2006-10-07 22:09:43 · 5 answers · asked by marushi 1 in Cars & Transportation ➔ Aircraft
Out-of-balance vibration is different than shimmy.
Out-of-balance vibration is usually felt as a rapid up-and-down movement, while shimmy is more of a side-to-side movement. You've probably seen out-of-balance vibration while driving if you've ever noticed a tire on another car hopping up and down (this is greatly exaggerated if the shock/strut is worn out).
Shimmy is a vibration in which the wheel moves rapidly left and right. The severity of the vibration depends on the amplitude and frequency of the movement. Amplitude is the amount of movement (i.e. the number of degrees of displacement from straight ahead); frequency is the time between each displacement.
Airliners have shimmy-dampening devices on the landing gear to minimize this vibration. The main gear trucks may have hydraulic or mechanical (spring-type) dampeners. Nosewheels typically rely on the hydraulic nosewheel steering actuators to dampen shimmy.
Most of the vibration you feel during landing gear extension and retraction comes from two sources. The most prominent is mechanical: hydraulic motors that drive the gear mechanism; up and down-locks engaging and disengaging; and the mechanism itself, which must translate rotational motion from hydraulic motors to linear motion to move the gear. The other source of vibration is aerodynamic. The airstream loads on the gear change continuously during extension and retraction. Since the landing gear, gear bays and gear bay doors aren't generally designed to be particularly aerodynamic, they cause some minor vibration due to airstream disruption.
If you're sitting up front, you may hear and/or feel a vibration from the nosewheel after retraction is complete. Since nosewheels don't have brakes, they're still rotating rapidly when they retract. There are snubbers inside the nose gear bay that rub against the tires' tread to stop them quickly as soon as the nose gear stows. Sometimes these cause a significant vibration, especially if the tire is worn unevenly and isn't perfectly round, or if one snubber is worn more than the other.
2006-10-08 13:34:37 · answer #1 · answered by Anonymous · 1⤊ 0⤋
It's hard for me to answer your question because it's kinda vague, but I'll giver a shot. The first most practicle step would be to shorten your landing gear to the absoulute shortest you could safely get it. The next best step would be to design the gear in a more aero dynamic way, such that it would not "drag" on the flight so much. And of course it goes with out saying a retractable gear that is bayed inside the fuselage. If the gear is supported by a suspension system it will vibrate less, as well.
2006-10-08 03:28:27 · answer #2 · answered by G B 2 · 0⤊ 0⤋
Most of the vibration that you are feeling is when the gear is retracted, right? That vibration you feel is called "nosewheel shimmy". The other wheels don't do it because their rotation is stopped prior to or during the retraction process with their wheel brakes. However, there are no brakes on the nosewheel and as such, the gear will continue to rotate during and after the retraction process. It is caused by unbalanced tires/wheels.
2006-10-08 04:14:50 · answer #3 · answered by Kelley S 3 · 0⤊ 0⤋
If you'r asking about the vibration that you feel when it is lowered, than there is no way. Dont you think if there was a way Boeing or Airbus would know about it?
2006-10-08 02:47:47 · answer #4 · answered by Charles 5 · 0⤊ 1⤋
Get out and push
2006-10-07 22:11:26 · answer #5 · answered by Pauline 5 · 0⤊ 3⤋