To What Extent Has Subsonic Air Travel in the 21st Century Become Primitive?

7/28/2019 To What Extent Has Subsonic Air Travel in the 21st Century Become Primitive?

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To what extent has subsonic air travel in the 21stcentury become primitive?

The century following the conception of the first fixed wing aircraft by the wrightbrothers in 1903 saw a monumental increase in technological advances andbreakthroughs regarding flight. Flying at 26 knots or 30 miles per hour, OrvilleWright flew for a total of a mere 12 seconds, the first arguably sustained flight inmodern history had been established. By 1969, the Arospatiale-BAC Concorde

was blasting through the stratosphere at a cruise speed of Mach 2.2 or 1350miles per hour.It is intriguing to visualise that in 66 years, humanity was able to enrich aircraftsystems such as avionics, hydraulics, propulsion and aerodynamics to such anextent, that the cruise speed of Concorde was now 4500% greater than that ofthe Wright brothers aircraft. The range, which was 120 feet, had now increasedto 3900 nautical miles, not to mention that other aircraft at the time such as theBoeing 747-100 had a range of up to 5300 nautical miles.The general size of aircraft increased so dramatically, that the wright brotherscould have completed their initial flight within the economy class section of the

Boeing 747-100.All being said, it is evident that there were enormous advances in the disciplineof commercial flight within this time frame, however, beyond this era (circa1970) there has been, to a large extent, a stagnation of evolutionary andrevolutionary developments regarding commercial flight.As of 2013, Concorde no longer exists, and one of Boeings most state of the artaircraft, the Boeing 747-8 is rather similar to the 747-100 that first flew in 1969as illustrated below.

Figure 1, Image 1: An early 747-100 (1969). Source: Aviation Model store [2010]

Figure 2, Image 2: A Boeing 747-8, the most modern version of the 747 (2010)Source: Airliners illustrated [2013]


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At this point it is evident that the majority of the aircraft used today for travel arefundamentally based on the technological breakthroughs of the 20th century thathave been implemented in hundreds of aircraft throughout the globe andcontinue to be until this day. Of course, there have been major developments in

terms of efficiency such as the successful introduction of cleaner and quieterengines, the upgrade of computer systems to such an extent that crew memberssuch as the flight engineer is no longer needed. Aircraft are being introducedmanufactured out of carbon fiber instead of the conventional aluminium but inessence, the question arises due to these advances, why does it takeapproximately the same amount of time to travel a particular distance today, as it

did in the 1970s? In actual factthe answer to this question is that indeed, planesdo not fly quicker today than in the 1970s but slower, it takes more time due tothe permanent withdrawal of Concorde from service. The fastest commercialtransatlantic crossing in the 1970s was approximately 3 hours and 20 minutes;today that time has more than doubled.

This is the basis of this project, why do we, in the 21stcentury still rely onsubsonic air travel a time where it is ever so important to increase efficiency,reduce time and become leaner in the processes that run our world, why do wesettle with subsonic air travel to transport the most valuable commodity acrossthe globe, man.

The objective is to establish the main barriers thwarting the implementation ofsupersonic airliners by assessing the issues that supersonic airliners in recentmodern history experienced, the reasons why they were indefinitely grounded,

assessing whether these problems were significant enough to cause what theydid especially on Concorde, whether these problems could have been overcomeand whether any advances in the 21stcentury could eradicate any barriers andtherefore give potential for further development. From this, it will become clearif subsonic air travel really is primitive or if the barriers are too high tosuccessfully overcome.


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Concorde was the only supersonic airliner that was introduced into consistentpassenger service, although it should be mentioned that a soviet version, theTupolev TU-144 also entered service two years after Concorde but was plaguedwith mechanical and structural faults with regular catastrophic failures of the on

board computers which lead to the TU-144 being converted into a cargo planeand then discontinued.Concorde however was largely successful, and is therefore the only example thatcan be effectively studied; however there were of course underlying problemsthat subsequently lead to its demise. These are listed below:

The Concorde effectively operated in a niche market, that is, a subset of themarket on which a specific product is focusing. In this case, that market wassuccessful & wealthy businessmen and celebrities. A typical transatlanticcrossing during the final years of Concorde cost in the region of 5000-10,000,with subsonic fares costing a fraction of this

amount. Despite this, Concordesprofit margins were still slim, tickets sold in vast numbers, but the thirstyConcordes fuel supply diminished at an astonishing rate, burning 2 tonnes offuel just taxiing to the runway prior to take off, this was 2% of its fuel capacity,which in turn had detrimental effects on the aircrafts range. Concorde could fly3900 nautical miles on a full tank, which was just about sufficient for its popularLondon to New York service, however Concorde was unable to reach otherimportant worldwide destinations in the American west coast or Asia (where alarge market existed) without re-fuelling. Re-Fuelling took up time, which wasundesirable for time conscious passengers of Concorde. The TU-144 had a rangewhich was even less than Concordes, which signifies that this was a problem on

supersonic airliners due to the enormous quantities of fuel that they required.

A particular feature of supersonic flight that distinguishes it from subsonic flightis the sonic boom, the sound associated with the shock waves created by anobject that travels through air faster than the sound it creates. This isnt aproblem for the aircraft; however, it has an effect on its surroundings no matterwhat altitude the plane is flying at. The shockwaves produced have the ability tocause vibrations sufficiently powerful to damage buildings. This severelyrestricted Concorde due to the fact that it was limited to sub sonic speedswhenever over land. It could only establish super cruise (sustained periods ofsupersonic flight) when it was over water, thus making transatlantic crossingsideal for Concorde, which is why the London to New York route was so popular.

Travelling at such high speeds, supersonic aircrafts such as Concordeencountered vast amounts of air friction, which in turn generated heat. At theend of flights, surfaces used to be hot to the touch, demonstrating the level offriction. This meant that the livery Concorde was painted in was limited to aheat-reflecting majority white, otherwise non reflecting generic paint wouldcause the aircraft structure to heat to unsafe temperatures. Today, airlinesdistinguish themselves from other carriers through use of different liveries andeven advertise by painting their websites and other information to stimulate

sales, concurrent with todays global economic market.


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longer on board than they would (if they could afford) on Concorde. Wealthybusinessmen and celebrities are today content by 1stand business classes wherethey are able to enjoy a much more comfortable environment than that thatcould have been offered by supersonic airlines (Passengers seated next to eachother on the Tupolev Tu-144 had to shout to communicate with each other due

to the excessive noise in the cabin).


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The coefficient of linear expansion is the ratio of the original length by which astructure expands per degree rise in temperature. At Mach 2.0, Concordeexperienced monumental rises in its aluminium airframe due to thermal heating.

Figure 5, Image 5 showing the extent of thermal heating on the structure ofConcorde at Mach 2 or 1320 miles per hour. Source: Celebrating An AviationIcon, [2004]

Concorde was limited to the speed of Mach 2.2 due to the fact it was constructedfrom aluminium instead of titanium, which would have allowed for greaterspeeds but was problematic to use at high altitudes. A unique alloy of aluminiumallowed for an acceptable level of kinetic heating and expansion along withsustainable thermal fatigue.Primitive understanding of particles teaches us that once heat is supplied tometals, the particles obtain more kinetic energy, vibrate, excite and take up moreroom.To summarise the above, I will calculate the temperature of Concordes outer skinduring super-cruise.Taking into account the length of Concorde is 61.6m whilst sitting on the tarmacat 14 degrees celsius. It is generally known that at twice the speed of sound,Concordes fusalage lengthens by 0.25m.Taking the coefficiant of linear expansion of aluminum = 2.40105 or alpha forsimplicity allows the following calculation where:The change in length = alpha(the initial length)x(the change in temperature)

Therefore 0.25 = (2.4 x 10^-5)(61.6)(-14)(0.25/2.4x10^-5/61.6)+14=TT=183 degrees celsius.

Comparison between this and the image illustrated above highlightdiscrepancies in the results. It must be acknowledged that the calculation is anapproxiamation and does not take into account factors such as cooling of theairframe at high altitudes where the outside temperature can be as low as -57degrees celcius.


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Bibliography.

Boeing 737 Accident reports, 2013. [online] Available at:http://www.b737.org.uk/accident_reports.htm

Boeing 747-8R7F Experimental N747EX [online] Available at:http://www.airlinersillustrated.com/Boeing_7478R7F_Experimental_N747EX/p1737690_8139157.aspx

Celebrating An Aviation Icon, 2004. [online] Available at:http://www.concordesst.com/whatsnew.html

Edwin D, Sayre. 2005. Development Of New Supersonic Aircraft

Gillman, P. 1977. The story of the Concorde. Volume 239, No 1; p72-81

J, Acoust. 1974. Propagation Of Plane Sound Waves Of Finite Amplitude InInhomogeneous Fluids. Volume 56, Issue S1, p 42

Transverse And Longitudinal Waves, 2000. [online] Available at:http://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.html

What Happens When An Aircraft Breaks The Sound Barrier? 2002. [online]Available at:http://www.scientificamerican.com/article.cfm?id=what-happens-when-an-airc
http://www.b737.org.uk/accident_reports.htmhttp://www.airlinersillustrated.com/Boeing_7478R7F_Experimental_N747EX/p1737690_8139157.aspxhttp://www.airlinersillustrated.com/Boeing_7478R7F_Experimental_N747EX/p1737690_8139157.aspxhttp://www.airlinersillustrated.com/Boeing_7478R7F_Experimental_N747EX/p1737690_8139157.aspxhttp://www.concordesst.com/whatsnew.htmlhttp://www.concordesst.com/whatsnew.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.htmlhttp://www.scientificamerican.com/article.cfm?id=what-happens-when-an-airchttp://www.scientificamerican.com/article.cfm?id=what-happens-when-an-airchttp://www.scientificamerican.com/article.cfm?id=what-happens-when-an-airchttp://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.htmlhttp://www.concordesst.com/whatsnew.htmlhttp://www.airlinersillustrated.com/Boeing_7478R7F_Experimental_N747EX/p1737690_8139157.aspxhttp://www.airlinersillustrated.com/Boeing_7478R7F_Experimental_N747EX/p1737690_8139157.aspxhttp://www.b737.org.uk/accident_reports.htm


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Source 4

Information collected from this source was in the form of an article. From it I wasable to obtain Government plans to develop supersonic aircraft, their advantagesand more specifically the performance of Concorde. Mr Edwin D. Sayre

composed the article and further reading allowed me to establish the fact that heis a retired engineer residing in Los Gatos, California. Los Gatos, according toBloomberg BusinessWeek, (a well established and sought after magazine) ranksLos Gatos 33rd in affluence in all of the United States. The fact that Mr Edwin D.Sayre lives in a prosperous town leads me to believe his career as an engineerwas successful and thus suggests that his article must be a reliable source ofinformation regarding its familiarity with engineering concepts. On his planetforward account he self declares that he is indeed a retired engineer with 60years of experience in manufacturing and maintaining energy systems such as jetengines, gas turbines, rocket engines, nuclear power plants and space systemsand is a retired naval aviator. The information presented to me allowed me to bereassured by the credibility of information included in my report stemming fromhis article.

Source 5

Peter Gillmans 1977 article gave me a thorough understanding and insight intothe life, function and capabilities of Concorde intertwined with the politics of thetime that influenced aviation. Mr Peter Gillman is respected British writerspecialising in a wide range of topics. Although he doesnt hold any relevantqualifications directly In sync with Supersonic flight, he does 40 years

experience writing in the national press, 25 of which involved training otherjournalists. He is the author/co author of a dozen books and his results areclassed as exceptional. The range of experience Peter Gillman has allowed himto construct an article involving a wide range of global factors, which someengineers may have been unaware of at the time. This aided him in publishing abalanced, informative and peer-reviewed document that more than satisfied mycriterion for information to be included in this report.

Source 6This source was interesting due to its in depth analysis of wave behaviour. Itallowed me to illustrate appropriate formulas for sound waves in differentmedia. The Acoustical Society of America (ASA) published this particular articlein 1974. The society was instigated 46 years earlier by a group of 40 scientistsand engineers and is one of three scientific societies that form the AmericanInstitute of Physics, a gargantuan organisation with more than 135,000scientists, engineers and educators with an annual budget of $74 million. TheASA published journals, articles, books and videos all relating to the field ofacoustics, most of which are peer reviewed. I was content in relying on thisdocument in order to explain the sonic boom, a fundamental concept, critical tothe function of supersonic aircraft.

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To What Extent Has Subsonic Air Travel in the 21st Century Become Primitive?