August 14, 2019 | International, Aerospace

Precooler Technology Could Bring Advantages To Fighter Engines

By Tony Osborne

Technology developed by Britain's Reaction Engines for its SABRE (Synergistic Air-Breathing Rocket Engine) hypersonic powerplant is to be fitted on the Eurojet EJ200 engine from a Eurofighter Typhoon to understand if the technology can help transform the powerplant's operating envelope.

The £10 million ($12 million) project announced by the Royal Air Force (RAF) Rapid Capability Office (RCO) in July will see BAE Systems, Reaction Engines and Rolls-Royce engineers work to better comprehend Reaction's precooler technology and how it could be integrated for use on a jet engine—perhaps even the powerplant for Britain's future combat aircraft, the Tempest.

Two-year project will scope integration to better understand precooler potential benefits

Heat exchanger is an enabler for Reaction Engines' SABRE technology

The trials represent the first acknowledged application of the precooler technology

At high speed, jet engines struggle with a thermal challenge as air entering the intake becomes too hot, reducing thrust and limiting the ability to reach speeds beyond Mach 3. Reaction's precooler, essentially a highly efficient heat exchanger, already has proven its ability to quench megawatts of heat energy from the incoming air. Trials in the U.S. have shown the precooler technology to cool intake airflow from more than 800F (426C) to around 212F in just 1/20th of a second, helping to maximize performance.

Applied to a fighter engine, the precooler could allow it to work more efficiently at high speeds but also enable manufacturers to be less reliant on exotic, expensive and heat-resistant materials such as titanium. This could lead to lower costs in terms of purchase and maintenance, which are both key focuses of Britain's Future Combat Air System Technology Initiative (FCAS TI). The goal of the FCAS TI is to research and develop new technologies that can be spiraled into Britain's Eurofighter Typhoons and Lockheed Martin F-35s, but also potentially featured in a combat aircraft to replace the Typhoon in the 2030s.

“This is Phase 1 of something more,” Air Vice Marshal, Simon “Rocky” Rochelle, chief of staff for capability and the brainchild behind the RAF's RCO, said at the Royal International Air Tattoo, where the contract was signed. “There is something here that needs to be explored, investigated, tested and tried.”

Over the next two years, engineers will study how the precooler can be integrated onto the EJ200. Once this is established, the engine and precooler will be ground-tested together.

“This isn't about a new market for EJ200. We are using existing assets to try and address that heat challenge,” Conrad Banks, Rolls-Royce's chief engineer for future defense programs, tells Aviation Week.

“If you can cool the intake air down, suddenly you can expand the flight envelope of your gas turbine and it introduces some exciting supersonic and hypersonic applications.”

There is no suggestion the UK is looking for a hypersonic fighter, especially with the high costs associated with the airframe alone. Nonetheless, the technology could enable higher supercruise performance—sustained supersonic flight without the use of afterburner, or more simply better fuel economy.

“What we will do on the testbed is assess the drop in temperature and then see how that affects the core of the engine, that then validates our model. . . . This is not about massively changing the engine,” Banks explains.

How the precooler could be fitted to the engine is also part of the scope of the study. One option could be a donut-like configuration around the intake, Banks suggests. The work also will consider how the introduction of a precooler affects the rest of the airframe and whether such an installation is affordable. The precooler fitted to the EJ200 will be “designed and scaled to the engine to match its performance,” says Banks.

As Banks describes it, the technology will not change the low-observability aspects of the platform such as the engine's infrared signature, pointing out that will depend on what is done on the back end of the engine. However, officials note such a heat exchanger also could be mounted to the rear of the engine.

For Reaction Engines, the trials build on its lightweight heat exchanger (HTX) experiments, which were conducted in Colorado and used a J79 engine from an F-4 Phantom to feed the precooler. The technology is key to the company's SABRE concept, which is targeted at air-breathing hypersonic and space access vehicles. In this role, the engine is designed to efficiently extract oxygen from the atmosphere for rocket combustion. In the fully integrated SABRE, the chilled air will be passed from the HTX to a turbo-compressor and into the rocket thrust chamber, where it will be burned with sub-cooled liquid hydrogen fuel.

Reaction Engines has raised over £100 million in the last three years from public and private sources. In addition, the UK government in 2013 announced a £60 million commitment to assist with the demonstrator engines. Strategic investments also have been made at BAE Systems in 2015 and more recently in 2018 by Rolls-Royce and by Boeing's capital venture arm, HorizonX.

https://aviationweek.com/defense/precooler-technology-could-bring-advantages-fighter-engines

On the same subject

December 21, 2020 | International, Aerospace

The military is this close to nabbing Gremlins from midair
Nathan Strout WASHINGTON — The U.S. military recently came within inches of successfully retrieving three unmanned air vehicles in flight with a C-130 aircraft, bringing the Gremlins program tantalizingly close to a significant milestone. The Defense Advanced Research Projects Agency, the Pentagon's emerging technology arm, wants to demonstrate the ability to launch and recover four cheap, reusable unmanned aerial vehicles — the Gremlins — within 30 minutes in flight. The program uses X-61A Gremlins Air Vehicle (GAV) developed by Dynetics, a Leidos subsidiary. The GAVs are built to dock with a C-130 aircraft via an extension, similar to an airborne refueling operation. Dynetics secured a 21-month, $38.6 million award for the third phase of the Gremlins effort in 2018. While GAVs are relatively small, they have a range of more than 600 miles and can be equipped with a variety of sensors and technologies for different missions. The ability to distribute and collect GAVs from the air could keep them beyond the range of adversary defenses, according to DARPA, expanding the potential impact of unmanned aerial vehicles on the battlefield. Once recovered, GAVs are expected to be mission ready within 24 hours. In the latest demonstration Oct. 28, DARPA made nine attempts to collect the GAVs with a docking mechanism extended from the C-130 aircraft. While none of the attempts was successful, with each GAV eventually parachuting to the ground, DARPA insisted the effort validated all autonomous formation flying positions and safety features. “All of our systems looked good during the ground tests, but the flight test is where you truly find how things work,” said Scott Wierzbanowski, program manager for DARPA's Gremlins effort, in a Dec. 10 statement. “We came within inches of connection on each attempt but, ultimately, it just wasn't close enough to engage the recovery system.” Given the GAVs' performance and the data collected over the nine attempts, Wierzbanowski said success is imminent. “We made great strides in learning and responding to technological challenges between each of the three test flight deployments to date,” he said. “We were so close this time that I am confident that multiple airborne recoveries will be made in the next deployment. However, as with all flight testing, there are always real-world uncertainties and challenges that have to be overcome.” The next attempt will take place in spring 2021. While the Gremlins effort is ongoing, the U.S. Army has made strides in its own effort to retrieve small drones midair. During a recent demonstration, the Army was able to snag air-launched effects (ALE) — effectively small drones — from the air using the flying launch and recovery system (FLAReS). FLAReS uses a hook to catch the ALEs by the wing in flight, saving them from the wear and tear of a belly landing on the ground. https://www.c4isrnet.com/unmanned/2020/12/18/the-military-is-this-close-to-nabbing-gremlins-from-mid-air/
April 28, 2020 | International, Aerospace, C4ISR

Saab’s new fighter radar in the air
Saab has successfully completed the first air trials with its new fighter X-band Active Electronically Scanned Array (AESA) radar, which will be offered as a new addition to Saab's PS-05/A radar family. Saab continues to develop core AESA technology and has now successfully completed the first air trials with the new X-band AESA radar. The trials were flown successfully, collecting data while detecting and tracking objects. The radar is designed for fighter aircraft and can be adapted to a variety of platforms. As Saab previously announced, a version of the new AESA antenna has been sold to a U.S. Government customer. “This is an important step in the development of our new fighter AESA radar. We see great possibilities for the radar, and its modular, adaptable and scalable design means it can also be used for a range of other applications,” said Anders Carp, SVP and head of Saab's business area surveillance. The host aircraft during the air trial was a Gripen D aircraft, which is currently offered with Saab's latest Mk4 radar. The new version of the radar can be offered to Gripen C/D operators, as an upgrade. The new AESA radar features GaN, a material that gives lower power consumption and improved heat resistance. This enables wider bandwidth and greater reliability, availability and efficiency. The new fighter X-band AESA radar will, for example, have better performance against small targets, enhanced Electronic Counter-Countermeasures (ECCM) capability as well as improved ability to support more advanced weaponry. https://www.skiesmag.com/press-releases/saabs-new-fighter-radar-in-the-air
February 2, 2021 | International, Aerospace, Naval, Land, C4ISR, Security

These five items should top Biden’s defense priorities
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