Yet it was while looking into wider elements of the special that the ‘Son of Blackbird’ story emerged. That’s because the road to the SR-72, like the story itself, really begins with the high speed strike weapon (HSSW), a hypersonic cruise missile program still in its formative stages. The Skunk Works wants to change the paradigm on the cost of hypersonics and, for the missile at least, is trying to alter the ‘silver bullet’ mindset around this propulsion technology. If the hypersonic weapon becomes affordable then so to, argues the company, can larger scale applications – including ISR/strike.
HSSW - first steps on the path to affordable hypersonics? (Lockheed Martin)
But it takes more than mass production of missiles and repeatable hypersonic know-how to when it comes to developing a Blackbird-sized penetrating ISR platform. That’s where Lockheed Martin’s apparent breakthrough in turbine based combined cycle propulsion comes in. The game changer is the ability to integrate a scramjet for hypersonic performance with a slightly modified version of an existing combat engine for the subsonic and supersonic part of the flight.
SR-72 viewed from above (Lockheed Martin/AWST)
You can read Lockheed Martin’s take on the story here, and a comparison of the SR-71 and SR-72 engine cycles here. Also, for excellent weekend viewing, here’s a classic Aviation Week produced video on the SR-71.
My travels (all flown at subsonic speeds unfortunately) for the special took me from San Jose, Calif, to a remote rocket range some 300 km north of the Arctic Circle in Norway, and back to the Society of Experimental Test Pilots (SETP) meeting in Anaheim, Calif. The AIAA’s Joint Propulsion Conference at San Jose provided a good entre to the HSSW story, which begins on p.36 of this week’s edition, while the SETP provided a chance to meet Lt Col Timothy Jorris of the U.S. Air Force’s Hypersonic Combined Test Force and Capt. Thomas Meagher, who piloted the B-52H that launched the final X-51A on its successful flight on May 1. The story of how the test team battled against the odds to get the X-51A to the release spot at the right time and place is related on p.40.
Off the California coast, at the edge of its flight envelope, the B-52H readies to launch final X-51A on May 1. (USAF)
As the X-51A story shows, getting to test condition is half the battle when it comes to hypersonics research. However the challenges can be just as great, if not harder, when the experiment relies on ground launched rockets to put the payload into the correct test window. The Hyper Hurdles feature starting on p.38, describes the incredible frustrations encountered by the Australian Scramspace project during the attempted hypersonic test of its scramjet payload on Sept 17.
With the failure visually undetectable at first Scramspace launches from the Andoya Rocket Range (UQ)
Seconds later and the vehicle begins to go wildly off course (UQ)
Led by the University of Queensland, the remarkably ambitious flight ended before it could properly achieve test condition when part of the first stage booster failed on launch. Despite the loss of the experiment, Australian expertise in the rarified world of hypersonics research was boosted by the Scramspace project and the country’s pioneering skills in the field will be honed because of it.