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Post by nuuumannn on Oct 31, 2022 20:16:45 GMT 12
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Post by tbf2504 on Nov 1, 2022 8:15:47 GMT 12
Interesting angles on the main undercarriage boggies between the different types of aircraft on their final approach
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Post by hardyakka on Nov 3, 2022 20:38:51 GMT 12
Interesting angles on the main undercarriage boggies between the different types of aircraft on their final approach The main factor for determining landing gear tilt is actually wheel bay space. What position do the wheels/bogies need to be in to fit into the allocated space in the wing or fuselage when they retract? There is a hydraulic gear tilt actuator arm that sets the gear "truck" into the right angle to fit in the bay. No matter whether it is tilted for front-axle-first or rear-axle-first, the initial wheel set to touch down and get weight on it opens a valve and depressurises the actuator so the wheel bogie axles can all be at the same level for rollout. That touchdown sensor also can be made to deploy speedbrakes on the wing, autobrakes on the wheels, and unlock the restrictor that stops you selecting engine reverse thrust in flight. Airliner technology is pretty sweet. Everything has an engineering purpose. Apparently the B777-300 series even has another hydraulic actuator on the rear axle that operates separately. It holds the tilt at takeoff as the bogie lifts and makes sure that the last set of wheels to come off the ground keeps the fuselage at an angle where the tail won't strike the ground at rotation. This is because the fuselage is 10m longer than the B777-200. The story I've heard is that the pilots call these the 777-300's "high heels". No idea if that is true or not... It's a good story regardless. |
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Post by nuuumannn on Nov 14, 2022 12:30:53 GMT 12
That touchdown sensor also can be made to deploy speedbrakes on the wing, autobrakes on the wheels, and unlock the restrictor that stops you selecting engine reverse thrust in flight. Airliner technology is pretty sweet. Everything has an engineering purpose. The system is known as Weight-on-Wheels. The WoW sensors detect small unpainted target squares on the gear and in the door frames and during maintenance the aircraft can be fooled into thinking its flying by blocking the targets with dissimilar metals mounted on what we called cheaters. That's done to test certain functions that only work "in flight" so to speak. |
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