飞机起落架设计(中英文对照)
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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
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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 plane’s 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 ． However，
there are
numerous other designs that have also been used
over the years， and each has its
own
advantages and disadvantages． Let’s 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
piston－engine 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 plane’s
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
propeller－driven 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 plane’s
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
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DC－3的后三点起落架
Good examples of
taildragger aircraft include the Spitfire and DC－3
of World War II．
后三点起落架的典型例子：喷火战斗机、道格拉斯DC－3。
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 non－retracting 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 F－16 and
Cessna 172．
F16 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 plane’s 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 carrier－based aircraft． Unfortunately， the
method proved impractical，
but it shows the
lengths some will go to while attempting to
eliminate the need for landing
gear！
很不幸，这个试验暂未完成成功。（意译）
We have seen that
landing gear come in many varieties and each
option has its own
advantages and
disadvantages．
我们看到，有各种各样的起落架，每一种都有它自己的优缺点。
Selecting the best arrangement for a given
aircraft is a trade－off between these
strengths and weaknesses as they apply to the
environment the plane is designed for．
实用中，需要根据飞机及外界环境，综合优缺点考虑来进行选择。
As a
result， designers try to select the simplest，
smallest， lightest， and least expensive
solution possible to do the job while
maintaining safety．
在保障安全的前提下，最简单的、最小的、最轻的、最便宜的方案是比较好的选择。
That
is why most planes only have three landing gear
rather than four because fewer gear
weigh
less， require less structure aboard the plane，
take up less space when retracted， and
generate less drag．
分析现在的飞机，就是按照上面的说法设计起
落架的。如：重量更轻、简洁的结构、更小的阻力、收
放式。