It goes without saying that the wheels of airplanes are not – and certainly cannot be – like those of cars. Yes, obvious, but in this post we’re going to explain a little bit more about why that is. The wheels of a road vehicle, are under normal conditions not subjected to extreme temperature changes in a short time, nor do they need to support the massive weight of commercial airliners. In addition, though an automobile’s wheels are in constant use, in the case of airplanes they’re only used during takeoffs and landings. [LINK]
So with that said, here are a number of interesting facts about aircraft wheels:
They’re Made to Withstand Abrupt and Dramatic Changes
It also goes without saying that the wheels are an essential part of aircraft safety. They go from being at absolute rest to moving at more than 200 kilometers per hour (124 miles per hour) on landings. During these maneuvers they heat up to 100º Celsius (212º Fahrenheit) on average and even as high as 200ºC (392ºF) due to friction with the runway, and then when flying they rapidly drop to well below 0ºC (32ºF). Just like cars, to prevent blowouts they must be carefully calibrated and ready to handle enormous weight, except that in this case it’s vastly more enormous – a car weighs an average 1½ tonnes, but an Airbus A350 like the ones flown by Iberia weighs a whopping 275.
The First Airplane Wheels Were Introduced in 1909
They were made by the U.S. company Goodyear – which 114 years later continues to produce them – though obviously the technology and engineering involved has come a long way since those early years. Like Goodyear, aircraft tyre manufacturers are mostly (but not exclusively) the same companies which produce tyres for cars, trucks, and other terrestrial vehicles – familiar names such as Michelin and Bridgestone.
They’re Manufactured Using more than 200 Materials
These wheels’ rubber portion alone is composed of some 200 materials – the main ones being rubber, followed by silica, which gives the rubber hardness and therefore resistance. There’s also a series of metal threads which bind the rubber to the wheel and are arranged around and inside it, along with several layers of casing and other reinforcing plies (the latter arranged only along the tread).
Their Treads Contain only Parallel Lines
The treads are the patterns on the part of the tyre which come into contact with the ground, and those of airplane wheels of airplanes differ markedly from those of cars and trucks. This is because planes don’t need to grip the pavement like ground vehicles. So whilst car tyres have complex patterns of grooves and tracks of different thicknesses and sizes, in the case of airplanes they’re smooth parallel lines.
How Long Do They Last?
A rule of thumb is 200 to 300 landings (maybe six months’ worth), but this depends on various factors, including the temperaturas they’re regularly subjected to; the type of aircraft they’re attached to (passenger jetliners, cargo aircraft, and so forth); and even the condition of the runways they utilise. And of course as with automobiles, it also depends to a degree on the “human factor”. In any case, aircraft tyres regularly undergo rigorous inspections to make sure they’re in optimal condition for each and every flight.
Are They Inflated Like Car Tyres?
No, aircraft tyres are inflated with nitrogen rather tan regular air, because nitrogen is an inert gas, meaning it reacts minimally to the extreme pressure and temperature changes encountered during a flight. Regular air does react to such changes, which could make the tyres explode.
How Much Do They Weigh?
Unsurprisingly, extra big loads require extra big dimensions. The average aircraft wheel weighs between seven and nine kilograms (TK pounds) [<DB CK] and can reach up to 250kg (TK lbs).
How Many Wheels Does a Commercial Aircraft Have?
If you’ve seen a video of operators mounting tires on airplanes, you’ve probably seen that they can be like those of a truck – around a metre (39 inches) in diameter – but normally they’re actually closer to those of a car, about 70 centimetres (just over 28 in.). It also depends on the model and type of plane; some can mount up to 32 wheels, though this isn’t normal; an Airbus A350 has a total of 14.
Fun Fact: Automobiles Have ABS Brakes Thanks to Aircraft
Although all cars have had anti-braking systems for years (the first one that was the forerunner of today’s systems for automobiles was developed in the early 1970s), the truth is that it was created almost a century ago, in 1929, for airplanes. The reason is that they need to brake strongly during landing and avoid slipping due to the blocking of the wheels. Experimental ABS for motorcycles and cars were worked on in the late 1950s and though the 60s, but it wasn’t till 1971 that a reliable, relatively inexpensive system was invented by a Fiat engineer.
Photo | kabantsev