How Hypersonic Vehicle Works - How It Works

Blink and you'll miss them, but you'll definitely hear them. Hypersonic aircraft may look similar to the jet planes we're familiar with, but these engineering marvels are completely different beasts. Able to attain speeds that would literally tear conventional passenger jet apart, hypersonic aircraft possess unique engines, are built from advanced materials and are packed full of intelligent tech. 

So just how fast are hypersonic jets? By definition, supersonic vehicle can move faster than the speed of sound or Mach 1- which is 1,235 kilometers per hour, or 343 meters per second. But to be classed as hypersonic, planes must fly at least five times this speed 6,175 kilometers per hour, or 1,713 meters per second. And their speed isn't limited to Mach 5; that's just the beginning.

We've already created aircraft that can reach Mach 20 that's nearly seven kilometers per second! As long as these vehicles can withstand the pressure in the atmosphere, they can keep moving faster and faster. For over 30 years we were able to use Concorde to fly at supersonic speeds. It broke through the sound barrier and revolutionized air travel. But now the aim is to go faster than ever, with jets and commercial airliners capable of reaching even greater speeds. This is, of course, no simple task, but we're still building new and innovative aircraft. 

This technology reveals new realms of possibility that would make air travel more efficient and convenient than ever before. Imagine travelling halfway around the world in just few hours, or seeing spacecraft climb into the upper atmosphere without gigantic rocket. The most exciting part is that this isn't the stuff of science fiction we've already flown vehicles at hypersonic speeds, and researchers are now developing hypersonic planes suitable for public use.

Hypersonic vs Supersonic 

For many years experts believed it was simply impossible to fly faster than the speed of sound. But that all changed in the 1940s, when US test pilot Chuck Yeager flew faster than Mach the speed of sound for the first time in human history. Onlookers below heard the sonic boom as the pressurized air gave way to the Bell X-1 rocket plane, and they realized that supersonic aircraft were dealing with new extremes. But although supersonic aircraft have to overcome many obstacles to break the sound barrier, these factors are compounded when moving at hypersonic speeds. At Mach and above, the air does more than just form shock waves. At such high speeds, the air heats the surface of the aircraft to very high temperatures enough to melt steel and the engines have to cope with huge pressures. 

• Below Mach 1: The aircraft compresses the air in front as moves forward and emits noise from its engines, forming waves that move away at the speed of sound.
• At Mach 1: When the aircraft reaches the speed of sound, the air being compressed cannot move away fast enough, so the waves accumulate at the nose of the plane.
• Above Mach 1: As the plane exceeds the speed of sound, overtakes the waves. This causes change in air pressure, or shock wave, which is heard as sonic.

Building hypersonic vehicle:

 

Supersonic aircraft such as Concorde differed greatly from their subsonic counterparts. They had adapted wing designs and advanced engines. These changes allowed Concorde to smash through the sound barrier, which is something subsonic commercial jets were simply unable to do. The difference between supersonic and a hypersonic aircraft is even more striking, because at hypersonic speeds the rules change completely. The previously benign air starts to become serious problem, as aircraft moving at hypersonic speed generate huge amounts of friction. This results in temperatures hot enough to melt the frame of standard jet, so hypersonic aircraft must be built from robust heat-resist materials such as ceramics. And they can't stop there, because even if they are able to withstand the heat, the pressure at low altitudes is simply too great to fly at hypersonic speeds. 

Hypersonic vehicles need to climb high up into the atmosphere, where the air is much thinner, in order to lessen the strain on the aircraft. Perhaps the biggest consequence of the intense airflow is that hypersonic vehicles can't even use the same engines as subsonic aircraft. Air moving through supersonic plane engines does so at subsonic speeds (the supersonic airflow is slowed by an engine inlet), but if you tried using similar setup when travelling at hypersonic speeds, it would melt or simply explode before your eyes. But rather than rely on rocket engines the only proven systems to power hypersonic vehicles engineers asked themselves more ambitious question: could we take what we've learned about the jet engine and design an equivalent that works at high supersonic, and even hypersonic, speeds? 

This led to the invention of the supersonic combustible ramjet, or scramjet. Taking the principles of a jet engine and stripping away all of the unnecessary components for hypersonic travel such as a turbine and a compressor allows air to move through much more quickly. With few moving parts, these simple-looking engines produce enough thrust for an aircraft to soar at incredible speeds; and in doing so, have started to bring the future of air travel to life.

If there's one lesson that engineers have learned about hypersonic flight so far, it's that heat, weight and power are all major obstacles. Too much weight, and you can't reach the desired speed. Too much heat, and your aircraft will melt mid-flight. And then there's the question of how we can power our machine to hypersonic speeds and keep it there. Fortunately, solutions for each of these critical problems have been suggested and some seriously cool aircraft have been designed in the process. 

Innovative engineers such as Charles Bombardier have been at the forefront of these endeavors. His envisioned aircraft, called Skreemr, would take to the skies with the help of an electrical launch system such as a railgun-so we could be bidding farewell to runways one day. A railgun is an electromagnetic strip that uses electricity to launch projectiles at incredible speeds, and could be used to fire the Skreemr into the air. This would eliminate the need for tons of extra rocket fuel for take-off, reducing the aircraft's weight considerably. Another design by Bombardier, known as the Antipode, could tackle the heat problem as well as the menacing sonic boom. By using counter flowing jets of air that move outwards in front of the aircraft, the temperature generated from aerodynamic friction and the sound produced by the sonic shock waves would be significantly reduced. And these features would help Antipode fly up to Mach 24, equivalent to 29,500 kilometers per hour! These designs are still some time away from being realized, but Airbus and Reaction Engines have recently generated two concepts that could have us cruising at hypersonic speeds that much sooner. Sooner or later we will be traveling using hypersonic planes.

Frequently Asked Questions: Hypersonic

Question No. 1: What is the speed of hypersonic vehicles?

Answer:  Hypersonic planes must fly at least five times the speed of sound 6,175 kilometers per hour, or 1,713 meters per second. And their speed isn't limited to Mach 5; that's just the beginning.

Question No. 2: Do we have hypersonic planes?

Answer: Yes, we do have hypersonic planes such as Concorde etc. but we are trying to built hypersonic passenger planes.

Question No. 3: What engines does hypersonic planes use?

Answer: Hypersonic planes use combustible ramjet, or scramjet. Taking the principles of a jet engine and stripping away all of the unnecessary components for hypersonic travel such as a turbine and a compressor allows air to move through much more quickly. With few moving parts, these simple-looking engines produce enough thrust for an aircraft to soar at incredible speeds; and in doing so, have started to bring the future of air travel to life.

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