how hard is this to land like this?

I think just about every plane has a demonstrated cross-wind capability. I landed in Iceland one time with a 40 knot cross-wind. fortunately for me, the runway was 200 feet wide. When you have a cross wind, you correct for it, that why the plane looks like it's sideways.

Art

 

In this case the pilot had the wind on his port side. To stay lined up on the centerline of the runway he had to feed in A LOT OF LEFT RUDDER to keep the wind from blowing the airplane off to his right. All I could think of when watching the hard contact with the runway is that it was also pretty hard to design the oleo strut and torque links to hold up to the harsh torque applied to the truck or axels.

 

You could really see the torque as the RH gear touched down. Single axle more forgiving than a multi-axle truck in this situation. In addition to the gear itself drift landing designs a lot of support structure.

 

Paul- Two techniques, crab and wing low or a combination of the two. On some aircraft, like most airliners, wing low does not work too well close to the ground because of clearance concerns with the engine nacelles. On modern fighters, wing low works very well combined with crab, kicking both out at touchdown. On the airliners, as you can see, they land in a crabbed condition and straighten once touched down. On lighter aircraft, you have to hold your crosswind corrections as you roll out or risk getting blown off the runway.

So, it depends, but basically use the flight controls so your flight path lines up with the runway centerline. In heavy high altitude crosswind conditions, aircraft also fly crabbed to keep the aircraft on the centerline of the desired ground track. The slower the airspeed for a given cross wind, the more crab required.

 

I was working near the guys designing the 777 landing gear and there were untold numbers of things that they had to design for but the worst was the torsion applied to the trucks and oleos in a cross-wind landing. One of the interesting concerns was keeping the front wheels on the runway from tire bounce. Worse than a 4 wheel truck.

 

Narita airport in Japan is famous for crosswind landings, thanks to some very active Japanese videographers. Do a search on YouTube for "Narita crosswind landing" and you'll see dozens of these.

 

Crosswind landings take practice to master but are very satisfying. There are two techniques: 1) Sideslip 2) Crab.

For the sideslip you bank the plane into the wind to correct for drift, then line up the nose of the plane with the runway centerline by using opposite rudder to correct for track.

With the crab you simply fly the plane in a direction that results in the plane traveling towards the runway (although it will not be pointed at the runway). Then around the time of the flare, you use rudder to line up the nose as much as possible with the runway. Usually when you are very low to the ground and starting your flare, the crosswind will be reduced due to surface friction of the Earth, trees, buildings, etc, so the last minute cross control is smaller than on the sideslip.

The sideslip LOOKS very elegant and it is taught to a new pilots, but airlines use the crab technique. The reason is not that engine nacelles will hit the ground (there is enough clearance even with flat tires), it is because of the uncomfortable forces placed on the passengers. With the crab, you can be at a 45 degree angle, but if you didn't look out the window, you would never know. You are just sitting in your seat waiting to land. With that same wind, during the sideslip the cross control will result in you being pushed outward toward one side of the airplane. Like going around a turn in a car, you get pushed to the outside of the turn. When doing this for 5 or 10 minutes on final approach, passengers will get sick. Then their vomit will be pushed toward the side of the airplane too!

 

You will also see the trucks and wheels briefly twisting sideways amid lots of smoke and then straightening out as they should. This always reminds me of a new engineer that came into our group that asked what the "knee action scissors" where for on the landing gear strut. We had a lot of sessions at lunch time after that.

 

In the 747, you will hit the inboard engine nacelle at about 6 degrees of bank. 6 isn't a lot. So side slipping is out of the question. We fly a crab until just before touchdown. I believe the Boeing manual suggests landing in a crab. Anyways, the tricky part is taking the crab out at the right time. Too early, and you start to drift downwind. Too late (touchdown) feels awful as the direction of motion isn't the same as the planes heading. Inevitably, one wing wants to raise when this happens.

As I usually only do about 5 landings a month, I don't get to practice them often. I can easily go a full year between serious crosswind landings. They can be interesting, especially if it's gusty and turbulent. Narita gets this way on SW winds. Also in a bigger aircraft, the cockpit and landing gear are two vary different locations on the centerline during a crosswind. You always want to keep the cockpit on the upwind side of the runway.

 

The C-5A used to have a way to rotate the landing gear to account for crab angles so the gear would be lined up with the runway on crosswind landings. This minimized side loading of the gear when landing in a crab. Since the landing gear rotates 90 degrees to be retracted anyway, this feature was probably not hard to build in. The landing gear was already complex enough. As a side note, when the Russians tried copying it for the AN-124 they just gave up and made the gear retract directly into the fuselage, eating up a bunch of cargo space.

The A models don't have this capability anymore, and they chose not to build this capability into the B model. I'm not sure why it was removed from the A and not incorporated in the B. It probably, like a lot of things on the jet, broke a lot.

 

Tim- The BUFFs have crabbed main landing gear as well.

 

Now that you mention it, that a lot of total sense. The upwind tip gear (or whatever its called) would probably snap off like a twig if you slipped it in.

 

Yes, I remember watching the first B-52 landing at Boeing Field with the crabbed landing gear. The crabbed angle of the gear pretty much matched the opposite angle of the rudder displacement. It almost made you sick to see this behemoth coming in crooked to the runway. The advent of the canted gear led to the decreased height of the vertical tail. In those days a lot of early flight tests were run out of Boeing Field and there were some very exciting incidents there in the 50's.

 

Here's a B-52 demonstrating that on landing at Fairford. It's a bit strange to see an aircraft still crabbed even after touchdown!

[ame]http://www.youtube.com/watch?v=94AcSHpcZbI[/ame]

 

B-52 is such an awesome machine!

 

BUFFs have some interesting flight characteristics. Only aircraft I have seen that climbs like a banshee with the nose down.

 

If you do try a slip in the B-52 , you do it very carefully. Crabbing is bad enough. The outrigger gear doesn't touch the runway until the wings have quit lifting. They are delicate and when the airplane is refueled on the ground they cannot "top it off" because the weight outboard would be too much for the outriggers and the airplane couldn't lift it anyway. "Topping off" is done after take off from a tanker in the air.

 

The Cessna 195 could also be had with a swiveling gear. Didn't help much, it was still a hassle to land in an x wind.

 

I prefer to slip than crab, but I do forewarn my passengers about the "uncomfortable feeling."

 

I used the slip most of the time in straight wing aircraft but in a swept wing airplane you can invite a roll into the downwind wing and you have to be alert to stop it if it occurs. This has killed some people in the past.