lørdag 17. november 2012

Cat-launch

Airbus: Passenger jets should use aircraft carrier-style catapults


 
Aircraft carriers have a really short runway, so to get the jets up to speed crews use special catapults to fling planes into the air. Now, Airbus is saying that we should be using similar technology with passenger jets, saving fuel while reducing noise for people who live near airports.

Accelerating a jet to takeoff speed uses tremendous quantities of fuel, with engines pushed to maximum thrust to get a plane off the ground before the runway ends. Even after it leaves the runway, a plane's engines still need to be on full-blast to get to a cruising altitude. This not only uses lots of fuel, but those maxed-out engines make lots of noise, and can disturb populated areas.

The proposed Airbus Eco-climb system would work a little differently from those steam catapults used on carriers, and would put the plane on a sled that travels along a track on the ground. The sled would be driven by electric induction motors, and coud get the plane up to takeoff speed in just 2/3 the distance of a regular takeoff. Once up to speed, the plane simply lifts up from the sled without turning a wheel, at which point the engines take over.

One big advantage the electric induction sled has over the steam catapult is that the acceleration force can be applied gradually, making for a smoother ride for the passengers. If properly applied, Airbus says that the maximum g-force during takeoff will be no higher than the 2.5 g that's currently typical.

Another big benefit of this rapid acceleration is that the takeoff speed will be higher, allowing the plane to climb out of the airport more rapidly. This reduces the jet's noise footprint, bothering fewer people on the ground. It also saves fuel, at a time when fuel costs are a major factor in the overall cost of flying. It also clears space over an airport so that more planes can operate.

Airbus figures the Eco-climb could deliver about a 3% fuel savings on a typical 560-mile flight. That might not sound like much, but the air carrier points out that once the system is widely adopted, future planes could be developed using smaller engines, resulting in greater savings.

This all sounds pretty cool, but I hope they don't plan to use those arrestor cables to slow the planes on landing. Those suckers can stop a plane so fast that your fillings might fall out.

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