飞机起落架设计.docx

Aircraft Landing Gear Layouts 飞机起落架设计（中英文对照 图）发布人：圣才学习网发布日期：2010-06-25 14:36共 292人浏览大 中 小Most aircraft today have three landing gear许多现代飞机使用三点式起落架。Two main landing gear struts located near the middle of the aircraft usually support about 90% of the planes weight while a smaller nose strut supports the rest重心附近的两个大的主轮，承担约 90% 的重量，小轮子承担余下部分。This layout is most often referred to as the tricycle landing gear arrangement However， there are numerous other designs that have also been used over the years， and each has its own advantages and disadvantages Lets take a closer look at the various undercarriage options available to engineers目前的飞机以前三点起落架为主，让我们来回顾一下后三点起落架及其优缺点。（意译）Tail wheel or Tail dragger Gear后三点尾轮式与后三点尾橇式起落架Though the tricycle arrangement may be most popular today， that was not always the case The tail wheel undercarriage dominated aircraft design for the first four decades of flight and is still widely used on many small pistonengine planes虽然前三点起落架比较普遍，但是在几十年前的飞机，及当今的许多小型飞机是使用后三点起落架的。The taildragger arrangement consists of two main gear units located near the center of gravity （CG） that support the majority of the planes weight后三点起落架，由两个在重心靠前位置的主轮支持大部分的飞机重量。A much smaller support is also located at the rear of the fuselage such that the plane appears to drag its tail， hence the name一个非常小的尾轮装置在机身，看上去这个小轮子是被拖着走，所以，英文 Taildragger 也因此而得名。This tail unit is usually a very small wheel but could even be a skid on a very simple design它即可以是一个小尾轮，也可以是一个尾橇。后三点起落架What makes this form of landing gear most attractive is its simplicity后三点起落架最吸引人的优点就是“简洁”。The gear are usually relatively lightweight， and the two main gear can also be easily encased in streamlined fairings to produce low drag in flight后三点起落架通常重量都比较轻。两支主轮子可以配置整流置用来减小飞行中的阻力。Another potential advantage results from the fact that the plane is already tilted to a large angle of attack as it rolls down the runway另一个潜在的优点，是飞机在跑道滑行时，机翼已经有一个较大的迎角。This attitude helps to generate greater lift and reduce the distance needed for takeoff or landing合适的大迎角，有利于在较低的速度下产生足够的升力，以便于减少起飞滑跑距离。This attitude is also an advantage on propellerdriven planes since it provides a large clearance between the propeller tips and the ground 对于牵引式螺旋桨飞机，机头向上抬起，使螺旋桨不会接触跑道。（意译）Furthermore， taildragger planes are generally easier for ground personnel to maneuver around in confined spaces like a hangar同时，后三点起落架的飞机，更便于地勤人员把飞机拖到停机棚等窄小的空间里。However， the greatest liability of this landing gear layout is its handling characteristics另一方面，后三点起落架也有一个最大的 缺陷着陆时的操纵（handling characteristics）This design is inherently unstable because the planes center of gravity is located behind the two main gear造成此天生缺陷的原因，是因为两只主轮在重心的前面。If the plane is landing and one wheel touches down first， the plane has a tendency to veer off in the direction of that wheel如果着陆时起落架只有一只主轮前触地，这时，飞机有向此轮子一边转弯倾向。This behavior can cause the aircraft to turn in an increasingly tighter ground loop that may eventually result in scraping a wingtip on the ground， collapsing the gear， or veering off the runway严重时，这种转弯的倾向（ground loop）将可能使翼尖触地、起落架受损、滑出跑道。Landing a taildragger can be difficult since the pilot must line up his approach very carefully while making constant rudder adjustments to keep the plane on a straight path until it comes to a stop这就要求在飞机着陆触地前，需要使用方向舵修正自己的航线，使它能够笔直的滑翔直到安全触地。Many taildragger designs alleviate these handling problems by fitting a tailwheel that can be locked instead of swiveling on a castor Locking the tailwheel helps keep the plane rolling in a straight line during landing使用尾橇，能减轻这种现象。（意译）前三点起落架与后三点起落架的安定性对比Another disadvantage of the taildragger is poor pilot visibility during taxiing since he is forced to peer over a nose that is tilted upward at a steep angle后三点起落架的另一个缺点，许多飞机在地面滑跑， 机头向上翘起时，会影响飞行员的视线。（意译）It is also often difficult to load or unload heavy cargos because of the steep slope of the cabin floor对于货机，飞机的迎角不利于货物的装卸。Similarly， pilots and passengers are forced to walk uphill during boarding and downhill after arrival此问题，对于乘客来说，也是一样的道理。（意译）Many aircraft also rely on gravity to bring fuel from tanks to the engine， and some planes have been known to have difficulty starting the engine because it is uphill from the fuel supply发动机抬起，有时也不利于供油，造成启动困难。道格拉斯DC3的后三点起落架Good examples of taildragger aircraft include the Spitfire and DC3 of World War II后三点起落架的典型例子：喷火战斗机、道格拉斯DC3。Tricycle or Nosewheel Gear前三点起落架Now the most popular landing gear arrangement， the tricycle undercarriage includes two main gear just aft of the center of gravity and a smaller auxiliary gear near the nose前三点起落架，由两支在重心后的主轮，与一个在机头的辅助前轮组成。（意译）The main advantage of this layout is that it eliminates the ground loop problem of the taildragger前三点起落架最大的优点是不会像后三点那样，着陆时容易打转。This arrangement is instead a stable design because of the location of the main gear with respect to the center of gravity这得益于主轮子在重心后部的设计。As a result， a pilot has more latitude to land safely even when he is not aligned with the runway这样，就算着陆时飞机没有对准跑道，飞行员还是有办法修正方向的。前三点起落架Furthermore， the tricycle arrangement is generally less demanding on the pilot and is easier to taxi and steer前三点起落架更容易操纵。（意译）The tricycle gear also offers much better visibility over the nose as well as a level cabin floor to ease passenger traffic and cargo handling水平的机身，使视界比较好，而且便于装货及乘客行走。A further plus is that the aircraft is at a small angle of attack so that the thrust of the engine is more parallel to the direction of travel， allowing faster acceleration during takeoff机翼的小迎角，螺旋桨在水平方向产生的力，有助于飞机更快获得速度。（意译）In addition， the nosewheel makes it impossible for the plane to tip over on its nose during landing， as can sometimes happen on taildraggers另外，由于前轮距重心较远，就不会出现后三点起落架容易发生的“拿大顶”现象。（意译）The greatest drawback to tricycle gear is the greater weight and drag incurred by adding the large nosewheel strut前三点起落架最大的缺点是，较重的重量及较大的阻力。（意译）Whereas many taildraggers can afford to use nonretracting gear with minimal impact on performance， planes with nosewheels almost always require retraction mechanisms to reduce drag另一方面，固定式后三点起落架耐冲击性能较强。而前三点起落架，需要收放式以减小飞行时的阻力。Some planes with tricycle gear also have difficulty rotating the nose up during takeoff because the main wheels are located so close to the elevator， and there may be insufficient control effectiveness Similarly， the closeness to the rudder reduces its effectiveness in counteracting crosswinds前三点起落架影响舵效。（意译）Another critical factor when designing tricycle gear is to properly balance the load carried by the main gear versus the nosewheel Too little load on the main wheels reduces their braking effectiveness while too little on the nosewheel reduces its steering effectiveness Careful balancing of weight is also important to prevent the plane from tipping back on its tail while at rest on the ground前三点起落架对飞机重心的要求也比较高。747 加油次序不当，造成机尾触地的危险。There are many examples of aircraft with tricycle landing gear， including the F16 and Cessna 172F16 与 Cessna 172 都是前三点起落架的经典案例。Summary总结Landing gear serves three primary purposes起落架的三个主要任务：to provide a support for the plane when at rest on the ground，一、把飞机停放在地面。to provide a stable chassis for taxiing or rolling during takeoff and landing，二、起飞及着陆时提供稳定的支持。and to provide a shock absorbing system during landing三、着陆时减震。Regardless， all of these tasks are secondary to the planes primary role as an efficient mode of travel through the air飞机的飞行性能还是很重要的。（意译）To aircraft designers， landing gear are nothing more than a necessary evil since planes are designed primarily for their performance in flight rather than on the ground飞机的飞行性能比在地面的性能重要的多。（意译）There have even been attempts over the years to eliminate landing gear entirely The most extreme case was a study done by the Royal Navy to see if a jet plane could make a belly landing on the deck of an aircraft carrier coated with a rubberized surface有人尝试过不使用起落架，直接用机腹在航母甲板上着陆。（意译）If successful， the method would eliminate the need for the very strong and heavy landing gear used on carrierbased aircraft Unfortunately， the method proved imp