We’ve covered airplane fuel economy before, and there are a number of approaches to improving it, including use of lighter materials, lighter hybrid control systems, and more efficient engines.
We often think of airplane fuel economy in terms of how many miles each seat can go per gallon, referred to as seat-miles per gallon [sMPG]. The Airbus A350-XWB, recently flown at the Paris Air Show, boasts up to 82.3sMPG, but what about when it’s on the ground?
There are a couple problems with airplane fuel economy on the ground, as well as maneuverability. First, a jet airplane cannot reverse, so that means it needs to wait for a tug to back it out of its spot at the terminal and get it pointed in the right direction. Once the airplane is on the taxiway, it uses its jet engines to thrust forward, a very inefficient use of fuel.
A new innovation developed by Honeywell and Safran could solve both of these problems. An Airbus A320 has been modified to include a 50kW electric motor in each of the two main landing gear struts. The outside wheel is controlled forwards or backwards to move the airplane. It can even turn on a dime, so to speak, by stopping one motor and rotating on that wheel.
Electricity is drawn from the onboard generators that are used to power the airplane when the engines aren’t running. Honeywell estimates that, on the ground, fuel economy is improved by about 83% over using the engines to thrust about. The new system could also save time on the tarmac, since they airplane won’t have to wait for a tug to back it out of the gate.