Crosswind landings

(Sorry... stole this off the S2k board, but it's worth the watch)...

Quote:

---

Crosswind Landing Testing

This little item shows the Boeing factory determining the demonstrated crosswind landing limits on the 777 and the 747SP. The engineers make educated guesses, but then the test crews have to go actually prove the numbers. They sneak off to Brazil to do these tests at a certain remote BAF airbase famous for its continual atrocious crosswinds...Should the gear sideloads be excessive and fold one up, there is nobody there to take nasty pix for the Airbus guys to wave around in the press.

This is some good piloting in getting these planes down. It comes close to "incredible".... tire change anybody????

If you haven't seen these it's pretty amazing to watch planes of this size crab walking in on a landing. I can hear the whole crew in the pilot just yelling Yeehaaaa at the top of their lungs.

Note the rudder action on landing

---

VIDEO LINK

Holy crap! I hope I'm never on a flight that has to do that, even though I'm glad Boeing's planes can take the abuse! :mrgreen:

S.

Quote:

---

Originally Posted by srivendel

Holy crap! I hope I'm never on a flight that has to do that, even though I'm glad Boeing's planes can take the abuse! :mrgreen:

S.

---

Oh come on..Where's your Spirit of Adventure?
Nice clip Dave.....:clap:

So it looks like they can steer the rear wheels to get them to land straight on the tarmac. Is that right?

Quote:

---

Originally Posted by Bell

So it looks like they can steer the rear wheels to get them to land straight on the tarmac. Is that right?

---

I don't think so.... it looks like right as the wheels hit, the pilot is throwing the rudder hard over to try and straighten the aircraft to minimize the affect, but I'm betting at touch down, they are still a bit crooked.

Landing like this puts a lot of stress on the tires and landing gear for that very reason.

Crazy...

way too cool. THose guys have mad skillz.

That's wicked cool! I'm with srivendel though. I'll watch but I'd rather not experience it first hand.

I wonder if you can try this out on those Flight Simulator games?

Quote:

---

Originally Posted by Dave04

I don't think so.... it looks like right as the wheels hit, the pilot is throwing the rudder hard over to try and straighten the aircraft to minimize the affect, but I'm betting at touch down, they are still a bit crooked.

Landing like this puts a lot of stress on the tires and landing gear for that very reason.

---

Take a look at that last two landings. As it approaches the wheels look very skewed. Could some planes do that? Maybe it's just visual tomfoolery.

Wild stuff.

FWIW, it's easy to force a plane to get crossed-up like that regardless of crosswinds - you hold the rudder in one direction and counter it with the ailerons. In fact, this is a skill that is taught to all private pilots in this country, as it is necessary for short-field landings. "Crossing up" or "crabbing" a plane like that allows you to greatly increase your descent rate while keeping the nose up and maintaining low airspeed, which is exactly what you need to do for a short-field landing (come in "steep & slow").

In fact, it doesn't look that windy to me in the footage (based on a lack of visible evidence in the surrounding vegatation, no sand/dirt blowing around, and the direction the tire smoke clouds blow out upon touchdown), I'd suggest that this video is actually of short-field testing and not high crosswind testing. Runways are almost always aligned with the prevailing winds (that's why DFW's main runways are almost due north/south), and only in cases where surrounding geological features prevent this (like a mountainside, cliff face, or body of water) would runways be designed and built where they would normally be subjected to high crosswinds. The airfield in the video doesn't appear to have such natural constraints present.

All that said, I've practiced short-field landings in a Cessna 152. I sure as hell wouldn't want to have to try one in a 747!

Iain:

I'm not sure I agree with your last assessment here.

During a crosswind landing in a small aircraft you're cross-controlling to keep the aircraft pointed down the runway. The envelope that determines the aircraft's maximum safe crosswind component is defined on one side by the aircraft's ability to perform in the cross control and on the other side by the aircraft's ability to accept side loads.

With jets there are a number of reasons that heavy cross-controlling is counterindicated. (The aircraft doesn't have enough power to overcome the cross-control performance loss on final while far on the back side of the power curve and very dirty, among others.) Generally the aircraft is flown in a "crab" down final and accepts a large side-load on touchdown and rights itself along with aerodynamic help from the pilot's input. You can see the brief and relatively severe rudder input on touchdown in the video as described by the original poster.

(Along those same lines, you can clearly see rudder deflection from the video's camera angle, so if they were cross-controlling down final, you'd see the rudder deflected. It isn't.)

Cross-controlling to point the nose 20 or 30 degrees like you see in the video would cause the 777 to drop like a rock -- creating a MUCH steeper approach than the relatively flat one you see.

Finally, cross-controlling for a steep approach only applies to landing over an obstacle, not all short-field landings. The best short field landing is accomplished with a flat approach using aerodynamic devices (flaps, and even the elevator after the aircraft stops flying) to increase drag.

(BTW: If you look at the last landing, you do see the wind blowing pretty good. The tire smoke and exhaust blows quickly to the side. Unfortunately, the grass is so short it doesn't really show much. Of course, we're probably only talking about a 20 or 25 knot direct crosswind here, which is an Imperial s***load for the aircraft, but not that amazingly much for people standing there.)

Chuck

Chuck,

All good points! On closer examination, I think you might be right.:D

Quote:

---

Originally Posted by altiain

Chuck,

All good points! On closer examination, I think you might be right.:D

---

Who are you and why do you have Iain's logon? ::Clown::

Quote:

---

Originally Posted by black roadster

Who are you and why do you have Iain's logon? ::Clown::

---

:nutkick:

S.

Quote:

---

Originally Posted by black roadster

Who are you and why do you have Iain's logon? ::Clown::

---

A real man can admit when he's wrong. It's just not that often that I get the opportunity. ::Bleh::

It's my understanding that the large jets have separate front wheel controll from the rudder. I think they steer with a small steering wheel at the side of the cockpit. However, they may be able to turn on and off a forced link with the rudder.

This is true, but has nothing to do with the video as the yaw correction occurs while the nose is still in the air. (On some military jets there's a button on the stick that engages nose wheel steering.)

C