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66

I'm a programmer and private pilot, so maybe I can help dispel some of those fears. The computers that run a commercial airplane are conceptually much simpler than the one that runs your phone. This means far less chance of a bug in the software, just because there's less for the programmer to keep track of. If your phone restarts, it doesn't imperil ...


57

If no, why not? While I can't say categorically that it's not happened, I'm pretty sure. Solar radiance is approx. 1kW/m^2. A 737 has approximately 100m^2 wing area. Solar cells are approximately 20% effective. If you covered the entire wings in solar panels, that would work out to 20kW of electrical power at best. At night, it would be close to zero ...


45

The reason for the failure is important actually. If all the electrical systems on an EC135 helicopter fail in your classic EMP scenario then the helicopter has to make an emergency landing as the jet engine is run by a computer system which requires electricity. A power failure of that system would most likely cause the engine to revert to manual backup, ...


33

It's the second option. In any other context, a small aircraft's electrical system would be called "24V". But the alternator regularly puts out 28V, so that's what's typically expected if you hook up your multimeter while the engine's running. Of course, the on-board equipment can operate over a wide range of voltages, often down to as little as 20V.


32

Image source The generators are usually driven from the Accessory Gearbox. This CAD drawing is from the company that makes accessory gearboxes for the Rolls Royce Trent engines driving the A330 and A350, and it shows the connection of the accessory gearbox to the high pressure rotor. This picture from the book The Jet Engine by Rolls Royce shows the ...


31

Short answer In flight, unless you use external energy sources like the Sun, each change in the use of electricity leads to a proportional change in the quantity of fuel burnt in the engines (or in the APU). On an aircraft, generators only convert fuel potential chemical energy into something else, usually electricity, hydraulic energy or pneumatic energy. ...


30

Stays where it is. The mechanism is a leadscrew and like most leadscrews it's "self-locking", which means that it's held in position by frictional forces whenever the motor isn't turning and it can't be back-driven even by substantial loads. The 20 degree (etc) "stops" are just reference positions for which aircraft performance and load limit data have been ...


27

Induction motors turn at a speed proportional to frequency, so a high frequency power supply allows more power to be obtained for the same motor volume and mass. Transformers and motors for 400 Hz are much smaller and lighter than at 50 or 60 Hz, which is an advantage in aircraft (and ships). Transformers can be made smaller because the magnetic core can be ...


27

The generator (IDG) is located on the accessory gearbox The general design is to group elements that need to be driven by the engine around one "accessory gearbox" which is located away from the engine centerline. A driving axial shaft in therefore required. In some cases, there are multiple accessory gearboxes. The IDG goes on the accessory gearbox. On ...


25

Multiple sources indicate that the 28 VDC bus on aircraft powered by 24 VDC batteries, and the 24 VDC systems on truck powered by 28 VDC alternators, are basically the same thing, and that is is just a naming convention. The number of cells is a function of the nominal voltage and the cell type. From this site: Lead Acid: 2 volts/cell Nickel based for ...


24

Before we start, it's important to say that your concern is not irrational. If this were to happen, or if your plane's control systems were to otherwise malfunction in a dangerous manner, your life would genuinely be in danger. You aren't the first person to have thought of this, though. For this reason, we have a category of control systems we describe ...


23

Other than the APU, there are multiple ways to provide electrical power to an aircraft: Battery: The battery is typically the first thing you would turn on and it usually provides DC power to emergency systems only (at least on an airliner, smaller aircraft are fully powered by the battery). Running only on battery power will however deplete the battery ...


21

Yes, because (like a car for example), the aircraft is a closed system, and all energy must be provided internally. So, in flight, that energy must come from the engines, and therefore, the engine must either slow down, or use more fuel.


19

Are there any still commercial airplanes in use that are still steerable with complete loss of all electric systems? Do some commercial airplanes still have mechanical backup steering mechanisms? Yes and Yes. On most(*) Airbus aircrafts, In case of a complete loss of electrical flight control signals, the aircraft can be temporarily controlled by ...


19

This is one of the four Variable Frequency Generator (VFG) of the Airbus A380. It's apparent power is 150 kVA. Rotor, source: Safran The total power available from the engines is 600 kVA. Seen from the other side: Stator, source: Thales The A380 is a one of these "more electrical" planes, where hydraulics tends to be replaced by electric devices, and ...


19

The three most important factors in passenger air travel are safety, safety & safety. So that is where most of the questions will focus on, and where most of the engineering effort will be put into. Couple of questions: Artificial stability: what happens if the stability circuit breaks down? What happens if one of the motors fails, for instance one of ...


19

Cable is not just the metal wire. It's also insulation, installation, cable channels, extra space at tight bends where cable flexibility is insufficient, and maintenance of said cable. Aluminum corrodes in a lot of conditions and happens to be one of the most fatigue-susceptible metals. For these reasons, most aircraft wiring is copper and silver-plated or ...


18

The biggest problem with an all-electric-powered aircraft is the same as those plaguing all-electric cars; our current battery technology has nothing on the energy density of fossil fuels: There's just no contest in being able to pack the energy needed to push a plane through the air into a volume and weight compatible with an airliner. Jet fuel is kerosene,...


18

For the complete electrical failure in the aircraft, the following systems have to fail: The onboard power generation system, usually a synchronous generator has to fail in all the engines. The APU (Auxiliary Power Unit) has to fail. The RAT (Ram Air Turbine) should fail to deploy. The batteries and static inverters should fail (this won't help in ...


18

The cockpit is clean and uncluttered thanks to the absence of the large circuit breaker panels that we’re used to in traditional types. Almost all circuit breakers are ‘virtual’ and are accessed via the forward Multi-Functional Display (MFD). — flight.org The 787 and its contemporaries have moved away from physical CB's and use virtual CB's instead. ...


18

I will expand a bit on @Noah Krasser's answer with some situations where you would want one or the other. FWIW under-volt scenarios are typically far less of a problem than over-voltage scenarios. Bad Voltage Regulator: Alternators vary their voltage output with RPM. To keep your system operating properly a voltage regulator is installed on the alternators ...


17

AC is easier to produce with the engines, that act as generators. The engines have a rotating shaft that it is easily equipped with magnetic dipoles all around. Then, depending on the instrument, the current is either used directly or, by the use of converters, in DC form as not only it is easier to produce, it is also easier to convert. So electronic ...


17

It's not even true that most airliners use fly-by-wire. Among Airbus and Boeing models, the A320 and beyond use FBW on the Airbus side (note that the A300 was produced until 2007), and the 777 and beyond use it on the Boeing side. This is probably a majority of major commercial aircraft, but it's by no means a vast majority. Among these aircraft, virtually ...


17

There are several max ratings of a particular generator, depending on the duty cycle: peak rating (5 sec); max. Continuous (no time limit); and often an intermediate value for 5 minutes is given. The generator produces internal heat together with the electricity, which is not easy to remove by forced cooling and must dissipate through convection. The ...


16

This is how it works on all aircraft with a Constant Speed Drive (CSD) Generator or an Integrated Drive Generator (IDG) - doesn't matter who the airframe maker is. When you press the disconnect button (the red arrow), the disconnect circuit is completed and the solenoid pulls the pin out of the pinion shaft (the blue arrow) which then engages the worm gear ...


16

There is a pretty great article on the design of the 777 electrical system here. Power for avionics needs to be clean to ensure there are no spikes or dips that would cause avionic failures as this could lead to otherwise avoidable emergency declarations. The avionics and passenger power systems are two completely different systems. The 28V ...


16

Let me start of with two facts that pretty much answer your question: A 24V battery is a battery that can output at least 24V over the majority of its capacity. To charge a rechargeable battery you need to push charge into it by providing it with a higher voltage than what the battery is currently at. To put a bit more meat on, here is a typical discharge ...


15

What the other answers have failed to note is that on a plane, its not just AC power, but 3 phase AC power. Depending on how the plane is wired up, you will either get the benefit of reduced cable weight or higher reliability (or some blend of the two). Delta If the plane is wired up with a Delta transformer, then 3 wires are used to carry the electricity....


15

When is the GPU disconnected? Airports rules are applicable, for example airports may prevent the use of APU when the aircraft is at its stand (to reduce noise and pollutants release). The airline operating procedures also provide directives regarding when to start APU and engines. The general principle is that GPU energy is cheaper than APU energy, hence ...


15

The shed bus powers non-essential aircraft systems. In the case of the phenom 100 this is things like the air conditioning, passenger power sockets and entertainment systems, the toilet and some lighting. The shed bus is the first thing to lose power (be shed) should the aircraft not be generating enough electricity through, for example, a generator ...


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