Future of Engineering

No, this is not an aircraft on fire. This is just an aircraft firing up!

From its current contribution of less than 3%, aircraft pollution is set to grow so rapidly that all homeowners, car drivers and businesses will have to reduce their carbon dioxide output to zero for levels to remain safe, a recent UK study warned. The study says that even if the growth in air travel were halved, the rest of the economy would need to cut greenhouse gas emissions far beyond the UK government's target of 60% by 2050.

One of the biggest environmental issues with jet airliners is the nitrogen oxide emissions (NOx ) spewed into the atmosphere during takeoff and landing procedures. The emission of NOx at cruise altitudes may promote enhanced greenhouse effect, photochemical smog formation, and also depletion of the stratospheric ozone layer. But it is not just NOx. The emissions from air traffic can change the atmospheric composition – (a) Directly: by emitting CO2, water vapour, unburnt hydrocarbons, soot, sulfate particles and of course NOx, and (b) Indirectly: by chemical reactions that contribute to ozone formation.

The goal for most airlines is to reduce NOx emissions during landing and takeoff to 70 percent below the international standards created in 1996. While experts admit that we're not there yet, some feel that airlines are making good progress.

Aircraft also emit the notorious global warming villain CO2. Like most others in the transportation industry, the aircraft industry has been talking smooth about and making plans for reducing CO2 emissions. EasyJet for instance last year unveiled the prototype for an aircraft that could slash carbon dioxide emissions by half. But most of these have remained just at the planning and prototype stages.

In sum, their grand pronouncements and prototypes aside, not too many are convinced that airlines have done enough to reduce NOx and CO2 emissions.

Grade for Emission Control: B-

Alternative Fuel & Fuel Efficiency



Richard Branson of Virgin Atlantic has been talking big about biofuel powered Virgin flights, and his company actually flew one last week.

This first flight by a biofuel powered commercial airline took place on 24 Feb 2008, amindst much fanfare, when a Virgin Atlantic jumbo jet flew between London's Heathrow and Amsterdam using fuel derived from a mixture of Brazilian babassu nuts and coconuts. Earlier this month, Airbus tested a synthetic mix of gas-to-liquid.

If these news make you look forward to travelling on a biofuel powered airplane anytime soon, you will be disappointed. Most of these alt energy / fuel efforts have really been a lot of show. All research work being carried out are in their very initial stages. (by the way, here’s a nice Q&A on alt fuels in airplanes, from Airlines.org)

Grade for Alternative Energy Use: B-

Fuel Efficiency

Airlines' record in fuel efficiency is not exactly bad – a 103 percent improvement between 1978 and today. Fuel efficient aircraft designs and less-fuel-guzzling aircraft engines have been on the radars of the aircraft engineers for many years now, and some of their earlier research has started to bear fruit.

Boeing in 2007 launched what it says is the most environmentally-friendly aircraft ever built. The Boeing 787 achieves fuel efficiency by having a significant percentage of aircraft made from composites, making it lighter and more fuel efficient than traditional aircraft. While environmental groups say the aircraft is far from green, some do admit that its lighter weight will enable it to use 20 per cent less fuel than its aluminium predecessors.

In Nov 2007, Boeing said it was developing a new single-aisle aircraft made of composite materials to replace the 737, its most popular aircraft ever. According to the planemaker, the 737-RS would also incorporate new engine types that achieve greater fuel efficiency. The advanced materials, comprising ceramic matrix composites and such, also allow engines to burn at higher temperatures. When engines operate at these high temperatures, they are more efficient. Other lightweight materials like Titanium Aluminide and other superalloys are also being researched for potential engine material.

Relatively speaking, the airlines have done reasonably well in their efforts for fuel efficiency.

Grade for Fuel Efficiency: A-

Noise Pollution



Researchers found the sound of planes taking off and landing while people sleep increases blood pressure, and those living closest to airports were almost 50 per cent more likely to suffer from hypertension..

So what are airlines and aircraft companies doing about this?

Thanks to technology, today's aircraft are 50% quieter than those 10 years ago. Research initiatives target a further 50% reduction by 2020, according to IATA. Further, in January 2006, a more stringent noise certification standard was introduced by IATA for new aircraft designs. These aircraft should be at least one third quieter than those currently certified.

Specific efforts have been underway in reducing the noise from two main components – engines and the airframe, especially the engine.

Much of the noise from gas turbine engines comes from air flowing back through the rapidly spinning fan blades at the front of the engine. Behind each blade is a wake, or an area of lower-speed air. When these wakes move over stationary blades they produce strong, unsteady pressures, and consequently most of the sound.

Most noise-control measures, such as acoustic liners in the engines, had traditionally focused on reducing the amplitude of the sound after it is produced, and these have had only limited success. But scientists are now working on a method of cutting down on noise at the source. Their idea is to "fill in" the wake behind each rotor blade by pushing air through the trailing edges of the rotating blades, where it mixes with the air flowing around the blade and makes the flow into the stator more uniform.

Another recent approach to noise reduction is the active noise control effort. The primary principle of active noise control is to sense the noise disturbances in the engine and cancel them before they leave the engine. In effect, negative noise is made to cancel out the engine's sound waves so that no noise is heard.

On noise control, one wishes to give the airlines and aircraft industry a good grade for all their efforts, but until our friends and folks living near airports are able to have a good night's sleep in their houses near airports, we have no choice but to give it a rather mediocre grade.

Grade for Noise Control: B

Plane Deicing



De-icing is the process of removing ice from an airplane's surface.

The chemicals normally used to deice aircraft - ethylene glycol and propylene glycol – are both deadly substances even in small quantities. Ethylene glycol causes central nervous depression and kidney and liver damage and propylene glycol is just as toxic. While no studies have been done on its effects on humans, each winter large amounts of fish and wildlife are poisoned to death by aircraft deicing chemicals.

Additional pollutants, including fuels and other toxic substances, are also washed off the planes during deicing procedures.

Compared to the rest of components of aircraft pollution, this is a minor one, though it could have harmful effects on those few who perform this activity, and on some unfortunate fish and fowl. This aspect of aircraft pollution has not received much attention so far.

Grade for Deicing Pollution Control: B


Not There Yet, But Hopeful

Labels: Aerospace-Engineering, Energy-Environment-Engineering