31–40 of 71 posts
Can't we just have exercise bikes linked to generators in economy class? About time the lower orders did some work.
Hey, if I could get something out of it (like fare), I'd gladly pedal away.
Come to think of it. Maybe we should have excercise bikes in 1st powering economy. On board gym?
Given that, in most overseas flights, sufficient voltage is available at every seat to power in-flight entertainment, I wonder if it's an easier engineering problem to have a 15-20 volt outlet instead (though I'm not sure if there's enough juice for the extra 2-3A). True, not laptops have the same AC plug, so an adapter would be necessary.
Not necessarily. Some sockets can cope with the majority of the AC plugs in Europe and America. http://img.hisupplier.com/var/userImages/old/selong/selong$7...
So it's definitely doable, and I'd be prepared to bet money that it runs off the same APU that powers the entertainment system.
"I wondered whether, as a technical matter, an airliner could actually produce enough power to keep a planeful of laptop users plugged in through a whole flight. [...] Short answer: No, you probably couldn't make this work." Given that the power output of the engines of a Boeing 747 is 140MW [1], enough to power 15 copies of the Empire State Building at peak business hours[2], I find this impossibility a bit depressi…
It is all about costs. Those engines are producing energy to keep the plane flying at 500mph. If you pull some power to spin an alternator then you need to run the engines faster and burn more fuel (which means you need even more fuel on board at takeoff to lug all of this extra fuel to the destination.) Add in the weight of the various inverters and equipment necessary to make this system safe on an airplane and I a…
Earlier quoted context omitted.
It is all about costs. Those engines are producing energy to keep the plane flying at 500mph. If you pull some power to spin an alternator then you need to run the engines faster and burn more fuel (which means you need even more fuel on board at takeoff to lug all of this extra fuel to the destination.) Add in the weight of the various inverters and equipment necessary to make this system safe on an airplane and I a…
Some math: 120V * 2A = 240W * 300 passengers = 72 kW. That's 1/50th of a percent of the existing power output of a 747. If you figure a $600 plane ticket, I'd gladly pay 1/50th of a percent ($0.30) of that for electrical power on the flight. The numbers get a bit more complicated when you figure in the weight for transformers, alternators, inverters, etc. But fuel is not a major component of this. The math really doe…
More to the point, 240W is irrealistic for a laptop. Most laptops consume under 40W. With this better estimation, this is 1/117th of a percent.
Here's my personal solution. It works for all airlines. It can also power my Cradlepoint 4G hotspot and recharge my iPad, iPhone, and any device using USB power. http://www.tekkeon.com/products-mypowerall.html I bought a male Adaptaplug and a Magsafe cord from eBay, and after 5 minutes with a soldering iron, it works for my 13" unibody MacBook as well. I plan on upgrading to a 13" MacBook Air soon. I should be able t…
Someone please correct me if I'm wrong, but I believe this article is defeated by the actual fact of the matter that some planes do have AC to all the seats.
"I wondered whether, as a technical matter, an airliner could actually produce enough power to keep a planeful of laptop users plugged in through a whole flight. [...] Short answer: No, you probably couldn't make this work." Given that the power output of the engines of a Boeing 747 is 140MW [1], enough to power 15 copies of the Empire State Building at peak business hours[2], I find this impossibility a bit depressi…
Earlier quoted context omitted.
It is all about costs. Those engines are producing energy to keep the plane flying at 500mph. If you pull some power to spin an alternator then you need to run the engines faster and burn more fuel (which means you need even more fuel on board at takeoff to lug all of this extra fuel to the destination.) Add in the weight of the various inverters and equipment necessary to make this system safe on an airplane and I a…
Some math: 120V * 2A = 240W * 300 passengers = 72 kW. That's 1/50th of a percent of the existing power output of a 747. If you figure a $600 plane ticket, I'd gladly pay 1/50th of a percent ($0.30) of that for electrical power on the flight. The numbers get a bit more complicated when you figure in the weight for transformers, alternators, inverters, etc. But fuel is not a major component of this. The math really doe…
How do you figure?
Say some extra weight delta_w in additional equipment is required, and say that the fuel required to complete a given flight is a function f of the plane's weight, and that the cost of the fuel is C. Further, let the lifetime maintenance cost of the new equipment be E, and the lifetime maintenance of the plane's structural components be g, also a function of its weight. As a rough approximation, the additional cost should be
E + C df/dw|_W * delta_w + dg/dw|_W * delta_w
(Note that, really, f is a function of both passenger power consumption and of weight, both of which we're varying here, but I'll buy your argument that df/dp|_P * delta_p is neglible in comparison to f(P,W))
The article asserts that one or both of the derivates in this equation are large enough that its product with delta_w is non-negligible (in fact, prohibitive). I'm guessing that df/dp is not the problem, which is the only term you really addressed.
They already have 400hz power (not sure of the voltage) from the engines. Why not just use a switching power supply to change that to 60hz 110v? Why this whole business with inverters?
Switch-mode power supplies are essentially DC rectifiers, which will never ever give you 110V, 60Hz (an AC voltage). One way to change the frequency of a power source is through a double-conversion type AC/AC converter, i.e. 1st stage is a rectifier which outputs a DC voltage - this is an arbitrary DC voltage, but it needs to be within the voltage tolerances of the 2nd stage - an inverter, which reconstructs an AC vo…
It is in fact possible to use a switching circuit to convert an arbitrary ac voltage/frequency to another arbitrary ac voltage/frequency directly without a DC link intermediary. This is called a "matrix converter." http://en.wikipedia.org/wiki/AC/AC_converter
So it should theoretically be possible to take say 200VAC at 400 Hz and convert this to 120VAC 60Hz. In fact this would probably be more compact/less expensive than the usual inverters mentioned in this article, since these are usually meant to be powered by a low voltage DC source and thus have to deal with taking a low voltage and very high current and first stepping this up to several hundred volts, then modulate it into an AC sine wave. A matrix converter (or even AC-DC-AC converter) would have no such requirement if it were powered from the already high voltage aircraft power bus.
At this point I think it's a matter of the technology catching up, since this is a highly specialized application that has just recently become an opportunity for innovation.
EDIT: Also - 240W per person? This seems outrageously high as a baseline load. I would estimate more like 50-100W per person on average, with 300W peak (like when the power supply is first plugged in.) The peak loads would not all happen at once unless everyone decides to plug in and turn on their computers at once, in which case the power limiting would kick in...