Future SST Development

However both governments were also made aware of the extremely high cost of SST development, so it was decided that the two projects would be merged to produce an Anglo-French aircraft – development costs and production would thus be shared, and the two countries would not then be competing for a small niche market. A formal protocol agreement was signed on 29 November 1962; the first Concorde flew in 1969, entering commercial service seven years later.

T he Concorde team – headed by airframe manufacturers BAG (which had absorbed Bristol and itself became a part of BAe in 1977) and Aerospatiale (incorporating Sud), with engine companies Rolls-Royce andSNECMA-fullyintended to develop a commercially successful aircraft, and it was initially spurred on by several major airlines exhibiting a strong interest in the revolutionary new airliner – there were expectations at one stage of selling as many as 200 aircraft! However the 1973 fuel crisis and initial public uncertainty about supersonic travel soon resulted in airlines losing interest in the costly, highly fuel inefficient SST ; at the same time development costs skyrocketed.

T his was also the era of the new generation wide bodied 747s, DC-10s and Tristars, offering seat kilometre costs half that of their 707, DC-8 and VC10 predecessors and as much as a fifth less than any SST. It was also a period of severe economic downturn that saw many airlines even deferring orders for their new widebodies.

Ultimately just BOAC (now British Airways) and Air France ordered the Concorde-both mainly because of political pressure-and commercial services were first flown on 21 January 1976. T he project had survived several threatened cancellations, however it continued despite the fact that it was obvious the Concorde would not be a commercial success (it was only really saved by the political implications of abandoning a project which had already cost France and Britain so much!). Extensive design changes had been contemplated to win back other potential customers, however these were not undertaken.

Even after the Concorde entered service, it looked for a time as if it would never be anything more than an expensive novelty. BP:s services to Bahrain and Singapore (after New York these were key destinations) were failures, primarily because supersonic overflight rights were not granted readily by countries under the Concorde’s route and because many travellers were initially wary about SST safety. Politically, the lack of range meant that the aircraft was generally at the mercy of any government on its projected flightpath that wanted to introduce a negotiating claim against either Britain (or France) or even its immediate neighbour.

Malaysia was a classic case in point where that nation successfully caused the joint BNSingapore Airlines London/Singapore SST service to be abandoned due to the Malaysian Government banning Concorde, even subsonically, from using its airspace. With insufficient fuel to fly Bahrain/Singapore whilst skirting Malaysian airspace the service eventually had to be abandoned. T he primary reasons for Malaysia’s independence was a long simmering feud with neighbouring Singapore and a wish for additional rights into the UK for its own airline, MAS. Concorde, as was often the case, was merely a pawn in a power play never envisaged by either its designers or operators- the proverbial ham in the sandwich of international politics. Contributing to this was the aircraft’s operational problems (relatively short range, noise footprint, etc) which meant that BA could not effectively link Asia and Europe with supersonic services.

Air France had more success on its Paris to Dakar and Rio de Janeiro services (both primarily overwater routes), however like BA, services to New York were not as strong as initially expected and in fact Concorde flights were originally met with stiff opposition. More vocal New York citizens and politicians strongly objected to the aircraft’s sonic boom and noise footprint (even though supersonic arrival and departure was over the Atlantic), and in the midst of an emotion packed debate (spurred on by an eager US airline and manufacturing lobby) the FAA created strict environmental noise restrictions for Concorde, effectively ruling out (not unexpectantly) overland supersonic flights; Braniff’s brief Washington/Dallas Fort Worth Concorde services (using leased aircraft) were unsuccessful because at subsonic speeds there waslittlepoint of passengers flying the more expensive Concorde.

Politics and national sentiment again had reared their ugly head with many Americans believing Concorde a major marketing threat to their own US SST project. Indeed, Governor Byrne of New York State was later heard to state that “If the Concorde people had sold one plane to Aer Lingus, another to EIAI and another to Alitalia the residents of New York would by now be saying “what noise”?”

It was not until both BA and Air France had restricted Concorde operations to key transatlantic routes and passengers grew to better accept the aircraft that it became a highly successful niche market airliner. High speed transatlantic crossings (with supersonic flight only over water) are now the Concorde’s forte; but the fact remains that the aircraft is of only limited operational value (refer p. 28 Jan 87 AA).

Of even less operational value however was the only other SST to attain commercial status, the now retired Tupolev Tu-144. Spurred on by the Anglo French effort, Tupolev initiated its own SST program (at the behest of the ruling Communist party, concerned with Soviet prestige) and the Tu-144 – or “Concordski” as the Western media quickly labelled it-made its first flight on 31 December 1968, several months ahead of Concorde.

T he production Tu-144 carried up to 140 passengers in five abreast seating but only limited freight and baggage capacity. Services with Aeroflot (the only operator) proved brief, being marred by at least one crash in 1978, and the aircraft was effectively barred from flying over Western Europe; most commercial services were from Moscow to Alma Ata (southern USSR) and Khabarovsk (USSR Pacific coast) over largely uninhabited land where the supersonic footprint didn’t really matter and citizens could hardly complain! In the end the Tu-144 became little more than an expensive high speed mail plane, carrying few passengers in the final years before being forced into retirement in the mid 1980s.

But at least the Soviet Tu-144 did fly. Other studies, most notably that of US manufacturers, resulted only in ‘paper planes’ and abandoned projects. Though several US companies initiated ambitious design projects for an SST (the US was determined to compete head on with the Concorde), the thrust of the mainly government financed US effort fell behind Boeing which in 1966 unveiled a $US2m mock-up of its proposed Boeing 2707-200 swing wing SST. However the US SST was doomed to failure: Boeing’s designers were attempting a tremendous leap forward in technical complexity; project costs rocketed from an original $US1bn to $US4. 5bn by the time of the program’s launch; and public opinion, swayed mainly by the costs but also environmental (ie noise) concerns, turned against it-the US SST was popularly caricatured as the “SST White Elephant”, and was soon actively opposed by politicians and strong citizens’ lobby groups.

The US effort was as much aimed at preserving national prestige as seriously competing against its European rivals. There was therefore little surprise when mounting costs, declining market interest and the expected commercial failure of the opposing Anglo French effort resulted in funding being abandoned – the US effort collapsed.

New SST Studies

But now, nearly three decades on from the main thrust of first generation SST development, industry is again supporting the SST concept as the next step in long distance premium fare air travel – and lessons have been learned from past experience.

Preliminary studies into the next generation SST were initiated in the mid to late 1980s as a result of growing market interest. These studies were aimed primarily at gauging market requirements and determining possible design and operational problems. Surprisingly, the studies showed that besides technology very little has actually changed since the Concorde first took to the air – if anything, the environmental and economic requirements for the new SST have simply been made more demanding.

The initial studies were undertaken by several sectors of the aerospace industry (including both manufacturers and airlines) and most were in basic agreement, with several key points raised which ultimately will determine the shape of things to come. Most of these draw on past experience to determine future needs:

• market – the new SST must satisfy very long range markets, with flight sectors encompassing Europe/US, US/Pacific Rim and Pacific Rim/Europe. It will therefore be a more effective piece of equipment than the limited range, niche market Concorde. At its full commercial load it must have a range with reserves of at least 5,000nm and preferably ({000nm and must be able to economically fly overland sectors subsonically at no less than Mach . 90 at an altitude higher than competing subsonic jet transports in order to avoid airways congestion.

• older equipment-the new SST will take the Concorde’s place but, as was the case with the Concorde itself, the latest generation of widebody transports will certainly not be made obsolete by the new airliner.

• costs – the SST must be cost effective so that passenger fares can be pegged at a rate only marginally (1. 5 times) above that of subsonic airliners. Purchase price and operating costs must be within reasonable parameters. type-market needs are for only about 500 aircraft, which will effectively sustain production of only one SST type.

• cooperation-with only one SST type being required,international cooperation is essential. Just as the Concorde was the result of a two nation effort, the new SST will be the result of global cooperation. Industry cannot and will not allow competition between different designs to threaten the SST’s viability. It is likely that a consortium of Boeing, Airbus and a number of other major players will team to jointly produce what would truly be the world’s first global aeronautical project.

• timing – there is no urgent need for the introduction of new SST services, though an entry into service of about 2010-20 is desireable. Air France is planning to phase out its SST services around late this decade whilst BA will maintain Concordes operations till around 2002 if airframe fatigue audits continue as expected.

• government involvement – financial involvement must be expected to be kept at a minimum. Gone are the days when governments could wantonly pour copious quantities of funds into such a project without a strong public backlash; there can be no cancellation or threats thereof(as with the Boeing 2707-200 and Concorde respectively) because of political sensitivities. Governments must however cooperate from the start to pass common laws and provide supersonic flight corridors if the SST is to be an international success.

• technical barriers-there are several technical design problems which must be satisfactorily tackled before the aircraft can enter service. Not the least is that it must meet strict environmental requirements; as with the Concorde, the new SST will be constantly subjected to environmental monitoring – now however regulations will be stricter. The new SST cannot be operationally limited by regulations such as those that curtailed both Concorde and Tu-144 services. Indeed, environmental concerns, particularly those revolving around the issue of ozone depletion, will prove to be the single greatest challenge facing a future SST program.

• public opinion – airlines and manufacturers must adopt a common campaign to highlight the advantages of supersonic travel to an often wary public, with efforts being made to counter “nonrational” public reactions such as those that followed the Concorde’s initial entry into service. The public must be educated to accept SSTs flying above them and to be confident that they are a safe mode of travel.

Perhaps the most important point raised by all parties concerned is the need for cooperation to make the next generation SST a reality. With the vast technical research that will have to be carried out by industry, cooperation will be the only way aheadit will provide the key to new technology, will spread the costs of development, and will ease the entry into service of the new SST.

Advanced studies

Having determined the basic needs of the next generation SST, international efforts are now underway to determine the specifics of the aircraft itself. These should be positively identitied within the next two years, at which time it will be decided whether work on the new SST will proceed as planned.

Cooperation is already the word, with some of the world’s major airframe manufacturers involved in international study groups. British Aerospace, Aerospatiale, Deutsche Aerospace, Boeing and McDonnell Douglas have joined forces for research; the Japanese were welcomed as active partners (Japan has both technology and cash support to spare) and Soviet manufacturers are vying to join the group, in particular Tupolev which can bank on its previous supersonic military and airliner experience. With an international effort on this scale, development costs could be shared, essential in a program expected to ultimately cost at least $US10 billion.

The main thrust of current research by this international grouping is to clearly define capacity, performance requirements and market demands.

Capacity inparticular is a big question. The two main chains of thought are to build a Concorde sized airliner (about 100 seats) which essentially would be a replacement for this aircraft, or instead build a much larger SST in the 250-300 seat class.

Most research teams at this stage appear to support the larger aircraft; there is the fear that a Concorde sized airliner’s capacity would make it little more than a dedicated niche airliner, restricting the number and type of passengers to very high fare paying travellers on a few key routes, a situation many airlines have said they wish to avoid. On the other hand, there is concern that a larger SST will be restricted to flying only sectors with higher demand and with less frequency-the smaller capacity of a Concorde sized aircraft would at least offer greater frequency and services into smaller cities.

Perhaps an aircraft can be produced in both standard and shortened fuselage versions, however at this stage this is considered an unlikely option-it would inflate development costs and perhaps create a compromise situation whereby neither airframe operates to its fullest potential. Most tend to agree that only the one SST size will be acceptable-but which size?

Performance is almost a cut and dry question. Besides being able to operate existing supersonic routes such as London/New York, the new SST-whatever its capacity -must be able to fly long range routes linking the Pacific Rim with both Europe and North America. This range capability is considered a key to the operational success of the SST. It is on such long range routes that passengers will gain the greatest advantage over current widebody airliners, and it is on these routes that most growth is expected in the coming century. Range therefore would need to be at least around 5,500nm, with a cruise altitude of about 50-60,000ft to provide fast, comfortable. . flight well above the congested subsonic air routes.

Speed is most likely to be in the Mach 2. 2 to 2. 5 range. Faster aircraft have been proposed with Mach 4 and Mach 5 speeds, however this is believed to be just too big a technological jump for the new aircraft with little real time saving. Thus such aircraft as the proposed Aerospatiale AGV (150 passengers at Mach 5 cruise) are considered not yet realistically possible in either technical or economic terms.

The market demand, as already stated, will be sufficient for no more than one SST type. Perhaps a long term order book of 500 aircraft would be required, and indeed necessary to guarantee economic production whilst the monthly production rate would have to be no less than three units to ensure commercial viability. Five hundred SSTs could provide services on most long sector routes, leaving subsonic airliners to fly shorter routes or high capacity services.

New engine technology

But whilst airlines and manufacturers can relatively easily determine the market requirements for the SST over the next one to two years, the main challenge for the project rests with developing a successful engine/airliner combination over a much longer period Airframe manufacturers are quite confident that they could build a prototype Mach 2. 5 capable SST tomorrow if they wanted to. The technology to build the fuselage and systems already exists- indeed, as the Concorde and Tu-144 both show, it has existed now for a quarter century.

Significant improvements over the first generation SST could be implemented using new technology, with composites -and modern flight control systems being introduced. But though an SST could be built, it is much less likely that it could attain the operating parameters required and definitely could not adhere to the strict environmental regulations that would be imposed, at least not with present engine technology.

Studies are already well advanced on producing an engine to power the next generation SST and give it the range that it needs to link Asia with North America and Europe,thereby preventing a recurrence of the Concorde situation where lack of range has always limited potential operations. Engine companies also are teaming up to design new engines, besides working on their own designs. Teamings to date include Pratt & Whitney and General Electric, who are together working on an engine to provide the range capability for a new aircraft by 2005 (refer p. 72 Aug 91 AA), and Rolls-Royce and SNECMA, the joint designers of the original Concorde Olympus powerplant.

Engine manufacturers are presently developing the variable cycle engine (VCE), preferably to be based on present technology (General Electric for instance will use the experience of its military F120 engine). Such an engine would have a bypass ratio of between 0 and 1. 1, and would deliver the range and speed figures required for the SST. A VCE engine designed for Mach 2 cruise could use a front mounted, split fan layout in which during supersonic flight the entire airflow would pass through both low pressure compressors and through the core. However, this is an early option and studies continue.

Technological development being what it is, one would think that it is only a matter of time before a new SST powerplant providing sufficient long range will be developed-however there is more to the engine than the power it produces.

The crux-the environment

Developing an engine to provide the required speed and range sounds fine in theory, but it will not in itself guarantee success. Concorde and Tu-144 operations have both shown what effect environmental protection laws can have, with both aircraft restricted by their particularly loud noise footprints to flying supersonic services either over water or over largely uninhabited land. Airlines will not accept this situation in a new SST.

Both governments and citizens are more acutely aware of environmental needs and will be more critical of any new supersonic transport which in any way adversely affects either them- selves (ie noise) or the environment (ie destruction of the ozone layer). Just as they did in the 1970s-but perhaps now on a wider scale – people will demand that they not be inconvenienced by SST noise. Therefore to meet existing noise regulations the new SST will have to generate significantly fewer decibels than the Concorde. In fact, it will have to be a full ICAO Stage 3 aircraft.

With new technology, researchers believe that this will be pos- sible, however at this stage they are still working largely with the- ory. (Aircraft noise is largely the result of jet exhaust velocity, and with VCE engines this would be reduced, thus making operation of the engine quieter during cruise; a new exhaust nozzle system could also be designed. ) But what of the initial burst into supersonic cruise, signalled by the sonic boom? This is an even more perplexing problem. Whilst the engine itself can be made to operate quieter, it is not known whether it is possible- or practical-to somehow muffle or even prevent the sonic boom. If the new SST’s sonic boom cannot be controlled, then the aircraft’s commercial operations will suffer. Sonic boom is a major irritant with supersonic aircraft, most at present being mainly restricted to entering supersonic flight only away from inhabited land. It is unreasonable to expect 500 SSTS to be similarly restricted to initiating supersonic flight over water. Concorde’s sonic boom covers an area 30km either side of the aircraft and typically 80kms ahead.

Many major cities-particularly in the Pacific Rim- are however located near or on the coast, so it is at least conceivable that if the aircraft’s supersonic cruise noise footprint can be minimised, it will at least be allowed to operate out of such cities, provided it was over water during the sonic boom. This would restrict many operations such as into central USA or Europe, however others such as US West Coast/Sydney would prove practical. But again, this operational constriction is one which operators and regulatory authorities would prefer to avoid if at all possible.

Noise control however is just one of the factors in the SST equation. Perhaps the ultimate factor- and the one in which there can be no compromise whatsoever-is emission pollution control. With engine/exhaust emissions as they are on current technology engines, the potential effect on the upper atmosphere of some 500+ SSTs flying at altitudes of 50-60,000ft is tremendous. Environmental agencies will simply not allow the new SSTs to fly unless they are satisfied that they are “environmentally friendly” – with present environmental awareness, an aircraft which is too damaging to the environment could be grounded by controversy alone.

This then is the greatest challenge. To develop the new SST to operational status will require radical changes in design and operation of the aircraft. To protect the environment and the increasingly fragile ozone layer, researchers must develop an airframe/engine combination which is not only relatively quiet, but which also will not emit destructive gases. Studies are only now seriously commencing around the world – including Australia, Boeing for instance working with the CSIRO to study effects on the ozone layer-and it will be some time before research results can be determined.

Many doubt that an environmentally friendly engine can be developed for an aircraft to enter service before 2010-If at all! To do so would require a completely new engine concept, perhaps a radical new fuel. To develop these would require both time and money-and a lot of each. Researchers are determined that the environment will not defeat SST development, however only an international effort will result in the ultimate SST engine system being built. Ultimately, if a new system is developed, it could well change the way that mankind lives-new fuels, new transport, new ways of thinking.

But before this can happen developmental research must continue. Industry has learnt what lessons it can from the SST story to date: international cooperation will replace serious competition for the benefit of all; there will be no new SST built which does not suit market needs; the SST must also satisfy strict environmental requirements.

These facts are already known-now SST research must enter a truly new, exciting era to develop a viable supersonic transport.