SEP 17

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.

Comments (8)

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moo
written by mafuga mamuga, September 17, 2010

coolest thing ever. wow

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written by jpw, September 17, 2010

Turboprop jet aircraft are also quite a bit more efficient than turbofan engines. Unfortunately, speed is largely dictated by the fact that the tips of the rotors can not be allowed to reach supersonic speeds. There are quite a few great new designs which focus on this, increasing the prop rpm and thrust, while decreasing the tip speeds.

Neat.

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written by Evan, September 18, 2010

Have studies shown whether piston powered planes release less NO? Do they create the high temperatures required to form the bond?

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Does it matter?
written by Tracy, September 18, 2010

The thing is at this point it really doesn't matter that they are more efficient on fuel because all air planes are gas hogs. They waste some much fuel.

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written by EV, September 19, 2010

Actually, if you read the original report cited in the article, they had to estimate the Constellation's fuel efficiency. No hard data for any of their piston estimates. Further, even if the estimates are accurate, Jets reached the same efficiency in 1985. One difference that isn't taken into account is the vastly improved safety of today's jets vs. the Constellation and other aircraft of the era. When was the last time you saw a life insurance machine in an airport?

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Altitude is important
written by Foraker, September 20, 2010

Jet aircraft can be faster, but usually only at higher altitudes. At lower altitudes the prop planes are almost as fast as (and more efficient than) jets.

The airlines are starting to take notice. The short-hop planes are almost all prop planes now, leaving the higher altitudes and longer distances to the larger jets.

The next step (in the US) is to get rid of the less-than-an-hour flights altogether and replace them with more efficient passenger rail.

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Airplanes efficiency
written by the writers' board, September 30, 2010

According to the article, is it gas or fuel but it should be ECO friendly maintain speed which is enough.

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Speed and Efficiency not the issue with Turbines
written by Andrew, October 06, 2010

Just to note, the switch from piston to turbine had little to do with efficiency at all. Nor was speed the driving factor. While they are much faster, even the props of today's commercial aircraft are not piston driven, but turbine driven (hence the name "Turboprop"). The real reason we use turbines is because the failure rate is so much lower than a piston engine that it actually makes it safe to fly long distance without worrying about an engine failure.

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