Text Aircraft hydraulic systems

· Do you agree with the statement «Aircraft Hydraulics is a means of transmitting energy or power from one place to another efficiently»?

· Do an aircraft hydraulic system and a car hydraulic system have a lot in common? What can you say about it?

· Match these words with their definitions:

1. unit a. a rechargeable electric cell

2. to handle b. to make or become smaller or less

3. auxiliary c. the quality or degree of being viscous

4. controls d. to touch, move or operate with the hands

5. pump e. a machine for raising or moving liquids

6. to reduce f. switches and other devices by which a machine is controlled

7. accumulator g. a device with a specified function forming part of

a complex mechanism

8. viscosity h. subsidiary, additional

 

 

· Translate the forms of the verbs remembering that there may be more that one translations depending on the grammar:

increased, required, were introduced, are controlled, to start, permitting.

 

 

· Find the mistake. There are two wrong forms in each point:

1. valves, laws, controls, various, pumps, systems, comes, actuators, specifications, references.

2. Braking, permitting, during, obeying, starting, extinguishing, repairing, servicing.

· Before you start reading the text look through it and define the functions of the infinitives in the sentences.

 

Words and phrases:

braking systems системы торможения

performance рабочие характеристики; эксплуатационные показатели;

to obey соответствовать требованиям

auxiliary power unit вспомогательная силовая установка

cannon артиллерийское орудие

to permit разрешать, позволять

redundancy резервирование; состояние резерва

flashpoint точка вспышки, точка воспламенения

stringent строгий, точный

to adhere приклеивать, придерживаться

 

The use of hydraulic systems in aircraft almost certainly began with braking systems.

As aircraft performance increased in mid-20th century, the amount of force required to operate mechanical flight controls became excessive, and hydraulic systems were introduced to reduce pilot effort. The hydraulic actuators are controlled by valves; these in turn are operated directly by input from the aircrew (hydro-mechanical) or by computers obeying control laws (fly by wire).

Hydraulic power is used for other purposes. It can be stored in accumulators to start an auxiliary power unit (APU) for self-starting the aircraft's main engines. Many aircraft equipped with the M61 family of cannon use hydraulic power to drive the gun system, permitting reliable high rates of fire.

The hydraulic power itself comes from pumps driven by the engines directly, or by electrically driven pumps. Electric pumps can provide both redundancy and the means of operating hydraulic systems without starting the engines, which can be very useful during maintenance.

Aircraft hydraulic fluids fall under various specifications:

Common petroleum-based:

Mil-H-5606: Mineral base, flammable, fairly low flashpoint, usable from – 65F to 275F, red color;

Mil-H-83282: Synthetic hydrocarbon base, higher flashpoint, self-extinguishing, backward compatible to – 5606, red color;

Mil-H-87257: A development of – 83282 fluid to improve its low temperature viscosity.

Phosphate-ester: Skydrol – Typically light purple, not compatible with petroleum-based fluids, will not support combustion.

Special, stringent care is required when handling aircraft hydraulic fluid as it is critical to flight safety that it stay free from contamination. It is also necesary to strictly adhere to authorized references when servicing or repairing any aircraft system.

(from http://www.thetravelinsider.info/2003/0314.htm)

· Answer the questions in your own words:

1. What is the purpose of hydraulic systems?

2. How the valves are operated?

3. Describe the work of hydraulic power.

· Is it true that…:

1. hydraulic systems installed on the aircraft were to make easier the job of the pilots?

2. braking systems can be considered as the first hydraulics in the aircraft?

3. the hydraulic power can be used to drive the gun system?

4. the hydraulic power itself comes from engines?

5. aircraft hydraulic fluids are of one specification?

· Change into Active the following sentences:

1. The hydraulic actuators are controlled by valves.

2. Hydraulic power is used for other purposes.

3. Stringent care is required when handling aircraft hydraulic fluid.

· Put the verbs in brackets into the correct form:

 

The actuating cylinder (can, to change) ___ hydraulic power to linear or rotating motion. It has a reduction gear in it to reduce rotating motion to that amount which (to be, to need)__. Previously, systems used to control motion by (to use) ___ steel cables connected by pulleys between the controlling mechanism (such as the pedals) and the controlled surface (such as the rudder). The cables (to be, to affect) _____ by expansion rates of the cables due to temperature changes. Hydraulic systems can control motion without (to worry) ___ about the effect of temperature since it is a closed system (not open to the atmosphere) (to compare) ____ to a cable system. This means better control of the plane and less lag time between the pilot's movement to control the plane and the response by the control surface.

 

· Translate the text with the help of a special dictionary and learn the terms by heart:

Some Devices Operated by Hydraulic Systems in Aircraft

Primary control boosters

Retraction and extension of landing gear

Sweep back and forth of wings

Opening and closing doors and hatchways

Automatic pilot and gun turrets

Shock absorption systems and valve lifter systems

Dive, landing, speed and flap brakes

Pitch changing mechanism, spoilers on flaps

Bomb bay doors and bomb displacement gear

 

· The following sentences have been removed from the text. Look at the gaps in the text and decide where they fit.

 

 

1. The two chambers are called the piston rod side chamber and the bottom chamber.

2. The generation power for this system is actually the hydraulic pump, which brings a regulated flow of fluid into the cylinder tube.

3. Typically, hydraulic cylinders are used in the manufacturing and of vehicles.

4. This fluid is usually a form of oil, though other options can be used.

 

 

Hydraulic cylinders are also referred to as linear hydraulic motors. Hydraulic cylinders are a mechanism that is utilized to apply a force that is linear through a stroke that is linear. 1 __________.

The power that hydraulic cylinders operate from comes from hydraulic fluid that has been pressurized. 2. ________. The cylinder is merely a barrel with a piston connected to a rod that stays in motion while the piston is being acted upon. The barrel is closed at the bottom and the top where the piston rod is inserted. The piston has seals and rings that slide. The inside of the cylinder is divided into two separate chambers using the piston. 3. _________. The hydraulic pressure forces the piston to conduct linear work.

In other words, it forces the piston to move backwards or forward in a straight line, with no deviation. Hydraulic cylinders act as the motor in this particular type of system. 4. _________. In addition to the piston rod there are mounting brackets called clevises affixed to the bottom of the cylinder that allow the cylinder to be mounted where needed.

(from http://www.hydrauliccylinders.com/)

· Read about the advantages of hydraulic systems (over other systems for aircraft use) and make the statements shorter:

Ø It is lighter in weight than alternate existing systems.

Ø It is dead beat, that is, there is an absence of sloppiness in its response to demands placed on the system.

Ø It is reliable; either it works or doesn't.

Ø It can be easily maintained.

Ø It is not a shock hazard; it is not much of a fire hazard.

Ø It can develop practically unlimited force or torque.

(from http://www.allstar.fiu.edu/aero/Hydr01.htm)

· Find grammar mistakes in the sentences of the following text:

Landing gear consists of the wheels that stick out below the fuselage so that an airplane can roll down the runway during landing and takeoff. In early aircraft, they were fixed in an open position so that they protruded at all times, even while the plane was flying and nowhere near the ground. The researchers found that reducing the drag produced by the landing gear would significantly improve the performance of the airplane in flight.

When designing an aircraft, engineers have always had to address five conflicting requirements. These are: performance, weight, cost, reliability, and maintenance.

Airplane designers explored numerous ways to retract aircraft landing gear into the fuselage. In some aircraft they were pulled straight up, usually into cowlings behind the engines, sometimes with part of the wheels protruding outside the airplane. In other cases the struts folded inward so that the wheels fit into the bottom of the fuselage horizontally, sometimes covered with a door to further reduce drag. Some of the drive mechanisms were electric, whereas others were hydraulic. The designers had to ensure that the gear deployed and locked in place. (In a landing gear the hydraulic motor can produce enough power to pull up the landing gear system without trouble even though air loads act on the system and the slip stream air is impinging against it).

Today, many low-speed private aircraft still have fixed landing gear because of cost and maintenance concerns. Some even have the streamlined "pants" coverings over their wheels. But virtually all larger and faster aircraft have completely retractable landing gear. Designing such gear presents engineers with a number of problems, particularly how to mount them on the airplane without affecting other parts of the aircraft design.

(With the help of http://www.centennialofflight.gov/essay/Evolution_of_Technology/landing_gear/)

· Translate from Russian into English:

Гидропомпа – это насос в гидросистеме самолета, создающий нужное давление, а в авиационных двигателях жидкостного охлаждения – циркуляцию охлаждающей жидкости.

Гидросистема – это замкнутая, заполненная специальной жидкостью система, состоящая из силовых цилиндров, трубопроводов с арматурой, бака для жидкости и источника давления – насоса или сжатого воздуха в баллоне, служащая для приведения в действие агрегатов и устройств. Гидросистема в самолете применяется для разнообразных целей: подъема и выпуска шасси, торможения, управления створками люков и др.

 

 

Unit 5