About the wheels in an Airliner?

Question

An airliner has about 8 sets of huge wheels and when the plane takes off the wheels go into the aircraft body. now this action i believe should occupy a very large section of the aircraft right?

I have walked the full lenth of aircrafts because i have traveled alot but never noticed the space the wheels occupy when they go in

why is that?

Answer 1

That is because when you are walking through the cabin, you are walking on the main deck. Below you are the cargo holds. The main landing gear wheel wells sit between the fore and aft cargo holds. The nose gear well sits beneath the cockpit.

On a 747, the nose gear well sits under the first class (usually) section of the aircraft.

So, even though you have "walked the full length of aircrafts" you have not walked on the area that the wheels are housed in.

Answer 2

The nose gear folds up beneath the flight deck.  The main gear are right behind the wing, under the pressure deck.

Answer 3

The main landing gear forms the principal support of the aircraft on land or water and may include any combination of wheels, floats, skis, shock-absorbing equipment, brakes, retracting mechanism with controls and warning devices, cowling, fairing, and structural members necessary to attach any of the foregoing to the primary structure.  The auxiliary landing gear consists of tail or nose wheel installations.  And yes they are very large on commercial aircraft sitting on the ramp.

However they fold up and are stowed in the wheel wells of aircraft so you will not see them from inside the aircraft..  Most large commercial aircraft such as B-737, B757, B-767. B-777, and B-747 are considered wide bodies with two deck the upper for passengers and the lower deck for cargo and the well wells.

The number and location of wheels on the main gear vary.  Some main gears have two wheels.  Multiple wheels spread the aircraft's weight over a larger area in addition to providing a safety margin if one tire should fail.

Heavier aircraft may use four or more wheels.  When more than two wheels are attached to one strut. the attaching mechanism is referred to as a "bogie," . The number of wheels that are included in the bogie is determined by the gross design weight of the aircraft and the surfaces on which the loaded aircraft may be required to land.

The main landing gear consists of several components that enable it to function.  Typical of these are the torque links, trunnion and bracket arrangements, drag strut linkages, electrical and hydraulic gear-retraction devices, and gear indicators.

Devices used in a typical hydraulically operated landing gear retraction system include actuating cylinders, selector valves, uplocks, downlocks, sequence valves, tubing, and other conventional hydraulic components.  These units are so interconnected that they permit properly sequenced retraction and extension of the landing gear and the landing gear doors.

Here is how the land gear system works.

The operation of a hydraulic landing gear retraction system is of such importance that is must be covered in some detail. First, consider what happens when the landing gear is retracted. As the selector valve is moved to the "up" position, pressurized fluid is directed into the gear up line.  The fluid flows to each of eight units; to sequence valves C and D, to the three gear downlocks, to the nose gear cylinder, and to the two main actuating cylinders.

Since the sequence valves are closed, pressurized fluid cannot flow to the door cylinders at this time.  Thus, the doors cannot close.  But the fluid entering the three downlock cylinders is not delayed; therefore, the gear is unlocked. At the same time, fluid also enters the up side of each gear-actuating cylinder and the gears begin to retract  The nose gear completes retraction and engages its uplock first, because of the small size of its actuating cylinder.  Also, since the nose gear door is operated solely by linkage from the nose gear, this door closes. Meanwhile, the main landing gear is still retracting, forcing fluid to leave the downside of each main gear cylinder. this fluid flows unrestricted through an o*****e check valve, opens the sequence check valve A or B and flows through the landing-gear selector valve into the hydraulic system return line. Then, as the main gear reaches the fully retracted position and engages the spring-loaded uplocks, gear linkage strikes the plungers of sequence valves C and D. This opens the sequence check valves and allows pressurized fluid to flow into the door cylinders, closing the landing gear doors.

Answer 4

You can't see the space they occupy unless you walk closer to the wheels and look under the Aircraft, directly where the wheels are sticking out from.

Answer 5

http://www.b737.org.uk/main_gear_ng_labe...

If you look up you can see a "hole" to the right of the wheel. That's where the gear goes.

Some planes have a door that closes after the gear is locked, 737's don't.

http://farm3.static.flickr.com/2241/1555...

When this 777's gear is retracted and put down, this door closes after its locked in place. (that thing sticking down on the right side of the gear is the door.

Here's the front landing gear of a 757.......http://www.serendipity.li/wot/757ng4ocup...

Retracts right into the body of the plane, where there's a small space for it.

Notice the door.

http://rubenerdshow.com/blog/wp-content/...

Every plane including the 737 has a door in the front landing gear.

Now the space that the landing gear is stored, is just big enough for the landing gear to fit. There may be some space, which is where stowaways find them self's crapmed for hours in the cold dark hellish place.

And you really cant see where the landing gear goes in.

Answer 6

They retract into 'wheel bays'. These are spaces inbuilt in the fuselage, wing fairings or wings. From outside, these are not noticeable with the gear retracted (for aero-dynamic reasons), but those bays which are in the fuselage appear as bulges from the inside. The space they consume inside the fuselage can be termed as a necessary evil, something which we need but also cannot do without. Yes they consume a lot of area.

Answer 7

walking the full length of the cabin where the passengers stay will not permit you to see the landing gear retracted.

To have a chance at seeing the gears inside the airplane. You need to be under the passenger deck, in the cargo deck. Even then, the wheels retract into the wheel wells ( the cavities built for them inside the airplane) so you usually won't be able to see them even from the cargo deck.

To get a peek, most of the time, there is a small window in a door or a bulkhead leading to these wheel wells. And that's how you can see them. Passengers will likely never see them retracted inside the airplane.

Answer 8

The landing gear retract into compartments that are under the cabin floor or in the wings.

Try an internet search on "retractable landing gear" for some pictures and diagrams.

Answer 9

You probably don't bump into any baggage either, right?  That's because it's in a cargo bin below the cabin floor.  So are the wheels, below the floor, I mean.

Answer 10

On many airplanes there is area added to the lower fuselage somewhat like a bubble to accommodate the gear.  In any case, there is ample room between the floor of the cabin and the bottom of the fuselage to accommodate the gear when raised.

Answer 11

When you say, "walked the full length," what exactly do you mean?

If you mean, you have walked the full length, inside, that is because the plane is much larger than what you see inside.  There are lots of electrical and mechanical spaces/closets, cargo storage (checked baggage and other items).  There are large open spaces above your head and even more below your feet.

If you mean you have walked outside and have not noticed where the landing gear goes, that may be because the bombay doors that would cover these spaces in flight are probably obstructing your view.  There are large gapping holes where the landing gear and all the mechanics and eletronics to operate them are situated.  They are designed to retract/fold up neatly inside and to save space.

Answer 12

Good engineering. The more you can hide the gear into the fuselage the better. It makes the planes more aerodynamic. Planes like the C-5, C-17, C-130, and MU-2 (longbody) have these bellies that sit around the retracted hear. That is becuase they needed the fuselage space for cargo.

Answer 13

The landing gear will retract into the wheel wells, these wheel wells are covered up by the landing gear doors. Before a movement of the landing gear either up or down, the doors will open allowing the gear to enter/leave the wheel well. The gear doors ensure aerodynamics on the underside of the aircraft when the gear is either down or up.

The only way you would be able to clearly see the wheel wells on the ground is if the gear doors have been manually opened.