TECH

The ambitious Chinese plan to build a hypersonic plane

Chinese scientists have come up with a new design concept for a hypersonic plane, said to be a major step toward technology that would one day connect Beijing and New York in a few hours - a journey today in about 14 hours on commercial flights.
Research in the area of hypersonic flights is not new, but it is usually concentrated in its possible military applications - an area where there are more resources for financing and less pressure for financial returns.
But will flights with five times the speed of sound someday make sense from a commercial point of view, transporting passengers from one point to another across the globe in a few hours?

Faster
When talking about speed, the most used reference is that of sound - or a Mach around 1,235km / h.
The subsonic is all that is below that level - the aircraft that currently carry passengers, for example. The supersonic is that which lies between a Mach and five Mach (five times the speed of sound), such as the Concorde, a commercial plane that flew between Europe and the United States between 1976 and 2003. The hypersonic, in turn, is that which is above 5 Mach, hit only by small experimental vehicles.
The Chinese have dedicated themselves to breaking the hypersonic barrier, with a team at the Chinese Academy of Sciences focused on one of the two biggest challenges of this endeavor - aerodynamics. The second obstacle is engine issue, more difficult to solve than aircraft design.

Regarding design, a hypersonic flight requires a structure that minimizes drag, which is resistance to air movement; the faster the plane, the bigger the problem.
"It works more or less with the speed square: if you double the speed quadruples the drag," explains Professor Nicholas Hutchins of the University of Melbourne, Australia.
What is new in the design proposed and tested in China is a second layer of wings, placed above the main wings and with the function of decreasing the "drag", a structure similar to that of a biplane.

So far, researchers have only tested a model on a smaller scale in a wind tunnel.
So the project would literally be far from taking off.

NASA's X-43A, which makes unmanned flights, is the fastest hypersonic aircraft known.

The X-43A achieved speeds equivalent to 9.6 Mach, 11,850 km / h in tests carried out in 2004

Arriving at 5 Mach

In the photo above the unmanned X-51 Waverider scramjet engine is a Boeing project to try to overcome some of the challenges of hypersonic flights | Image: USAF


The Falcon HTV-2 is a vehicle under test by the US Department of Defense's Advanced Research Projects Agency, Darpa, and scheduled to fly on March 20 at more than 20,000 km / h | Photo: Darpa

Even if the project succeeds in reducing drag, there are still other challenges.
One is heat resistance, for example. You will also have to deal with the so-called sonic boom issue.If an airplane breaks the sound barrier, it generates shock waves that are perceived as two very loud noises - the volume is size that is capable of breaking glass.Another challenge to put the plane in the air is the engine.From the moment the aircraft reaches the 5 Mach, it can be driven by the so-called scramjet engine - a type of internal combustion engine that can suck up air and use it to burn its fuel.But this type of engine only works from this very high speed. Thus, the aircraft needs, before, another jet engine to be able to take off and reach the 5 Mach.This equipment could be a traditional and extremely powerful jet engine, but eventually a combination of the two types would be needed, experts say."China has created a major project in the last two years that basically serves to design this [hybrid] engine," explains Professor Michael Smart, who studies hypersonic propulsion at the University of Queensland. "It would be a huge breakthrough."

Commercially feasible?In addition to technical advancement, the question is whether there will be a market for hypersonic flights.And that is not something that can be taken for granted - just look at the history of the Concorde supersonic plane. The jet, made by France-England cooperation, was considered the future of aviation when it flew for the first time in 1969. But few were built and it ended up being retired in 2003 - with no sign of a successor.The first reason for the failure is that flights were too expensive for most travelers. And the sonic crash issue meant that the Concorde could only fly above the speed of sound when it was over the ocean.This restricted travel routes across the Atlantic Ocean, hampering its commercial viability.In recent years there has been an increase in interest in supersonic airlines, but it is still at an early stage - both because of the sonic crash and the price, which would be even higher.A scientific paper published last month in the journal Physics, Mechanics and Astronomy states that, in the future, hypersonic flights will be "more convenient and efficient" than a traditional plane.But it will take at least 15 to 20 years for these plans to be commercially viable, says Flight Global's Ellis Taylor."It's hard to imagine a market for that right now," he says. "In fact, historically, ticket prices have fallen, not risen, so it would be difficult to get a clientele for a flight that would necessarily be more expensive.""It would be a really niche product - and that, of course, could hinder the viability of a commercial service."

Military competition

According to Chinese media, the scientists behind the research are also involved in the hypersonic projects of the army - and it is the interest of the military that drives China's ambition for ultra-speed.
Air surveillance, for example, could be employed very quickly and would be difficult to intercept.
We can also think of hypersonic missiles that would make the current anti-aircraft defense system useless.
The main competitors in this race are the USA, China and Russia.
But military research is much more secretive than civilian research - for obvious reasons - so it's hard to say who's ahead.
"The US historically has the lead, but China is approaching very quickly," says Smart.
So the plans for the commercial hypersonic jet, even if still in early stages, are a strong example of Chinese ambition.

Source:bbc.com