Boeing, US Navy to demonstrate ramjet missile technology

Boeing revealed on October 20 that it has been contracted by the US Navy to co-develop the Supersonic Propulsion Enabled Advanced Ramjet (SPEAR) flight demonstrator with the Naval Air Warfare Center Weapons Division (NAWCWD).

Under the US$30m deal, Boeing and the US Navy will team up to demonstrate advanced missile technologies that will make carrier air wing strike fighters more lethal into the next decade. The contract award came after the US Department of Defense requested information from industry to help the US Navy to identify the technical requirements of future carrier-based land and sea strike weapons systems. Under the current plans, Boeing and the NAWCWD aim to conduct the first flight of the SPEAR demonstrator in late 2022.

US Navy F/A-18Es [US Navy/Lt Cmdr Darin Russell]
A pair of Boeing F/A-18E Super Hornets - assigned to Strike Fighter Squadron (VFA) 136 'Knighthawks' - fly in formation over the Sea Test Range after completing a training sortie in July 2016. The SPEAR project seeks to develop advanced missile technologies to be employed by US Navy strike fighters, such as the F/A-18E, in the 2030s. US Navy/Lt Cmdr Darin Russell

Steve Mercer, Boeing’s SPEAR programme manager, said: “The SPEAR flight demonstrator will provide the F/A-18 Super Hornet and carrier strike group with significant improvements in range and survivability against advanced threat defensive systems… We have a talented team of engineers to meet the challenging technical demands and schedule timeline that the SPEAR programme requires. We look forward to working with navy experts to advance technologies for the navy’s future capabilities.”

In its press release, Boeing noted its prior successes in developing supersonic and hypersonic technologies. The latter of which is defined when an object travels at speeds greater than Mach 5. The company also cited its success with the X-51 Waverider hypersonic test aircraft and the Variable Flow Ducted Rocket (VFDR) propulsion system.

Boeing’s X-51 Waverider is an experimental hypersonic unmanned test aircraft, which is powered by a single air-breathing scramjet engine and can exceed speeds of Mach 5. The platform conducted its first hypersonic test flight on May 26, 2010.

X-51 Waverider [USAF]
An artist's digital rendering of Boeing's X-51 Waverider in flight. USAF

The VFDR propulsion system was developed under the Defense Advanced Research Projects Agency’s (DARPA’s) Triple Target Terminator (T3) programme in 2014. The project sought to explore concepts for and develop a high-speed, long-range missile that can engage aircraft, cruise missile and ground-based air defence targets.

A VFDR propulsion system is a throttleable ducted rocket ramjet that mixes solid fuel with compressed air collected through air intakes to produce thrust. The system is unique in that it features a valve which allows its gas generator exhaust to be throttled, enabling the vehicle’s thrust to be controlled.