AutoblogGreen

The Yahoo news story, and then you Jeremy, have confused two issues here. The proposed aircraft engine improvements are about reducing CO2 emissions (and noise). The NASA figures quoted are about contrails. Contrails are the result of H2O emissions and exhaust particles. Reducing CO2 won't reduce contrails, so the NASA figures quoted are irrelevant to this story.

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Clearly a PR-stunt from EasyJet. An airline, and definitely a low-cost airline, does not have the knowledge nor the funding to propose any airplane-design. I'm pretty sure engineers at Boeing and Airbus had a good laugh seeing this... And maybe they got the point that it's time they started thinking about radically new designs, like the one proposed by MIT.

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Those engines are nothing new, they call them "turbofan" engines... they are turbine engines that don't use the exhaust as thrust, but have external fan blades mechanically linked to the internal turbine. They ARE more efficient than jet engines (and piston engines for that matter), but they also have a slower top speed and cruise speed. They are typically used in short-run commuter airlines and shuttles. They also have other variations like turbo props (same concept but 2-4 full-size propeller blades instead of dozens of fan blades).

My guess is the thing about reduced emissions comes from the increased fuel economy... burning less fuel = less emissions.

These will still have contrails. Even piston engines have contrails at high altitude (the ones that can run at high altitude). All engines that burn hydrocarbons produce water in their exhaust (in comes N and O2 and hyrdrocarbon fuel, out comes O2, H2O, CO, CO2, and NO2). Contrails are formed because the ambient temperature at that altitude is below the dew point so any water vapor (water vaporizes in hot exhaust gases) will condense (which is the same way clouds are formed by moist wind blowing over a mountain top). You can also see it coming out car tail pipes on cold mornings before the engine and exhaust systems are warmed up.

Maybe they're saying by cutting emissions in half that the density of contrails will be cut in half.

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But contrails dissipate rather quickly.
Chemtrails linger.

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How long contrails last depends on the relative humidity of the surrounding air. If the relative humidity is very low, the contrails evapoate quickly. If the relative humidity is high, they last much longer. If the relative humidity is saturated (or supersaturated) the contrails will grow into full fledged clouds.

"Chemtrails" exist only in the minds of paranoid conspiracy ranters.

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#3: you're half right. Turbofans use the gas turbine engine to run a many-bladed fan which provides the majority of the thrust, as you say, but generally the blades are enclosed in a shell and located at the front of the engine rather than the rear (called a ducted fan). Nearly all modern airliners use turbofans, including long-haul aircraft such as the 777 and the A340. EasyJet is calling this an "unducted fan" design, and I'm at a bit of a loss as to why this is supposed to be better than a standard turbofan.

They also say they're removing leading edge slats...that might decrease noise and drag coefficient levels a bit, but it also makes landing a lot more interesting because you're reducing the lift coefficient, meaning you need to land at a higher speed. If the article mentioned anywhere that they'd collaborated with some sort of aerospace company and didn't just think this up in-house, I'd be able to take it a bit more seriously.

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EasyJet basically wants to go back to turboprops for short-haul service, without their customers thinking they're riding on small, loud, less-safe turboprop puddle jumpers. Note: I don't believe they're less-safe, I fly on turboprops all the time, but there's a perception among the flying public that turboprops are a less pleasant, less safe flying option. But there's no escaping the fact that turboprops are significantly more fuel-efficient than turbofans for short-haul trips. They fly lower and slower, which matters less for short trips (

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I know! Let's power everything with clean and safe hydrogen. We can make it by reforming cheap and plentiful natural gas. They can easily pump the excess Co2 back into the ground. Think of all the money the friendly oil companies will make by selling their natural gas to their subsidiaries who already make the vast majority of the planet’s Hydrogen at their refineries and use it to remove the sulfur from gasoline.

We will get a greener earth as a benefit. How? Well, when this smallest known element escapes and quickly raises into the upper atmosphere it will combine with the oxygen there to create a water vapor. (we have too much oxygen anyway) Since there is little particulate matter for the vapor to cling onto to create rain, this vapor will remain in the stratosphere causing a great big greenhouse and accelerate global warming thus bringing us a greener earth! This has been another wonderful “green house” idea from the nice folks who brought you oil. ;)

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Nils: "..And maybe they got the point that it's time they started thinking about radically new designs, like the one proposed by MIT."

Oh no, not more US=The Universe thinking! The proposal is actually from the Cambridge-MIT research group, a UK-US collaboration. The current model is the SAX-40 a low-emmissions / low-noise delta-wing aircraft. Compare:

www.easyjet.com/en/News/easyjet_ecojet.html

with

http://silentaircraft.org/efficiency/

Stupidly, they quote the performance in imperial Units (instead of Metric). But in any case, let's do the conversion: EasyJet quote 47g CO2 per passenger/km; the SAX-40 is 89.5g CO2 per passenger/nm, approx: 56g CO2 per passenger/km.

Conclusion: the EasyJet EcoJet will be 19% more radical. Furthermore it will work well in Europe where short-haul flights are the norm and it can be built by 2015 using existing technology wheras the CAMBRIDGE-mit design is decades away from production (est 2030).

-cheers!

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Hey Tim - I must say like your input the best. Clearly you have adopted and applied a more holistic perspective!

The quad bottom line is that airline travel as we currently know it is simply unsustainable. So all we need is another 'opportunity to travel farther, more often, for less'- in order to accelerate the demise of fossil fuel powered flight.

But heck we all know this so it's business as usual.

Wow, just look at this - it's 'greener, cleaner, quieter and smarter than ever before'. What a beauty - just watch it turn into a tropical rainforest in front of your very eyes!:
http://www.airbus.com/en/aircraftfamilies/a380/

I can only hark to Gevon: http://en.wikipedia.org/wiki/Jevons_paradox

See we are not saving anything - just using more and more, but more cheaply and efficiently!

Geo
PS I wonder if that ecojet or that A380 for that matter, seeds saplings at the same time - heck, that'd be a real bonus!

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