Air Platforms

USAF using X-51 lessons learned to weaponise hypersonic vehicles

18 May 2015
The X-51A Waverider carried under the wing of a B-52. The programme has become the basis for several follow-on weapons aimed at producing a hypersonic capability for combat aircraft. Source: USAF

Key Points

  • The USAF is using X-51 lessons to develop HSSW and other follow-on efforts
  • The goal is to produce a hypersonic missile concept suitable for future bomber and fighter aircraft

A 2013 demonstration of the Boeing X-51A Waverider is the basis for the US Air Force's plans to weaponise hypersonic vehicles, an Air Force Research Laboratory (AFRL) official told IHS Jane's on 14 May.

"We're taking lessons learned from X-51 and using them in development of HSSW [high-speed strike weapon]," said John Leugers, the principal aerospace engineer at the AFRL munitions directorate.

HSSW is a Lockheed Martin Skunk Works concept under which the company plans to demonstrate hypersonic flight and to provide the basis for future hypersonic programmes, including both expendable missiles and reusable aircraft.

On 1 May 2013, the X-51 performed a successful flight on its fourth test. The vehicle detached from a B-52H and was powered to Mach 4.8 by the booster rocket. It separated from the booster and ignited its own engine. The X-51 then accelerated to Mach 5.1 and flew for 210 seconds until running out of fuel. The USAF collected telemetry data for 370 seconds of flight.

Leugers said the emphasis on hypersonic technology is based on a threat assessment and highlighted a particular need for long-range systems.

He added that ordnance and a guidance system are under development via two demonstration programmes: the high-speed air-breathing weapon concept (HAWC) and the tactical boost glide (TBG). Leugers said the warhead under development for a hypersonic missile is in the 250 lb class, about the size of a small diameter bomb (SDB).

The Pentagon's Defense Advanced Research Projects Agency (DARPA) in April awarded Raytheon USD20 million to continue development of the TBG programme. The goal is to accelerate a weapon to Mach 5 or greater and allow it to glide to its target. Such weapons would have to be highly heat-resistant and manoeuvrable. TBG could ultimately fly at altitudes of nearly 200,000 ft.

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