Landing gears have too many wheels- doe it mean -dead weight ,speed height of flight?

Question

a cluster of wheels in the back give an idea about air craft 's heavy ness ,is that mean that the air craft has made an exordinary speed in an exorddinary flying height

Answer 1

Ánother important reason for those wheels is braking power. As you might know, braking is translating kinetic engergy into thermal energy. The more wheels you have the better your braking power. This because you have a larger contact surface with the runway so you can induce more friction since every single wheel has a pack of brakes and a 3000PSI hydraulic pressure to activate that brake.

Answer 2

Heavier aircraft need more and bigger wheels to hold them up. Can you imagine a 747 being held up by cessna wheels?

Answer 3

Aircraft landing gear designers calculate a factor called the ACN number, which expresses the load per wheel and post and the spacing between them.  Airports have a maximum ACN they can tolerate at each runway.

If you think about a runway, it is like a ribbon of concrete afloat on compacted dirt.  When an airplane rolls on it, it flexes.  If the airplane is too heavy, or the weight is concentrated on too small an area, the bending stresses in the concrete could crack it.   Thus the airport's ACN reflects the construction standard, and the airplane's reflects how it loads the runway and taxiways.

747 and A380 have a lot of wheels because they are big and heavy.  In addition with 4 posts there is extra redundancy for safety.

777 has 6 wheels per post, which causes some steering issues with the long truck, but is more efficient than a 3-post gear (DC-10, A340) because 3 post gears have to accomodate runways which are crowned (higher in the middle for drainage) so the center strut has to be softer, thus carries less load (as well as complicating the airplane's wheel well).

It's been said that the gear is the FIRST part of the airplane configuration to determine- it limits everything else from loadability (center of gravity range) to takeoff and landing weights.

Answer 4

The number of wheels only suggest the weight of the plane plus cargo it would carry and nothing else.

Answer 5

Airplanes have multiple wheels to distribute the weight and landing forces over a larger area.

For the sake of illustration, let's assume that an airplane's weight is evenly distributed and the weight is the same on every wheel.  This isn't exactly true, but it will help you understand the concept.

A Boeing 747 has 18 wheels.  A fully-loaded 747's weight distributed over 5 struts and 18 wheels exerts a force of around 175,000 pounds per strut and 48,000 pounds per wheel.

If a 747 only had 3 struts and 3 wheels, the force exerted would be close to 300,000 pounds per strut and wheel.  That's about a 2x increase per strut and 6x increase per wheel.  That would create problems for both the tire itself and the runway/pavement it is sitting on.

Answer 6

"Too Many" is not an expression popular in aeronautical design. "Just enough" is the paradigm, and in implementation it sometimes becomes "insufficient"

If you see too many wheels, then all of them are required. It is not very wise to think of weight saving when the most important phase of flight is the landing. You dont want the single port landing wheel bursting on your airliner and destroying it, do you? Practically speaking, the benefits gained by weight reduction on safety features doesnot add up to the cost of the aircraft (not to mention life). So for most civillian airplanes, safety dominates and so the illusion of too many wheels.