fast into future Aviation

With carbon footprints and noise reductions becoming more significant guiding factors in the development of commercial aircraft, in addition to ever-increasing speeds and passenger comfort levels, what lies ahead for the future air traveller?

Boeing's concept Sonic Cruiser © - AD&D Magazine

Recent successful scramjet tests conducted in the Australian Outback that saw a rocket exceed Mach 10 speeds of 11,000 kmh (6,800 mph) pose a potential revolution in air travel, making it theoretically possible to connect anywhere in the world within three to four hours.
While this achievement is breath-taking in its commercial potential, the reality is that such capabilities are very unlikely to find their way to your nearest airport anytime soon.
More extensive tests need to be conducted before the engines and the airframes can be safety certified, since the technology offers tantalising hypothetical speeds of up to Mach 24! But once the basics have been achieved with the prototypes, there is still another complicated process in the next stage of ensuring average passenger comfort.
In short, we’re at least two decades away before the first commercial scramjet flight is ready to accept bookings. And chances are that when we actually reach this horizon, these flights will most likely be far from the envisioned fantasy.

Artist impression of a scramjet © - AD&D Magazine

Like the supersonic Concorde, which has been retired in 2003 after almost three decades of lording the skies, the commercial scramjet is very likely to run smack into overland flight restrictions with stringent controls on noise levels and now, possibly even carbon dioxide and other fuel-related emissions.
Take-offs and landings would probably need to be within existing speed limits to minimise noise pollution; sonic booms resulting from speed transitions would be restricted to non-residential zones – most likely over barren seas, assuming there won’t be further restrictions related to the protection of possibly dwindling aquatic creatures.
As a result, scramjets are a promise of faster travel speeds which still faces an uncertain future.

Carbon footprint

With the ever-increasing rate of air-travel, fuelled by rising prosperity levels, there is clearly a need for more planes – better if they’re faster, pack more people, cheaper to run and economical to maintain.
With new concerns on global warming intensifying so soon after sharp hikes in oil prices, coupled with shortages of available aircraft and congested airports, the issue of travel has never been so high in most people’s minds.
Travel today is a basic necessity; and the modes used to move more and more people around – may it be on land, sea or air – has come under fire for the rapid consumption of fossil fuels and increasing pollution effects on global warming.
The main problem with air-travel is that there are very few alternatives available, unlike eco-friendly options of bicycles and electric trains for land transport and wind-powered sailing maritime vessels.
Hence, all new aircraft coming onstream like the gigantic 853-seater capable Airbus A380 and the mid-sized Boeing 787 Dreamliner, together with its slated competitor A350XWB, are all being watched very closely for fuel emissions and the size of their carbon footprints.

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Aviation industry figures claim that the carbon emissions calculated on the basis of per kilometre travelled are very close to that produced by cars transporting single passengers. Also, since there are far more cars running compared to airplanes (plus manufacturing industries pollution), overall contribution by aircraft around the world currently make up only three percent of overall carbon emissions.
This may be a positive spin on the overall picture in the near future, but it is unlikely to remain so if – and that’s a very big if – land-based pollutants drop drastically with hybrid fuels and electric power.
Research into more eco-friendly aviation technologies is progressing rapidly, foremost with better engines and fuels. To conserve on fossil fuels, there is already much focus on bio-fuels – an emerging development that is still very far from living up to its promise. Even so, such bio-fuels still don’t fully address the issue of carbon emissions and there is simply no available alternative to the existing aviation fuel that packs enough power needed to send multi-tonnes aircraft aloft.
As such, until better high-powered sources can be obtained, we may be stuck with the kerosene-burning physics. Or is there another way forward?
The magic promise of clean electricity has been around for a while, as has the lure of limitless solar energy supplies. Reality check has shown that such concepts still remain far from a practical solution unless…

Superconducting turbojet

NASA's concept PAVE craft © - AD&D Magazine

An all-electric aircraft with high-powered lightweight compact engines beckons – thanks to high-flying scientific research published in the Institute of Physics' journal, Superconductor Science and Technology.
The new type of aircraft, currently on the drawing board, could be far more efficient than conventional aircraft, produce less greenhouse emissions, and be quieter with the use of superconducting motors.
Secientists Philippe Masson and Cesar Luongo from Florida State University, who have collaborated with Gerald Brown at NASA and Danielle Soban at Georgia Institute of Technology, explain that because superconductors lose no energy through electrical resistance, they could be very efficient components for a new type of aircraft propulsion.
The researchers explain that to build an electric aircraft will require propulsion motors that are high power, lightweight and compact. Current technology cannot meet these demands because an electric motor using conventional magnets can weigh up to five times as much as conventional jet engine and not be as fuel efficient.
In contrast, a superconducting motor would be very lightweight and far more efficient electrically, generating three times the torque of a conventional electric motor for the same energy input and weight.
In addition, an electric aircraft would be far quieter than a conventional jet as there are no internal combustion processes involved. It is the combustion of fossil fuels to drive a conventional aircraft that makes them so noisy.
However, superconducting magnets not only have to be cold, but require a unique energy supply. Masson and his colleagues believe they could solve both problems by using chilly liquid hydrogen to run an electric fuel cell.
Liquid hydrogen is cold enough to make the superconducting magnets work but also has four times as much energy weight-for-weight than aviation fuel.
A fuel cell produces no polluting emissions, just warm water as the hydrogen combines with oxygen. This, say the researchers would mean zero carbon emissions from the aircraft as it flies.
"The idea is to reduce the emissions from the aircraft and airports," explained team leader Masson, "The energy needed to produce the liquid hydrogen could come from a remote powerplant". Such a powerplant might be solar or wind powered.
"We could potentially build a superconducting motor and generator smaller than a gas turbine, which would make possible electric propulsion," said Masson. Electrical propulsion would not only decrease emissions but also reduce to a minimum the needs for maintenance as all hydraulic systems would be eliminated, he adds. The team has designed such systems with high fidelity models and optimization tools.
Masson added that the team is now looking for an industrial partner to build a prototype of the superconducting "turbofan".
"The technology is there, it is a matter of finding a source of funding."

More advances

Apart from the more obvious pollutants, a lot of effort has also gone into the make-up of aircraft itself as well as follow-up maintenance.
The A380 and the 787 Dreamliner are new generation aircraft that use more composite materials in the overall design – reducing tremendously energy wastage in the smelting and shaping of metals like aluminium and steel.

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Much effort has also gone into overall weight reductions (without compromising aircraft integrity and safety) that require higher power which leads to more pollution, a fact that Airbus is proud to boast of since the new A380 can land within existing aircraft runway dimensions.
Moving further, there is also ongoing research into "superhydrophobic" – or extremely water-repellent – coatings that promises even more improvements to aircraft operations and maintenance.
Should this research currently being conducted within the nanotechnology program at General Electric produce a special coating durable enough for metal and ceramics, any moisture would simply bead up and roll off, picking up dirt particles along the way.
Program manager Margaret L. Blohm has described the opportunities as being "pretty incredible," with examples like aircraft that won't accumulate ice while awaiting winter takeoff or engine parts with self-cleaning capabilities to boost efficiency or even toilet bowls that require little to no washing.
So far, "hydrophobicity" technology into the properties of water repellence has focused on mimicking the surface structure of the lotus plant as its texture consists of microscopic "hills and valleys" which create a thin layer of air that prevents full contact with water or dirt. As a result, water rolls off its leaves, taking the dirt with it.
While there has been various products incorporating such technology ranging from new lines of spill-resistant clothing to self-cleaning paint, duplicating the lotus structure on steel and other metals has not been very successful.
This is because the intrinsic nature of metal is "hydrophilic," meaning moisture tends to slide, or smear, on it instead of beading up. There is also the added issue of high melting points for metals – which makes it very difficult to form these microscopic structures due to the need to find suitable mould materials.
Assuming these basic issues could be resolved, there is a matter of durability since metal is often deployed in extreme conditions like gas turbines but GE labs had achieved some laboratory successes in lotus-style coatings for metal and ceramics with a number of patents pending, Blohm said.
Another research C.P. Wong, a scientist at the Georgia Institute of Technology, said his effort to develop a titanium-based "superhydrophobic" coating for use over steel is showing substantial promise.

Potential threats

Virgin Galactic's proposed WhiteKnightTwo © - AD&D Magazine

However, major technological advances also pose another threat in the form of other travel modes which could potentially siphon away the projected bulk of future air travellers.
There is already talk of supersonic marine vessels skimming on liquid surfaces, powered by the same water used in hydrogen fuel production or electricity generation. Also, some headway is being made on the possibility of high-speed electric trains connecting the lowermost tip of South America upward through Alaska via a bridge to Siberia with the link ending in London via the Chunnel.
Africa could be similarly connected at two points – Suez and Gibraltar, leaving only Australasia and unconnected islands like Japan or Taiwan still dependent on air or sea transport.
These high-speed rail links may be very expensive propositions but the mammoth financial investments required are now being seen as being possibly worthwhile when compared to the cost of purchasing substantial numbers of aircraft plus constructing new purpose-built infrastructure like airports.
Long-term benefits clearly favour the high-speed rail links when it comes to affordable mass movement of people – especially when operational issues, maintenance and depreciation matters are also factored in.
As a result, air travel may simply shrivel into a niche industry by default as travellers get an option previously unavailable.
The possibility of even more options becoming more widely available for the average person is looking more likely, with even NASA joining the fray with its Personal Air Vehicle Exploration (PAVE) – essentially a car that flies short hops. The program aims to have a flying demonstrator dubbed TailFan by 2009.
There is also the Airphibian, a 150-horsepower vehicle with detachable tail and wings that could be removed for street driving which was developed by Robert Fulton in 1946 and Moller's Skycar. Other future developments could include an aerial vehicle X-Hawk by Israel's Urban Aeronautics Ltd the SkyRider X2R by Macro Industries.
The reasons why these future personal fliers are extremely attractive to the average consumer are very similar to why people buy cars today – the freedom to travel as and when the desire arises; a choice currently available only to the rich with business jets.
If such personal fliers become capable of longer-distance aerial travel, with pitstops to refuel and refresh the driver, it could very well spell a dirge for the mass commercial aviation industry.

Science fiction

Travelling beyond the earth’s atmosphere – a privilege that had hitherto been limited to a select few – will soon be available to a slightly larger favoured group once the Virgin Galactic service takes off sometime in 2009.
At any one time, for an initial ticket cost of US$200,000, six passengers can reach into space on the air-launched SpaceShipTwo – which will be hauled into launch position by WhiteKnightTwo, a massive carrier craft currently under construction by Scaled Composites.
Virgin Galactic passengers will get a 300-minute flight aboard SpaceShipTwo and launch from an altitude of about 60,000 feet (18,288 meters), while buckled safely in seats that recline flat after reaching suborbital space.

Advanced wing concept plane © - AD&D Magazine

The experience itself isn’t for everyone ready to cough up the cash needed as there will also be various physical and medical requirements to be complied with before one is allowed to get into a personal spacesuit before heading to a maximum altitude of at least 68 miles (110 kilometers).
To boldly go where no man has ever gone before – to steal a phrase from the Star Trek television series – is still many decades away, for still futuristic technologies like warp-drives and worm-hole generators remain pipedreams as is the vision of teleporting with a “Beam me up Scottie.” Travel to Mars remains very much out of reach for now and the stars have to wait another few generations.
A more interesting approach that scientists have yet to lick is that of anti-gravity devices which can effortlessly float to any height desired. Such a technology would be far more passenger-friendly as there would no longer be the major stress of escape velocities, making for a very relaxed journey instead of being subjected to high-G forces.
Coupled with force-shields that could neutralize impacts or even crash-landings – now that would be a flying carpet experience come true.