design, development, constructionand testing of asolid rocket engine (thrust class up to 20 kN)
CASSIDIANcommissioneda feasibility studyin2011, thedevelopment of asolidengine with up to20 kNmaximum thrustand a total impulsedefinedas a boosterrocket.Here, a veryquick thrustbuild-upwas of greatimportance. WEPA/ARTdesigned theengineincluding allhardware componentsinaccordancewith the prescribed requirements, buildtheprototypesand performed thestatic firing tests. A solid propellant system based onnitrate/polymer base (composite propellant) was used, compared toconventionalammonium perchlorate-based fuels, muchsafer in handling. As part of thedevelopmentthe inner ballistics of the engine was modified several times, until the requirements were met.The manufacturing processof the fuelwas optimizedduring developmentcampaignto allowa quality assuredpreparation. As part of theassignment, theperformances specifiedby the customerhas been obtainedandverified.
Unbreakable mounting of a load sensor
Unbreakable mounting of a load sensor
Sometimes it happens that a rocket motor explode on the test stand. Even with very small engines you can reach forces which cannot be underestimated. With the correct installation method a load sensor can be mounted that it can withstand loads far above of the specified breaking load. Double beam load sensors are best suited for this installation. These sensors have a certain deviation gap. The sensor is fitted with a washer that is exactly the same distance. At rated load is on the sensor thus leads the entire force in the foundation, and no further deformation of the load sensor is produced.
The photo shows a double bending shear beam with 200kgf rated load of aluminum with a deviation gap (left) of 3mm. On the right side where the beam is mounted on the foundation is therefore a correspondingly thick sheet placed underneath.
The bar itself is mounted with 4x M6 bolts in the foundation. The foundation here has more holes to mount it on the actual test stand. As the beam moves in parallel, you can also set up on top a sheet in order to achieve the same effect.
In this case, the engine adapter is mounted with an round plate directly on the left side. It can also be mounted above in the center with a massive cross-beam. In the case of an overload thus the force would be derived through both sides of the bending beam.
In addition two sheets with 90 ° angles were fitted to the side to protect the sensor. IT is important that the sheets have a gap to the sensor and the foundation. Otherwise the measurement is affected. With this type of assembly, it should no longer be possible to destroy the sensor by a motor failure. All components are found in a hardware store and can be built by simple means. Only the motor mount and the adapters were made with a lathe.
The new system for testing of rocket motors is ready to have.
The test system has the following main features:
USB 2.0 port for direct connection to a notebook;
7 selectable channels for a signal of ± 10 V for standard industrial sensors;
Total sample rate of 200,000 samples per second;
An ignition channel, with 13.8 V and 8.5 A (44 A short-term);
2 channels for solenoid valves with max 43 V and 8.5 A (44 A short-term) external power source;
External control box to operate the system;
Cable lengths up to 100m;
2 internal power supplies for the electronics and the firing channel;
Drivers for Windows XP SP2 / Vista / 7/32 - or 64-bit and Linux;
Libraries for Visual Studio (.net), Visual C + +, Visual Basic (.net), LabVIEW, MATLAB Data Acquisition Toolbox;
Sensors for thrust, pressure and temperature measurement available as an option;
Optional DMS tension analyses of engine parts also available.