In 1996, a British Airways plane flew from New York to London in a record-breaking two hours and 53 minutes. Today, however, passengers flying the same route can expect to spend no less than six hours in the air— twice as long. So why, in a world where everything seems to be getting faster, have commercial flights lagged behind?
1996. godine, avion Britiš Ervejz je preleteo od Njujorka do Londona u rekordnih dva sata i pedeset tri minuta. Ipak, danas putnici koji lete istom rutom mogu da očekuju da će provesti ne manje od šest sati u vazduhu - duplo više. Zašto, u svetu gde se čini da sve postaje brže, komercijalni letovi zaostaju?
The British-and-French-made Concorde began shuttling passengers across the sky in the 1970s. Jetting between destinations like New York, Paris, Bahrain, and Singapore, it clocked in at over 2,000 kilometers per hour, more than twice the speed of a normal airliner. However this was also about 800 kilometers per hour faster than the speed of sound. And that created a surprising problem for people on the ground. When an object moves at supersonic speed, it generates a continuous moving shockwave known as a sonic boom. This produces a loud, startling noise, as well as rattling windows and dislodging structural elements of buildings. Since a plane flying at an altitude of 15 kilometers can affect an area with an 80 kilometer diameter on the ground below, complaints and concerns from residents in the Concorde’s flight path restricted it to mostly ocean routes.
Britansko-francuski Konkord je počeo da prevozi putnike nebom u ’70-im. Letom između destinacija kao što su Njujork, Pariz, Bahrein, i Singapur, dostiglo je brzine od 2 000 kilometara po satu, duplo veća brzina od normalnog putničkog aviona. Ipak, ovo je bilo i za oko 800 kilometara po satu brže nego brzina zvuka. I to je stvorilo iznenađujuć problem za ljude na zemlji. Kada se objekat kreće supersoničnom brzinom, stvara kontinuirani pokretni udarni talas poznat kao zvučni prasak. Ovo stvara glasni, zapanjujuć zvuk, kao i zveckanje prozora i pomeranje strukturnih elemenata zgrada. Pošto avion koji leti na visini od 15 kilometara može da utiče na oblast prečnika 80 kilometara na zemlji, žalbe i brige od stanovnika na letnom putu Konkorda ga je ograničilo na većinski okeanske rute.
Because of these restrictions and other fuel and engineering requirements, supersonic flights turned out to be very expensive for both airlines and passengers. A single transatlantic round-trip could cost the equivalent of more than $10,000 today. With additional strain on the airline industry due to decreased demand for flights after September 11th, 2001, this became unsustainable, and the Concorde was retired in 2003.
Zbog ovih ograničenja i drugih zahteva oko goriva i inženjerstva, supersonični letovi su ispali vrlo skupi i za avionske kompanije i za putnike. Jedan povratni let preko Atlantika bi mogao da košta više od 10 000$ danas. Sa dodatnim naporom na avionsku industriju zbog smanjene potražnje za letove posle 11. septembra 2001. godine, ovo je postalo neodrživo i Konkord je penzionisan u 2003.
So even when superfast flights existed, they weren't standard commercial flights. And while we might think that advances in flight technology would make fast flights less expensive, this hasn’t necessarily been the case. One of the biggest concerns is fuel economy. Over the decades, jet engines have become a lot more efficient, taking in more air and achieving more thrust— traveling further for every liter of fuel. But this efficiency is only achieved at speeds of up to around 900 kilometers per hour— less than half the speed of the Concorde. Going any faster would increase air intake and burn more fuel per kilometer flown. A standard transatlantic flight still uses as much as 150,000 liters of fuel, amounting to over 20% of an airline’s total expenses. So any reduction in fuel economy and increase in speed would significantly increase both flight costs and environmental impact.
Čak i kada su vrlo brzi letovi postojali, nisu bili standardni komercijalni letovi. Iako možda mislimo da bi napreci u tehnologiji letenja načinili brze letove jeftinijim, ovo nije nužno bio slučaj. Jedna od najvećih briga je ekonomija goriva. Tokom decenija, mlazni motori su postali efikasniji, uzimajući više vazduga i postižući više pogonske snage — putujući dalje za svaki litar goriva. Ali ova efikasnost je postignuta samo na brzinama do 900 kilometara po času — manje od polovine brzine Konkorda. Kretanjem bržim od ovoga bi se povećalo uzimanje vazduha i sagorevanje goriva po preletenom kilometru. Standardni let preko Atlantika i dalje koristi čak 150 000 litara goriva, iznoseći preko 20 posto ukupnog troška avio kompanije. Tako da bilo kakvo smanjenje u ekonomiji goriva i porast u brzini bi znatno povećalo i cenu letova i uticaj na okolinu.
What about ways to make a plane faster without burning lots of fuel? Adjusting the wing sweep, or the angle at which wings protrude from the fuselage, to bring the wings closer in can make an aircraft faster by reducing aerodynamic drag. But this means the wings must be longer to achieve the same wingspan, and that means more materials and more weight, which in turn means burning more fuel. So while airplanes could be designed to be more aerodynamic, this would make them more expensive. And generally, airlines have found that customer demand for faster flights is not sufficient to cover these costs.
Šta sa načinima da avion bude brži bez sagorevanja mnogo goriva? Nameštanjem strele krila, ili ugla pod kojim krila izlaze iz trupa, da bi se krila približila može da učini avion bržim smanjivanjem aerodinamičnog otpora. Ali ovo znači da krila moraju biti duža da bi se ostvario isti raspon krila, i to znači više materijala i težine, što znači sagorevanje više goriva. Dakle, iako se avioni mogu dizajnirati da budu aerodinamičniji, ovo bi ih načinilo skupljim. I generalno, avio kompanije su otkrile da potražnja kupaca za bržim letovima nije dovoljna da se pokriju ovi troškovi.
So while military aircraft conduct high speed flights over water and at high altitudes, supersonic commercial flights seemed like a brief and failed experiment. But recent advances may make them feasible again. Research by NASA and DARPA has shown that modifying an aircraft’s shape can reduce the impact of its sonic boom by 1/3. Extending the nose with a long spike can break the shockwave into smaller ones, while another proposed design features two sets of wings producing waves that cancel each other out. And new technologies may solve the energy efficiency problem with alternative and synthetic fuels, or even hybrid-electric planes. It may yet turn out that the last few decades of steady flying were just a brief rest stop.
Tako da, iako vojni avioni sprovode letove velikih brzina preko vode i na visokim nadmorskim visinama, supersonični komercijalni letovi se čine kao kratki i neuspešni eksperiment. Ali skorašnji napreci će ih možda ponovo učiniti izvodljivim. Istraživanje NASA-e i DARPA-e je pokazalo da modifikovanje oblika aviona može da smanji uticaj soničnog praska za trećinu. Izduživanje nosa sa dugačkim šiljkom može da razdvoji udarni talas u manje, dok još jedan predložen dizajn ima dva seta krila koja stvaraju talase koji poništavaju jedni druge. I nove tehnologije možda reše problem sa efikasnosti energije sa alternativnim i sintetičkim gorivima, ili čak hibridnim električnim avionima. Možda će ispasti da su poslednjih par decenija postojanog letenja bile samo kratko odmorište.