Questions tagged [landing-gear]

The wheels of an airplane. Sometimes replaced by floats or skis.

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69
votes
2answers
26k views

Why are aircraft tires not pre-spun prior to landing to preserve them?

Why has someone not designed a landing wheel with a fin or fins on it so that the air will start the wheels turning before the wheels touch the ground? Wouldn't that preserve the tires longer from ...
38
votes
4answers
7k views

Do commercial aeroplanes use ABS to brake?

I have read that the wheel brakes on an aeroplane are by for the most efficient means of stopping it. I was wondering whether in low grip situations, such as in rain or snow, an ABS (Anti-lock Braking ...
25
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2answers
6k views

Are large passenger aircraft steered during taxi by changing the angle of the front landing gear?

When moving to and from the runway, does a large passenger aircraft turn by changing the thrust difference on its side engines, or by turning the front landing gear to a different angle? If it is by ...
12
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3answers
3k views

Is there a best number of wheels per bogie?

I understand the need of having more wheels when the aircraft is designed to be heavier. The number of wheels per bogie and the number of bogies differ from an aircraft to another. For example, there ...
65
votes
3answers
21k views

How are brakes cooled on heavy aircraft?

As kinetic energy is not stored or recycled, large quantities of heat have to be evacuated in a short period of time when aircraft abort their takeoff or land: B777 brake test, Youtube Which ...
47
votes
11answers
41k views

Why do planes always land on rear wheels instead of the nose wheels?

Various times, I have seen and felt myself that the plane always lands on the rear wheels, but not the front wheels. Why do the pilots land it on the rear wheels instead of the front? Does it have ...
28
votes
8answers
11k views

Is there a good reason why modern airliners can't have conventional landing gears (vs. tricycle landing gears)?

By "good reason", I mean a reason that we definitely cannot overcome with reasonable changes in aircraft design, control laws or procedures. As possible benefits of this I see a much smaller (= ...
25
votes
6answers
7k views

Why tap the brakes on take-off in fixed gear aircraft?

The Socata TB10 checklist indicates that you should touch the brakes after lift-off. I assume this is to stop the wheels from turning, but why? In a retractable gear aircraft this would make sense to ...
14
votes
3answers
7k views

What are the advantages and disadvantages of having landing gear doors?

To make comparison easy, let us take the example of B737 and A320, both similar aircrafts with retractable landing gear. As seen on the photo below, the B737 doesn't have gear doors for the wheels, ...
13
votes
2answers
8k views

How is the 737 main landing gear protected from weather?

I really like the 737, it is perhaps my favorite airliner. One curiosity of this aircraft (afaik, it is the only commercial airliner) is that the main landing gear has no cover: Here is another ...
18
votes
3answers
3k views

Why do most aerobatic aircraft have conventional landing gear?

I was browsing images of aerobatic aircraft on Google and noticed that the vast majority of them have conventional "tail-dragger" landing gear. Is there any practical reason why this is the case, or ...
15
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8answers
8k 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 ...
10
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2answers
2k views

Why is the main landing gear of the Cessna Caravan placed so far forward?

Why is it that the rear landing gear of the Caravan is placed so far forward? I understand that the center of gravity must lie somewhere in the middle between the nose gear and the rear gear but ...
4
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2answers
3k views

How are forces on the landing gear reduced or compensated for at touchdown?

When an aircraft lands with the tires of the landing gear at rest, as soon as the the aircraft touches down, the landing gear experiences a large amount of wheel-spin up forces (because of the static ...
19
votes
3answers
7k views

How are modern jets modified to takeoff/land on a dirt runway?

I've been reading a lot about the Soviet and Russian military aircraft, and it seems a lot of them are built to work on dirt runways, or modified to do so. How is this accomplished? Is it a simple ...
23
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6answers
19k views

Could airline tires be deflated in mid-flight to reduce weight?

As a means of weight reduction to reduce fuel consumption, could the tires on an aircraft’s landing gear be deflated once airborne then re-inflated just prior to landing? Is that feasible and safe?
37
votes
4answers
12k views

Why don't modern aircraft have landing gear that can swivel to compensate for crosswinds?

When landing, crosswinds can be very expensive. They cause go-arounds, diversions to other airfields and even crashes. Currently pilots crab in the air to counteract crosswinds and, at the last ...
22
votes
2answers
6k views

Why do some A380 main wheels have no brakes?

The A380 has 20 main and 2 nose wheels. Apparently the nose wheels have no brakes (compare with Are there any aircraft with a nose wheel braking system?). While researching for this question (How are ...
20
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3answers
9k views

What is the temperature of the brakes after a typical landing?

On an airliner, what is the temperature of the brakes after a typical landing, and how long does it take to cool down? Is it hot enough that mechanics should wait before servicing an aircraft that ...
21
votes
2answers
12k views

How do fire crews handle hot brakes?

Let suppose an emergency aircraft has made an overweight landing. The brakes are white hot, and the fire crews are requested to be on scene. What can be done about the hot brakes? Can they just shoot ...
19
votes
1answer
3k views

Is the main landing gear of a large airplane designed for sideways (crabbed) touchdowns?

Is it just my imagination, or is it a fact that many large airliners actually touch down "crabbed" on difficult crosswind landings? Here's what I mean in this video, or as shown in this picture: Is ...
17
votes
3answers
18k views

How long do airliner tires last? Can this be improved?

I imagine that the tires on commercial jets wear out pretty fast with all those squealing landings as the tire suddenly has to spin up from zero to the speed of landing. 2 questions: How many ...
12
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4answers
3k views

What effect would there be if the brakes were locked at touchdown?

I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's ...
7
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1answer
12k views

How does the squat switch work?

This question came up after reading the following comments on the answer to this question: Raising the flaps right after touchdown. Good or bad? Philippe Leybaert Jan 20 at 23:00 The retractable ...
45
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2answers
9k views

How can the landing gear fit in the small room in the engine bay on the Tupolev Tu-144?

I recently went to the museum in Sinsheim, Germany, where a Tupolev Tu-144 is on display. I noticed that the landing gear of this plane is actually way wider than the space it has available when ...
14
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5answers
21k views

Why do airplanes have to retract landing gear?

Why do all the airplanes have to retract their landing gear, once they reach some specific height? Why can't they simply leave their landing gear deployed all through the flight?
17
votes
1answer
3k views

Why is there a difference between nosegear retraction directions?

I've noticed that on almost all aircraft (Boeing, Airbus etc.) the nose gear rotates forwards for retraction. However, on a some aircraft, in particular a few Russian models, the opposite is used: ...
15
votes
2answers
1k views

What causes an airplane to rhythmically bounce during taxiing?

Some time ago, I was on a commercial flight and while the airplane was taxiing around, there was this rhythmic bouncing. Here is a video I made of the takeoff. You can notice the bouncing at the taxi ...
10
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2answers
3k views

How much extra drag does landing gear incur?

How much extra drag does landing gear incur? I'm interested in large commercial airplanes. For a concrete example, let's say a 747 flying at 1,000 m above sea level at 800 km/h. Edit: Looks like 800 ...
20
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3answers
2k views

Do landing strips suffer from landing wheel tire tracks?

I've now seen several landing strips up close and there are lots of tire tracks from planes' landing wheels. I wonder if it somehow modifies the properties of landing strips to make for poorer landing ...
16
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4answers
3k views

Why does the Harrier jet have four landing gears?

I was looking at pictures of Harrier jets and I noticed something. They have four landing gears. That seems pretty unusual for a fighter jet - most have only 3 in a triangle formation. What is the ...
15
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1answer
2k views

Do landing strips suffer from potholes or rutting?

In companion to the other question asking about wheel tire tracks. Planes come down and stop with a significant amount of force which I would expect to cause either rutting or potholes. Are runways ...
13
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2answers
10k views

If the landing gear is stuck in an airliner, can the crew go down and manually open it?

There are several instances where we see the landing gear getting stuck before landing. In these kind of situations, can the crew, or one of the pilots, go down to the landing gear area and solve the ...
10
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1answer
2k views

Why do some commercial aircraft have no landing gear cover? [duplicate]

The B737 has no cover on its landing gear, as may be seen in this picture. Doesn't this increase the air drag? Almost all other airliners have doors that close off the rubber of the wheels, for ...
9
votes
2answers
2k views

Why does landing gear retract with an offset?

I've noticed this often in flight simulators, and have, to be honest, never paid attention to it in real life, though I'm quite sure it happens there too: When landing gear retracts (and I believe ...
9
votes
5answers
5k views

Will the landing gear work mechanicaly in case of total power loss?

In case of a total power failure in all the aircraft systems like engine failure and APU failure, would it be possible to use mechanical means (Manually) to open the landing gear bay door and deploy ...
8
votes
4answers
1k views

Will landing gear with wheel fairings keep spinning due to airflow?

I asked this in a side note to a previous question, but I figured it warranted its own question. If a fixed gear aircraft is fitted with wheel fairings, even if you tapped the brakes after lift-off, ...
7
votes
2answers
4k views

What is the typical weight distribution ratio between nose gear and main gear?

On an airplane with tricycle gears, the main gear supports most of the weight and is therefore the strongest. The nose gear prevents the nose tipping down, since the center of gravity is forward of ...
49
votes
3answers
16k views

Can the landing gear be pulled up while the plane is on the ground?

If a pilot makes a mistake and inadvertently touches the gear up lever, will it actually activate while on the ground and make the plane drop onto its belly? I suppose that there would be some sensor ...
16
votes
2answers
11k views

Why do certain aircraft's landing gear tilt up?

Why do the main landing gears of aircraft like the A330, 777, 787, etc tilt up? This does not happen with the 767. Interestingly, for the 747, the inner landing gear does not tilt up while the outer ...
10
votes
5answers
5k views

Is the landing gear controlled by the pilot or is it automatic?

I have been watching a few aircraft landing videos in crosswind situations and I noticed that if the airliner missed the runway the landing gear would go back into the aircraft. So I'm wondering if ...
77
votes
1answer
10k views

How is tire rubber removed from the runway?

Every time an aircraft touches down, the tires are spun up rapidly. As a result, some rubber is left at the touchdown zone. (image source) As time goes on, more rubber is accumulated at the ...
47
votes
3answers
16k views

Why does the landing gear control have 3 positions (up/down/off) on Boeing 737-800?

I've noticed that Boeing 737-800's cockpit has a 3-position landing gear lever. During takeoff, the pilot moves the lever from DOWN to UP and then to OFF position. What's the point of the OFF position?...
31
votes
3answers
9k views

Why would one plane in this picture not have gear down yet?

This image (as posted in another question) is a YouTube video's thumbnail: I noticed that the lead twin (737?) has gear down, the 747 behind does not (appear to) have gear down, but the third plane ...
30
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4answers
5k views

Why were flying boats phased out?

Before WWII, flying boats were a popular form of transport, and the advantages are many: No need to build runways, capability of emergency landing on water, availability of large landing sites and no ...
20
votes
2answers
4k views

Why is the nose landing gear of a Rutan Vari Eze up during parking?

I recently saw a Rutan Vari Eze parked at the airport and I was wondering why the nose landing was up during parking. How does it work for a pilot to get in? Can the pilot put down the landing gear ...
12
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4answers
2k views

How to execute a gear up landing on aircraft with low propeller?

On some GA aircraft such as the Piper Malibu, the propeller would touch the ground if the gear was up. How would you land the plane when gear actuators fail? I would pull out the mixture knob and ...
5
votes
2answers
5k views

How can I calculate the force on the nose gear at landing?

How can I calculate the force applied on nose gear during landing as nose gear touches the runway little after the landing gear? I understand force calculations in this question but I think it applies ...
5
votes
1answer
688 views

What is the air temperature inside of a tire right after landing?

What is the maximum design air temperature inside of a tyre of an Airbus A380's and a Boeing 747-800's main gear fitted with brakes, before landing after a 10 hour flight and right after landing? Are ...
4
votes
1answer
3k views

What is the stress tolerance of landing gear of commercial aircraft?

Context: The landing skills of commercial airline pilots vary widely -- ranging from the ability to routinely make feather-touch landings and taxi and almost imperceptible deceleration on the one hand,...