Fuel efficient aircraft are critical to maintaining the bottom line in the airline industry. Recent developments in engine and aircraft design, such as the Airbus A350-XWB, have helped to push that number ever higher.
Airlines don’t measure fuel economy quite the same way as automobile manufacturers do. Where the average Toyota Prius might measure 50mpg and carry four passengers, this is hard to correlate to an airline. Instead, airlines use Seat-Miles Per Gallon [sMPG], that is, how many miles per gallon each seat gets. [No, Economy Class doesn’t get any better sMPG than First Class] According to a report in 2009 from the Department of Transportation [DOT], the average airline fuel economy was 64sMPG.
This makes the Toyota Prius, at 12.5sMPG, look like a gas-guzzler! Correction: A Toyota Prius would be properly rated at 200sMPG.
By combining lightweight composite materials and a more-fuel-efficient engine design, as well as lighter electrical and electronic flight control systems, aircraft designers are pushing fuel economy higher. The latest jumbo jet from Airbus, the A350-XWB looks to beat the averages with a new line of jumbo jets seating from 270 to 350 passengers. Depending on the variant, the airline can expect better than average fuel economy, up to 25% better, according to Airbus. If my math is correct, the A350-800 is rated at 69.8sMPG, while the larger A350-1000 gets a staggering 82.3sMPG.
Last week, Airbus test-fired the engines on its new fuel efficient craft, but wasn’t ready to take off exactly yet. After testing, the Airbus A350-XWB was finally ready for its maiden flight this morning at 4am EST in Toulouse, France. The test flight went as high as 25,000ft and didn’t push to full speed, but flew well. One important part of the test flight was making the switch in the electronic control system from “direct law” to “normal law.” When under “direct law” control, the onboard computers move control surfaces exactly as the pilot commands, but under “normal law” the onboard computer calculates control surface adjustments and engine output based on the pilots’ intentions.