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21st Century Green Tech

• 1. Piston-Powered Airplanes More Fuel Efficient (But Is That Enough?)

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Piston-Powered Airplanes More Fuel Efficient (But Is That Enough?)  

2010-09-17 16:31

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A recent article from Low-Tech Magazine brings up the interesting note that only the most recent jet planes are as fuel-efficient as propeller planes. Many people believe that jets are very efficient, but, "on a per passenger mile basis, the most efficient modern aircraft, the Airbus A380, has just managed to match that which was achieved by the piston engined Lockheed Constellation series in the 1950's."

Unfortunately, passenger-mile fuel efficiency isn't the sole metric that airlines have to consider. Fuel cost is certainly a big chunk of the operating budget for a passenger plane, but so is the cost of crew wages and benefits. Jets travel faster, better utilizing the working hours available for each flight crew. Piston aircraft may be more fuel efficient, but there are other things that jets do better.

Piston aircraft cannot operate at the higher altitudes that jets can reach. The Constellation's ceiling was 24,000 feet (7,315 meters), while contemporary jets can reach an altitude of about 40,000 feet (12,192 meters). Flying at higher altitudes allows jet aircraft to avoid weather systems that would delay or halt aircraft operating at lower altitudes.

None of this means that we are in favor of retaining the status quo. While jets can fly higher, they also release their exhaust higher in the atmosphere, which is likely more damaging than exhaust released at ground level. The environmental costs of any form of air travel are not fully incorporated into the costs to consumers. Both technologies should continue to be developed, and we've also seen hybrid propeller-turbines, which are intriguing, too.

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