科技英语阅读7内容太长了 到8里接着看吧

科技英语阅读7内容太长了 到8里接着看吧
There are two main things that make aircraft engineering difficult；the need to make every component as reliable as possible and the need to build everything as light as possible. The fact that an aeroplane is up in the air and cannot stop if anything goes wrong,makes it perhaps a matter of life or death that its performance is absolutely dependable.
Given a certain power of engine,and consequently a certain fuel consumption,there is a practical limit to the total weight of aircraft that can be made to fly. Out of that weight as much as possible is wanted for fuel,radio navigational instruments,passenger seats,or freight room,and,of course,the passengers or freight themselves. So the structure of the aircraft has to be as small and light as safety and efficiency will allow. The designer must calculate the normal load that each part will bear. This specialist is called the ‘stress man’. He takes account of any unusual stress that may be put on the part as a precaution against errors in manufacture,accidental damage, etc.
The stress man’s calculations go to the designer of the part, and he must make it as strong as the stress man says if necessary. One or two samples are always tested to prove that they are as strong as the designer intended. Each separate part is tested, then a whole assembly,for example,a complete wing,and finally the whole aeroplane. When a new type of aeroplane is being made,normally only one of the first three made will be flown. Two will be destroyed on the ground in structural tests. The third one will be tested in the air.?
Two kinds of ground strength tests are carried out. The first is to find the resistance to loading of the wings,tail,etc. until they reach their maximum load and collapse. The other test is for fatigue strength. Relatively small loads are applied thousands of times. Each may be well under what the structure could stand as a single load,but many repetitions can result in collapse. One from of this test is done on the passenger cabin.?
It is filled with air at high pressure as for high-altitude flying and completely submerged in a large tank of water while the test is going on. The surrounding water prevents the cabin from bursting like a bomb if there is a failure.
When a plane has passed all the tests it can get a government certificate of airworthiness, without which it is illegal to fly, except for test flying.?
Making the working parts reliable is as difficult as making the structure strong enough. The flying controls,the electrical equipment,the fire precautions,etc. must not only be light in weight,but must work both at high altitudes where the temperature may be below freezing point and in the hot air of an airfield in the tropics.?

【1节】有两个主要的事情,使飞机工程困难;必须尽一切组成部分可靠的,可能和需要建立的一切轻如可能.事实上,飞机是在空中,不能停止,如果任何事情都会发生错误,这使得或许是生死存亡,其性能绝对可靠.鉴于某些权力的发动机,因此,一定燃料消耗,有一个实际的限制,总重量的飞机可以飞.在体重尽可能通缉燃料,无线电导航仪器,乘客座位,或货物的房间,当然,乘客或货物本身.因此,结构的飞机将作为体积小,重量轻的安全性和效率将允许.设计者必须计算出的正常负荷,每个部分将难以承受.这个专家称为''强调人' .他考虑到任何不寻常的强调,可能是把一部分作为一个防范错误的制造,意外损坏等.男子应力的计算去设计的一部分,他必须一样强烈的应力男子说,如果必要的.一个或两个样品的测试总是证明他们是强烈的设计意图.每个单独的部分进行测试,然后整个装配,例如,一个完整的机翼,并最终整个飞机.当一种新型的飞机正在取得,通常只有一个头三个提出将飞行.两名将被摧毁在地面上的结构试验.第三是将测试空气中.【2节】两种地面强度试验进行.首先是寻找抗负荷的翅膀,尾巴等直至他们达到其最大负荷和崩溃.其他测试是疲劳强度.相对较小的载荷应用数千次.每个可以及在什么样的结构可以作为一个单一的负荷,但许多重复可能导致崩溃.一位从这个试验是这样做的客舱.这是充满空气在高压力,高超低空飞行,完全淹没在一个大罐的水,而测试正在进行中.周围的水无法从机舱爆裂像一个炸弹,如果有一个失败.当飞机已通过所有的测试可以得到政府的单机适航证,没有这一点,是非法的飞行,除了飞行试验.制作可靠的工作部件是困难的,因为决策的结构足够强大.飞行控制,电气设备,防火措施等.不仅必须重量轻,而且必须在高海拔地方的温度可能低于冰点和热空气的一个机场在热带地区.【翻译的还不错吧!】 ?