A team led by the Johns Hopkins University Applied Physics Laboratory (APL) is developing a dual-combustor ramjet (DCR) engine for a long-range hypersonic cruise missile with application-to time-critical strike missions in support of the US Navy’s Hypersonic Weapon Technology Program.
In tests recently conducted at APL’s Avery Advanced Technology Development Laboratory, researchers are said to have demonstrated for the first time that pure JP-10 liquid hydrocarbon fuel can be successfully injected and burned in a supersonic combustion engine required to power a hypersonic missile.
The DCR engine design is said to be simple, safe and fuel-efficient compared to earlier supersonic combustion engine concepts, which required fuel additives to burn properly. ‘The DCR engine design avoids use of highly reactive and toxic fuels or complex heat exchangers required for other supersonic combustion engine concepts,’ said Mike White, program area manager for Advanced Vehicle Technologies at APL.
APL’s DCR engine design injects pure liquid fuel with air captured from the atmosphere into a fuel-rich pre-burner. The by-product is then mixed with more captured air and combustion is completed downstream in a tandem supersonic combustor. ‘We’ve demonstrated that we can burn cold, liquid JP-10 fuel at Mach 6 very efficiently in an engine sized to propel a tactical missile at hypersonic speeds,’ said Steve D’Alessio, project manager for Dual Combustor Ramjet Technologies at APL.
The DCR engine is designed to fly at speeds up to Mach 6.5 at ranges exceeding 400 nautical miles. ‘It’s a throttleable engine design,’ said White. ‘You can fly above Mach 6 and get ranges in excess of 400 nautical miles or, should the mission dictate, fly at Mach 4 to almost double the range.’
Air-breathing engine designs are said to have several advantages over rockets for hypersonic applications.
They can provide a significant increase in range for a given missile weight. They can also be powered all the way to the target, which means a missile can fly a programmed trajectory to improve lethality against hardened and protected targets.
Air-breathing engine designs also enable target aim points to be updated during flight so that a target or its co-ordinates can be changed as necessary. The high degree of survivability that results from Mach 6 flight at high altitude also enables rapid mission planning and a high probability of mission success.
Testing at APL’s Avery Laboratory is scheduled to continue through spring 2001. The team plans to conduct additional tests of the fully integrated engine geometry in the autumn.