Questions tagged [landing-gear]

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

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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 ...
69
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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 ...
65
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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 ...
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 ...
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 ...
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?...
47
votes
1answer
6k views

What is the purpose of the extra wheel on the XB-70 main gear?

This photo of the XB-70 Valkyrie's main gear shows a small wheel between the two main wheels: Courtsey of AirPigz.com This smaller wheel doesn't touch the ground, though I can see where it might as ...
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 ...
40
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3answers
2k views

Why is the Eurofighter's nose gear door shorter than the bay?

The Eurofighter Typhoon has an interesting "feature" in that the nose gear door is shorter than the nose gear bay itself by a good few inches, as shown here: Can anyone shed any light on the reason ...
39
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4answers
9k views

Do military bases still employ wheel watchers?

When I was in the air wing in the '70s, I had the unpleasant opportunity of pulling wheel watch. The unfortunate individual sat in a small shack (maybe 3 x 6 ft.) with a pair of high-powered ...
38
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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 ...
37
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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 ...
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 ...
28
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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 (= ...
28
votes
2answers
4k views

What is the purpose of the Dash 8’s “TOUCHED RUNWAY” warning light?

The DHC-8-400 (and possibly other DHC-8 variants) has (or, at least, had in late 2007, according to Appendix G of this AAR) a warning light labelled “TOUCHED RUNWAY”. The extract of the DHC-8-400’s ...
27
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6answers
8k views

Why use an airplane with non-retractable landing gear for aerobatics?

I'm watching footage from Red Bull Air Race 2017 in Kazan (one example is ) and clearly at least some of the airplanes used have non-retractable landing gear. I was ...
25
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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 ...
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 ...
24
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2answers
2k views

Why burn fuel at departure airport instead of flying to destination before emergency landing due to deflated tire?

A Southwest airliner recently had an issue where a "deflated tire indicator" showed on one of the landing gear tires after takeoff from Oakland, CA. They circled nearby for 4 hours while burning off ...
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?
22
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3answers
4k views

Is there a landing gear system that extends automatically to prevent belly landing?

To my knowledge, most aircraft with retractable gear are equipped with a landing gear warning system that makes repetitive beeping sounds in case the pilots try to land without the gear down. I ...
22
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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 ...
22
votes
1answer
4k views

What airframe designer/manufacturer is credited with the first retractable landing gear system?

A quick follow-up to Why do planes always land on rear wheels instead of the nose wheels? What airframe designer/manufacturer is credited with the first retractable landing gear system? I ran past ...
21
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3answers
6k views

When do pilots deploy landing gear?

The landing gear should be down in order to qualify as a stabilized approach. Other than that, what are the guidelines on when to deploy landing gear on approach?
21
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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 ...
20
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5answers
7k views

Why do landing gear tires smoke upon touchdown?

I have been observing several aircraft landings and have noticed that when the aircraft's landing gear touches down, it precipitates the rising of a cloud of smoke. Why is this? (Source: airliners....
20
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5answers
3k views

Is it better to shut down the engine(s) or leave it (them) running when a gear up landing is imminent?

Is it better to shut down the engine(s) or leave it (them) running when a gear up landing is imminent? I noticed that the pilot in this video chose to shut down his engine before touching down during ...
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 ...
20
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2answers
5k views

Why do aircraft sometimes bounce while landing?

I've seen a few youtube videos where an aircraft bounces once/twice while landing on the runway. Why does this happen?
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 ...
20
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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 ...
19
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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 ...
19
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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 ...
18
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1answer
2k views

What's the technique for landing without one set of wheels?

A Boeing 747-400 recently made an emergency landing without the wheels under the right wing: News story Photo of the undercarriage Video of the landing from the end of the runway What's the standard ...
18
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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 ...
17
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1answer
1k views

What is the purpose of aluminium foil on the wheels?

I saw this plane on a remote ramp at BKK today. What is the purpose of aluminium foil on the wheels? Does it mean the plane is in mothball? I don't see other planes, even in maintenance, with ...
17
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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 ...
17
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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: ...
17
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1answer
1k views

How do you perform a gear-up landing in a large airliner?

How do you perform a gear-up landing in a large airliner (say, a Boeing 747)? Would you fly it like a normal landing, or are there special considerations (angle of touchdown, use/non-use of thrust ...
16
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5answers
4k views

Why are military and civil aircraft landing gear generally so different?

Why do military aircraft have a lower landing gear than civilian? I have in mind the difference between a Lockheed C-130 Hercules and a Boeing or Airbus. The first possibility that jumps to mind is ...
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 ...
16
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2answers
3k views

How can the Pipistrel Apis land safely?

I just saw a photo of the Pipistrel Apis motor-glider, and it got me wondering: How can it safely land with only 2 wheels total? To me it seems that falling to the side would be inevitable, and with ...
16
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2answers
2k views

How are skis stowed on retractable gear aircraft?

This image of a LC-130 taking off from a snow runway shows that in addition to wheels on the landing gear, it's also been equipped with skis. Source: Wikimedia Commons.We're getting a lot of use out ...
16
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1answer
8k views

How did the nose landing gear of JetBlue Flight 292 get stuck sideways?

The nose landing gear of the Airbus A320-200 was jammed, but the tires were perpendicular to the fuselage. How did that happen?
16
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4answers
4k views

How do landing gear retracting into the wing affect performance when deployed?

On many aircraft with low wing, landing gear (either wheel, leg, or both) retracts into the wing. Thus, when deployed, a significant part of the lower surface of the wing is not as clean as when the ...
16
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1answer
4k views

Helicopters with landing skids, no wheels; How are they taken in and out of a hangar?

I'm sure many helicopters also need/use Hangars frequently. How do you take them to a hangar and take them out of it without wheels? Specially when they have to be taken indoors for some maintenance ...
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 ...
15
votes
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 ...
15
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1answer
2k views

Are there any aircraft with powered landing gear?

My student asked me a question this morning. It was: A car drives by turning its wheels against the Earth. An airplane taxis by rolling on its wheels while the engines push against the air. Are ...