An Historical Overview of Waverider Evolution

The 1950's

The waverider design was evolved from work done in the U.K. in the 1950's and early 1960's on winged atmosphere re-entry vehicles. Terence Nonweiler had first published work on the waverider concept in 1951, when he suggested the use of a waveriding wing shape for atmospheric re-entry vehicles. By the late 1950`s, Nonweiler, then at Queen`s University, Belfast, was working on the mathematics concerning basic 'wedge' flow for a manned re-entry vehicle developed by Armstrong-Whitworth Aircraft Ltd, to be launched off the nose of the British Blue Streak rocket (sadly cancelled).

To ease his calculations, he started by assuming a 2-D flow as seen from the side, i.e. no spillage. Nonweiler, while lamenting the fact that in 3-D, the underside flow would spill over the sides, causing cross-wise components of flow complicating his calculations, and causing loss of lift, decided to find a way of preventing the spillage.

He did this in order to keep his 3-D equations essentially 2-D, but realised that real hypersonic vehicles could utilise this principle, known as (shock) Wave-riding to improve their lifting performance.

The work done at Armstrong-Whitworth Aircraft Ltd between 1957 and 1959 produced a pyramid shaped design with a flat underside and short wings. This design sought to reduce the total heating experienced by the vehicle on entering the Earth's atmosphere by means of low wing loading (also later adopted in the Waverider design), and by conducting the heat generated on the underside of the vehicle up, through the hot skin and outer fuselage structure, and dumping it off the cooler topside into the wake behind the vehicle, rather than allowing heat to sink into a heat shield enveloping the vehicle itself.

The geometry of the Waverider wing was a result of the efforts of Nonweiler, as part of the above work, to produce a design, the hypersonic performance of which could be calculated from exact shockwave theory. This led to the shockwave-riding anhedral, or cavity, delta wing. Also, following from Professor Nonweiler's conclusion that re-radiation of the considerable heat generated on re-entry would be the best method of cooling for such vehicles, the Waverider would re-radiate heating from its upper surface, into the high or partial vacuum created over the upper side of the vehicle during the re-entry phase, due to its capture of the flow in the under-wing cavity.

Nonweiler then went on to, and still is, developing more and more accurate thermal models of the vehicle heating rates experienced. Concern has been voiced that the neccessarily sharp wing leading edges of a Waveriding craft would overheat and melt, but this is not the case for other reasons.

The 1960's

The 1960`s saw work continue on the waverider concept at the Royal Aircraft Establishment in Farnborough. At this time, the waverider concept was being examined for its suitability as a Mach 6 airliner.

In the 1960's, Nonweiler also moved to Glasgow University in Scotland, as Dean of Engineering, and joined the then student spaceflight society ASTRA. It was at this stage that ASTRA's interest in waveriders started.

The 1970's

A study by Hawker Siddeley Limited in 1971, examined the feasibility of developing a British 2 stage to orbit system, using 2 manned winged stages, in a similar manner to the early US Space Shuttle designs. The 121 foot long first stage was designed as a classical Nonweiler waverider, with airbreathing propulsion. The upper stage was designed as a lifting body, and would have carried an 8000 pound payload to Low Earth Orbit.

In 1974, one Robert Shaw suggested that ASTRA should undertake practical research into waveriders, concentrating on the lower speed range. This suggestion was also backed up by a novel study into the feasibility of firing a waverider equipped with a Cuckoo solid rocket motor booster rocket, off a high altitude balloon, known as Project WHALE (Waverider High Altitude Launch Experiment).

The author most credited with the production of good, readable papers on the subject of waverider re-entry trajectories since the sixties is Leo Townend, who is an authority on adapting credible re-entry vehicle designs to Waveride. His papers cover all the vehicle issues cropping up from re-entry to landing.

The 1980's

Rasmussen at the Department of Aerospace Engineering, University of Maryland, U.S.A., in 1981, kicked off the Waverider renaissance by publishing a paper on a new 3-D flow solution-derived underside shape, as opposed to Nonweiler's simple 2-D derived 'Caret' design. These new Waverider underside shapes were derived from conical-flow solutions produced by cone-shaped shock-surfaces. These shapes have superior lifting performance, and also less shock-drag, but require computational calculation.

This started the ball rolling, and since then, whole families of cone-derived Waveriders have been designed using more and more complex conic shocks, and more and more highly complex software.

In 1984, ASTRA members gave a talk in the U.S.A. on Waveriders. One of the members of the audience was Dr James Randolph, the head of advanced mission planning at J.P.L., who saw the potential of using Waveriding craft to augment gravitational slingshot manoeuvres around planets that had a thick enough atmosphere.

The 'Aero-gravity-assist' trajectory involves dipping into the top of the planetary atmosphere at ultra-high mach numbers, and flying UPSIDE DOWN, i.e lifting in towards the planet to combat the centrifugal forces attempting to throw you out again. Waveriders appear to be the only craft capable of performing this 'mega'-sonic manoeuvre without loosing most of the incoming velocity to drag. Prventing the Waverider melting is another story however, and Randolph's subsequent papers deal with the ferocious heating issues. A double Aerogravity assist trajectory, around both Venus then Mars, with a burn at perihelion, allows a craft launched from a Titan rocket to get from Earth to Pluto within 4 years, a speed not to be sneezed at!

As the ASTRA experimental research through the Waverider Aerodynamic Support Programme (WASP) became all but dormant, so a new Scottish group comprised of the ASTRA waverider talent decided to separate and form a new organisation specifically to actively engage in a serious scientific study and experimental flight programme concerned with waveriders. Thus was born STAAR Research, which was finally established as a totally separate organisation with ambitious aims for waverider development, in July 1989.

Also in 1989, the First International Hypersonic Waverider Conference was held at the University of Maryland, cosponsored by NASA.

The 1990's

The early 1990's saw the establishment of another waverider research programme in the United Kingdom, with the start of the AspireSpace waverider research. The ambitious aims of AspireSpace were attractive to STAAR Research, and encouraged STAAR Research to establish a rapport with AspireSpace early in 1993, which led to their present collaboration.

The STAAR Research / AspireSpace collaboration is focussed on the development of a small manned waverider, initially to be flown sub-orbitally, but eventually to be flown to orbit.

Research is continuing into hypersonic sail waveriders, following work done by other parties back in the sixties where mach 6 waveriding 'hangliders'were investigated: The modern hanglider evolved from Rogallo's hypersonic-sail deltawing designs.

An interesting waverider proposal which builds on ideas originally formulated in the 1970`s, has recently been suggested by U.S. based Marshall T. Savage of the First Millenial Foundation. This uses a launch system using ice propelled waveriders, accelerated by electromagnetic launchers. The ice at the rear of the waveriders being vapourised by powerful ground based lasers.

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Copyright, STAAR Research, 1995-1999.