They seem to be so small and unstable, thinking about the weight of the airplane, especially filled with passangers and luggage. How do they carry the weight, as well as being able to accelerate and break and everything?
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A 747 (for example) has 18 wheels that are 52″ tall and 21″ wide each. I wouldn’t call them tiny and they’re usually in pairs or fours to spread the weight on each truck.
Bigger planes have more, smaller planes have less. They’ve been specifically engineered for the job.
A 747 (for example) has 18 wheels that are 52″ tall and 21″ wide each. I wouldn’t call them tiny and they’re usually in pairs or fours to spread the weight on each truck.
Bigger planes have more, smaller planes have less. They’ve been specifically engineered for the job.
One point, the wheels don’t make the plane move on the ground. The engines do that by moving air. The wheels do have brakes to help slow the airplane down, but they aren’t powered and aren’t what makes the plane accelerate on the runway during a takeoff.
One important thing about airplane wheels: they do not move the plane. Their only job is to allow the plane to roll, which removes much of the delicate parts that a car wheel (as an example) would have. They are more like the casters on a cabinet or table in that regard instead of the wheels of a land vehicle.
Instead, a plane is moved either by their engine (the same thing that lets them move forward in air, just lower powered until they are taking off) or an extra car that pushes/pulls them along.
A 747 (for example) has 18 wheels that are 52″ tall and 21″ wide each. I wouldn’t call them tiny and they’re usually in pairs or fours to spread the weight on each truck.
Bigger planes have more, smaller planes have less. They’ve been specifically engineered for the job.
One point, the wheels don’t make the plane move on the ground. The engines do that by moving air. The wheels do have brakes to help slow the airplane down, but they aren’t powered and aren’t what makes the plane accelerate on the runway during a takeoff.
Best ELI5 I can think of is they are small compared to the size of the plane, just like a fully loaded shopping cart has tiny wheels too. They do the exact same job, just roll, not much else.
Also, the amount of engineering and processing that goes into airplane suspension and wheels compared to cars would make your head spin.
One point, the wheels don’t make the plane move on the ground. The engines do that by moving air. The wheels do have brakes to help slow the airplane down, but they aren’t powered and aren’t what makes the plane accelerate on the runway during a takeoff.
One important thing about airplane wheels: they do not move the plane. Their only job is to allow the plane to roll, which removes much of the delicate parts that a car wheel (as an example) would have. They are more like the casters on a cabinet or table in that regard instead of the wheels of a land vehicle.
Instead, a plane is moved either by their engine (the same thing that lets them move forward in air, just lower powered until they are taking off) or an extra car that pushes/pulls them along.
Airplane wheels are huge and they have a lot of them. The look small compared to the size of the airplane. Airplane are compared to the volume lighter then cars or trucks.
Here is a human sitting on the wheels of a Boeing 747 [https://qph.cf2.quoracdn.net/main-qimg-9f2d76bc87612ad7b70333439ddac6e0-lq](https://qph.cf2.quoracdn.net/main-qimg-9f2d76bc87612ad7b70333439ddac6e0-lq) The tire is 49 inch in outer diameter and have 19 inch thread area.
A typical car has 15-19 inch diameter and an area around 9 inches wide. So a 747 tire is 2x as wide and 3x as tall but that is not the main difference
The bogie we see has 4 wheels and there are 4 of them in the rear so a total of 16 tires. Add to that the two in the front and you have 18 wheels.
The max takeoff weight is 412 tonnes for the freighter version. That means 26 tonnes per wheel.
The wheels are inflated to 205 PSI compared to around 30-40 that a regular car has. Trucks are around 115 to 130 PSI. This is the main difference between car and airplane tires 5-7x the pressure
The ground pressure of a tire will be very close to the pressure it is inflated too. 26 tonnes=57320 pounds 57320/205= 279 square inch contact area. It looks like the thread is 19 inches which means a distance of 279/19=~15 inches is in contact with the ground. If the pressure was the same as a car tire you need around 86-inch long contact area and it would require enormous tires.
So the answer is they are larger they just look small because airplanes are huge in volume. They have a lot of tires with high pressed and the resulting ground contact area get quite small. It is around 19 inches x 15 inches per tire for a Boeing 747
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