Scientists at the Aerospace Systems Directorate (ASD) searching for new thermocouple radiation shields, are very interested in the Silicon OxyCarbide (SiOC) because of its potential for building missiles capable to flight at continuous hypersonic speed.
Specifically, the refractory qualities of the SiOC, its ability to maintain strength and form at high temperatures, and the geometric complexity offered by Additive Manufacturing have a wide range of Air Force applications. This is the reason why nowadays, the ASD is researching into applications for the 3D printed SiOC under a Collaborative Research and Development – Material Transfer Agreement (CRADA-MTA) between the U.S. Air Force Research Laboratory (AFRL) Aerospace Systems Directorate and HRL Laboratories, a research center owned by Boeing and General Motors Corporation.
The design, development and manufacturing of the 3D Printed, electric turbo-pump fed Rutherford Engine began in 2013, with the first test fire taking place in December of the same year.
Rutherford is produced by Rocket Lab via EBM (Electron Beam Melting), an advanced form of 3D Printing. Its engine chamber, injector, turbopumps, and main propellant valves are all printed and assembled into a lightweight shape.
Rocket Lab has produced a total of 40 flight-ready engines to date, and aims to produce another 100 engines by the end of this year. The Rutherford engine’s production scalability is facilitated by Additive Manufacturing, or 3D Printed primary components.
With a 3D printed combustion chamber, injectors, pumps, and main propellant valves, Rutherford has the most 3D printed components of any rocket engine in the world. Actually, Rutherford has two versions weighing just 35kg and offering 24 kN (5,500 lbf) thrust / 311 s (3.05 km/s) specific impulse (First Stage Engine) or 24 kN (5,500 lbf) thrust / 343 s (3.36 km/s) specific impulse (Second Stage)
As said, Rutherford features the use of electrically driven propellant pumps, rather than turbomachinery, further reducing complexity and build-time. This unique approach allows unmatched precision and control of propellent flow and a significant increase in performance through mass savings: “The Rutherford engine was designed from the beginning to be both high performing and fast to manufacture on a mass scale,” said Lachlan Matchett, Vice President of Propulsion. “By enabling faster, scalable engine production we speed up production of the whole vehicle. We can print an entire engine in as little as 24 hours."
Solid-propellant rockets are used for many applications, including military technology, scientific research, entertainment, and aerospace education. This study explores a novel method for design modularization of the rocket airframes, utilizing Additive Manufacturing (AM) technology.
The new method replaces the use of standard part subsystems with complex multi-function parts to improve customization, design flexibility, performance, and reliability. To test the effectiveness of the process, two experiments were performed on several unique designs:
ANSYS CFX® simulation to measure the drag coefficients, the pressure fields, and the streamlines during representative flights and fabrication and launch of the developed designs to test their flight performance and consistency.
Altitude and 3-axis stability was measured during the eight flights via an onboard instrument package.
Data from both experiments demonstrated that the designs were effective, but varied widely in their performance; the sources of the performance differences and errors were documented and analyzed.
The modularization process reduced the number of parts dramatically, while retaining good performance and reliability. The specific benefits and caveats of using extrusion-based 3D Printing to produce airframe components are also demonstrated:
3D printing, particularly extrusion-based processes, is an excellent method for producing the complex multi-feature parts needed for optimized airframes.
The print lines on 3D printed parts seemed to provide an advantage, not a disadvantage, to the rockets as it reduced the drag coefficient of the nose cone.
