self-built check valve, intended to keep the propellant in the oxidizer tank after detaching the filling umbilical, failed. As a consequence oxidizer leaked from the tank and excessive cooling of the motor bay electronics occurred. To prevent this from happening again and to allow for oxidizer dumping in case of an emergency, the check valve has been replaced by a servo-actuated ball valve.
The servo-actuated ball valve.
The system is also upgraded by a quick connector system, sponsored by Teesing BV, to allow for remote disconnection of the filling umbilical. The Weh TW-17 quick connector will connect the oxidizer filling rig to the filling valve which is placed inside the rocket’s motor bay section. After filling of the oxidizer tank is completed, the quick connector is remotely actuated to disconnect from the rocket, ensuring safe and smooth launch pad operations.
The WEH TW-17 automated disconnect from Teesing BV.
To prevent unpleasant surprises during the actual launch campaign in October, a small scale test of the fuelling system will be conducted in Delft before we leave for Spain. During this test, a shorter tank will be attached to the motor-bay section. This tank will be equipped with the same bulkheads, valves and peripherals as the actual Stratos II+ rocket. Liquid nitrous oxide, supplied by Airliquide, will then be fed to the test tank trough the WEH TW-17 quick connector. After the tank is filled sufficiently, the quick connector will be remotely disconnected from the tank and the liquid nitrous oxide in the will be dumped via the new servo actuated ball valve on the filling line.
One of the 5 infra red lamps that will be clustered on the launch tower provided by Jac de Vries Infrarood Techniek BV.
A second goal of this propellant loading test is to check the new flight tank heating system. The DHX-200 Aurora hybrid rocket motor has been tested with a nominal tank pressure of 60 bar. In order for the nitrous oxide be at this pressure, it needs to have a temperature of approximately 25 degrees Celsius. However, during the actual filing of the tank, the nitrous oxide cools down significantly and hence the tank will be at lower pressure. Depending on the sun to heat up the tank back up and get it to a pressure of 60 bar means valuable time is wasted during the actual launch operations. This problem will be solved by the Infrared Heating System supplied by Jac de Vries Infrarood Techniek. The Infra red Heating System consists of five infra red heaters which are mounted on the launch tower. They are then pointed towards the oxidizer tank. Their contribution speeds up the pressurization process of the tank significantly. This will prove an invaluable addition to the launch pad operations required to launch Stratos II+ halfway into space.
About Jac de Vries Infrarood Techniek BV:
For more than 35 years Jac. de Vries Infraroodtechniek has been manufacturing infrared drying and heating installations. Located in Middenbeemster, the Netherlands, they are fully equipped to provide their customers with a quality product, from off the shelve stock to developed and produced on customer specifications.
http://www.infraroodtechniek.nl/en/