The Failure Of Concorde And Current Developments In Supersonic Transport

Since the Concorde retired from service in October 24th 2003, supersonic travel has been absent from commercial transport. However large strides have been made into refining the design standards to make moving faster than sound not only safer, but more economically viable and energy efficient. The British-French supersonic turbojet powered passenger aircraft, Concorde, was in operation between the years of 1976 and 2003. But many argue it was too far ahead of its time and many flaws were identified with the aircrafts design and business model. According to an article by mentalfloss the average ticket price for a round trip from London to New York would cost more than 5000 USD in the 1980s. Significantly more than a subsonic flight which could be $1200 USD cheaper.

This may be due to the fact that the aircraft could only hold a maximum of 100 passengers due to the sleek design, and the limited number of seats would have to counterbalance the massive costs of the fuel, crew and the license fees the airline pays to use the airports at a certain time. However the most memorable moment of the Concorde for many people was the horrific incident of Air Frances flight 4590 from Paris to New York. On the 25th of July 2000 a wheel puncture shortly after take-off resulting in the death of 100 passengers along with the 9 crew members and 4 third parties. The aircraft crashed in a commune called Gonnesse which is situated in the north-eastern suburbs of Paris. The Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile conducted an investigation shortly after the incident with a preliminary report being published on the 1st September 2000 and a final report being made public on 16 January 2002. The report stated that “A few seconds after that [take-off], the right front tyre on the left main landing gear was destroyed, very probably after having run over a piece of metal. ”

This piece of metal is believed to be from a continental airlines DC-10 aircraft that had taken off “5 minutes before”. The tyre is believed to have been thrown towards the left wing and pierce fuel tank 5 causing a fuel leak. This directly led to “A severe fire… under the left wing” and engine 2 placed on the left wing suffered a severe loss of thrust with engine one on the opposing wing also suffering slightly. Due to the tragedy the Concorde was temporarily grounded to make safety improvements such as lining some of the fuel tanks on the wings with Kevlar to give a resistance to large breaches in the fuel tank. The Kevlar doesn’t make the fuel tank bulletproof but while testing, the BBC report that only “one litre of fuel per second” was leaking after a similar impact to that of the AF4590 crash which was leaking 100 litres per second. Also making sure to reinforce the tyres to prevent the same incident occurring again. The next time the Concorde would fly commercially would be on 7th November 2001. Critically after the 9/11 attacks. The attacks caused a collapse in the aviation market and air travel in general let alone the supersonic jet that killed over 100 the year prior. The number of passengers boarding flights in the US took a hit dropping over 40% according to the BBC. All of these factors along with the introduction of the Boeing 747 piled together which eventually resulted in the retirement of the Concorde being announced on the 10th April 2003. However, the failure of Concorde was a valuable lesson to have when engineering the next models of supersonic transport. There are many obstacles that occur when traveling faster than sound that the Concorde overcame.

For example, at very high speeds the air particles around the aircraft become superheated and transfer that energy to the craft. Concorde had paint was twice as reflective as the conventional commercial planes as to be a measure against the massive heat transfer. Another limitation was that to achieve the most efficient speeds the design of a craft would have to be very sleek and that would mean that passenger numbers would have to suffer as such happened with Concorde. The sleek body would also have to be flanked by a small wingspan, which was addressed by using the iconic ogival delta wing to provide enough lift to compensate for its size but still fly comfortably at high speeds and altitudes. The small wingspan also resulted in the aircraft to have a high angle of attack when taking off or landing, this complication would reduce visibility for the pilots when landing so engineers designed the droop snoot to drop the nose of the plane to increase visibility.

Furthermore to achieve Mach 2 aircraft would have to be flying high in the atmosphere where the air is thinner as to reduce air resistance and making flying more efficient. The Concorde flew at 48000ft above sea level. However, there are major environmental concerns when burning fuel at that altitude as some scientists believe that the harmful gasses would have an easier time reaching and effecting the ozone layer and increasing climate change and global warming. Additionally designing and maintaining a supersonic jet is very expensive. Developing an efficient and sustainable aircraft would require very specialised engineers at the top of their field. And the maintenance crew would have to have very specialised training to deal with the specific aircraft, all leading to large expenses to airlines. There are many difficulties with supersonic air travel, but many engineers have speculated that most of these problems would be non-existent if instead of traveling in the air in the future going subterranean. Many concepts have been drafted using cutting edge technologies such as the hydrogen tube which had a patent filed in February 2010.

The basics of the design was to have a vehicle propelled within a tube containing hydrogen gas and have the vehicle “breathe” the hydrogen to power fuel cells in order to produce power. The h2 atmosphere is said to lower drag on the vehicle as is much lighter than our mainly nitrogen atmosphere. The propulsion system is to be a propeller that will essentially “fly” the vehicle through the tube whilst further reducing drag through a low friction surface that guides the vehicle along the tube. The combination of using a clean fuel and having extremely low drag makes the hydrogen tube one of the most efficient and green modes of transport. Furthermore, the predicted supersonic speeds would be very attractive to many people as well as the low costs and therefore low-ticket prices. Another benefit would be that the conduit could connect 2 land locked locations with supersonic travel unlike supersonic flight which is prohibited over land. On the other hand, to establish this mode of transport a conduit would have to be bored between 2 locations and would have to be air tight as not to let any of the extremely volatile fuel out. This would not only be extremely an expensive initial cost but may also affect the existing subway or underground train systems. Likewise, the concept of using an atmosphere of extremely flammable hydrogen gas will have many safety concerns.

For example, a small spark could spell disaster as the entire conduit would be engulfed in flames. Or if the cabin was to spring a leak and fills with the toxic hydrogen gas the passengers would perish. These worries could be why the hydrogen tube remains a concept. An evolution of the hydrogen tube design would be a concept first proposed by Tesla and SpaceX founder and CEO Elon Musk called Hyperloop. The idea relies on similar principles of transporting a cabin through a conduit at supersonic speeds. However, many improvements were made such as the pods being propelled through a pressurized tube by electronic means with magnetic levitation technology also present. With the promise of slashing journey times between destinations. In a publication from Musk released in the next year, he outlined his concept of a cutting edge super highspeed rail system that would have the passenger capsules move through a part vacuum and floating above the rails. Eliminating the two largest factors that slow conventional methods of transport; friction and air resistance. Musks original designs had the pod floating above the rails using “air bearings” supplied by compression fan at the front of the vehicle. The fans would also be responsible for the propulsion of the vehicle through the conduit creating a difference on pressures between the front and rear of the vehicle moving the pod forward at break neck speeds. With Musks involvement in his two other businesses he could not continue progressing the project and explicitly that the hyperloop concept would be strictly open source allowing others to contribute to and develop the necessary technologies. Several start-ups sprung up from the announcement such as the company formally known as hyperloop one, now being acquired by Sir Richard Branson’s Virgin. Virgin Hyperloop

One slightly deviated from Musks original designs and improved upon it. The use of magnetic levitation technology would allow for the conduit to be a complete vacuum therefore further reducing the air resistance. The technology could also be used as the propulsion system as such used in the “maglev” trains in japan. The designs do satisfy the guidelines of musks early designs such as being faster, lower cost, immune to weather and arguably safer than alternative modes of transport.

The Hyperloop

One pod accelerated to one hundred and thirty-six miles per hour in just over two seconds making it one of the quickest vehicles designed for commercial use. They could only get the vehicle up to those speeds due to the limited amount of test track the have available to them, however the goal is for the pod to achieve supersonic speed and cruise at that speed or at even greater speeds. So, the hyperloop would be the fastest mode of commercial transport to date. Furthermore, the design being a rail system, there would not be the long waiting times as such associated with flight and if there are many destinations in the future then there would be less overall travel as the passengers would not have to go to their respective airports. In addition, the magnetic levitation and electric propulsion would also result in the vehicle requiring much less energy to get up to speed. And the energy would not be lost as much as in conventional methods of transport, such as air resistance and friction. This reduction in energy loss would result in lower running costs for the system which could translate to the ticket prices for the hyperloop being much lower than that of other methods such as air travel.

Furthermore, due to the vehicle being encased in a complete conduit the capsule would be protected from the weathering and harsh environments of where it is proposed to be implemented such as the deserts of the middle east. This would lower maintenance costs substantially and therefore could further reduce the price compared to other transport methods. The lower energy consumption would also be very beneficial to the environment. The conventional methods of transport contribute to over a quarter of the worlds carbon emissions according to the epa. The lower consumption would result in the overall emissions being slashed if the technology becomes widespread. Also, the environmental pollution would not be the only pollution effected. Previous methods of supersonic travel were prohibited over land due to the sonic booms that follow them. With hyperloop the conduit is under near vacuum conditions which would eliminate longitudinal waves such as sound, eliminating the effect of sonic booms. And a further countermeasure could be to submerge the entire system to reduce the visual pollution too such as done with the London underground. This would also make it available to more destinations such as cities which are already built up area that do not have the space to house a or multiple hyperloop stations. One of the main problems would be the safety of the hyperloop concept. Being propelled at supersonic speed inside a negative pressure tube would be worrying to many. With the vacuum surrounding the cabin the ventilation within the pod would be problematic especially if there is a fire for example then an air recycling system which was proposed would not solve the issue. Furthermore, if there was an issue with the hull of one of the pods, the pressure difference between the inside and outside of the pod would cause massive and catastrophic de-pressurisation. However, is there is a malfunction with the vacuum conduit that the pods travel through the effects would be even worse. The entire system would depressurise which could cause massive damage. This would require repairing before the system could function again, causing huge delays and closure of certain or all destinations and routes. Not to mention the harm that could come to passengers of the transit if they are unfortunate enough to be present when a failure happens. On the other hand, many believe the hyperloop could be a much safer mode of transport then the conventional methods we have today.

Virgin Hyperloop

One are proposing the system to be completely autonomous in order to eliminate human error and making sure there are no grade or level crossings as to reduce interaction with other traffic and therefore reduce the risk of any accidents. Furthermore emergency braking “techniques” are equipped on the pod in case the vehicle is required to stop suddenly. Also the entire system would be monitored by sensors throughout, constantly feeding information to the system making sure that if any issue occurred then the appropriate action is carried out quickly, effectively and autonomously unlike methods used by most train services which would see a malfunction that would require an inspection and maybe a closure for engineers to fix. Another reason would be that there are only specific routes that the system can travel like all rail vehicles eliminating the risk of unexpected incidents occurring from either side, especially considering that the hyperloop is enclosed in a tube. In spite of all the positives associated with the hyperloop, the one factor that looms over the concept and which could be its downfall is the economics behind it. Elon Musk’s initial predictions state that the hyperloop would be in the several billions of dollars in total and goes into further details breaking down the costs. The capsules alone would be equating to approximately 1. 35 million dollars each, with the 40 capsules proposed building up to a total of around 54 million dollars. However, these estimates are for the original designs that included the air suspension system that would be much cheaper than the magnetic levitation method that most other hyperloop development companies are using. So, the cost of the capsules can only go up. The main cost of the system however would be the conduit that the vehicles travel within. Musk believes that the tube would equate to 70% of the cost of the entire system with the tube being elevated on pylons instead of being submerged underground. The system going subterranean would only increase the cost of the manufacturing due to the need of tunnel construction, but the pylon system may have to be employed to make the system economically feasible. Musk approximates the total cost of the tube to be between 4 billion dollars and 6 billion dollars.

Musk intends to have a vehicle depart from a station every 30 seconds and carry around 30 passengers each. With some simple multiplication, If the system is constantly running filling each seat the system would transport over 31 million passengers a year. However, a more realistic approximation would be that around half of the seats would be occupied taking into account rush hours etc.

So, an estimate would be that the number would be more around 15 million. With Musk’s proposed 20 dollar fare the revenue per year of hyperloop would be around 300 million which would make the payback period of hyperloop not taking into account running costs would be approximately 20 years. This may seem like a long time but seen as though the first basic rail transport system was said to be from 600 BC if the hyperloop keeps improving and becoming more profitable the system could become a massive contributor to the global economy.