Following previous entries here and here, on whether you could actually operate an airliner full of laptop users all plugged into 120V AC sockets -- or whether, on the contrary, the necessary power-supply gear would be so heavy that the plane would never get off the ground -- here is one last round of tech-talk reports. This is a sampling to reflect the range of views that have come in.

1) There's a lot of power available, but.... A technically-trained reader writes:

>>Thanks for honoring your nerd readers with this info.

As a PhD physicist and radio amateur, I'd chime in to say that all the difficulties with generating up to 240 Watts of AC power (120 Volts times 2 Amps) show that this is not the right solution. (For one thing, a typical laptop needs no more than 60 Watts. Your lap would suffer dreadfully if the computer was using 240W!) The laptop can't use 120V power directly; it has to be converted to about 20V DC. So direct DC distribution is the "correct" idea, bypassing your AC plug-in power supply and all the waveform issues. Some airlines have supported DC, as you mention, but we run into problems because laptops don't have standardized power connections -- requiring the airlines to sell or rent you an expensive adapter cable.

Power on an aircraft is not in short supply. One engine on a 747 is calculated to provide 87,000 horsepower or 65,000 kW at cruise (Mach 0.9 at 40,000 ft) That would keep about 3 million laptops running happily, if used for electricity. (http://www.aerospaceweb.org/question/propulsion/q0195.shtml)<<

2) Harrrummpph! Another tech veteran writes:

>>1. This is a subcase of rich people complaining about their situation.
2. You call yourself a "nerd," but you have a bare mailto href on your page. The title has to be *earned*.<<

Point 1: Yes, agreed. Point 2: Hey, it's not my "real" address!


http://www.theatlantic.com/technolog...:+The+Atlantic