Nikolai Puumalainen EPQ

Will we be Flying Supersonic in 20 Years? IntroducAon: Over the course of the last year, I have invesAgated the possibility of commercial supersonic flight within the next 20 years. Here I will discuss the benefits, drawbacks as well as any other details which may impact the feasibility of supersonic travel in the future.

What is supersonic flight? In summary, supersonic flight is a means of travel by aircraM which exceeds the speed of sound, which is 330m/s or 1236km/h. The speed of sound is oMen referred to by using ‘Mach’ numbers. These are numbers which signify how much faster than sound an object is travelling at. For example, Mach 1 would be the speed of sound and Mach 3 would be three Ames the speed of sound. 1

Speeds around Mach 1 are called transonic, Mach 2-5 is called supersonic and any speeds above Mach 5 are called hypersonic speeds.

The Concorde: In my research, I will be referencing the Concorde a lot as I found it to be a very useful case study as it was the first, as well as the most well-known passenger carrying supersonic plane. It was operated between 1976 and 2003 by BriAsh Airways and Air France, and could take you from London to New York in just under 3.5 hours, flying at Mach 2.2 (about 2200km/h). However, it also had a major downside which was the fact that its small cabin allowed for a very limited number of passengers, making each Acket much more expensive than a normal Trans-AtlanAc flight. 2

What are the advantages of supersonic flight? Time savings: An obvious advantage of supersonic flight would be the significant decrease in flight Ames for passengers. For example, the Concorde only took 3.5 hours (including taxi, takeoff and landing Ame) to fly passengers from London to New York. That is two Ames quicker than most airliners during Concorde’s service life, or even today. However, this service is no longer available, due to a major incident with the airplane, which I will discuss later.

Such Ame improvements would be seen on most long-haul flights which would be taken over by supersonic jets as they would cruise at twice the speed and the only limiAng factor would be the Ame it takes to get up to about 60,000 feet as supersonic jets can only fly supersonic at high alAtudes, since they are significantly faster than other planes. If they could fly lower, the spacing between planes would get dangerously close and therefore could cause accidents. Therefore I believe that only long-distance flights will be made supersonic in the future.

Heather R. Smith, What is Supersonic Flight? (hcps://www.nasa.gov/audience/forstudents/5-8/features/nasa-1

knows/what-is-supersonic-flight-58.html 4/8/2017)

Edwin D. Sayre, Development of A New Supersonic Aircra< (hcps://www.nist.gov/document/2

241developmentofnewsupersonicaircraMpdf)

Nikolai Puumalainen EPQ

Greater passenger capacity per day: Another advantage of supersonic flight is that for long-distance flights, such as the one menAoned before, you can carry more passengers as say the flight Ame is about 3 hours (assuming a speed of Mach 3.4 + taxi, takeoff and landing Ames), adding another hour between the flights for cleaning and other ground duAes, we can see that airlines will be able to accommodate 5 flights per day. On the other hand, with the much slower cruising speeds of normal jet airliners, airlines could only operate 3 flights per day. Assuming that the planes are able to carry the same number of passengers (e.g. 250), the supersonic service would be able to carry 1250 passengers in one day, compared to the 750 of the subsonic, more common, jets. 3

To put these numbers into context, Concorde was able to seat 200 passengers and modern aircraM such as the Airbus A320 neo can sit 150 passengers, with larger models sihng similar numbers of people to the Concorde. This shows that unless the aircraM is a large jumbo jet, it is unlikely to seat more passengers than a supersonic jet. 4

What are the disadvantages of supersonic flight? Market change caused a change in passengers: During the development of the Concorde, it was noAced that the primary customers of airlines were no longer businessmen, however they were students or vacaAoners, who would purchase cheaper Ackets long ahead of Ame, making supersonic flight not very feasible as it would cost a lot more than most customers would be willing to pay. Furthermore, charter airlines had come about, creaAng compeAAon with the airlines meaning that people had another cheap alternaAve, so Concorde's compeAAon became tough. AMer this, the idea for a so-called mixed fleet idea was developed, where some Concorde planes would have first class only cabins and normal subsonic planes would be all economy and a survey conducted across the USA, asking about 300 business travelers who all had flown across the AtlanAc, showed that they would pay the premium fare for the significant Ame savings, showing that it is sAll possible that we may have some supersonic flights in the future. However, not all passengers agreed with this as about 10% did not, and more rejected the idea for their Hawaiian route. 5

The change in market for travel can be acributed to advances in technology such as video conferencing. This new invenAon has allowed businesses to have meeAngs over long distances, reducing the need for travel as once set up, this technology is significantly cheaper as well as simpler. This is because new technologies have automated a lot of the systems, reducing labour and costs, making it definitely more economical than flying to a desAnaAon. This would also decrease the down Ame of the businessman or 6

woman as they do not need to waste Ame flying on a plane to get to or from a meeAng, thus allowing that person to be more effecAve to their business. This would mean that businesses would therefore be more likely to implement such systems when compared to flying, due to the overall cost savings aMer the first installaAons as well as the increase in producAvity.

Edwin D. Sayre, Development of A New Supersonic Aircra< (hcps://www.nist.gov/document/3

241developmentofnewsupersonicaircraMpdf)

Airbus S.A.S, A320 neo (hcp://www.aircraM.airbus.com/aircraMfamilies/passengeraircraM/a320family/a320neo/, 4

2017)

Gordon, Supersonic Proving (hcp://www.concordesst.com/history/eh4.html)5

James H. Stephens Jr. , System and method for video call configuraAon and scheduling (hcps://6

www.google.com/patents/US6633324 , 14th October 2003)

Nikolai Puumalainen EPQ

With the average income of an American household being about $59,000 , it is logical to assume that 7

they will take a much cheaper flight booked in advance compared to an expensive Concorde or supersonic flight.

FAA Banned supersonic flight above the USA: Another major disadvantage of supersonic flight is the fact that the FAA (Federal AviaAon AdministraAon) has banned all commercial supersonic flight above the United States of America. This was in response to noise complaints by residents, as well as the fact that the constant creaAon of sonic booms meant that glass in buildings could shake/shacer, causing injury, as well as the general shock of hearing such constant noises. For example, if a supersonic plane flew as oMen as it could (5 flights a day, as discussed earlier), it would create constant sonic booms over one area as the routes are unlikely to vary much. This would mean that flight Ames would be increased since they would have to fly subsonic and there would no longer be such a difference in overall travel Ames between normal jet travel and supersonic. However, the FAA has also said that they might reconsider this if there is new technology to limit such sonic booms to an acceptable noise level. 8

Why do sonic booms occur? To understand why sonic booms occur, we must first understand what happens as an aircraM moves through the air. The simplest way to visualize it is looking at a boat. As a boat moves through the water, it creates waves in front and behind it. A plane does the same as it flies, except these waves are pressure waves and travel at the speed of sound, therefore as the speed of the plane increases to above the speed of sound these pressure waves cannot leave the airframe fast enough. This causes the pressure to build up on top of each other (waves superpose into one wave) and eventually this energy has to be released, which it does in the form of sound and some pressure changes, which causes the air around the plane to form into a mist, as the water in the air condenses due to the difference in pressure. 9

Fuel (in)efficiency: It should come as no surprise to most, that supersonic jets will have a lower fuel efficiency than a modern day jet airliner. For example, the new Airbus A320neo is said to decrease fuel consumpAon per seat per 100km from 2.61L (from the old A320) by up to 15%. This is a huge cost savings for the airline 10

as the major deciding factor in modern air travel is fuel cost, seeing as many budget airlines such as say EasyJet (who have already ordered 100 new A320neo’s) no longer serve food or have many other creature comforts, making them able to offer such cheap flights. With already over 4500 planes

Jessica L. Semega, Kayla R. Fontenot, and Melissa A. Kollar, Income and Poverty in the United States: 2016, 7

(hcps://www.census.gov/content/dam/Census/library/publicaAons/2017/demo/P60-259.pdf, Sept 2017), page 5

Carl Burleson Director of Environment and Energy , Civil Supersonic Airplane Noise Type CerLficaLon Standards 8

and OperaLng (hcps://www.faa.gov/about/office_org/headquarters_offices/apl/noise_emissions/supersonic_aircraM_noise/media/noise_policy_on_supersonics.pdf, 16-10-2008), page 2

Tobias Rossmann, What happens when an aircra< breaks the sound barrier? (hcps://9

www.scienAficamerican.com/arAcle/what-happens-when-an-airc/, )

Jacky Simmonds, Efficient Fleet (hcp://corporate.easyjet.com/corporate-responsibility/environment/efficient-10

fleet, 2016)

Nikolai Puumalainen EPQ

delivered worldwide since 2014 and with another 4000 on backorder, it seems that the new neo series of planes is gaining immense worldwide popularity. 11

The main reason that supersonic aircraM (mainly the Concorde) burn so much fuel is that they use what is called an ‘aMerburner’ to create extra thrust from the exhaust gases release from the aircraM. The way that this works is that extra fuel is shot into the exhaust gases aMer the main combusAon chambers. This creates up to 50% more thrust but is extremely wasteful seeing as a lot of fuel is needed for this to work. AMerburners were used in Concorde likely due to the massive weight of the aircraM, since it was constructed mostly out of older materials such as steel instead of carbon fiber, which is extremely heavy, however an aircraM would sAll likely need such features due to the fact that they will be larger to carry more passengers and therefore weigh more and need more thrust to do so.

Knowing this, companies will be extremely hesitant to operate jets like the Concorde, which had a fuel efficiency per passenger per 100km of 16.7L , which is almost 8 Ames higher than the old A320. Now 12

even with new advances in technology, all the new materials like carbon fiber and even evoluAon in design, it is extremely unlikely that they can get a fuel efficiency nearly as low as that for 2 major reasons, the first being that to get to supersonic speeds and to maintain that speed takes immense amounts of energy, with Concorde having four engines, each outpuhng 170kN (38,050lbs) of thrust, totaling to 680kN (or 152,200lbs) of thrust at full power. On the other hand, a modern commercial jet 13

(taking the A320neo as an example again), produces 110–160 kN (24,000–35,000 lbs) per engine, of which is has two, bringing its total to about 270kN (or 59,000lbs) of thrust using the mean values of the two engines combined when used at full power, however this was rarely used as even during takeoff the flight crew calculate the amount of energy needed to get off the ground and set the engine power accordingly, usually between 80% and 90% to prevent engine wear. So as you can see, a normal jetliner uses approximately less than half of the thrust produced by the Concorde. Secondly, a supersonic jet usually has fewer passengers than a jetliner (Concorde had 200 seats, which were rarely filled), however an A320neo has 150, with a 2 class seaAng system and its enlarged version, the A321 has even more, which are almost always full due to the lower seaAng cost. This, combined with the much lower fuel efficiency of the supersonic jets make them highly uneconomical to run.

Concorde’s problems: In this secAon, I will be introducing the main problems with Concorde which were discovered over its service life. I shall hope to find ways of solving them or show that they have already been solved or are now irrelevant due to technological advances.

Over the 25 year history of Concorde, it has unfortunately had a lot of smaller, but necessarily any less scary, accidents, such as in January of 2000 where it suffered an engine failure on final approach to London Heathrow (LHR) and in June of 1999 it had a hydraulic failure, forcing it had to make an emergency landing again at LHR. To clarify, the hydraulic system on an aircraM is comprised of tubing filled with oil, which is used to transfer inputs from pilot controls to the relevant control surfaces. This also allows the pilots to control very heavy objects with light pushes of the control column (an airplane’s equivalent to a steering wheel) as the pressure in the oil pushes actuators on parts of the wing,

Airbus S.A.S, A320 neo (hcp://www.aircraM.airbus.com/aircraMfamilies/passengeraircraM/a320family/a320neo/, 11

2017)

Airbus S.A.S, A320 neo12

Gordon, Powerplant (hcp://www.concordesst.com/powerplant.html ,)13

Nikolai Puumalainen EPQ

extending or retracAng parts of it, allowing the airplane to turn or change its alAtude. Such systems are built with mulAple fail safe features (mainly that there are several lines which make up the enAre system, each controlling different parts of the plane and some can be used as backups to other systems in case of a failure), however it does not mean they cannot fail in the event of a major catastrophe.

Unfortunately, there are also many more accidents like this . If this informaAon were seen by the public, 14

they could link these accidents with all supersonic flights and could cause fear, possibly making them less likely to want to fly supersonic. This could cause companies to not invest in such technology due to fears of it becoming unprofitable for them.

A simple engine failure mid-flight could also be extremely dangerous when flying above the speed of sound, since the stresses on the airplane will be unevenly distributed. This could cause a catastrophic failure of the structure and possibly a breakup of the enAre plane, which would kill all on board. An example of this is when a military jet which was flying at around double the Concorde’s maximum speed, about Mach 4, suffered an engine failure and the plane disintegrated . Thankfully the pilot was able to 15

eject and survive the crash but his assistant did not as his neck snapped when the cabin lost pressure as he released the glass above him (which is standard procedure before ejecAon) due to the massive force exerted onto him by the air. This shows the possible safety concerns of cabin depressurizaAon, which 16

are already dangerous events at normal subsonic speeds.

The 2000 Concorde crash report: In the crash report, it was stated that the aircraM had a few problems before takeoff, which were noAced and taken care of. For example, there was a slow leak in one of the hydraulic systems (the 'blue' system). This could mean that there were other issues with this hydraulic system which weren't noAced and could have caused problems for the flight crew when trying to prevent the crash, as without hydraulic fluid, it would be impossible to control the plane's elevators or rudder, effecAvely meaning the plane couldn't be steered. Whilst there is no proof of this, a leak in one system could have been caused by something like a rock or a sharp piece of metal, which could have also cut one of the other hydraulic lines.

Another possible issue with this plane was that the deflectors on the front of the Ares, which were designed to move water out of the way and prevent it from entering the engine and it's air intakes were designed specifically to shacer, however this could pose a problem as to the fact that if it shacered the deflector itself could enter the engine. There was a proposed soluAon to this, being to install two cables on the inside of the deflector to keep it from flying off, however Air France did not add this upgrade to their planes . Whilst 17

this was not deemed to be the issue causing the crash of the plane, what really caused it to crash was another object on the runway.

Gordon, Concorde Past Accident History (hcp://www.concordesst.com/accident/past.html, )14

Tony Moore, Blackbird Losses (hcps://spaceflight.nasa.gov/outreach/SignificantIncidents/assets/blackbird-15

losses.pdf, 15-04-1996)

Tony Moore, Blackbird Losses16

Bureau d’enqueKes at d’analyses pour la securite de l’aviaLon civile – France, Accident on 25 July 2000 at La 17

PaWe d’Oie in Gonesse (95) to the Concorde registered F-BTSC operate by Air France (hcps://www.bea.aero/uploads/tx_elydbrapports/f-sc000725a.pdf, 16-01-2002)

Figure 1- Water deflectors in front of the Lres

Nikolai Puumalainen EPQ

However this shows that if the deflector had come off during a takeoff run, this could have caused a very similar crash and the fact that Air France decided to ignore this safety warning, which would likely not even have cost them much, shows that there is a possibility that they also ignored other safety recommendaAons, meaning that we must dig deeper to uncover the full truth about this crash.

As well as this in secAon 1.18.2 of the crash report, it was menAoned that one of the central spacers in the leM bogie was not reinstalled during the last maintenance, which ended just a few days before the accident. This could show that the maintenance crew was being negligent and could have caused issues further down the line. There was an invesAgaAon into the possible effect this would have on the crash, however no conclusive answer was found. However, the repair crews did conduct all the required tests which were done for all planes at the Ame, showing that they were likely not being negligent, but instead were not properly trained in the new type of aircraM that they had to maintain. The landing gear was retracted and extended, however this test was done with the plane raised into the air, so the lack of the spacer was impossible to noAce. I feel therefore that the tesAng process should be made more thorough and rigorous, to ensure a problem like this does not occur again. This probably was an issue only because Concorde was the only plane to feature a design like this, so Air France was likely unaware that they needed to change their tesAng process, however tesAng oversights like this could concern the public, leading them to believe that supersonic flight is very dangerous and that crews did not know how to test and maintain the airframe, making them unlikely to want to fly on it. 18

So in summaAon, the major problems that the Concorde had were its extremely poor fuel efficiency, increasing Acket prices as well as that maintenance crews simply did not receive adequate training to carry out correct repairs to the aircraM, which could compromise safety of passengers. The final issue that I have found so far is that Air France seemed to have acted negligibly, not installing the recommended upgrade to the bogie system to prevent possible engine damage by the water deflector breaking off. The reasoning behind this is unknown. This negligence could show that the company was acAng in the best interests of profits and with passenger safety being a secondary priority. I believe that this would lead to massive public outcry and fears due to mistrust in airline companies, making them less likely to fly.

How far has technology advanced since Concorde? Since the Concorde, the US Air Force has developed new supersonic jets, such as the SR-71 ‘Black Bird’ – this plane could fly from London to New York in just 1 and a half hours. However, the materials used in the construcAon of this plane were significantly more advanced than the ones available to the Concorde designers, since they were specially created for the SR-71 project and were highly secreAve as this was a military project. The reason the plane needed such high-tech material is that it flew at about Mach 3, which is around 50% faster than Concorde’s Mach 2.0. This extra speed meant that the heat caused by fricAon from air resistance was immensely higher, as well as the massive increase in stress levels on the plane. Not to menAon, this plane was much smaller than the Concorde as it was only designed for a two-

Tony Moore, Blackbird Losses (hcps://spaceflight.nasa.gov/outreach/SignificantIncidents/assets/blackbird-18

losses.pdf, 15-04-1996)

Nikolai Puumalainen EPQ

man crew, instead of ferrying passengers across the AtlanAc Ocean. Despite this, I believe that the 19

technology developed for this program will help advance future design. Since the plane had to be made extremely aerodynamic and new materials were invented, I am sure that future designs can take ideas from the SR-71 and use them for commercial travel.

The “BOOM”: The BOOM is a new supersonic project aircraM which is being developed by a private company in the USA. It has a maximum cruising speed of Mach 2.2, which is 10% higher than the Concorde’s Mach 2.0, and about 260% faster than an average jet airliner of today, which flies at approximately Mach 0.85. This plane would take a person from London to New York in 3 hours and 15 minutes, the fastest Ame yet for a commercial plane. Unfortunately, this plane only exists in the form of a 2-seater demonstrator plane. However, even though this project is only in its infancy, it already demonstrates the theoreAcal possibility of supersonic flight, as well as it possibly being somewhat cost effecAve to operate and even affordable to fly on, which I will touch upon later. 20

The ‘BOOM’ also uses new advances in materials, such as carbon fiber, which allows it to cope with extreme heat (heaAng up to as much as 174oC on a hot day) much becer than the aluminium used in the Concorde, which would grow about 40cm when flying supersonic. This would mean that designers had to account for this, making the design much more complicated and therefore also more expensive. With these new advances in materials, the design could be made much more simplisAc, allowing for cheaper fares with flights from LHR to New York’s John F Kennedy airport (JFK) cosAng just around $2500 USD (according to an internal esAmate by the company making the BOOM). However, just because the design was simplisAc, does not mean that it was completely simple. Their engineers found a way of fixing a big issue with supersonic planes, which is that as you speed up, controlling the plane becomes more and more difficult as the control surfaces become less effecAve, due to the fact that the center of liM is shiMed towards the back of the planes. This prompted them to create a new design which stretches the Ap of the wing to the front of the plane, as shown in the diagram to the right. This creates more liM at the front as the plane is flying supersonic (however is virtually ineffecAve during subsonic flight), meaning that it will balance out the liM when flying at higher speeds, meaning that controlling the aircraM will be made easier and therefore also safer as there will likely be a lesser need for technology (which can all fail) to control the plane, and a human will not be overworked, which has caused significant numbers of accidents in the past. 21

Their own internal study also menAoned that these costs could be in line with current prices of business class flights and sAll be economical for airlines to operate, assuming an 80% capacity of the plane. A 22

leading aviaAon consultant has also even said “The BOOM airliner will be a core part of the

Edwin D. Sayre, Development of A New Supersonic Aircra< (hcps://www.nist.gov/document/19

241developmentofnewsupersonicaircraMpdf)

Boom Technology, XB-1 Supersonic Demonstrator (hcps://boomsupersonic.com/xb-1/, 2017)20

Boom Technology, XB-1 Supersonic Demonstrator (hcps://boomsupersonic.com/xb-1/, 2017)21

Boom Technology, Offer passengers more of what they value most: Time (hcps://boomsupersonic.com/airlines/, 22

2017)

Figure 3 - Wing extensions running up the fuselage

Nikolai Puumalainen EPQ

interconAnental airline fleet”. This shows that experts in this field believe that this technology is commercially viable, showing that airlines could also be considering such projects for the future. 23

What causes a change in the center of liM? Before we discuss changes in liM, first we must understand what causes liM in the first place. This is done by the wing, which causes a difference in pressure of air moving above and below it. To rise, pressure below the wing must be greater than above, thus basically pushing the plane upwards. This change in pressure is created by the so-called ‘camber’ of the wing, basically how curved it is, the more camber, the more liM (unAl the point of stalling), which is why we see wings with a curved front ‘leading edge’. As the control surfaces are moved, there is an increase in camber of the airfoil (see Fig 4). 24

However, camber only creates liM at subsonic speeds, which means that the way that the plane is controlled must be made more effecAve at supersonic, meaning that our enAre way of controlling modern planes has to be reworked. Whilst I believe that this could be done since we already have companies who are currently working on such tasks, I do not believe that it will be completed within the next 20 years as there have not been any promises made by airlines as to a Ame frame within which such technologies would be adopted.

The main issues with supersonic flight: One of the main issues with supersonic flight is that during the transonic phase of flight (between Mach 0.8 and 1.2), there is a sudden increase in air resistance experienced by the aircraM. This is caused when a plane is flying around what is called a ‘criAcal Mach number’, unique to each aircraM, where air parAcles at some points accelerate around the wings of the plane and go supersonic. This causes shock waves to resonate through the aircraM and is felt as a sudden or significant increase in drag, making it much harder for a plane to accelerate. Therefore most modern planes have a specific speed which they do not exceed since it would burn much more fuel (due to the increased air resistance) but prevents them from acceleraAng more. This is likely why we see such an increase in power requirement for the 25

Concorde’s engines, when compared to a modern commercial jet. This could possibly stop supersonic flight from being commercially viable, since we have yet to find a way to prevent drag from increasing as it seems to be a rule of physics. The effect of this on the idea of commercial supersonic travel could be catastrophic, seeing as the goal of airlines is to make profit and with their profit margins already being so low, this might make such services even less feasible to operate. However, profits are rising with them going from 2.4% to about 5.5% which equates to only about $5.42 per passenger. However an expert did

Mike Boyd, Boyd Group InternaLonal23

(hcps://forum.kerbalspaceprogram.com/index.php?/topic/46067-control-surfaces-and-supersonic-flight-far/ )24

ChakrabarL, Sandip (1990). Theory of Transonic Astrophysical Flows. Singapore: World 25

ScienAfic. ISBN 981-02-0204-0 (through Wikipedia)

Figure 4 – how camber affects li<

Nikolai Puumalainen EPQ

say "If you look at the last 20 years the average net profit margin for airlines in terms of revenue is zero." 26

Another, smaller issue with supersonic aircraM, is that they usually require what is called a ‘delta-wing’ design, like the Concorde, where the wings are swept back and connect to the fuselage over a large area. The main advantage of these wings is that they do not hit some of the shockwaves which are produced during supersonic flight, but provide the same amount of liM. However, the problem with this is that as speed increases, drag increases, but this large wing design creates more air resistance to start with, making it less efficient in some ways, meaning that we need to find a suitable compromise between the advantages and disadvantages of these design features.

What is being done about these issues? NASA engineers in California, Ohio and Virginia have embarked on an ambiAous project to create a supersonic aircraM which creates a quieter sonic boom. However, such a target is difficult to meet since the FAA has yet to specify the maximum noise levels allowed for a sonic boom. Despite this, NASA is working on designing aircraM which meet standards that they deem acceptable which is being achieved by altering the posiAoning of certain key components on an aircraM. For example, the locaAon as well as the shape of the components have been idenAfied as key factors in determining the noise generated by a sonic boom. Such designs are already being worked on by engineers and some esAmates say that they might be flying by the year 2025. Such design features include a needle like nose Ap as well as swept wings, similar to the wings of the Concorde. However, this kind of design would mean that the plane 27

would have to be quite small, in order to meet such regulaAons, possibly creaAng another issue for airlines trying to make a profit with supersonic planes. This would be due to the low passenger capacity a narrow-bodied aircraM would have.

Another new discovery made by the NASA team of engineers, in collaboraAon with Boeing and Lockheed-MarAn is the fact that one of the most important factors in reducing the sonic boom is the placement of the engines. Boeing engineers are now proposing to radically change the old way of designing aircraM and instead of mounAng engines under the wings, they are proposing to mount them on top of the airframe as this diverts a lot of the shock waves upwards and also has the fortunate side effect of simplifying wing design as they no longer need to be made to deflect and diffuse vibraAons as much. This would mean that designs could get lighter and therefore make the planes more fuel 28

efficient, though I am unsure if this will offset the increased fuel consumpAon during the transonic stage, thus sAll potenAally posing a financial risk to airlines.

Tupolev Tu-144: The Tupolev Tu-144 was a project developed under the Soviet Union (with the first flight being on the 31st of December 1968) for a passenger carrying supersonic jet. It had a few passenger carrying flights but due to technical limitaAons and safety concerns. This plane was capable of cruising at Mach 2.2 and flying at 16,000m (52,000M) which is much higher than most other planes, at higher speeds. However, this plane was grounded for passenger flight aMer only 55 flights, aMer one plane crashed at a Paris air

Dean Irvine, How Airlines make less than $6 per passenger (hcp://ediAon.cnn.com/travel/arAcle/how-airlines-26

make-less-than-6/index.html , 3rd June 2014)

Frank Jennings Jr., Karen L. Rugg, NASA Centers Team Up to Tackle Sonic Boom (hcps://www.nasa.gov/aero/27

centers_tackle_sonic_boom.html, )

Frank Jennings Jr., Karen L. Rugg, NASA Centers Team Up to Tackle Sonic Boom28

Nikolai Puumalainen EPQ

show, with 2 crew fataliAes as well as numerous other crashes. The plane was then only used to fly mail (for tesAng purposes). The main route which was flown was the Moscow—Alma-Ata, which even when passengers were allowed to fly on it was limited to 70-80 passengers per flight by the Soviet government due to safety concerns, well under the plane’s seaAng capacity of 277. This meant that the plane was not making much money or even meeAng the demands of the public, since many wanted to fly on it but were not able to due to arAficial restricAons. However, these restricAons were, in my opinion, warranted due to the numerous safety concerns caused by the many technical limitaAons. 29

An example of the reasons for the safety concerns was the crash of the plane during the Paris air show in 1973, which occurred aMer the Concorde demonstraAon flight where the Soviet pilot was quoted as saying “Just wait unAl you see us fly. Then you’ll see something” , talking to the Concorde crew as he 30

was confident that he would outperform his European counterparts. The crash then occurred on what looked to be a landing approach, but at the last second the pilot maxed out the engines and climbed, which is believed to have caused the plane to unexpectedly stall at around or below 2000M (610m), something the pilot was never able to recover from as the plane began to disintegrate when it pitched into a steep dive. It is unknown why the pilot decided to execute this maneuver. Amongst the dead were the 2 pilots, 3 children, as well as 60 others being severely injured. Sources cannot agree whether or 31

not this was caused by pilot error or a malfuncAon, and a common theory is that another plane which was photographing the Tu144 surprised the Soviet crew (they weren’t told about the plane and they had poor vision out of the cockpit, possibly causing more surprise as they only saw it at the last second) and as they iniAated the emergency maneuver they ended up overcompensaAng and thus caused the crash.

According to numerous other sources there were a further 2 crashes towards the end of the 1980s. In one case the aircraM caught fire and was forced to crash land in a Russian field. However, it is very difficult to find informaAon on these crashes which is supported by other sources. This is most likely due to the heavy censoring policies within the Soviet Union and them not wanAng anyone to find out that they had failed at something. There were also few ground witnesses as this occurred outside inhabited areas, making it even more difficult to find first-hand informaAon about these incidents.

From this experiment, we should learn that building a supersonic plane is not a cheap project and safety should be taken as the number one priority. For example, the poor cockpit visibility (which was also an issue with Concorde) should be improved. However I believe that these accidents were mostly caused due to the rivalry between the East and West and the Soviets released a plane which was not ready and was underfunded to becer their image. Whilst the Soviet Union does not exist, I believe that if Russia or another major Eastern power were to start developing a new commercial supersonic jet, the Western powers would be forced to create their own. This would create another race, like the space race, where one country would release an unfinished vehicle, just to beat the other. This would have devastaAng consequences to passengers as there could be flaws endangering their lives.

Flight anxiety A possible major issue is flight anxiety, and about a third of Americans are afraid to fly. I have loosely 32

menAoned this a few Ames in this report when talking about safety concerns making people scared, however here I plan to go into a licle bit more detail. For example, it was found that many people who

Tupolev Tu-144: Reasons for Failure and CancellaLon (hcps://en.wikipedia.org/wiki/Tupolev_Tu-144, 2017)29

Mikhail Kozlov (Tupolev Tu-144 Pilot), just prior to takeoff30

Nova PBS,"Supersonic Spies.", air date: 27 January 199831

Darrell Davis, Flying Safety StaLsLcs (hcps://flyfright.com/staAsAcs/, 10-5-2017)32

Nikolai Puumalainen EPQ

were afraid of flying (73%), were scared of mechanical failures or issues in the air, whilst 36% of those quesAoned were also afraid of problems on the ground. I unfortunately believe that because such a large amount of people are already anxious about flight, they would be even more anxious about supersonic flight due to it being a relaAvely new innovaAon. This would likely lead to low iniAal sales. I believe companies would know this aMer researching the market before implemenAng supersonic flight, making them less likely to invest in it.

A report on how airline economics affect airline safety, has menAoned that some airlines were forced to cut corners on their safety measures due to deregulaAon, which decreased their profit margins. This shows that airlines may not always take the safety of their passengers as seriously as they should. This 33

informaAon could cause even more fear within the flying public, meaning that flight in general could become less profitable to companies, meaning they would have less capital to invest in newer technologies and instead could have to spend it on markeAng to bring back their customers.

Safety is a large priority to customers as they see it as an aspect of the product quality when purchasing flights. However, it is difficult for the flying public to observe this measure of quality compared to other measures, such as comfort, schedule convenience or on-board service. This could show that the aviaAon industry might be less safe than members of the public might demand if properly informed. Proof of 34

the fact that customers lose trust in companies aMer a crash was shown aMer studying two crashes involving McDonnel-Douglas DC-10 aircraM. AMer two such crashes, the company lost about 10% of its share in the market, equaAng to about $100 million, only four days aMer the accident. 35

Safety aboard supersonic planes: A major concern with flight is cabin depressurizaAon. This is when a hole in the cabin causes air to leak out very rapidly. Using Concorde as an example again, it flew at 60,000M above ground level (about 18,300m). This means that the air outside the plane is extremely thin and if a depressurizaAon occurred (which would likely be what is called an explosive or rapid decompression, due to the massive difference in pressure as an aircraM cabin is maintained at about 0.8 atmospheres and the outside air is at under 0.1 atmospheres as seen in figure 5 (looking at about 18km). The reason that this is a 36

major concern, is that when the cabin depressurizes and oxygen masks deploy, passengers only have a short period of Ame to put on the masks before their brains begin to shut down and they lose fine and rough motor skills.

As shown in figure 6 , as alAtude increases the Ame you have to 37

Nancy L. Rose, Fear of Flying? Economic Analyses of Airline Safety (hcp://www.nber.org/papers/w3784.pdf, July 33

1991) pdf p13

Nancy L. Rose, Fear of Flying? Economic Analyses of Airline Safety pdf page 2134

Nancy L. Rose, Fear of Flying? Economic Analyses of Airline Safety pdf page 2335

Image 2 (hcp://www.aerospaceweb.org/quesAon/atmosphere/q0090.shtml)36

ATSB, AviaLon Research and Analysis Report AR-2008-075(2) (hcps://www.atsb.gov.au/media/27376/37

ar2008075_2.pdf, Jan 2009)

Figure 6

Nikolai Puumalainen EPQ

put on a mask decreases significantly. Unfortunately this is a really old study and didn’t plan on planes flying as high as Concorde, therefore they didn’t give data on alAtudes as high as 60,000M. However, we can safely extrapolate that by the fact that the Ame of consciousness decreases so rapidly up to 40,000M, at 60,000M you would have few seconds at the most before losing consciousness. Such an accident could have severe consequences on the supersonic flight industry as nobody would want to fly on an aircraM they thought unsafe. For example, the 2005 flight 522 operated by Helios Airways, which crashed because the air crew didn’t react properly to a loss of cabin pressure and passed out. 38

Such a major issue is likely to prevent commercial supersonic travel as it is impossible for the planes to fly lower, as they are travelling much faster than other traffic and would cause issues with spacing planes for safety. This forces them to fly high, where the risk of hypoxia (loss of consciousness due to oxygen starvaAon), is extremely high if a depressurizaAon occurred. This would mean that a new supersonic plane is unlikely to be cerAfied for commercial travel, as passengers would not be able to put on their masks in Ame to prevent death, prevenAng possible commercializaAon of this technology.

Conclusion Overall, I believe that the disadvantages outweigh the advantages. This is because of the total ban on all commercial supersonic flight above US soil due to sonic boom concerns, meaning that flights are limited to only going to coastal parts of the US (at least while supersonic), aMer which passengers are likely to take cheaper domesAc flights within the USA (seeing as the planes are cheaper, the fares should be cheaper, as well as the emergence of budget airlines dropping prices) meaning that not only would running supersonic flights to ciAes within the US be uneconomical, the Ame savings would not also be nearly as great, seeing as only around half of the flight distance would be flown at supersonic speeds.

However, I am limited in my decision by the fact that current technology has yet to advance far enough to create a quiet supersonic plane design. I menAoned earlier that the Boeing engineers working with NASA have designed a potenAal prototype of an aircraM with engines mounted on top of the plane, but have yet to figure out a way to reduce the decrease in performance which comes with such a design, which is caused by the difficulAes of taking in air at such a posiAon, since to reduce fricAon a lot of the air around an aircraM is diverted off the airframe by the nose cuhng through the air. This means that we are likely to have a quiet supersonic aircraM in the future, however I do not believe that we will achieve this goal in the next 20 years, at least not on a commercial scale. This is because I have found a lack of companies interested in supersonic flight, as the companies who hold a duopoly over long distance commercial flight (Airbus and Boeing) have either not shown an interest in supersonic flight, or in Boeing’s case, cancelled their project in favour of larger, slower aircraM. This occurred when the 747 was being developed, as they saw a shiM in the market where tourists were more likely to fly, compared to business people.

Another issue with design is the criAcal Mach number, which I menAoned earlier, prevents aircraM from acceleraAng to supersonic speeds. I believe that the closer this number is to Mach 1, the more efficient we can make our planes since it would be able to get to that number, then just as it passes that speed it has to use more fuel, but then the plane would go supersonic relaAvely soon aMerwards (as the point is very close to Mach 1), meaning that the Ame the aircraM is fuel inefficient is as small as possible.

HELLENIC REPUBLIC MINISTRY OF TRANSPORT & COMMUNICATIONS AIR ACCIDENT INVESTIGATION & 38

AVIATION SAFETY BOARD (AAIASB), AIRCRAFT ACCIDENT REPORT HELIOS AIRWAYS FLIGHT HCY522 BOEING 737-31S AT GRAMMATIKO, HELLAS ON 14 AUGUST 2005 (hcp://www.aaiasb.gr/imagies/stories/documents/11_2006_EN.pdf, Nov 2006)

Nikolai Puumalainen EPQ

However this seems to be very hard to achieve as this number is linked to the total surface area of the aircraM and is determined using the ‘transonic area rule’. This adds another complexity to the design, which makes me more certain that we will not have efficient supersonic passenger transport in the next few decades.

I believe that fear of supersonic flight will be a major factor for many people. This is because out of the people I have come to talk to about supersonic flight, many had heard of the major Concorde crash and were somewhat nervous about another such incident occurring. This would mean that it would likely take a lot of adverAsing to get the word out that supersonic travel was truly safe and would sAll need more funding to show that it was safe by having demonstraAon flights. All this would likely not be worth the effort as there are already cheap trans-AtlanAc flights which are making air companies money and since there is already such high compeAAon, with many companies lowering prices to stay compeAAve, I find it hard to believe that an airline (especially a major one, which would be the only ones likely to even have enough money to finance such a project) would risk such a large amount of money on purchasing/developing a supersonic airplane and then markeAng it. For example, a flight from London’s Heathrow airport to New York City can cost as licle as US $500 one way (this is from SAS airlines, checking prices between 29.07.17-31.08.17, looking at the cheapest fare). This means that supersonic jets would have an extremely low profit margin, if it even existed at all due to the immensely increased fuel costs for the plane, as menAoned previously. To prove this point, I checked the average price of a Concorde flight back when it used to operate and I found that it cost approximately $7995 in 1997 for a return flight from LHR to New York’s JFK. To compare, the cheapest Acket I found was $500 one way offered by SAS airlines. 39

This, combined with the previously menAoned fact that the primary customers of airlines had now changed from businessmen to holiday makers, who are less likely to have as much money to spend on flight. With average US family income being around $59,000 , the families are unlikely to be able to 40

afford an almost $8000 flight on a supersonic jet.

I believe that the issue of safety is the most serious with supersonic flight. This is because of the low amount of Ame a passenger would have to put on oxygen masks at high alAtudes, as well as the risks of structural damage at extreme speeds like Mach 3, where the slightest change in stresses on the airframe could cause a catastrophic failure, as seen in the SR-71 crash. This could not only disintegrate the plane, but even if it did not, the passengers could have their spines or necks broken by the sheer force of the air outside them, as occurred to the assistant of Bill Weaver in the SR-71, even though he was wearing a protecAve pressurized suit, not dissimilar to a space suit.

However, I sAll believe that scienAsts will conAnue to develop supersonic flight, I simply doubt that we will have the technology to make sonic booms quieter and thus do not believe that the ban on supersonic travel above the USA will be possible in the near future, making it uneconomical to run a passenger service, especially towards the central USA. I believe that this is a major factor since there are few other desAnaAons which take a long Ame to reach by modern jets, meaning that a Europe-USA route would be the only one with enough demand to make it remotely economical, assuming scienAsts can even get such a plane to work. The costs associated with such an endeavour would also be extremely

H. Sobieczky, New Design Concepts for High Speed Air Transport (hcps://books.google.com.kw/books?39

id=F2D_CAAAQBAJ&pg=PA1&redir_esc=y#v=onepage&q&f=false, ) SecAon 1.1

U.S. Census Bureau, Income, Poverty and Health Insurance Coverage in the United States: 2016 (hcps://40

www.census.gov/newsroom/press-releases/2017/income-povery.html, 12-9-2017)

Nikolai Puumalainen EPQ

high, meaning that without government interest, it is also unlikely that they will conAnue at any rapid pace.

Nikolai Puumalainen EPQ

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Nikolai Puumalainen EPQ

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w3784.pdf, July 1991) pdf p13 accessed 28/11/2017 26. ATSB, AviaLon Research and Analysis Report AR-2008-075(2) (hcps://www.atsb.gov.au/media/27376/

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