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Questions tagged [landing-gear]

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

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11
votes
1answer
2k views

What does shimmy in nose landing gear mean?

While I was reading a small article on "Reasons for RTO", I came across a situation where the pilots aborted takeoff because of "landing gear shimmy". What does that mean?
6
votes
1answer
226 views

Why does the A330 sit nose-down on the ground?

The passenger versions of the A330 have a small but noticeable nose-down angle when sitting on the ground: (Image by contri at Flickr, via russavia at Wikimedia Commons.) In contrast, A330s built as ...
20
votes
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?
-1
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1answer
73 views

How is the impact force on the landing gear distributed in fighters?

Upon landing, what percentage of weight is distributed on the main and the nose landing gears of fighters? Upon landing of a fighter aircraft, what would be the approximate time of transfer of the ...
1
vote
1answer
86 views

Exceeding VLO and by how much is too much?

Piper Seminole (PA-44-180) VLO (max gear retraction speed) is 109 KIAS. I've heard that manufacturer published limitations are significantly lower than actual structural and system limitations. What ...
5
votes
4answers
1k views

What are the advantages and disadvantages of tail wheels that cause modern airplanes to not use them?

Photos' source: Cessna 140 and Cessna 150. According to Wikipedia here, the Cessna 150 is successor of Cessna 140. Both have two-seat capacity and a single engine. Why was the Cessna 150 changed to ...
4
votes
1answer
272 views

Do landing gear doors need repairs after a gear gravity deploy landing?

I know that landing gears can be deployed even without hydraulic power by letting them go down by gravity, as seen on this video: I was wondering: do the landing ...
6
votes
1answer
418 views

What is the material of snubber brakes?

What is the material of snubber brakes that is used for stopping the spin of the nose landing gear? KC-135, Boeing 747, 727 are the aircraft that I saw with these snubbers.
5
votes
2answers
277 views

What main landing gear actuator does the Boeing 777-300ER have?

I can't remember the name of this system was, but all I do know is that is a big actuator that only exists on the Boeing 777-300ER variant. It will pressurize the actuator according to the thrust ...
6
votes
2answers
256 views

How are the 747-400 rudder pedals and tillers connected to the nose wheel?

The Boeing 747-400 Before Taxi Procedure says (emphasis mine): [...] Flight controls .............................................. Check C [...] Hold the nose wheel tiller during ...
3
votes
1answer
401 views

Why would a Blue Angels pilot leave their gear down?

In a recent Blue Angels airshow, one of the pilots had their landing gear down during the first 5 minutes of the show. What possible reasons would justify leaving the aircraft in this state? No ...
1
vote
2answers
160 views

For large commercial aircraft, how are the tires changed?

Something at least the size of a 737, all the way up to the A380. How are aircraft tires changed for large commercial aircraft? Are they actually jacked up like with a car?
4
votes
1answer
655 views

Why do some helicopters have wheels instead of skids?

I have noticed that Black Hawk helicopters have tires, but I have not seen one take off like a plane. When would a helicopter need to use a running take off or landing? When is it determined ...
0
votes
1answer
136 views

What indication will appear in case of one of A320 LGCIU is inoperative?

What indication and where it will appear in case of one of LGCIU (landing gear control and interface unit) is inoperative?
11
votes
1answer
2k views

Why does the A-4 Skyhawk sit nose-up when on ground?

The rear of the plane is nearer to the ground, while the front part of the plane is away from the ground (see image below). Other planes are more flat. I think it was for high AoA but these planes ...
0
votes
1answer
121 views

How does landing gear affect thrust on a light twin-engine airplane?

I'm working on my commercial multiengine rating. And I got this question from my examiner, and I answered: landing gear produces penalty drag, so it decreases thrust. But the examiner says this isn'...
3
votes
2answers
182 views

Why does only one hydraulic intake line from the reservoir have a filter on the Arrow II?

This is a portion of an Arrow II landing gear hydraulic system diagram. I noticed that there are two intake check valves, one located on each side of the pump, that would allow flow from the ...
2
votes
0answers
140 views

What is the difference between a pressure switch, high-pressure control, and low-pressure control in a landing gear hydraulic system?

This is an Arrow II landing gear diagram. In the diagram, the high and low pressure controls look like check valves. The pressure switch is unclear. What are these three items, and what purpose ...
1
vote
2answers
515 views

What is the purpose of the shuttle valve in a Piper Arrow's landing gear system?

This is the PA-28R-201 landing gear hydraulic system diagram. I am wondering how this shuttle valve functions. Research I have done indicates that a shuttle valve blocks one attachment to the valve ...
12
votes
3answers
3k views

Does Nitrogen inside commercial airliner wheels prevent blowouts on touchdown?

I just watched the first episode of Inside Mighty Machine where civil engineer-turned-host, Chad Zdenek, discussed innovations of the 747. One innovation he discussed was the increased number of ...
3
votes
1answer
454 views

How can the landing gear of an A320 be lowered in the event of a simultaneous hydraulic and electrical failure?

What is the process for lowering the landing gear of an A320 when the hydraulic and electrical systems are not operational? What happens to the aircraft when you lower the landing gear with ...
3
votes
2answers
2k views

Why complex landing gears are used instead of simple, reliable and light weight muscle wire or shape memory alloys?

Muscle wires actuators are really simple, have a high power density and are reliable. Landing gears on other hand are used only twice per flight while taking off and landing (if everything goes well ...
6
votes
3answers
1k views

Nose gear failure in single prop aircraft: belly landing or nose landing?

Let's say we are flying a single prop airplane with tricycle format retractable gear, such as a Mooney Bravo or a Piper Comache. The nose gear fails mid-flight and is unable to be lowered. Is it safer ...
9
votes
3answers
3k views

Why is the Constellation's nose gear so long?

The Lockheed Constellation has an enormously long nose gear, which causes the aircraft to slant appreciably backwards when sitting on the ground: L-049 (Image by Greg and Cindy at Flickr, modified ...
-4
votes
1answer
113 views

Are hydraulic retractible landing gear possible

One of the impediments and drawbacks to extending landing gear in light of building larger engines are the larger space required for the taller gear. Would hydraulic retractable gear that works as a ...
6
votes
4answers
2k views

Are taller landing gear bad for aircraft, particulary large airliners?

Buiding larger engines for larger aircraft as opposed to smaller but many engines has proved to result in more fuel efficiency. Having established one of the main drawbacks or impediments to building ...
1
vote
1answer
89 views

What are the three sources that are relayed to the brakes and steering control unit of an A320?

There is the sentence: Electrical signals from the three sources are relayed to the brakes and steering control unit (BSCU) and are computed into the nose steering angle. The question: What are ...
0
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0answers
110 views

What purpose of the thermal relief valve in PA-44?

In landing gear part, As I know, the valve will open to relieve pressure as a result of temp and pressure changes as airplane climbs or descends, but I do not know What purpose of the thermal relief ...
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 ...
-4
votes
3answers
260 views

Why Buy A C182/172 Instead Of An C180/170? [closed]

So a thought came to my mind which covers not only Cessna planes but all others. The Taildraggers need a little bit less runway becayse AOA on takeoff is good and that AOA eliminates the need of ...
1
vote
2answers
226 views

How does pulling back provide better steering during rollout for light GA planes?

I had requested clarification on an answer to the question, How do I keep a C172 straight on the centerline during landing/rollout? I did not comprehend how pulling back after touch down provides ...
5
votes
2answers
460 views

Why are landing gear retraction mechanisms mostly based on the four bar system?

I would like to know about the principles of landing gear retraction system and I struggle to find clear information about it. It seems to be about a four bar systems in most cases. This seems more ...
4
votes
2answers
493 views

Why don't nose landing gears have brakes?

Nose brakes can help the aircraft in braking and it can also help in reducing the travel on the runway length. So why don't we use brakes in the nose landing gear?
-6
votes
1answer
262 views

How can I find the communication with ATC following an aborted landing?

On February 7th, I was on a UA 4694 from DEN to SAF, upon approach the landing was aborted; upon second approach, we heard the landing gear come down, which we did not hear on the first approach; the ...
3
votes
1answer
346 views

How does retracting the gear affect weight and balance?

In many of the POHs, in the W&B section it is indicated that there is a moment change due to gear retraction. For example : Moment change due to gear retraction +780 in-lbs. Two questions : If I ...
3
votes
4answers
1k views

Wheel or skid? Which advantages does each one have when used as the landing gear system compared to the other one?

I would like to discuss this topic in depth, as I have not found a clear answer yet. Which are the advantages of using skids instead of wheels (or viceversa) for the following considerations?: -As ...
5
votes
1answer
353 views

Why don’t aircraft use run-flat tyres?

Tyre failures on aircraft during takeoff are fairly common, and are usually (though not always) caused by flat or underinflated tyres (via the overdeflection and overheating experienced by tyres with ...
3
votes
1answer
236 views

Do airplanes have sensors to detect landing gear fires?

Given that retracting a landing gear that happens to be on fire is a suicidally bad idea, for reasons that should be immediately obvious, do airplanes have temperature sensors on their landing gear in ...
0
votes
0answers
92 views

Landing gear sequence [duplicate]

{With reference to this video} Is there any particular reason that land gear retract half way then 2nd gear retract half way and then proceed to retract completely. Is it related to center of ...
2
votes
1answer
85 views

What are the potential threats of having the landing gear dirt from mud in a rectractable landing gear airplane?

Recently I have been flying an aircraft with the landing gear very dirt with mud due to the parking area of the airfield on grass and the meteo conditions in recent days. I wonder what are the threats ...
3
votes
4answers
370 views

How can drag induced by the landing gear be reduced?

What are some of the methods used to reduce the drag caused by the landing gear for aircraft with non-retractable landing gear?
5
votes
1answer
306 views

Does the PA-44's squat switch disable the stall warning?

I've read the AFM and looked online about the gear system for the PA-44 Seminole and there is apparently a squat switch on the right main gear that disables the stall warning whilst on the ground. ...
39
votes
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 ...
1
vote
1answer
586 views

What is the purpose for two nitrogen charged chambers in an oleo strut?

What is the purpose of a twin nitrogen charged chambers oleo, such as the one illustrated below? Why is it used and what are the advantages compared to a conventional mono-nitrogen chamber? Training ...
7
votes
1answer
3k views

How often is a tire replaced on a 777?

Given that it is long haul aircraft, and is most widely used by airlines in that capacity: How often do they replace the whole tire? How much does 1 tire cost the airline?
2
votes
3answers
397 views

Are all tires on an aircraft replaced at the same time?

On cars, it is often to replace all four tires at the same time. Is this true also for aircraft? I imagine the nose gear and main gear probably can be replaced at different intervals. However, are ...
15
votes
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 ...
1
vote
1answer
243 views

How to determine the maximum servo torque required for a nose gear?

It's pretty much it. I know how to calculate the friction force on the nose gear for a three-point landing condition using the method set forth in ...
9
votes
1answer
2k views

What did the “gear warning horn” on the North American P-51 sound like?

I'm working on a sound project for a P51 simulation and I'm having real trouble trying to find a reference on how the P51 gear warning horn sounded like. What mechanisms were used in the '40s to make ...
6
votes
1answer
2k views

How is a light plane's nose wheel straightened during retract?

Assuming a light aircraft has direct cable linkage to the rudders, during taking off in a very strong crosswind with the pilot correcting with hard rudder, what keeps the nose wheel from remaining off ...