# Tag Info

61

Blown tire - can't raise gear, shredded tire will not fit in the bay. -> Gear down - much lower maximum speed and lots of additional drag -> Both of those mean very poor fuel economy -> Very poor fuel economy means not enough fuel to reach destination So that's off the table. Given that, there's no question that it's better to follow the safest ...

52

It depends on the airfield. Landing on grass is only recommended if the ground is maintained to a reasonable standard and clear of obstructions. Some airfields have grass strips maintained for that purpose, on others the grass has lights, wires and cables, or just lots of holes/ruts which will be far worse than the tarmac. Some airfields are only grass, ...

47

Simply put, for the weight bearing factor bias-ply is a lighter tire, and when building a spaceship weight is the top concern. The reason they were thin and single use also had to do with weight, according to NASA: Weight: Since weight is of extreme importance, the tires are made with a minimum amount of tread to conserve weight, allowing for larger ...

41

That kind of thing would be a judgment call on the part of the crew (ultimately the capt) and would come down to what is the safest action based on the circumstances, with logistical/convenience considerations being a distant second. When you have a blown tire you will want to avoid raising the gear, because they can catch fire and you don't want to ...

36

Well, you're using land that is under the authority, or delegated authority, of somebody, so technically you need that authority's permission to use other than a designated landing area under the airport's license. Remember that there could be liability issues for the person responsible for the airport, completely aside from the physical suitability of the ...

15

From this Goodyear document on aircraft tires, both types exist. For the 747, they are all tube-type. Tires are tube-type unless otherwise indicated. The listed 747 civilian variants do not indicate otherwise (page 18). (Source: wikimedia.org) Cross section of a 747 tire. Full resolution via link is a must see. You can make out the inner tube (flap) ...

10

Because an emergency landing is preferred to gambling the airplane and the lives of everyone on board just to save a few bucks. One of the fundamental rules of professional flying: Never attempt normal operations or try tricks with a compromised airplane. You might get away with it once, but sooner or later it will get you and, with a $300 million ... 7 Aircraft tires are replaced on condition, but maingear tires usually last about 250 cycles. A 777 in longhaul usage might only get two cycles a day, so a set of tires would last about four months. The 777 uses a 50x20.0r22 with 32ply rating. I couldn't find that exact tire but a similar one costs$4700 new. It is common practice to retread or remold worn ...

6

It really depends on how you intend on landing the vehicle, how you intend on using the vehicle, and generally any design limitations that may come into play. For fixed wing aircraft that need to land with a forward velocity you can chose either skids, wheels or a combination of both. Skids are beneficial as they are, simple, light and take up less space ...

6

The same reasons that run-flat tires aren't more common on cars or trucks are amplified with aircraft. They're more expensive and can wear out faster. They will also be much heavier. This has to be traded against the cost of an occasional flat tire. They typically have a maximum speed when flat. Aircraft tires need to operate at much faster speeds than ...

6

Car tires aren't really comparable. Car tires: make a lot of miles, but in mostly benign circumstances. Low speeds mean little heating (and slow changes in temperature). failures are often caused by debris in the road rather than structural failure of the tire itself. (Although on trucks, structural failure is more common) must be replaced when the tire ...

6

I'm not sure that there is a maximum design temperature and even if there was it wouldn't be that high, probably no more than 120C. The problem is not the temperature inside the tyre but actually the temperature internal to the carcass. The hot spots are around the bead area and around the cords on the shoulder of the tyre due to the loading. The rubber ...

5

In general, the jack is put under the axle of the wheel to be changed. Thus the oleo still carries the weight of the airplane and stays at the same extension, and the jack just has to lift the wheel far enough to be able to get it off the axle. Unlike a car, you don't lift the body off the wheel, you lift the wheel off the ground.

5

Yes, there is, but it is not by regulation. It is in Advisory Circular 20-97B. For example, section 7 would apply to most of your pictures: (7) In-Service Inspections (Operator). (a) Tread Damage Removal Recommendations. Tires that exhibit any of the following characteristics symptomatic of damage should be removed from service: (1) ...

5

It's absolutely normal. Above is how the manufacturer even depicts the nose tire in the airport planning manual (.pdf, page 42). The pressures are checked by line engineers typically before leaving the hub, as well as an inspection by a flight crew member before every flight. While not available on the CRJ900, there are many jetliners that have tire ...

3

It really isn't that common in the big scheme of things, but there may be a factor that makes them more common than they might otherwise be. A lot of airlines retread their tires because they go through them so fast (try the life of a tire, going from 0 to 140 in half a second, then having to deal with producing extreme braking friction, 6 times a day, and ...

3

Any time you make a modification to a certificated aircraft you need FAA approval. Even what appear to be minor things, like replacing you sun visors with better ones requires an STC. Putting in shoulder harnesses requires and STC. I could go on forever, but you get the idea. Putting tundra tires on your Cherokee is a major change. If you look in the parts ...

3

High tire pressure means less rolling resistance at least on a good road. However it also reduces grip that makes braking less efficient (source). Hence high pressure may make sense for a bicycle but not for a plane where the power is more than abundant.

3

I have never seen an airline (or the military) have a maintenance procedure where a tire can be changed with pax on board the aircraft. Normally, if the problem is found when pax are on the aircraft, they are asked to deplane, the maintenance is done and the pax are then boarded once more. The biggest reason is that pax moving inside the aircraft can cause ...

2

The idea is good in concept but it would be pretty difficult to match the rpms to the actuual ground speed, in fact if the wheel was spinning faster it would actually wear the tyre more! Another factor is that aircraft wheels often do not hit the runway straight on. In a crosswind situation they could be off a few degrees so the tyre would still scrub. ...

2

I stood on the tarmac at Ben Gurion TLV/LLBG and watched them change a tire on an El Al 747 prior to departure. My dad and I were the last two to board and we were walking our dogs prior to putting them in their crates prior to being loaded for the flight to JFK. They got an extra long walk. The plane was full of people at the time. This was in 1984, so ...

2

Wheels on the 747-400 are the same all round. One operator I worked with had a mixed fleet of -400 and -200s. They used the -200 wheels on the -400 nosewheel (mainwheels had to be -400).

2

A "PIREP" (pilot-report) is an in-flight report of weather or other things that other aircraft should be aware of that ATC may not know. I'm not sure what MAREP you are referring to, the only one I can find is a "marine report" which wouldn't apply here, so I assume you mean "maintenance report". If you are talking about a commercial aircraft, this would ...

1

The obvious one: when you land an airplane on skids, the skids abrade. This makes skids suitable only for aircraft which fly only occasionally (like the Dream Chaser): if you have 6 flights in a year, the maintenance on the skids is acceptable. For daily flights, not so much.

1

Helicopter specific answer As a vary general rule, any smaller [less than 10 passenger] helicopter designed for general utility etc. work will often have skids, conversely large helicopters, military, VIP and Naval helicopters tend to have wheels. Skid Gear is great for landing in softer terrain, it gives you a platform for people working from the side of ...

1

It turns out a skid is the safest option. There are potential issues with tires in the space environment and this eliminates one of the tires. there will be one major difference when the nose is pitched forward, given the Dream Chaser will not be using a traditional Nose Landing Gear (NLG) wheel for its rollout. Instead, and inbuilt skid strip will touch ...

1

Neither car nor aircraft tires are supposed to be inflated to the point where only a small percentage of the tire is in contact with the ground. If you can think of a scientific argument why they should be, post it. It's very common knowledge that inflating tires to maximum pressure reduces sidewall effectiveness and overall tire performance.

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