Tire Engineers?

[dik]

From another thread:

thread815-490359

"It's different to that.

When you to that one you get rolls of rubber and tears in the tyre groves.

And for it to happed you need to have the weight on the ground and braking hard. The whole plane is shuddering and you have to work the rudder to keep in a straight line because the braking action is constantly changing.

This only occurs with a silky smooth wheels kissing the runway on water. The wheels won't be turning yet so no braking and the weight of the aircraft is still on the wings.

The rubber hydroplane causes significant reduction in tyre life. This just about more than normal wear.

Must admit if there are any tyre engineers looking at this I would love to know more. Tyres are one of these things people don't think about but I think they are an amazing bit of engineering.
"

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Alistair_Heaton]

I believe ABS was first brought in for aircraft and Concord was one of the first to have it.

We used to have an analogue system on the jetstream which was a spinning thing in the hub matzarette? I am waiting for a mate to message me the proper name of it.

Modern stuff the A220 has 2 brake control units with 2 main protected channels in each and a third emergency channel. Which then drive the Electro mechanical Actuators (EMA'S) which there are 4 of them.

I haven't flown anything that is over 5 tons which doesn't have some form of antiskid.

The Jetstream you could land with the brakes on and the tyres lasted under a second before deflating after flat spotting. A220 you would need to be in down graded emergency braking mode for that to happen. If one channel out it would be normal brake mode you could land with your feet pushing hard on the brakes and it would not blow out. You would touch down and then there would be a 6 second pause reduced breaking as the nose comes down and then it would give you max breaking available for the surface conditions.

Auto break systems are all linked to a G meter and will brake to meet a G value depending what you have selected off/low/med/high. And as DAve says they keep everything symmetrical so if one side is slipping it reduces the other. There is a 4 th option which is RTO for take-off and its way way harsher than high. To be honest i have never landed with high selected in the real aircraft.

There is a system in development that will warn us if the achieved G deceleration is sufficient to stop before the end of the runway. But I suspect that's not going to appear for a a few more years.

 

[Alistair_Heaton]

What we are talking about though is the not so common event that the pilot gives an utterly silky smooth landing when people on board don't know they are even on the ground.

They tend not to happen by intention its usually weather related and the pilot actually wanted to thump it in to get the rubber onto the tarmac. But a gust has given you a bit of lift and killed the decent off.

Most aircraft OEM's recommend a positive landing so air ground logic kicks in and there is no messing about with lift dumps not deploying etc.

 

[Lou Scannon]

Apparently Maxaret has been around since the 50s Link

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[Alistair_Heaton]

that's them Lou

Got a bit interesting when one side seized and the other side wasn't.

Apart from that it worked very well as described in the article. Don't remember any issues with the reservoir filling up.