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Old 03-19-2009 | 04:57 AM
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UAL T38 Phlyer
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From: Curator at Static Display
Default Crab vs Wing-Low

Originally Posted by ryan1234
Call me crazy, but I just think that doing one wheel touch and goes puts a lot of bad pressure on that one landing gear, especially if it's just the slightest bit gusty.

I could just never really understand all of the logic in not side loading the gear (when every take-off in a single does), yet landing on one gear. I've seen many students and ever other pilots drop it in on one gear trying to keep it corrected for x-wind (maybe a fixed gear might take it - but what about when you transition to a retract?)
Touching-down on a single-gear (and then lowering the other wheel) is not an undue-stress on the gear, whether it is fixed, retract, a 172, or an airliner. (Trying to do a single-wheel touch-and-go is probably beyond a beginner's capability)

Depends on the airframe, but in some airplanes (A-320, as I recall) you did wing-low during a max-crosswind landing. 747, more crab---the problem there was not dragging an outboard engine if the wing was too "down."

The issue is the direction of the touchdown loads. Gear, especially most retracts with oleo stuts, can take significant vertical impacts. And they can obviously take big aft-loads....that's what the brakes do. But sideways loads put the strain on the mechanism that makes it retract or stay in the locked position--generally, the weakest part of the gear. In fighters, the issue is often the tires...side-loads can peel the tire off the rim when heavy-weight.

As to your comment that sideloads exist on takeoff: not really, unless you are weaving. If you are tracking straight down the runway, don't confuse aerodynamic sideload on the fuselage (which is relatively small) with inertia sideload that you get at the moment of touchdown, if crabbing. That load can be huge.

Personally, I like wing-low and minimal side-loads where the airplane Manual allows it.
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