Since the end of WW2 the US military has sometimes had their ability to take military action restricted by an inability to obtain the necessary over-flight rights of foreign countries. This was brought into particularly sharp focus when the US decided to retaliate against the deranged Libyan dictator, Col Muammar Gaddafi, whose support for a terrorist attack against nightclub in Berlin cost the lives of two US servicemen and a Turkish woman. The US military were directed by the US President, Ronald Regan, to plan a bombing raid against various targets in Libya mounted from the US Sixth Fleet and various bases in England. Operation El Dorado Canyon called for F-111F bombers from RAF Lakenheath, accompanied by EF-111 jammers and tanker support from RAF Upper Heyford, RAF Fairford and RAF Mildenhall, to overfly France en-route to Libya. However, the French President François Mitterrand as usual waived the French yellow anti-American flag and, despite considerable diplomatic pressure, refused to allow the American aircraft to over-fly France – Spain also refused the USA over-flight facilities. On 14 Apr 1986, as a result of the French and Spanish decision, the strike formation and supporting aircraft launched from England and had to fly over 1,300 additional miles, routing out into the Atlantic and around Spain before entering the Mediterranean via the Straits of Gibraltar to carry out the mission, before returning the same way.
To overcome the problem of access to foreign sovereign airspace when conducting military missions, in 1996/7 the US Air Force decided to simply circumvent the airspace itself by developing FALCON, an unmanned hypersonic strike aircraft with sufficient performance to go operate from the USA and if necessary simply go ‘over the top’ of denied airspace in a Military Spaceplane (MSP). FALCON initially stood for Force Application and Launch from the CONtinental United States and was a joint venture between the Defence Advanced Research Agency (DARPA) and the US Air Force to develop an aircraft capable of delivering a prompt strike capability to any location in the world within two hours. However, in 2004 the offensive strike part of FALCON was cancelled, and although the name was retained, the focus shifted to providing a platform optimised for reconnaissance with the following characteristics: payload, 12,000lbs (5,400kg), gross weight 500,000lbs (227 tonnes), range 10,000 nautical miles in less than 2 hours, a 12 hour turn-around between missions and runway type operations. Currently, FALCON would be about the size and weight of a B-52 and would use hydrocarbon fuels, instead of hydrogen enabling it to operate at up to Mach 10 at somewhere between 100,000 – 150,000ft or even higher.
The two key technologies that will determine the success or failure of the FALCON programme are the Thermal Protection System (TPS) and the engine. Lockheed’s solution to providing an effective TPS involves taking existing high-temperature materials, mainly silicon carbide and carbon-carbon composites, and improving them with coatings, such as a pre-ceramic polymer. Using these types of coating and combinations of substrates, the FALCON TPS is expected to operate from 10 minutes to 1hr in temperatures exceeding 1,650°C (3,000°F) and be capable of being reused up to 10 times before being replaced. Lockheed are also attempting to develop a combined turbine-scramjet to power the FALCON. This unique engine will rely on a variable cycle operating system with a turbojet, probably derived from a combination of the Rolls Royce/Liberty Works YJ102R engine in Revolutionary Approach To Time-critical Long Range Strike (RATTLRS ) a quasi-hypersonic missile and the Air Force Research Laboratory’s Advanced Versitle Engine Technology (ADVENT) programme mated to a scramjet . In Lockheed’s current design an inward-turning inlet provides air to the turbojet that accelerates the vehicle to beyond Mach 4, before a Pratt & Whitney Rocketdyne dual-mode ramjet/scramjet takes over to power the vehicle to its Mach 10 cruise.
Despite officially cancelling the strike part of the FALCON programme, I doubt there would be little difficulty in developing a dual reconnaissance/strike version, particularly if the payload area is configured appropriately in the initial design and I believe this will eventually happen when FALCON enters service. When this happens a strike version will almost certainly be used as a carrier vehicle for the Common Aero Vehicle (CAV), a manoeuvring hypersonic re-entry vehicle capable of dispensing a variety of payloads inside the atmosphere, derived from the X-41A programme. Although many aspects of the FALCON programme appear at the cutting edge of current technology, I suspect that Lockheed know considerably more about hypersonic technology than they are prepared to publicly admit and that is why I believe this programme will succeed where some others have failed.