Space

The original development schedule called for transfer of control to the USAF at the point when a production decision was to be made, in late 1989. The reorganisation of the programme was also coupled to a rescheduling which has set back the planned first flight to 1994-95.

The X-30 NASP programme was initiated in the mid eighties as a joint NASA/USAF/DARPA programme to develop a hypersonic scramjet-powered aircraft with the ability to cruise at suborbital altitudes and if required directly climb to low earth orbit. The air breathing Supersonic Combustion RAMJET with an ability to take off horizontally would free the X-30 and its derivative aircraft from fixed launch sites. As early as 1986 the X-30 was seen as a technology base for a long-range air defence interceptor, a strategic recce platform and a hypersonic civil transport. The latter aspect of the programme came to prominence in 1986 when US President Ronald Reagan outlined his vision of the ‘Orient Express’, a Mach 25 transport with sufficient range to cross the Pacific in a single suborbital hop.

As a direct result of the programme’s military objectives, it is today highly classified and seen primarily as meeting USAF strategic purposes. Any civilian spinoffs are seen as well into the next century. The immediate objective of the programme is to develop a hypersonic technology base and to build two X-30 airframes powered by air breathing hydrogen-fueled scramjet powerplants. The aircraft would be used to investigate flight at Mach 5-15 and eventually ascent to orbit at Mach 25.

At this stage six separate airframe designs are under consideration with General Dynamics, Rockwell and McDonnell Douglas each designing airframes about Rocketdyne and Pratt & Whitney scramjets. The powerplant competition is of particular interest as it involves a rocket engine manufacturer competing against a turbine engine manufacturer. Pratt & Whitney initiated testing on Mach 14 engine components in March this year, at the Naval Surface Weapons Centre.

The design of scramjet powered aircraft is unusually difficult aerodynamically due to the strong interaction of the airframe and engine inlet. Whereas in a Mach 2-3 design careful placement and design of the inlets and wing/fuselage/inlet junctions can control and often suppress undesirable coupling, no such luxury exists at hypersonic speeds. The nose of a hypersonic aircraft becomes in effect its inlet spike, determining the shape of the shock pattern which forms at the inlet. The designer must therefore reconcile the demands for inlet performance to allow stable operation of the scramjet, the demand for aerodynamic lift, stability and control and the demand for lightweight structure with the ability to cope with sustained elevated temperatures. These problems are exacerbated by the difficulty involved in measuring component performance, the implicit interaction demands what are virtually system level tests. This aspect has resulted in a major effort in computer aided design techniques as mathematical modelling is often the only practical way of investigating a large range of design configurations. Much of the photographic material released from this programme has in fact covered wind tunnel models used to calibrate the design software which will then be used to assess the performance of the real and very much secret airframe/inlet designs.

The final configuration of the design is understandably unclear although it appears that some debate is under way in the US as to the viability of a pure scramjet vehicle. The use of an auxiliary rocket engine to provide additional thrust during injection to low orbit has been raised.

The last year has seen a major effort in the areas of Computational Fluid Dynamics (CFO), airframe aerodynamics involving over 100 configurations and wind/shock tunnel testing of over 20 subscale models at speeds ranging from subsonic to Mach 20. This work has been coupled to testing of engine components and low speed propulsion systems. The area of materials has been equally active, with effort concentrated upon metal matrix composites, carbon/carbon composites and lightweight honeycombs. Each airframe manufacturer has concentrated upon a specific family of technologies, with GD aiming at a largely Carbon/Carbon lightweight vehicle. MDC at a silicon-carbide-fibre/titanium matrix structure and Rockwell at titanium-aluminide honeycomb materials.

The next year will see a major effort in the fabrication and testing of large scale nose, engine and wing leading edge models, these will be subjected to the extreme temperatures of hypersonic cruise and re-entry. This will be accompanied by the fabrication of hydrogen tank, thermal protection system and structural elements. Near full scale engine models are planned for test at speeds of up to Mach 8.

Florida and Hawaii State Governments Seek Commercial Space Ports

In a response directly targeted at the Cape York space port project, the US Transportation Dept Office of Commercial Space Transportation has endorsed moves by the Florida and Hawaii state governments to establish local space launch facilities. This is seen “as a means to keep dollars and jobs in this (ie the US) country”. The Americans appear to be sufficiently alarmed to move on this issue, with the Florida government seeking the use of some established Cape Kennedy facilities while also seeking money to initiate a feasibility study. The planned study would cover user fees, leasing of facilities, federal and state grants for the establishing of infrastructure industrial bonds, tax policy and financing of a Florida Spaceport Authority to generate revenue for the project. These measures would be supported by establishing an insurance fund for commercial space and a statewide Institute for Space Sciences and Technology has been proposed.

Florida is leading the US in the state commercial spaceport race, with Hawaii selecting an 11,000 acre site at Palima Point, near Pahala for detailed study and Virginia and Texas displaying considerable interest. While the Cape York space port is seen as the most threatening competitor, Indonesia has also been identified by virtue of a considerable drive by Arianespace to establish a local launch site.