The auxiliary power unit. APU aircraft

Today, very small article about the unit is not a small matter. Auxiliary Power Unit (APU)





The auxiliary power unit on modern ships are usually installed in the rear part. At the same time quite clearly visible holes or special hatches for the incoming air and exhaust gases.

MAT 737:



The fact that the auxiliary power unit - the unit is quite important and is widely used today to transport. The essence of it is that it provides a particular vehicle with the necessary energy, the source of which normally acts as the main power plant, which is simply the engine (or engines).

Outlet A380 APU:



The most widespread APU received in aviation. This is especially true for passenger aircraft and aircraft transport aircraft. For their ground handling needed electricity is often required pressure in hydraulic and air conditioning systems.
And to start the main engines also need energy. Is not always all it can be obtained by means of ground support, because not all airfields and airports equally developed in this regard.
It was then that position and saves the auxiliary power unit.

Open compartment MAT 320:



In modern aircraft APU - a miniature gas turbine engine. Or another turboshaft. This engine is a free turbine works "for the benefit":-). All useful energy, works on it, goes to the activation of the mineral aggregates (as well as on any turboshaft engine:-)).
Most cases are generators that supply power aircraft may be hydraulic pumps in the hydraulic system. Also the air that is extracted from the compressor APU can be used to operate the air conditioning system in the parking lot, or for the promotion of the rotor core engine when you start it.

APU TA-6A Tu-154:



On modern engines have appeared turbostarter function APU.
Through the turbine starter box drive units associated with the hydraulic pumps and generators can be parked lead them into action. This is typical of the MiG-29 RD-33 and Su-27 aircraft with the AL-31F engines.

All the Su-34, manufactured since 2011 are equipped with APU:



In addition to modern liners at APU, there is another very serious function. In the event of a failure in flight critical power units (eg generators), it can be started in the emergency mode and will supply the necessary energy to the side of the landing. In some cases, the APU can be used to start the main engines in the air. In my opinion - this is a great feature, it is extremely important for safety.

APU in the tail of the plane TU-134:



Transport aircraft APU is often placed in a gondola for the main landing gear.

APU C-160 in the nacelle chassis:



In general, the auxiliary power unit - this is optional and not necessarily aircraft turboshaft engine. This may well be a diesel, gasoline or steam unit and it can be used on various vehicles from tanks and special military vehicles to locomotives and gas-turbine. However, this is not the aviation theme ...

On Soviet anti-aircraft self-propelled ZSU-23-4 "Shilka" is a small turbine engine to operate the special systems of electrical equipment:



And as a supplement.



Imagine a stalemate in flight:
Denied 2 generators, ie if we talk differently - rose 2 engine ...
Refused / not start the APU ....



And here comes to the aid of Mr. Proper. © (aviokonstruktory, as it turns out, really do not want to be that you and I fell onto the ground, like the bird of toast in the Caucasian captive).
So, this was one of Mr. Proper, a very good idea, and her name - RAT (emergency wind generator).



"Wind", a power of 15 KW, with two-bladed propeller (blades are heated to prevent icing in flight).

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Under normal circumstances, he stowed in a special compartment. In case of failure of both generators in flight, RAT produced, untwisted ram air and feeds power to the left and right-board the bus. The whole process is automatic, but there is also a handle to force open the lock.
RAT allows you to safely continue the flight, up to start the APU, exit mode and connect it to the generator.

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Automatic release made at the idle APU generator and speed of the aircraft more than 92, 6 km / h.

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For symmetry, let me finish the story so tedious and take a bow.
On the grounds avia-simply.ru

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