During my ATPL training the subject of tires and braking was discussed.
- I understand the principle of the anti-skid and also the differences between aircraft and similar systems in cars.
- Physics also thought me that static friction is greater dynamic friction.
The script mentions that it has been shown that the maximum braking efficiency is obtained when the wheel rotates at a speed of 85% of the ground speed. [Clarification: imagine a identical tire wich rolls on the surface without any resistance/braking, this would be 100%. Every bit of slip therefore reduces the rpm. ]
Why would this be beneficial?
My ideas so far are:
- that if some slip occurs braking is mostly in the static friction range but some energy during braking is also put into deforming the tire (and thereby heating it) and possibly ripping small pieces of rubber (on a really small scale) off the tire.
- In order to find out where the tire begins to slip it actually has to slip, so in this process of: raising the pressure on the brake and if slip occurs, reducing the pressure, on average a slip of 15% occurs- whixh means a tire speed of 85%.
Is one of these correct?
Are there any other factors and processes?