Originally Posted by billt460
Astro,
Are the tires used on Navy fighters stronger, (thicker, more plies, higher bursting pressures, etc.), than Air Force fighters use? And are they filled to higher pressures? In commercial and private aviation blown tires on landing seem like a common occurrence. But you never hear much said about the same in Navy carrier operations. This in spite of how hard they are slammed on to the deck on landing.
Yesterday I just watched an episode of "Mayday", (an aviation show that deals with air disasters). It was based on an Air Transat A-330 flight from Canada to Portugal that had an in flight fuel leak. It resulted in both engines flaming out over the Atlantic, due to empty fuel tanks. The pilots were able to glide 65 miles to a dead stick landing in the Azores. They mentioned 6 of the 8 tires on the aircraft blew out on the landing. (This was said to be caused by the both the brakes locking up, combined with the hard landing). The plane is still in service today.
Again, you don't seem to see this with Navy jets. Is cost part of the reason why?
https://en.wikipedia.org/wiki/Air_Transat_Flight_236
Two questions in this...
First, Navy Fighters have conventional tires, but with a bit more structure than a tire for a similarly sized land-based airplane. The F-14 main tires were 37x11.5-16 28 ply. Inflated to 245 PSI on land, 350 PSI on the ship. Nose tires were 22x6.6-10 20 ply. 105 PSI land, 350 PSI ship.
A Boeing 757 has 40x14.5-19 tires, they are 26 ply, but there is a lot more airplane supported by the tires, and they're inflated to 225 PSI (I think). So, the increased ply rating for a Navy fighter, combined with less weight per tire, and a much higher inflation pressure, provides a lot of performance margin. We do have blown tires on a carrier, but it's rare. In 10s of thousands of landings I've seen as an LSO, and my own landings, I've never seen a blown tire on the carrier.
Next question: blown tires in airliners. Also very rare. They happen primarily for two reasons: debris on the runway, or pilot lands with brakes applied.
Air Transat was the result of really stupid fuel management. It's a classic case of not monitoring fuel. They had a leak from the moment they took off and it took them hours to realize that there was a leak. Stupid. But then, they did a brilliant job of gliding the airplane to the Azores. When they touched down, they had no flaps, and were about 220 KTS. Max tire speed is typically 190 KTS. NOrmal landing speed is about 135 KTS. They pounded that airplane on to the runway, like a carrier landing, because they had run out of speed to stay aloft. They hammered the brakes because they were so fast, and blew both tires trying to get it stopped. Anti-skid was not available due to the lack of hydraulic pressure with both engines flamed out, so they were braking using the accumulator. So, they couldn't modulate the brakes or they would've depleted the accumulator pressure.
So, I really don't fault them for the blown tires. That was completely understandable.
I fault them for failing to manage their fuel, though...
In any event, aircraft tires are very sturdy. They're inflated with nitrogen, by the way, for a couple of reasons: no support for combustion and the dryness. The N2 obeys the universal gas law, but the dryness avoids the water phase change (solid-liquid-gas) that would happen as tires go from -65C (in flight) to over 200C after heavy braking on landing. That phase change would cause real pressure variations, dry gas avoids that.
Aircraft wheels also have "fuze plugs" that melt to prevent the catastrophic failure of the wheel. Typically, they're designed to melt at about 450F, when the pressure inside the tire (PV=nRT again) becomes extreme. Without fuze plugs, at extremely high temperatures, the wheel could explode, with severe damage to the airplane, or worse, injuring or killing ground personnel.
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