Aircraft wheels

[Panic Button]

Following on from 1960darrenh's question I have often wondered something else about aircraft.

When they land the wheels are not spinning so there is a screech, a big cloud of smoke and huge black smears on the runway. Airlines must pay a fortune in replacements and remoulds.

Why don't the attach some sort of fan on the wheels to catch the air and spin the wheels in the air, a bit like a childs windmill on a sandcastle? After all the braking effect of hitting the runway must be small compared with the actual brakes and reverse thrusters.

(Should I have taken out a patent before asking this?)

[teash]

A mate of mine years ago came up with the idea of making sure the wheels (on landing) were already turning at the same speed to avoid wearing them out. But I guess these methods have already been thought through;(

[Mattk]

but surely its the crushing weight of the planes initial touchdown that does the wear and tear ?

[Panic Button]

Then teach the pilots to land more gently

[Mortartube]

I considered the fan idea a long time ago and mentioned it to my dad who worked on spitfires and other aircraft in the war. He said that the military had already tried this idea and abandoned it, so I assume that there were problems with cost or technical issues.

[Mortartube]

Further to my answer, it would appear that you are too late Panic Button.

http://www.freepatentsonline.com/6390415.html

[Clanad]

Here's a good site for understanding the difference between automobile tires and aircraft tires. http://www.goodyearaviation.com/faq.html ... The materials and construction are entirely different.
While the question originally centered on some ability to spool up tires before contacting the landing surface, the problems encountered in this attempt are many. Just a few; all aircraft tires have a maximum speed at which they may be operated. This has to do with expansion of the tire by centrifugal force as much as wear abilitily. The landing gear on most transport aircraft is capable of being lowered at speed exceeding the aircraft tire rotation limits. Therefore, if a device was attached to the tire to spool it up, it could easily exceed this limit. In addition, the tires would be spun up after lift off as well, requiring he application of brakes before retracting the rapidly spinning tire into a confined wheel well and many airacft do not have brakes on the nose gear tires. There are other, numerous problems, such as gyroscopic precession that are alittle difficult to describe in a limited forum such as this...

[Panic Button]

Clanad. A very complete answer.

Presumably on the brakes point, where there are brakes on nosewheel aswell the pilot could put the handbrake on.

All he has to do is put a post it note on the windscreen to remind him to release it before landing.

[Panic Button]

If we can land a man on the moon nearly 40 years ago we can crack this. Here we go.

Fit a closeable air intake duct feeding tubes to turbines on each wheel. As the aircraft will always have very similar airspeeds on approach it should be a relatively simple calculation to work out the size of intake required to produce enough pressure without overdoing it.

Rotational speed sensors on each wheel would sense when they are approaching optimum or maximum speed and shut off the ram air supply.

The air intake duct should default to the closed position so would not be active for take off. At a suitable point on the landing approach add "undercarriage ram air - on" to the pre landing check list. This could be done quite late to reduce some of the associated problems.

I'm not sure what gyroscopic precession is, but if it is to do with turning I am sure the aircraft controls have sufficient force to overcome the small effect. After all the wheels are spinning after take off for a while.

If Mr Boeing and Mr Airbus would like to start sending the cheques I will send a (small) donation to Mortartube's mate who nicked my idea and patented it.

[dennij]

Strange but true. Aircraft tyres are more likely to burst on take off rather than landing.

[vaughan1206]

wow im reading these answers at 4.04am and i can see that putting more stuff on an aircraft is wrong, more to go wrong me thinks. Please dont encourage plane maker to mess with the flying thing there good. MEN CAN FLY LIKE BIRDS aint that enought for you man.

[vaughan1206]

AND stealing patents is a bit naughty dont try it at home kids!!!

[Panic Button]

If God had intended us to fly he would have given us tickets

[stuartsjg]

Hi,
when i was about 10 i thought about the fan idea attatched to the wheels.

My pessemistic father who was also a technical thinker said that tyres were pennies to these big companies and the arnt botherd.

About a year ago i saw a thing on a program that some guy had patented a similar system and BA would trial it as the wheels are about �2k and need replaced every 6 months at least. A plane with 20 of them is a lot of cash.

If i had went to BA when i was 10 im sure they would have gave me some cash :(

The new airbus has an electric motor which gets the wheels to the same ground speed. This will help reduce wear and avoid skidding on touch down it has lots of wheels that are 5ft diamater and 1.5ft wide.

One drawback is, the weels can weigh several tonnes. When they hit the ground and suddenly gain speed, the rotational kinetic energy they gain reduces the speed of the plane. I am told that this is a breaking factor that is taken into account by the designers when sizing brakes, flaps etc.

Stuart.