Crosswind from right. What rudder to use, and why?
 

Just been lurking around regarding how jets work and what not.
Came across a section that said when the a/c gets a x-wind from the right, the Pilot will use the left rudder.
I don't understand why this is though.

Somebody please explain?

Thank you.

To track the runway center line you will need to be crabbing with the nose towards the wind.

When you eventually want to land you want to be pointing (heading) as well as tracking the runway center line.

So on approach your heading will be to the right of the runway track and to get the aircraft to also point in that direction you will have to yaw the aircraft to the left which is the left rudder input

There are many different techniques for xwind, there's not a lot of ground clearance with transport aircraft, holding a wing down like on a Cessna can get you into trouble. but you generally try to align the aircraft with the runway just before touchdown, with the wind from the right, the nose of the aircraft is pointed to the right, a few feet above the runway, you gently align the aircraft with the runway so there isn't any side load on the gear.

Firstly, thank you for the responses.
Second, I forgot to be more specific.
The x-wind is during take off, not landing.

Sorry for not being clear.

Most transports want to weather vane, so the nose is trying to turn to the right due to the length of the fuselage, so Left rudder pressure during the TO run.

Although most answers here are correct, referring to POSITIVE weathercocking, there are a few a/c types that display NEGATIVE weathercocking traits, where an oppsoite reaction is required.

In the transition though it can be wise to use a little in to wind rudder to correct for the wind dragging you across the runway on the takeoff roll. I do mean a little though.

Visualize the jet from top down, then visualize the crosswind from the right.

Now think which part of the aircraft offers the greatest amount of resistance to that wind. Correct, it's the bloody great big tail sticking up at the back end of the jet. The wind always tries to blow it around so that the tail is at the back and the nose is pointing into the wind. That's called "weathercocking".

With a right crosswind, that means the nose of the aircraft is trying to pull to the right on takeoff. Hence, you have to use left rudder to counteract it.

:ok:

I am curious, never heard or read about of this, nor can understand how aerodynamically it can happen. What planes do this, be interesting to look at the pics ?

Its all to do with the pivot point of the gear and which end of the aircraft produces most moment due to cross winds while on the ground.

But as with all these control inputs if you put the control input in to keep the picture correct you don't as such need to know which input to put in.

Just know what it should look like and deal with it if it doesn't look right.

The HS125s that I flew had negative weathercocking when the mainwheels were on the ground.

Thanks Dick,

Indeed HS125s and BAe/Raytheon 125-700s and -800s. I am not up-to-date with later versions of the beastie...