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Dipankar Ganguly
Instrumentation
30 Nov 2017
Why hasn't airline travel gotten faster?
In the 21st century when everything else is getting faster, it’s frustrating and even baffling to see that our commercial airline travel is still stuck at the same speed since the dawn of the Jet age. In some routes, airline travel has actually gotten slower than what it was used to be in the 1970s. Today an American Airlines flight from Washington D.C. to Miami in the United States takes 43 more minutes than in 1973 and a flight from New York to Los Angeles takes 45 minutes more than in 1967.
Now, what is it that seems like an immense lack of progress in the last 50 years that is stopping us from going supersonic or hypersonic in commercial aircrafts?
Speed is costly:
It is not the case that humans have never tried to build a faster passenger aircraft. We had the supersonic icon, the Concorde, built by the UK and French govt funding. It had a top speed of mach 2.04 (2,180 km/h or 1,354 mph at cruise) which is much more than twice the speed of our today's aircrafts sitting at just over mach 0.8. But by the laws of physics, drag is approximately proportional to the square of the speed, which means speeding up will dramatically increase the fuel consumption by the engines as the aircraft now needs more thrust. So while operating a faster aircraft does save the airline on personnel expenses but it loses far more money due to fuel inefficiency and maintenance.
The Concorde used the zero bypass Rolls-Royce Olympus Turbojet engines to get supersonic but they were extremely inefficient when compared to our modern day high bypass (10:1) Turbofan engines like the General Electric GEnx on the Boeing 787 Dreamliner. With a seating capacity for only 92-128 passengers, the Concorde burned around 21kg of fuel per mile flown while the Dreamliner uses only 8.5kg of fuel per mile flown with seats for 242 to 335 passengers.
This startling differences in per person fuel economy make supersonic travel ridiculously expensive. Most of the passengers while crossing the Atlantic, prefer to fly comfortably for 7 hours than pay around 30 times more to do that in 3hours on a cramped supersonic flight.
Sonic boom:
When airplanes cross the sound barrier by flying over mach 1.0, they produce a shock wave resulting in a loud booming sound as it passes overhead. This sound is displeasing to human ears and destroys glass windows while passing over human settlements, thus severely restricting the flight paths of supersonic aircrafts.
Now one might ponder, why not fly as close as possible to the speed of sound by trying not to cross it to avoid the sonic boom. Well, that is not feasible either. Airliners always try to fly their airplanes at their most fuel-efficient speed. For modern-day high bypass Turbofan engine equipped passenger aircrafts, the optimum speed limit is at around 800-900 km/h, well below the speed of sound at 1234 km/h. Also, flying at around the speed of sound is dangerous too as in this transonic range of 0.8-1.2 mach, air drag increases exponentially causing a destabilizing effect on the aircraft.
Also, check out this video from Business Insider explaining why modern flights take longer to travel the same distance than it did 50 years ago.
So what are your thoughts regarding the future of supersonic or hypersonic commercial travel? Will the technology ever come out of the military to fulfill the need of the masses? Voice your opinions in the comment section below.
Now, what is it that seems like an immense lack of progress in the last 50 years that is stopping us from going supersonic or hypersonic in commercial aircrafts?
Speed is costly:
It is not the case that humans have never tried to build a faster passenger aircraft. We had the supersonic icon, the Concorde, built by the UK and French govt funding. It had a top speed of mach 2.04 (2,180 km/h or 1,354 mph at cruise) which is much more than twice the speed of our today's aircrafts sitting at just over mach 0.8. But by the laws of physics, drag is approximately proportional to the square of the speed, which means speeding up will dramatically increase the fuel consumption by the engines as the aircraft now needs more thrust. So while operating a faster aircraft does save the airline on personnel expenses but it loses far more money due to fuel inefficiency and maintenance.
The Concorde used the zero bypass Rolls-Royce Olympus Turbojet engines to get supersonic but they were extremely inefficient when compared to our modern day high bypass (10:1) Turbofan engines like the General Electric GEnx on the Boeing 787 Dreamliner. With a seating capacity for only 92-128 passengers, the Concorde burned around 21kg of fuel per mile flown while the Dreamliner uses only 8.5kg of fuel per mile flown with seats for 242 to 335 passengers.
This startling differences in per person fuel economy make supersonic travel ridiculously expensive. Most of the passengers while crossing the Atlantic, prefer to fly comfortably for 7 hours than pay around 30 times more to do that in 3hours on a cramped supersonic flight.
Sonic boom:
When airplanes cross the sound barrier by flying over mach 1.0, they produce a shock wave resulting in a loud booming sound as it passes overhead. This sound is displeasing to human ears and destroys glass windows while passing over human settlements, thus severely restricting the flight paths of supersonic aircrafts.
Now one might ponder, why not fly as close as possible to the speed of sound by trying not to cross it to avoid the sonic boom. Well, that is not feasible either. Airliners always try to fly their airplanes at their most fuel-efficient speed. For modern-day high bypass Turbofan engine equipped passenger aircrafts, the optimum speed limit is at around 800-900 km/h, well below the speed of sound at 1234 km/h. Also, flying at around the speed of sound is dangerous too as in this transonic range of 0.8-1.2 mach, air drag increases exponentially causing a destabilizing effect on the aircraft.
Also, check out this video from Business Insider explaining why modern flights take longer to travel the same distance than it did 50 years ago.
So what are your thoughts regarding the future of supersonic or hypersonic commercial travel? Will the technology ever come out of the military to fulfill the need of the masses? Voice your opinions in the comment section below.
Satya Swaroop Dash
Computer Science
30 Nov 2017
Let me talk about another way how airline travel has slowed down over the years. This has nothing to do with the costs involved in the flights or sonic booms, it has to do with the time before the flight. The factor I am talking about is safety. Airline travel in the 70s and 80s would be much faster as there were almost no security measures in place. You could get into a plane just as quickly and easily as you did with the bus. In the 90s and 00s we had plenty of untoward incidents such as hijackings and security measures got really beefed up after 9/11.
Today when you get into a short haul flight, chances are you spend much more time waiting for the flight inside the airport getting through the security queues. Security measures like full body scan and the whole take out your electronics and put them in another tray is just time taking. I in no way condemn the security measures as they ensure safety of passengers but they take time. If you need any proof of how airline travel is slow, just watch any of the Top Gear (the old one with Jeremy, James and Richard) and you will find races where the car goes against public transport and public transport which almost always involves flights lose as they have to spend a lot of time waiting.
Today when you get into a short haul flight, chances are you spend much more time waiting for the flight inside the airport getting through the security queues. Security measures like full body scan and the whole take out your electronics and put them in another tray is just time taking. I in no way condemn the security measures as they ensure safety of passengers but they take time. If you need any proof of how airline travel is slow, just watch any of the Top Gear (the old one with Jeremy, James and Richard) and you will find races where the car goes against public transport and public transport which almost always involves flights lose as they have to spend a lot of time waiting.
Dipankar Ganguly
Instrumentation
30 Nov 2017
Agree with your point @Satya Swaroop Dash. But what I was pointing out is the increase in the in air time and NOT the overall time it takes one to get into the aircraft by clearing the security etc. Then in that context, we need to take into account also the time taken to reach the airport from our residences etc. That has also increased too as there are traffic jams nowadays which was not much an issue back in the 1980s maybe 😁
Time spent in airport formalities varies. Like the President or the VIPs can move faster through these checks via priority counters but even they cannot reach say from London to New York in 3 hours aboard the modern commercial aircrafts (with turbofan engines).
Time spent in airport formalities varies. Like the President or the VIPs can move faster through these checks via priority counters but even they cannot reach say from London to New York in 3 hours aboard the modern commercial aircrafts (with turbofan engines).
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