In examining the field of supersonic flight, we start with Boston-based engineering firm Spike Aerospace, which has unveiled plans to develop the Spike S-512, a 12 to 18 seat supersonic private jet designed for commercial use and capable of flying from New York to London in under four hours, about half the time taken by current commercial flights. The 14 to 16 hour flight time for a Los Angeles to Tokyo flight could be cut to eight hours.
The Spike team is made up of engineers, consultants and partners formerly from Boeing, Gulfstream, Airbus. Eclipse, NASA, JPL and other major aerospace companies. The founders are all pilots and have extensive backgrounds in physics, aerospace engineering, finance and management.
Spike Aerospace is a privately-held company founded in 2011, but with roots going back to 2006. The company is located just across the river from MIT, and is close to General Electric Aircraft Engines, Draper Labs, Avidyne, Lincoln Labs and a number of other aerospace companies. Its engineering team has spent the last couple of years designing the Spike S-512, which will be targeted for high-end business users. The estimated cost of the Spike S-512 is $80 million per private jet.
Although the aircraft is still in the design and development stage, the Spike team says the S-512 will have a maximum range of 4,000 nautical miles (4,600 miles/7,400 km). When completed, the aircraft will measure 131 feet long (40 m), have a wingspan of 60 feet (18 m), and cabin measuring 40 feet (12 m) long, 6.2 feet (2 m) high and 6.2 feet wide.
Supersonic Flight Defined
But what is supersonic flight? For those who don’t know, supersonic flight is one of the four speeds of flight, called regimes of flight. Vehicles that fly at supersonic speeds are flying faster than the speed of sound, which is about 768 miles per hour (1,236 kilometers per hour) at sea level.
Speeds of aircraft are referred to by a Mach number, which is the ratio of the speed of the aircraft relative to the speed of sound. Flight that is faster than Mach 1 is supersonic. Supersonic flight includes speeds up to five times faster than the speed of sound, or Mach 5.
As such, the Spike S-512 would qualify, as it is predicted to reach speeds of Mach 1.6 to 1.8 (1700-1900 km/h). The developers believe the aircraft could take off by late 2018, provided it can overcome certain challenges, such as the FAA prohibiting supersonic flights over land due to the sonic boom, with few exceptions.
A sonic boom is a loud, thunder-like noise heard on the ground when an aircraft flies overhead at supersonic speeds. This sound occurs because as objects travel through the air, the air molecules are pushed aside with great force, which forms a shock wave. The shock wave then forms a cone of pressurized air. When the pressure is released, the sound it makes is the sonic boom.
NASA is currently studying and testing devices that could be used on aircraft to lessen the noise and window-rattling effects of the sonic boom. Other companies, such as Boeing and Lockheed, are researching this as well. As a matter of fact, Boeing is now working with NASA on developing new fuel-efficient, quieter engines for supersonic commercial aircraft that will eventually be able to carry 200 or 300 passengers. It is also working on the Boeing X-51 WaveRider, a collaboration between DARPA, NASA, the U.S. Air Force, and Pratt & Whitney. Developed to facilitate long-range, rapid response military strikes, the X-51 could reach speeds as high as Mach 20. However, it has much to do before it can fly successfully, as its second test flight ended in failure when the aircraft lost control before the engine fired up. In June of last year it also failed when it rocketed to speed, but crashed before separating from its booster.
Japan’s national space exploration and development agency, JAXA, is also collaborating with NASA to research ways of reducing the impact of the sonic boom by developing quieter engines and by studying whether the impact for those on the ground can be mitigated. As far as the Spike team goes, it admits that reducing the sonic boom to acceptable FAA regulation levels will be a major challenge. If it can overcome this problem, the company hopes to make the first deliveries of the S-512 in December 2018.
“We are at the very early stages of developing this jet, and have a long, exciting road ahead of us,” said Vik Kachoria, spokesman for Spike Aerospace. “There will be a number of challenges, but with the right management and engineering team, we will be able to face the hurdles and achieve our goals.”
Supersonic Aerospace International (SAI) is another player that is tackling the sonic boom problem with its Quiet Supersonic Transport (QSST), the company’s project to develop a private supersonic business-class jet. Lockheed Martin’s Skunk Works has been developing the project for six years for SAI under a $25 million contract.
Designed to fly at speeds between Mach 1.6 and 1.8 (1,056 to 1,188 miles per hour), the two-engine gull-wing aircraft would leave a sonic wake that’s only one-hundredth the strength of the original supersonic business jet, the now-defunct Concorde. The reason for this is that while the QSST shares its general shape with the Concorde, it is less than half its size, and uses modified aerodynamics to control the pressure generated as the plane displaces air at supersonic speeds. As such, it generates more shockwaves of smaller magnitude rather than two loud and explosive booms. Another key to the QSST’s quieter flight is its distribution of lift-generating features. The QSST’s canards, which are the small wings near the front of the fuselage, and its swept-V tail provide greater lift, preventing the sharp pressure changes that create sonic boom.
Another concept aircraft being designed by Skunk Works is the Quiet Supersonic Plane (QSP), which is comprised of a single engine, a single tail, and a long slender fuselage, all done to eliminate the sonic boom of Mach 1 plus aircraft. When completed, it will have both military and commercial use.
Other Supersonic Projects
As one can see from the above mentioned aircraft, Spike isn’t the first company to promise the delivery of a supersonic jet. In 2009, Aerion Corporation announced its plans to create a 12-seat supersonic business jet, also slated to cost $80 million, with development costs ranging from $2.5 to $3 billion. The Nevada-based company has submitted plans for the development of its private jet, which could reach speeds of Mach 1.6. While Aerion’s jet was expected to enter the marketplace in 2017 or 2018, the company now expects flight testing to begin in 2019, with the aircraft reaching the market in 2021. “Aerion has invested in research to validate the key enabling technology for its efficient supersonic jet, which is the supersonic natural laminar flow (SNLF) wing,” said Jeff Miller, director of communications for Aerion Corporation. “The company has worked with NASA to conduct a series of proving flight tests, and with other institutions for wind-tunnel validation. This technology is now well understood and proven to be viable. Aerion is a small research bureau employing engineers who have become the world’s authorities on the commercialization of supersonic technologies. However, it must partner with a major aircraft manufacturer possessing the capabilities to build the aircraft. The company is in talks with aerospace manufacturers to this end, and is optimistic such a partnership will ensue in the near term.” Meanwhile, HyperMach Aerospace Ltd. has proposed the development of SonicStar, a jet the company claims could reach Mach 4 (about 4,200 km/h) travelling from London to Sydney in an afternoon or from New York to London in an hour. HyperMach CEO Richard Lugg said at the 2011 Paris Air Show that he plans to get the plane airborne by June 2021. When ready, it would fly at an altitude of 60,000 feet (18,300 m), and is slated to be powered by two currently theoretical 54,700 thrust SonicBlue S-MAGJET (Supersonic- Magnetic Advanced Generation Jet Electric Turbine) hybrid supersonic 4000-X series engines. It would carry 10 to 20 passengers in luxury accommodation, and would eliminate some of the sonic boom through an electromagnetic drag reduction technology that is currently theoretical as well.
Another supersonic jet that won’t be ready until 2050 is EADS’ ZEHST, which plans to run demonstration flights by 2020. The ZEHST will avoid climate-harming emissions by using electric power and biofuel made from seaweed. It will also fly 20 miles above the Earth, a height that EADS says will make the sonic boom inaudible from the ground. Flying at over Mach 4, it could cross the Atlantic in an hour and travel from Tokyo to Los Angeles in under two and a half hours.
XCOR’s Lynx is working on the idea of point-to-point travel of crossing the planet by leaving it altogether, an idea it hopes to make a reality by 2030. The two-seater Lynx will take off and land on a runway like a conventional airplane, but will fly outside the atmosphere, making it fast enough to get from London to Sydney in three and a half hours.
The current price of a Lynx flight is $95,000. In the future, the company hopes to develop and launch a larger passenger spacecraft.
Marketplace Fast Jets
Fast jets currently on the market include the Cessna Citation X, which is set to receive FAA certification in early 2014, and the Gulfstream G650, marketed as the world’s fastest civilian aircraft, thanks to a maximum operating speed of Mach 0.935. The Cessna Citation X is a long-range medium business jet aircraft powered by two Rolls-Royce turbofan engines built by the Cessna Aircraft Company in Wichita, Kansas. Although based on earlier Citation models, the Citation X offers a differing in its avionics, engines and wing design. The New Citation X offers upgraded engines and avionics.The aircraft also incorporates a number of innovative design features, such as the large diameter of the engine intakes, which reduces engine noise and improves fuel efficiency. Another new characteristic is the highly-swept wing and airfoil, used in order to increase the Mach number and therefore top speed. The Citation X also has 37 degrees of sweepback at the quarter chord, more than any other business jet, and the horizontal and vertical stabilizers are also highly swept and arranged in a T-tail configuration.
The Gulfstream G650 is a twin-engine business jet airplane produced by Gulfstream Aerospace, which began the G650 program in 2005 and revealed it to the public in 2008. The G650 is Gulfstream’s largest and fastest business jet, with a top speed of Mach 0.925 and a range of up to 7,000 nautical miles (13,000 km). It can be equipped with a full kitchen and bar, as well as satellite phones and wireless Internet. The jet utilizes two Rolls-Royce BR725 engines, which each produce a maximum thrust of 17,000 pounds of force, and it weighs less than 100,000 pounds (45,360 kg), enabling it to land at small airports. The G650 had a normal list price of $64.5 million for 2013, but there is a three-year waiting list for it at that price. Buyers who want immediate delivery have paid more than $70 million for it.
From its “spaceport” in the New Mexico desert, Virgin Galactic is planned to launch its first commercial flights into space before the year is over. The third supersonic test flight of the company’s SpaceShipTwo (SS2) took place in January, and all of its test objectives were completed successfully. Sir Richard Branson, founder of Virgin Galactic, will be on board the SS2’s inaugural flight. He will be followed on subsequent flights by an estimated 680 customers who have paid the $250,000 ticket price. Tickets are available from more than 140 “space agents” worldwide. Current passengers will include celebrities such as Stephen Hawking, Tom Hanks, Ashton Kutcher, Katy Perry, Brad Pitt, and Angelina Jolie. Each passenger will experience roughly six minutes of weightlessness during a two-hour end-to-end flight.
Sir Richard Branson unveiled SS2 on December 7, 2009 at the Mojave Desert in California. The vehicle underwent testing during the subsequent 18 months before being allowed to take ticketed passengers on short trips just above the earth’s atmosphere. Constructed from lightweight carbon composite materials and powered by a hybrid rocket motor, SS2 is based on the concept of a rocket plane that is lifted into the sky by a carrier vehicle before blasting off. SpaceShipTwo’s carrier plane is called WhiteKnightTwo. Finished in 2008, it has already begun its own flight trials. The SS2 will have a crew of two and room for six passengers.
SpaceShipTwo flies to a height of 110 km, going 10 km beyond the defined boundary of space and increasing the experience of weightlessness for its passengers. It reaches a top speed of 2,485 mph (4,000 km/h) which is faster than current fighter jets. Furthermore, to honor the science fiction series Star Trek, the first two ships are named after series’ starships Enterprise and Voyager. When it reenters the atmosphere, SpaceShipTwo folds its wings up and returns them to their original position for an unpowered descent flight back onto the runway.
“Virgin Galactic is at an advanced stage in their flight test program, and so far it’s going very well,” said Jessica Ballard, spokeswoman for Virgin Galactic. “They do encounter challenges along the way, but continually learn and adapt as they go. The SpaceShip One size motor design has been scaled up to the SpaceShip Two size rocket, requiring natural adjustments based on scale and testing of various data points to generate optimal performance. The very nature of flight test allows you to perform and perfect your capabilities.”
As part of this project, New Mexico government authorities are investing almost $200 million (£121 million) in Spaceport America, a purpose-built facility in Sierra County, New Mexico. It will feature a 10,000 foot (3,000 m) runway and a space-age terminal and hangar building designed by Foster and Partners. Additional spaceports are planned in Abu Dhabi and in Europe out of Spaceport Sweden.
While initial ticket prices may be high for the average commercial or business traveler, it is slated that the SpaceShipTwo spacecraft will eventually be affordable enough to take paying passengers.
“Virgin Galactic is very excited to open up the space frontier to many more people,” Ballard said. “They’ve designed their system to be the safest and most affordable system ever built to carry humans into outer space. Once they’ve begun commercial service — which they expect to do this year — VG will be able to operate in a way that allows them to offer great prices while still delivering solid returns to investors. VG is lucky to be able to offer people the chance to achieve their lifetime dream. They’ve been very pleased to see that so many people have signed up already. Having approximately 680 customers is a great validation of what they are doing and the price they are charging.”
In addition to the suborbital passenger business, Virgin Galactic will market SpaceShipTwo for suborbital space science missions and White Knight Two for “small satellite” launch services for LauncherOne, an orbital launch vehicle publicly announced in July 2012. It is designed to launch small payloads of 220 pounds (100 kilograms) into Earth orbit, with launches slated to start in 2016. Several commercial customers have already contracted for launches, including GeoOptics, Skybox Imaging, Spaceflight Services, and Planetary Resources.
Economic Feasibility of Supersonic Flight
While supersonic airliners are currently the objects of research and design, whether or not they will actually be feasible commercially and economically remains to be seen, due to the aforementioned sonic boom, high development costs, including the high expense of construction materials, large weight, and increased cost per seat. For example, just before the Concorde was retired, a round-trip ticket from New York to Europe cost about $10,000, making it too cost-prohibitive to most. As far as business travel went, there were not enough companies willing to pay the premium for faster flights. In the modern day, this remains the key non-technical issue – will corporations be willing to pay a premium price for executive flights?
Bayer and City Financial managers say no, as do executives from U.S. software group Citrix Systems and Carlson Wagonlit Travel, who site concerns about emissions and sustainable travel. Nevertheless, some experts believe the draw of cutting the time and misery out of long cross-Atlantic and cross-continental flights will be worth paying premium for frequent fliers.
Aerion’s Miller is one who concurs with that opinion.
“Aerion has conducted three major market research studies over 10 years showing demand for a supersonic business jet increasing during that period, and more than sufficient to justify the business case,” he said. “Supersonic flight will therefore begin with business jets, and in all likelihood expand to small airliners and then larger ones as supersonic technology advances and seat-mile costs come into the range where airliners will want to offer supersonic service.”
“Until the late 2020s, supersonic jets and tickets to fly them will be very high and probably out of the range of the general public,” Kachoria said. “The first supersonic jets will primarily be used by very large companies with international operations they need to manage and with customers and suppliers around the globe they need to be face to face with. The companies justify the high costs of supersonic flight based on the potential impact on revenue. For instance, Shell Oil and Exxon Mobil make about $450 billion a year. That is $51 million dollars an hour. Saving three hours flying time is well worth it to them.”
Miller agrees. “The initial users will be businesses, governments and ultra-highnet- worth individuals. Tourism would not be an initial application, except conceivably from an extremely high-end travel agent,” he said. “The first supersonic jets are likely to be business jets carrying up to about 12 passengers. Small airliners might follow some years later.”
Eventually though, Kachoria does see the price of supersonic jet flights going down to a level that would be affordable to most businesses and consumers.
“As the technology is developed further and the research and development costs of the first jets are recovered by these early adopters, larger airliner size planes will be built,” he said. “The ticket prices on these jets will come down significantly and be affordable by the general public. We like to point out that in the 1990s, flatscreen TVs were $25,000 and only the rich could afford them. Now a flat screen is only a few hundred dollars. The same will happen with supersonic travel.”
Nevertheless, he doesn’t see supersonic jet travel as ever fully replacing traditional commercial jet transportation.
“It isn’t going to replace commercial air travel, but rather will be incorporated into the operations of traditional airline companies like British Airways or American Airlines,” Kachoria said. “Just as we have minivans for young families and convertibles for singles and SUVs for adventurous types, there are different types of aircraft for different purposes. Supersonic flight will be for long-haul flights, typically over five hours long. Other more traditional jets will be used for regional flights. And even small prop planes will continue to be used for small airports, commuter service and limited passenger demand.”
As far as space tourism goes, Virgin Galactic is very optimistic about its future prospects.
“Virgin Galactic anticipates that their success will mean that space travel will become increasingly affordable over time,” Ballard said. “In much the same way that the early users of commercial aviation services enabled the commercial airline industry, VG’s early adopters will open up the space experience to a much wider group of people. The company expects to fly thousands of people in the first 10 years of operation.”