Deep in transportation

Past Visions of Transportation and Communication

In this day and age, instant messaging really is instantaneous; it only takes minutes to send data from Mars to Earth (1). Communication has come a long way since the 1830s, when the first telegraph was invented in the United States; 1876, when the first words were spoken through a telephone; and 1983, when the first “network of networks”—the Internet—was assembled. Although sending and receiving data has made significant progress in the last few centuries, there are still constraints in the speed of travel on land, water, and in the air.

Past visionaries from the world of novels and cinema accurately predicted current methods of transportation and communication. Joules Verne, a French novelist best known for his profound influence on the literary genre of science fiction, predicted inventions such as electric submarines, solar sails, newscasts, and lunar modules. In 1889, Verne described an alternative to newspapers, explaining, “Instead of being printed, the Earth Chronicle is every morning spoken to subscribers, who, from interesting conversations with reporters, statesmen, and scientists, learn the news of the day” (2). The first newscast didn’t happen until 1920 according to The Associated Press—nearly 30 years after Verne first mentioned it (2). The first network-television newscast occurred 28 years after that first newscast in 1948. By 1974, millions were able to watch President Richard Nixon resign on television (2).

Similarly, Star Trek envisions humans being “beamed up” through space and time by a teleportation device to meet with an older Spock. Will these visions ever become a reality? How close are humans to making any progress in the speed of human transportation?

The Supersonic Dream

For centuries, humans dreamt of flying. This dream was first realized in 1903 with the Wright Flyer, which flew at 30 mph. Why is the current average cruising airspeed for long-distance commercial passenger flights the same as that of the fastest aircraft in 1941? The average speed of air travel has remained constant for 75 years. Is that simply the fastest speed at which humans can travel in the air, or have innovators stopped trying to improve the average speed of air travel?

This question has come up many times. In a recent episode of the podcast The Aviation Week, James Asker, the host, asks, “Why in the world has speed plateaued?  Seems like we haven’t made any progress in terms of actual airplanes flying faster since the [introduced in 1966] SR71 Blackbird” (4).

A similar question was discussed at the Massachusetts Institute of Technology’s School of Engineering. Researchers explain that “In an era when everything else is accelerating, airplanes are actually flying at slower speeds than they used to. Specified cruising speeds for commercial airliners today range between about 480 and 510 knots, compared to 525 knots for the Boeing 707, a mainstay of 1960s jet travel. Why” (5).

Supersonic transport aircrafts (SSTs) tried to provide an escape from this constant speed for years. Out of the three most successful proposed projects, Boeing 2707, Concorde, and Tupolev Tu-144, only the latter two were commercial. The Concorde, which was speedier than the Tupolev Tu-144 and much more successful commercially, flew at a maximum speed of about two times the speed of sound, at 1354 mph at cruise altitude. It was in operation for 27 years before being grounded permanently in 2003. British Airways blamed the aircraft’s grounding on commercial reasons, including the constant fall in passenger revenue and the rise in maintenance costs (6). The Boeing 2707, although designed to have the highest speed and passenger capacity, was never commercialized. The project lost funding due to concerns that high altitude flights would deplete the ozone layer and that the aircraft’s speed would generate noisy sonic booms (7).

The Future of SSTs

With three failed attempts, it is necessary to ask: is the supersonic dream dead, or can challenges that grounded the first generation of SSTs be overcome to finally make a successful commercial product?

Research for supersonic aircrafts was never permanently halted. With each iteration of SSTs, there were three main concerns: the sonic boom, damage to the ozone layer, and the high cost of commercial operations (8).

Lapcat, or long-term advanced propulsion concepts and technologies, is the newest and by far the most successful project continuing this pursuit. At the AIAA Hypersonic Space Plane conference in Glasgow in July of 2015, Lapcat-II  researchers explained that “their early airliner tests suggested such a design would be greener than current aircraft, just as safe, and would not cost much more than today’s long-haul flights” (8). It seems as though Lapcat addresses all of the problems that caused the Concorde’s fall.

Lapcat has the potential to drastically change the air travel industry. According to Airbus and the Japan Aircraft Development Corporation, in another 15 years “the hypersonic aviation industry could employ over 500,000 people, and be worth 3.5 billion euros a year” (8). The ticket prices for such flights will resemble those of first-class international flights, which constitute about 10 percent of current ticket sales and suggests that there may be a steady market for supersonic travel. In addition, airlines may lower ticket prices, instead relying on volume sales for revenue given Lapcat aircrafts’ 300 passenger capacity and the large number of planned routes (8).

Lapcat stands out from all other aircrafts due to its powerful ramjet engine, which is an “air-breathing jet, with no major moving parts,” that enables planes to move at supersonic speeds (8). The technology is similar to that of new missiles used by the Eurofighter Typhoon fighter plane. However, the fuel used in ramjets could determine the Lapcat’s success; the Lapcat’s fuel should be affordable and minimize emissions. For this reason, hydrogen fuels rather than hydrocarbon-based fuels were chosen. Additionally, “Hydrogen, like kerosene, needs an igniter or a heat source to initiate combustion so it doesn’t ignite spontaneously,” says John Steelant, LAPCAT’s project coordinator. “This means that the risks of an explosion or fire are lower compared to conventional airline kerosene fuel” (8).

Can Hydrogen Fuel Lapcat?

The big question is whether it is possible to find an economical source for the hydrogen needed to fuel these aircrafts, which could have drastic effects on ticket prices and the willingness of consumers to fly on supersonic aircrafts. That can be possible if natural gases are used as a source for hydrogen, instead of the electrolysis of water. This adjustment could potentially help change the price of hypersonic airfare to about half the price of a business-class ticket (8). However, if airlines are unable to obtain hydrogen from natural gas, multiple sources project that a one-way ticket from Brussels to Sydney would cost €5,000 (£3,700), which is about three times the cost of current business-class tickets (8).

In addition to using natural sources of hydrogen to fuel these supersonic aircrafts, other research teams propose using wind turbines to produce hydrogen. Such wind turbines have already been used by a Belgian supermarket chain. They use forklifts that are powered by hydrogen which is produced from an on-site wind-turbine park (8).

However, there is one big issue with hydrogen as a fuel source. Though hydrogen-fueled engines, unlike current subsonic engines, do not emit greenhouse gases such as carbon dioxide, sulfur oxides, or soot, the hydrogen combustion produces water vapor that remains in the stratosphere for longs periods of time and could contribute to global warming (8). In fact, “that effect could be worse than the current fleet of long-haul airliners” (8).

Lapcat’s Remaining Challenges

Since 2004, the Lapcat project made significant process as a result of continued support. Researchers working on the project have found ways to overcome many of the challenges that Concorde faced in the 1990s. Some issues remain, however, such as the sonic boom that must be addressed in order to comply with regulations. More research must be done to secure an economical and green source for hydrogen. Most importantly, researchers should look for ways to prevent water vapor from staying in the stratosphere, or to reduce the amount of water vapor released from Lapcat’s engines.

Although Lapcat has yet to overcome many of its challenges, the air travel industry will progress regardless of its success. Since the last attempt at manufacturing commercial supersonic planes, airlines, the commercial side of air travel, have turned their attention to making travelers feel at home, as they cannot get customers to their destinations as quickly as hoped. In fact, the air travel business has made much progress in that regard. Airplanes are now equipped with personal TVs, internet access, personal air conditioning, ergonomic seats, and nutritious meals. This certainly was not the case decades ago.

Conclusion

Progress in the air travel industry and in supersonic aircraft development is inevitable. Evidence suggests that Lapcat will either itself be the commercial supersonic plane passengers have been waiting for, or that the research being done in that project will be applied in the next iteration of supersonic aircrafts. In the meantime, the air travel industry will continue to  innovate.

Figure 1: Flight airspeed records over time (3)

Flight airspeed records over time (3)

 

 

 

 

 

 

 

 

 

Figure 2: Approximate flight times’ comparison between a subsonic aircraft and a supersonic Mach 5 aircraft (9)

Approximate flight times’ comparison between a subsonic aircraft and a supersonic Mach 5 aircraft (9)

 

 

 

 

 

 

 

 

 

Figure 3: Artist’s impressions of LAPCAT Left: Mach 5 hydrogen fueled cruiser for 300 passengers with a MTOW of 400 tons Right: LAPCAT A2 compared with A380 (9)

Artist’s impressions of LAPCAT
Left: Mach 5 hydrogen fueled cruiser for 300 passengers with a MTOW of 400 tons
Right: LAPCAT A2 compared with A380 (9)

 

 

 

 

 

 

 

References:

  1. Questions About the Flight Plan. (n.d.). Retrieved from http://mars.jpl.nasa.gov/mgs/faqs/faq_mplan.html
  2. 8 Jules Verne Inventions That Came True (Pictures). (2011, February 8). Retrieved from http://news.nationalgeographic.com/news/2011/02/pictures/110208-jules-verne-google-doodle-183rd-birthday-anniversary/
  3. Flight airspeed records over time. (n.d.). Retrieved January 21, 2016, from https://plot.ly/~tedsanders8a01/60/flight-airspeed-records-over-time/Scatter plot used by Wikipedia
  4. Asker, J., Sweetman, B., & Warwick, G. (2015, November 24). Podcast: Why Don’t Airplanes Go Faster? Retrieved from http://aviationweek.com/commercial-aviation/podcast-why-dont-airplanes-go-faster
  5. MIT School of Engineering. (2009, February 19). Retrieved from http://engineering.mit.edu/ask/why-hasn’t-commercial-air-travel-gotten-any-faster-1960s
  6. Concorde grounded for good. (2003, April 10). Retrieved from http://news.bbc.co.uk/2/hi/uk_news/2934257.stm
  7. Environment: SST: Boon or boom-doggie? (1970, June 1). Retrieved December 26, 2015, from http://content.time.com/time/magazine/article/0,9171,878301,00.html
  8. Giordani, A. (2015, September 15). The challenges of building a hypersonic airliner. Retrieved from http://www.bbc.com/future/story/20150914-the-challenges-of-building-a-hypersonic-airliner
  9. Steelant, J. (n.d.). LAPCAT: High-speed propulsion technology. Retrieved from http://www.transport-research.info/sites/default/files/project/documents/20121105_121153_95683_Midterm_Review.pdf
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