Unit 3. Vertical Gyro Components

Essential vocabulary

Cartridge,n – патрон, катушка

Directional gyro,n – гироскоп направления

Figure of merit,n – показатель качества, добротности.

Pitch and roll,n – бортовая и килевая качка

Rim, n – обод

Accomplish, v – выполнять, завершать.

Employ, v – применять

Converge, v – сходиться в одной точке, сводить воедино

Curve, n – кривая (линия), изгиб;

v – изгибать,

Give rise to, v – давать начало, приводить к результатам, давать повод.

Trust, v – доверять

Blind, adj – слепой

Explosive, аdj – взрывчатый, взрывной

Text 3A. Gyro Motor or Rotor

So far we have examined what a vertical gyro is and how it is used. Now let us take a close look at some of the components used in the instrument to accomplish the performance.

The rotor is always circular and symmetrical about the spin axis. Any other shape would cause unbalances during rotation which could give rise to random torques, resulting in unwanted drift. Usually, the rotor has most of the weight concentrated around the rim. In this manner, the greatest inertia is achieved for a given weight. Remember that inertia times wheel speed equals angular momentum – and it is the angular momentum that gives the gyro its space stabilization. However, the weight only causes more load on the gimbal bearing, which may cause higher friction. This, in turn, causes drift. In fact, engineers sometimes use a figure of merit (the inertia divided by the weight) to compare performance of alternate designs. The higher this figure of merit, the better will be the gyro performance.

Because inertia depends upon the square of the radius, the rotor is made with the largest possible diameter. Therefore, the gyro motors are usually inside-out from the regular electric motors. On the usual induction motor, the rotor is a cylinder inside of the stator. A gyro motor is often made, though, with the rotor on the outside (or at a larger radius) than the stator.

A rotor and stator assume that the gyro motor is actually an electric motor, and in most instances this is the case. However, many aircraft gyros used in panel instruments employ an air jet to spin the rotor. In some missile applications, where the rotor must reach full speed in just a few seconds, the driving force may be a clockspring or an explosive cartridge. Where this type of drive is used, the gyro may only be needed for a few minutes.

Wheels driven as electric motors usually operate between 4,000 and 24,000 rev/min air driven rotors may spin as rapidly as 100,000 rev/min.

Questions to the text.

1. Why is the rotor always circular?

2. What does the gyro performance depend upon?

EXERCISES

EX.1. Mind the difference and translate the following words.

Later-latter-letter; through- though; then-than; so-so far; but-but for; this-thus.

EX.2.Find in the text the comparative construction, then translate the

following expressions:

Чем больше, тем лучше; чем быстрее, тем хуже; чем выше, тем сильнее; чем ближе, тем теплее; чем тоньше, тем ниже.

EX.3. Translate the sentences, paying attention to the words in bold type.

1.The faster an object moves , the greater is the resistance.2. The larger the diameter of the rotor, the less the inertia is. 3. The smaller the resistance, the more current will flow through the wire. 4. For any particular fluid the faster gimbal rotates, the more the fluid resists the motion. 5. The greater the density of fluid, the heavier a body for a given size can be floated. 6. The more pressure applied, the higher the friction level. The higher the friction level, the shorter the life. 7. The larger the projectile, or the faster the spin, the less is the precession.

EX.4. Find in the text the emphatic construction, then translate the following sentences:

1. It is the extremely high stability of the gyro that attracts the scientists’ attention. 2. It is the fuel cell that is the promising power source for the future. 3. It is in space flights that the fuel cells have been proved reliable in operation.4. It was Foucault who noticed this property of the spinning wheel.

EX.5.a)Find the gerunds in text 3A and define their functions.

b) Translate the following sentences.

1. Here are some general rules for manipulating exponents. 2. By working with the powers of 10 it is easier to keep track of the numbers. 3. We start out by making the spin axis point along the earth’s vertical. 4. After flying 6 hrs, the gyro spin axis would be tilted around the pitch axis about 26 deg. from the vertical. 5. Before accomplishing the precession the switch must close. 6. Semilinear system does a much better job of permitting the gyro to remember the average position of the pendulum than does the bang-bang system.7.One cannot use this instrument without its being regulated.8.We know of Foucault’s having made his discovery at the end of the 18 century.

Ex.6. a) Find in the text the word time ,define its part of speech.

b) Translate the sentences.

1. There was а time when people knew nothing about flying.2.One of the spheres is four times as large as the other one.3.Four times four is sixteen.4. At times a spark appeared between the two ends of the wire. 5. The experiment at question was finished in good time. 6. In those times lightning was a subject for legends. 7. What time is it? I think it’s time to stop the motor.