The Early Days
Ever since man gained the ability to fly, he kept pushing the envelope, going higher, longer, faster. The sound barrier was broken and a renaissance of aviation ensued: jet engines made mass aerial transportation cheap and fast enough for the majority of people. At the same time, records were being repeatedly broken by the fledgling NASA and the Air Force, each for their own purposes.
Aircrafts like the iconic X-15 (still holding the record for fastest manned aircraft) were instrumental in understanding the mechanics of supersonic flight at higher Mach numbers (the X-15 record is Mach 6.7). A lesser known aircraft, the XB-70 Valkyrie, was a huge leap in sustained controlled supersonic flight, since it demonstrated the capacity to fly at Mach 3 continuously, with a significant payload and range.
The techniques, ideas, and materials developed for the XB-70 Valkyrie,which was abandoned due to funding problems and the shift to using ICBMs (Intercontinental Ballistic Missiles) as a more practical solution for strategic nuclear bombing, made a commercial supersonic aircraft a viable idea. NASA started work on a SST (Supersonic Transport) space plane using the remaining XB-70 as a test-bed vehicle, but by that time the Concorde program had already begun, and soon the Soviets followed.
Eventually, NASA was denied further funding for the SST project, but both the Concorde and its Russian counterpart, the Tu-144, made it into production. From then on though, things became difficult for both SSTs, since the Tu-144 only made 55 scheduled flights with Aeroflot before being withdrawn from service in 1979. Concorde had a longer but still troubled life, with both operators, Air France and British Airways, struggling to make a profit out of the aircraft.
The Concorde, a Successful Failure
When it comes to grant ventures such as supersonic commercial transportation, being the fastest at any cost has no place in the aviation industry. It is all fine and well for a government to fund projects such as the XB-70 and the SR-71, but such aircrafts fill niche roles, with very specific flight profiles.
It seems that Aerospatiale and BaE were so overtaken by sheer enthusiasm at the prospect of producing a commercial supersonic passenger aircraft that they forgot to ask airlines how much they were willing to pay, and in the end only the government-owned airlines of France and the U.K. were practically forced to operate the aircraft, merely to save some political face. British Airways managed to turn in a small profit overall but Air France was significantly hurt by the Concorde.
A complicated sum of political and financial factors, as well as a small witch hunt about the effects of the Concorde on the ozone as well as its sonic boom effect, made operating the aircraft a nightmare. The Tu-144 never experienced the same amount of problems mainly due to its much more brief and constrained operational life.
Reasons for Failure
The SSTs fill a niche role in the aviation industry, flying people across oceans in a few hours. They can be operated with a small profit margin, but at the correct timing. Even if the Concorde flights had not been discontinued in 2003, they would eventually be hammered by the oil prices, because other aircraft can be rerouted, the fare policies changed, and a host of other tricks can be performed by airlines to minimize damages.
But an SST is a high cost, high maintenance, low profit business, since its passenger target group is so small that it cannot guarantee a minimum and stable income for the airline, especially when it is almost impossible to offer both Mach speeds and Jumbo ranges. In view of this, the SST seems altogether a bad idea, if you also take into account that the Internet has made the world a smaller place in many ways.
Most business can be now conducted without crossing the Atlantic, and airfares are becoming cheaper by using more efficient engines and aircraft designs. An SST right now would not be an exciting new supersonic way to fly, but a retro oddity. Still, the idea is being tossed around from time to time by various companies and agencies, re-emerging in various forms.
The cancelled High Speed Civil Transport, the proposed A2 and the associated European LAPCAT and ESRP programs, the
Japanese Next Generation Supersonic Transport and the Russian Tu-242 (in danger of being cancelled) have a very bad thing in common: they they take in no account whether the aviation industry needs or will need an SST by the time it is ready to fly, within the next decade. Most importantly these programs lack serious funding, and the SST concept is largely on life support.
Even if new experimental technologies make their way into real production, like pulse detonation engines, and SABRE engines (the Scimitar engine predominantly), with the resulting designs being able to achieve hypersonic flight and almost becoming SSTOs (Single Stage To Orbit), the perennial and true spaceplane (another unfortunate chain of failed and canceled projects), all the airlines will eventually ask for is the aircraft's TCO and profit margin.
What Might Work
The only possibly viable SST idea are SSBJs (SuperSonic Business Jets), which makes sense since large businesses and corporations usually employ private jets and might just be interested in a supersonic jet for selected flights of their choosing. And the sonic boom problem that plagued the Concorde and restricted its routes and flight paths has been proven to be halved with certain elongated fuselage designs, and is
much less of a concern in a small business jet.
In essence, we are not going to see a successor to the Concorde for at least two decades, and it still remains unknown whether the technology will have improved sufficiently so as to lower operating costs enough to attract sales from airlines which increasingly prefer aircraft with larger capacity and less operating cost (fuel and maintenance).
"New Supersonic Plane Could Hush Sonic Booms", Christian Science Monitor
Image Credit: Wikimedia Commons, https://en.wikipedia.org/wiki/Concorde