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![]() Bob Moore wrote: "Ramapriya" wrote Sorry for being naive here Bob, but does touching down with the nose not pointed down the center of the airstrip, which is what I presume would happen if you touched down in the crab, bust the wheels? Certainly not good for light general aviation aircraft, but the Boeings seem to take it easily. Unless you happen to be flying an Ercoupe, which is designed to land crabbed in a crosswind. The gear is purposely beefed up for this purpose. On most other GA aircraft, it's definitely not advisable. On one of my very first lessons, I was on final following a Tomahawk landing with a stiff crosswind. My instructor told me to watch the Piper closely to see how the pilot corrected the crab just before touchdown, to land the plane with the nose aligned with the runway. Well, the (student) pilot didn't correct for the crosswind and touched down while still in a crab. We watched the right gear leg fly off the bottom of the wing and take out the right side of the horizontal T-tail. The plane slid to a stop on it's right wing, with pieces of the tail scattered over the runway. My instructor then informed me that I had just learned a valuable lesson about crosswind landings at relatively little expense to me. John Galban=====N4BQ (PA28-180) |
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![]() "Ramapriya" wrote in message oups.com... Bob Moore wrote: the crab at the last second before touchdown. Boeing said that if one was not comfortable doing that, just touchdown in the crab. Of course autoland approaches always use the crab Sorry for being naive here Bob, but does touching down with the nose not pointed down the center of the airstrip, which is what I presume would happen if you touched down in the crab, bust the wheels? Think of it this way. All that mass is moving straight down the runway, still pretty fast. It is going to try to keep going straight pretty fast. The only thing to cause enough stress on the gear to try to break the gear is the tires. What happens when the tires first touch down? A big puff of smoke, as the tires spin up to speed. Just a little bit of force involved to do that. It would take a whole lot more force to make that big bird go sideways, right? So what happens? The tires skid a bit sideways for a while, until the FO (the captain wouldn't have screwed up by not kicking the crab out, right? g ) wakes up and corrects to get the thing pointed straight down the runway, right? It has been my experience, from riding the heavy iron, that the combination of a slightly low wing and kicking the crab out is what is used. I say that only from observation, as it feels like one side hits, followed *very quickly* by the other side landing. Sometimes, it does feel like you are taking a quick ride towards the lights. -- Jim ( I'm grading your landings, Captains) in NC :-) |
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On Sat, 25 Dec 2004 at 23:29:34 in message
, Morgans wrote: It has been my experience, from riding the heavy iron, that the combination of a slightly low wing and kicking the crab out is what is used. I say that only from observation, as it feels like one side hits, followed *very quickly* by the other side landing. Sometimes, it does feel like you are taking a quick ride towards the lights. I have a little book that describes in detail a 747 flight from Toronto to Heathrow. An autoland is carried out at Heathrow. It describes how, in the first stages of the landing, the aircraft is aligned with the runway in a crosswind by heading slightly into the cross wind. At 500 ft to go the auto-pilot changes to 'runway align' and the wing is lowered on one side and the rudder keeps the aircraft aligned with the runway. I understand that the maximum autoland crosswind is 25 knots. -- David CL Francis |
#4
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![]() Ramapriya wrote: 1. Like there are crosswind landings, are there crosswind takeoffs too? If yes, what's the procedure of takeoff? Yes. The aileron on the upwind wing is raised as if you were banking the aircraft in that direction. The aircraft is kept straight by use of rudder. The nosewheel or tailwheel is usually kept down a bit longer for steering. With light planes, flaps may be retracted so that the plane leaves the ground at a higher speed than normal. Once the plane leaves the ground, the pilot adjusts the controls to achieve co-ordinated flight. 2. In crosswind landings, it's recommended that one lands on only the upwind wheel. Since this would almost always tilt the upwind wing groundward, would there not be an engine strike? I'm especially thinking of aircraft like the 737 and A320... Yes. In aircraft with engines under the wing, the plane is usually landed by either landing sideways and allowing the gear to kick it straight or (more usually) coming in at an angle and kicking the aircraft in line with the runway by using the rudder just before touchdown. This latter method is called the "crab and kick" method. There are several old videos floating around of 747s landing at Hong Kong's old airport. In one, the plane obviously touches down at at least a 20 degree angle to the runway. The amount of smoke from the tires is impressive. In another, the plane banks just before touching down and loses an engine when the engine hits the pavement. 3. How to slip an aircraft sideward? I'm visualizing a situation on final when a draft of air suddenly blows the aircraft a bit off-center and when it might be a bit late to try and bank the craft to get it back into proper alignment. When you bank an aircraft and use the rudder to counter the yaw effect, it will turn. If, however, you don't counter the yaw, it will slide sideways towards the low wing. If you actually push the rudder in the opposite direction to enhance yaw, the plane will fly sideways. This is a slip. One use for a slip is to keep the plane lined up with the runway when a crosswind is trying to blow the plane sideways. Another use is to increase the rate of descent if you're too high on final. The gusty wind situation you describe is usually handled by normal maneuvers (such as a small S-turn) while using throttle to keep from touching down. In extreme cases, the pilot aborts the landing and climbs back up to try again. Slips are, however, one tool that a pilot can use to handle gusts, so it wouldn't be unusual for a pilot to do so. George Patterson The desire for safety stands against every great and noble enterprise. |
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