By Joyce Laird
New developments in materials and design will have a major impact not just on fuel efficiency of future aircrafts but also on how aerospace components will be manufactured in the future.
“What we are seeing today is a jump in jet aircraft efficiency of 15-20%, with the very real possibility of 25–30% improvement in the near future,” said Scott Thompson, US Aerospace & Defense Leader, PwC Industrial Products Practice.
While traditionally thought of as an industry-focused assurance, tax, and advisory service, PwC’s Aerospace and Defense (A&D) practice also addresses a full spectrum of industry-specific areas including operational improvement, supply chain management, compliance, export controls, government contracting and full scope information technology.
“On the design side,” Thompson added, “I believe that Pratt & Whitney’s change in architecture of the jet engine is one big driver. They introduced a gear that de-couples the fan from the high pressure turbine to allow the fan and turbine to operate at their optimal speeds. So now we are not talking about 1% per year efficiency increase, as has been the standard for the past fifty years, we are talking about 15–20% efficiency increase overnight. General Electric is promising similar improvements in their next generation engines. They report that this will come from using new and lighter-weight materials and aerodynamic changes in the design.”
Changes in the manufacturing process are also important. Every component in a jet engine is an opportunity for potential wear during operation. By reducing the number of parts used in the design itself, it makes manufacture more cost effective, reduces maintenance and improves reliability. “A good example of this is moving from fabricating a fan from a hub with separate fan blades to cutting the entire part from a single piece of alloy. It saves cost on the manufacturing end, eliminates quite a few steps, offers better quality control and reduces maintenance,” Thompson adds.
That said, innovations are coming from a wide spectrum of manufacturers. Some very interesting developments follow:
Nanotubes That Come in Sheets
Nanocomp Technologies, Inc (Concord, NH) is a unique company that has developed a very special nano-tube material-Nanocomp C-Tex and Nanocomp CNT Sheet-that is being targeted by the government and aero industries for some specific uses on aerospace engines. These include incorporation into the inlet nacells to help extract hot gases from the engine for de-icing, development of lightweight heater mats for similar de-icing applications and incorporating the outer engine housing to protect against blade blowout (to augment ballistic materials currently in use).
“We make a macro structure that comes in the form of a sheet of material. It’s a finished product that you can actually hold in your hand, not a component for a final product like the more common powder form,” John Dorr, vice president of business development for Nanocomp, says.
“We can take our material then and send it to a pre-pregger who can then go in and prepreg out material with a resin of choice and get a finished product ready for aerospace applications.”
Because most of his aero projects are under strict non-disclosure agreements, Dorr can only give generic information on the applications. One completely changes the paradigm for engines regarding how engine heating is done today for anti icing and de-icing.
“Transitioning from commonly used technology to a structure with embedded heaters within the composite material takes the application to a whole different level,” Dorr says. “If you apply that to satellites, you could wrap sub-systems structures and be able to turn them on and off programmatically to align with how the sun is behaving relative to the position of the satellite.”
“One real-world example is the Jupiter rocket engine. Lockheed Martin was the prime on that project for NASA and Lockheed implemented our nano-material as a layer on the engine to deal with electro-magnetic discharge from the engine that was interfering with the electronics on the spacecraft. That big boy is on its way to Jupiter right now. It’s nano-technology in action,” Dorr concludes.
Rocket Science in Action
Speaking of rockets, the development of rocket engines is going strong at Pratt & Whitney Rocketdyne (Canoga Park, CA) with new developments in the company’s expendable and human-rated rocket engines – specifically the RS-68A and J-2X propulsion systems.
The RS-68A, an upgrade of the RS-68 engine, is scheduled for its maiden flight on June 28, 2012, when it will boost a classified payload for the U.S. government. With 702,000 pounds of thrust (39,000 more pounds of thrust than a basic RS-68), the RS-68A is the most powerful liquid-hydrogen/liquid-oxygen booster engine in the world. It’s designed to provide increased thrust and improved fuel efficiency for the Delta IV family of launch vehicles. PWR also provides the RS-27A liquid-oxygen/kerosene engine, which has powered 237 Delta II and Delta II vehicles into space with 100% reliability. In 2011, PWR powered 14 successful launches that included three Space Shuttle missions.
John Malinzak, senior manager for the manufacturing, engineering and planning group at PWR, said the RS-68A engine was designed and developed for customers who would like to boost heavier payloads into orbit. To accomplish this, PWR needed to increase the thrust level on its RS-68 engine.
“The basic components of a rocket engine are all the same,” said Malinzak. “There are valves, a gas generator, oxidizer and fuel pump, a main combustion chamber and a nozzle. And there is ducting that connects all of these components together. So when it comes to upgrading an engine, it’s a matter of enhancing certain components to get the increased thrust, performance and efficiency. …The detail parts of the engines are manufactured at suppliers nationwide, as well as some of the major components at PWR’s factories.”
“All of our machines and equipment are commercially available, not custom,” Malinzak said. “But we try to buy machines that can do more than one operation in a set-up. We have vertical, turning-milling centers, where we can do drilling, turning, milling, tapping all on one piece of equipment. We run a lean manufacturing facility.”
The RS-68A received certification about six months ago, and the first three engines are set for that upcoming maiden flight for United Launch Alliance, headquartered in Denver, Colo. PWR is also developing and testing an advanced upper-stage J-2X engine under a NASA contract to power the nation’s next-generation space launch vehicle. The J-2X is the first human-rated rocket engine to be tested in the U.S. in more than 35 years, and it evolved from the J-2 engine, which took astronauts to the moon in the Apollo era.
Malinzak notes that while their parent company Pratt & Whitney (Hartford, CT) is the division that designs and builds aircraft jet engines, PWR does lend a hand. “They do use our expertise in engineering and manufacturing to help solve some challenges they may face.”
Components for Greater Power Density
Facing problems is never more real than when transmitting data. For decades military aircraft have used silicon and gallium arsenide (GaAs)-based products for transmitting data, as well as voice and in radar systems. Increased military demands have pushed silicon to its limits in many applications. Component makers are now turning to GaN (gallium nitride) for advanced solutions, and some regard GaN as the next step in the semiconductor evolution.
TriQuint Semiconductor, Inc. (Hillsboro, OR) has been in business since the mid 1980s with a focus on supporting high power/high frequency markets through GaAs and now GaN technology. “TriQuint grew out of GaAs programs that started in the ‘70s and came to the commercial market substantially in the early and mid ‘80s,” says Mark Andrews, strategic marketing communications manager. “We later added SAW [surface acoustic wave] and BAW [bulk acoustic wave] filter technology for a totally integrated portfolio. GaAs plays an important role in phased-ray radars for aircraft, ship and ground-based systems. The F-16, F-18, F-22 and F-35 all have TriQuint components in radar or communications.”
While silicon technology continues to play a key role in radio transceivers and computer processing chips, silicon is less efficient than GaAs or GaN in higher power RF applications. “This is where GaN technology shines. It offers much higher breakdown voltage and higher power handling,” he says.
“The ability to make a device that is smaller and more efficient, yet outputs more effective RF energy is key,” Andrews says. “We support the development of AESA [active electronically scanned array] or phased array radars for jet aircraft. A radar array is composed of numerous solid-state transmit and receive modules that rely on transistors like TriQuint’s. Phased array systems today are typically built using GaAs chips. GaN can increase efficiency and power, and will be the basis for future radar, communications and EW improvements for air, ship and ground-based systems.”
GaN-based solutions for phased array radar, communications and advanced electronic warfare (EW) applications are relatively early in development compared to GaAs. But GaN is seen by TriQuint as a leading technology for new aerospace, defense and high-performance commercial requirements due to the power density, power handling, efficiency, ruggedness and versatility it offers.
Whether aircraft, rocket engine or the smallest component, before it can be used, it has to be designed, built and tested. ANSYS, Inc. (Canonsburg, PA) is an engineering software company, focused on physics based simulation, that is turning that equation around to read: designed, tested and built.
“We create virtual representations. It could be a complete airplane, an engine or a single part. It could be multiple components placed within an engine,” Robert Harwood, aerospace and defense industry director, says. “We build on multiple scales, so instead of building an physical prototype to test, you can build and test everything virtually eliminating multiple physical prototypes. Of course, you still need to build a final product for real-world test, but when you get to that stage, it’s right on the money.”
This is not another CAD tool. It takes the design information from programs such as ProEngineer, CATIA and others and uses that model as the basis for analysis. “The laws of physics really are agnostic to all industries. Whether designing a car or an airplane, it still uses the same equations…it’s just a different shape, and travelling at different speeds. Aerospace is our largest unit,” Harwood says.
Automated contact detection and analysis, component mode synthesis, multibody dynamics and HPC make structural mechanics analysis fast enough to apply to vehicle structures, landing gear, wheels and brakes, gearboxes, and other components. Smart materials are optimized using finite elements for piezoelectric and shape memory alloys. Bird strike, crash and impact simulations are performed with explicit dynamics.
Automated adaptive meshing makes studies of EMI and EMC for antenna placement reliable. Hybrid methods based on integral methods enable optimization of electromagnetic performance, including radar cross section.
“A classic example in aerospace is the structure of the wings. The aerodynamics engineer can’t solve that by himself. The structural engineer can’t either. Both need to interact simultaneously. Another level of complexity is the increasing electrification of aircraft. You have to make sure the electron-magnetics work correctly. It’s truly multi-physics. Only by looking at this from a full system level viewpoint can you tell what’s going to happen.” ME
This article was first published in the March 2012 edition of Manufacturing Engineering magazine. Click here for PDF.
Published Date : 3/1/2012