Questions tagged [aircraft-systems]

The essential systems found on most aircraft, including power plants, fuel systems, electrical systems, and flight instruments.

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19
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6answers
13k views

Why is air mixed with bypass air on the A/C of an aircraft?

Air is taken from the compressors, then it is cooled by the air that comes from the ram air inlet. After that, it is compressed and cooled again by an expansion turbine. When finally air is condensed, ...
37
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3answers
36k views

Are fighter jets designed to be so inherently unstable that a human can't fly one unassisted?

I'm told that in order to be more maneuverable fighter jets are designed in a way that makes them impossible for a human to control without the help of a flight computer. Is this actually true? ...
8
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3answers
2k views

What is this device below the door of a 737 (and other aircraft)?

The other day I made a question about the External Power Hatch. Now I would want to know what's that hole below the door.
18
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3answers
31k views

What is a vortex generator?

I saw a vortex generator mentioned in an aircraft listing. What is a vortex generator?
35
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1answer
8k views

How does WiFi work on an aircraft?

I've noticed that when a WiFi system is set up on an aircraft, a small bulbous structure is added. What does it contain and how does this WiFi system work?
31
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6answers
9k views

What is propeller / engine sync and how does it work?

In some models of multi-engine airplanes there is a switch labelled something similar to "prop sync" or "engine sync". My questions are: What is engine synchronization? How is it achieved? Why is it ...
16
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2answers
10k views

What exactly are those openings in the bellies of many jetliners?

I have circled the areas (in yellow) under the belly of the 737. What exactly are those? (airliners.net)
33
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2answers
59k views

How does an alpha (AoA) vane work?

The alpha vane (also called AoA vane) is an external probe used to measure the angle of attack. I have been trying to understand how exactly it works, but I can't find any clear explanation or ...
31
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7answers
31k views

Why do airplanes use AC electric power?

Primary electric power on larger airplanes is provided as AC. What aspects of aircraft make AC a better choice than DC?
23
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2answers
11k views

What is a gust alleviation system?

Reading about the 787 it says it has an active gust alleviation system similar to the system used on the B-2 bomber. [1] The gust alleviation patent says: The gust alleviation system picks ...
25
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8answers
27k views

What is the purpose of having contra-rotating props on an aircraft?

Why do planes, like the famous XF-11 and the Tu-95, have contra-rotating props? What is their purpose? Image credit: Mike Freer / Touchdown-Aviation / Wikimedia
41
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2answers
26k views

How do aircraft stall warning systems work?

If an aircraft stalls, there are stall warning systems called as Stall computers. Anyone has idea how they predict that its a stall and how they raise the alarm/warning?
32
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7answers
14k views

Why do aircraft use hydraulics instead of pneumatics?

I was reading about how the F-35 is having trouble with the "fueldraulic" system. This made me wonder: Why don't aircraft use pneumatic systems instead of hydraulic/fueldraulic systems? There are ...
30
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3answers
16k views

How do Ram Air Turbines get deployed?

I understand that most larger jets have a Ram Air Turbine (RAT) in case of total electrical failure (for instance, when you run out of fuel) in order to at least have some hydraulics and a couple of ...
22
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2answers
17k views

What is Alpha protection?

This article states: An occurrence was reported where an Airbus A321 aeroplane encountered a blockage of two Angle Of Attack (AOA) probes during climb, leading to activation of the Alpha Protection ...
5
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3answers
24k views

What is the MEL (minimum equipment list)?

What is a minimum equipment list for an aircraft? How are MEL and MMEL related? Who creates the list, and how do they decide what is on it?
3
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2answers
8k views

What is the difference between variable and transient bleed valves?

What is the difference between variable bleed valves (VBVs) and transient bleed valves (TBVs)? What is their range of operations? Can they be used at all airspeeds?
37
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4answers
41k views

What is a "Flight Director"?

What is a Flight Director, and how does it differ from Autopilot?
26
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2answers
8k views

Is it possible to fly with counterbalanced single blade engines?

Refer the image for counterbalanced single blade (Source http://www.aviastar.org/helicopters_eng/bo-103.php). In ground school, they took us for aircraft inspection at end of our ground school ...
29
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2answers
9k views

How is fuel dumped in aircraft?

I have heard incidents in which commercial aircraft are required to dump fuel in event of an emergency to avoid landing over maximum landing weight. What systems do aircraft have in place to dump fuel?...
22
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7answers
37k views

Why do most single propellers have a clockwise rotation?

Why do most single propellers have a clockwise rotation (seen from the pilot's point of view)? There are though multi-engine planes that have each propeller rotating different directions, but in the ...
21
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1answer
4k views

Can the wheel brakes hold an airliner in place if its engines are at full thrust?

Are wheel brakes on most commercial jet airliners capable of holding the jet stationary on a dry surface, if all the engines are given full thrust? Could doing this be potentially unsafe or damaging ...
15
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8answers
10k views

What happens to the spinning wheels of the landing gear after takeoff, before retraction?

What happens to the spinning landing gear right after V2 on takeoff? Are they automatically or manually braked to a halt before gear retraction? Or are they allowed to spin to a halt in the wheel ...
12
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1answer
7k views

What are these spinning discs next to the throttle of the Boeing P-8 Poseidon?

The source video can be found here and the GIF is from 0:21 onwards. What are those 2 spinning things next to the throttle ?
50
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3answers
29k views

What is the technique or procedure to disable/disengage the MCAS on Boeing 737 Max 8 & 9 Aircraft?

What is the technique or procedure to disable the MCAS and manually fly the Boeing 737 MAX 8/9 Aircraft? To clarify my question, what I'm asking is can the pilot disengage the MCAS and if so, how do ...
13
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2answers
28k views

Why do aircraft use 400 Hz AC instead of the 50 or 60 Hz of wall outlets? [duplicate]

Large aircraft electrical systems usually use 400 Hz alternating current (AC), while common household electrical outlets deliver AC at 50 or 60 Hz. Why the difference?
31
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1answer
15k views

Which external instruments are visible on the A350's nose section?

Most pictures of airliner's nose sections show small dark tube- or fin-shaped instruments sticking out of the fuselage below the cockpit windows. For example this Airbus A350 shows them well: ...
11
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1answer
4k views

How can aircraft determine true north for inertial navigation systems?

Aircraft use GPS and inertial navigation systems in combination. Sometimes INS needs alignment (i.e. to be told where it is AND what orientation it has). How can an aircraft be be aligned to true ...
20
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1answer
3k views

Is Doppler navigation still in use for civilian aircraft?

Is it possible to find an airliner nowadays with Doppler radar used for navigation purposes?
8
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3answers
3k views

What radios are airliners / large aircraft equipped with?

I know that pilots have to talk to the tower over the radio, and apparently you have to tune the radio to the right tower frequency. I've also heard that in an emergency, you're supposed to "squawk ...
7
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2answers
887 views

What is a plausible scenario for aircraft sabotage for a science fiction novel?

I am writing a science fiction novel and my characters are about to board a private jet - they will be leaving Virginia and flying to CERN in Switzerland. Some factions are not happy with what they ...
16
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3answers
6k views

How is the actual ground speed of an airliner measured?

Do pilots have the "ground speed" information available? If so, how is the ground speed measured? Or do they rely on GPS info to calculate it?
13
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3answers
8k views

Why is there a compressor in an air cycle machine?

I'm a curious high school student. Why is there a compressor after the first heat exchanger in an air cycle machine? I've read that compressing the cold air is for the cause of efficiency because ...
11
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2answers
4k views

Is there a maximum airspeed to deploy a ram air turbine?

Is there any airspeed limit for deploying a ram air turbine? Can airspeed be determined from the rate of its propeller rotation? Could that data be used to determine altitude?
10
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1answer
4k views

Do lights on wingtips change color at different times of the day?

I have gone through this post which explained me why there are red lights turned on the plane but I doubt with the color code whether it's only during the environment specific conditions or its ...
2
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1answer
3k views

Where does the final cooling take place in the air cycle machine of the air conditioning system?

On aircraft with an ACM air conditioning, where does the final cooling take place? Is it in the ACM expansion turbine or in the ACM compressor?
42
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1answer
9k views

How does an Airbus aircraft connect to the Internet? [duplicate]

I would like to understand better where (physically in the aircraft) and how the Internet connection is received on an Airbus aircraft, in particular in an Airbus A380, and then how this system is ...
24
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7answers
10k views

Do safety-critical avionics systems run Linux?

I have heard diverse things about this. Some people claim that running Linux on safety-critical avionics systems is a very bad idea. On the other hand some people (who are rather unfamiliar with ...
15
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6answers
5k views

Why do most commercial airplanes use hydraulics instead of electric/servo motors?

I'm sure it's possible to use servo motors to get precise control of the ailerons, elevators or the rudder. But still, hydraulics are widely used instead. Hydraulics do have a disadvantage that a ...
41
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4answers
11k views

Why do flight control cables not slacken during the cold temperatures at cruise?

Image source Flight controls in airliners have long cable lengths in between the cockpit controls and the control surfaces. For instance in the picture above: the pilot operates the yoke, which ...
30
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5answers
14k views

Can a Boeing 777 be hacked?

All this confusion over flight 370 has me wondering if it would be possible to hack into an airplane and control the autopilot or other on-board systems in a way that the pilots couldn't regain ...
21
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6answers
11k views

When is an aircraft required to be pressurized?

For example a Cessna Grand Caravan doesn't have a pressurization system, but a Phenom 100 is pressurized, so what are the main reasons a manufacturer has to build an aircraft with a pressurization ...
17
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4answers
2k views

How does the Guardian counter-MANPADS system work?

I came across this picture of a FedEx McDonnell Douglas DC-10 equipped with an anti-missile defense system. (wikimedia.org) According to the picture description: FedEx became the first U.S. ...
15
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4answers
6k views

What are these grilles in the passenger cabin of this 787?

Below the windows, ahead of the seat, there are small grilles. Look: Source: Airliners.net What are those for?
13
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1answer
12k views

Why does manifold pressure increase when you turn on carb heat?

So everyone knows that carb heat decreases engine performance. Yet when we check the heat during run-up, the manifold pressure increases. Why is that? Shouldn't adding carb heat cause the intake air ...
10
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2answers
6k views

Why do similar Airbus and Boeing aircraft use different flap and slat mechanisms?

Why do most Boeing aircraft and their corresponding Airbus counterparts have different flaps and slats mechanisms (747 and A380, 737 and A320)? I'm assuming a lot of these mechanisms are patented. For ...
7
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2answers
20k views

What is the difference between deice and anti-ice?

Most aircraft contain systems which are used to mitigate problems which could be caused by ice. This includes everything from a heated pitot tube to a wing leading edge heated by bleed air. These ...
14
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1answer
4k views

Where are the circuit breakers on the 787?

(787 left, 777 right) Normally found aft of the overhead panel, where are they on the Boeing 787?
13
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5answers
8k views

Which is more accurate for height measurement: GPS or barometer?

I am not a pilot and have come to this site to ask a question about the measurement of height. This is as a result of the comments made as a result of a question in the Physics Stack Exchange forum "...
10
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2answers
3k views

Does the wifi uplink antenna affect aerodynamics or efficiency?

The wifi uplink antenna on airliners seems like a quite aerodynamically inefficient hump, just sticking up into the airflow above the main cabin. If it added even 0.1% more drag, I don't see how it ...