Is APU designed to produce thrust?

Question

In an emergency, when the APU is turned on, is it designed to give the aircraft some thrust or purely for power?

Answer 1

APU's are designed to provide electrical power and high-volumes of low pressure air for various aircraft systems. Using the APU to produce thrust would decrease the amount of electrical power and bleed air it would be able to provide to the aircraft. Also APUs are designed to produce torque (for running generators) and they have over sized compressors so they aren't really suited for producing thrust like a jet engine.

However there have been experiments using APUs to provide additional thrust for takeoff (on the 777 I think) since they are not being used in the takeoff phase except for electrical redundancy. Also the HS Trident used a fourth 'auxiliary engine' to provide additional takeoff thrust to supplement the three regular engines.

Answer 2

The APU is purely there to prvide power and hydraulics before the aircraft engines are started, as well as some airflow to start the first engine.

Once the first engine is started the APU is generally shut down, and I don't know of any aircraft which can start or run it's APU once the Weight On Wheels switch has been broken (aircraft is off the ground), therefore impossible to provide any power.

Answer 3

As stated above the APU (Auxiliary Power Unit) is what it means. The purpose is to provide back up electrical power, run an back up hydraulic pump, and hot air for cross feed bleed to start the engines. The bleed air is also used to run the air packs on the ground. The APU has nothing to do with thrust to assist the aircraft.

Answer 4

some do based upon the direction of the exhaust. I unquestionably have tech Rep for the Honeywell one hundred fifty for 10 years. interior the Astra 1125 it does provide approximately 25 lbs of thrust. although many plane that have an APU are no longer qualified to apply them air-born. the quantity of thrust is amazingly little, yet any thrust continues to be thrust. The APU is there for floor potential, and enables the plane to run the air cycle gadget ( A/C or warmth) and initiate the main suitable engines. it could help to proportion the burden of the main suitable turbines, offering they're paralleled wisely. different structures may well be began so the pilots can enter flight plans into the FMS's (flight administration structures) maximum APU's are turbine engines, that have a starter/generator related with the aid of a shaft. to start the engine, the Starter/Generator acts as a starter, and starts off turning the turbine, whilst gasoline and spark are further around 60%. At ninety 5% the engine starts off to run by making use of itself, and the Starter/generator now turns right into a generator, that could provide as much as approximately 3 hundred amps to the main suitable ships potential bus. I unquestionably have worked with a hundred's of plane with the solar strand, Genesis, Honeywell a hundred & one hundred fifty. the different questions in this section please ask.

Answer 5

The APU is a small engine that produces sufficient power to operate the aircrafts electrical system and to start the main engines. It takes a lot of juice to start a large turbine, so they use the APU to provide that power. In a lot of older aircraft they used to have a power cart at the airfield to start the planes. And these planes could not be started without it. So they started installing APUs inside the plane to make the aircraft less dependent on airport facilities.

Answer 6

The APU is only for ship's power. It does provide a little thrust but is not designed around that.

Interestingly, another system that provides a bit of thrust is the cabin pressurization system. The outflow valves are placed so that they provide thrust. This makes up for part of the loss in engine thrust due to tapping bleed air from the compressors to pressurize the airplane.

Answer 7

APU's provide power to the Electrical Air and Hydraulic systems. They cannot provide Thrust. While they are in essence Jet Turbines the placement of them within Aircraft gives them no ability to propel the Aircraft.

Answer 8

I agree with all here.

To AL R - for info. The P3 Orion is fitted with what is referred to as an "Airborne APU". All that means is that in an emergency, the APU can be started in flight.
The Orion has generators fitted to engines 2,3 & 4 plus the APU. In the unlikley event of failure of all three engine driven genes - the APU can be started to supply electrical power.

Answer 9

No... the APU (Auxillary Power Unit) is to provide electrical power, bleed-air to start engines (or to run air-conditioning).

In most cases, the exhaust vents into some strange locations / directions !!

Answer 10

No, Nada, zip, and DT32 knows not what he is talking about.