answersLogoWhite

0


Best Answer

Modern day commercial jets have separate Auxiliary Power Units, or APUs. These are used to supply electrical, hydraulic, and pneumatics while on the ground and, if needed for emergency back-up, in the air. The main engines, once started, are capable of supplying all of these needs in addition to the required thrust for flight. Under some conditions, pneumatics from the main engines may be reduced or shut off during takeoff or emergency conditions to increase available thrust to the engines. Modern commericial jets extract bleed air from the engines to operate the air packs that provide heat to the cabin during its flight. On most engines that I deal with, this bleed air is taken from two locations on the engine compressor: a low-pressure and a high-pressure stage of the engine. The low-pressure stage is about Stage # 7 or up to #10 and the high-pressure air is taken from Stage #14. The high-pressure bleed air is used for most normal demand and the low-pressure is used for peak demand. Engine description: Most commericial jet engines are high-bypass turbojet engines. The first stage is the large fan in front and then there are successives rows of blades that compress the air which increases the air pressure and temperature. After passing through the compressor stages, fuel is injected and the air/fuel mixture is ignited and the explanding gases go through another series of rows or the turbine stages. During take-off, the aircraft will shut off the bleed air so that the engine can produce its maximun thrust. I understand your Question to mean: What percentage of bleed air is extracted from the engines during normal operation? More of the answer to follow.

User Avatar

Wiki User

16y ago
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: How much of a jet engines power is used for auxillary power?
Write your answer...
Submit
Still have questions?
magnify glass
imp
Continue Learning about Engineering
Related questions

Why is aircraft battery is used in aircraft?

Aircraft batteries are there primarily to provide power should the engines fail in flight and work individually or alongside the auxillary power unit (APU). It provides 28V dc electric to the primary displays (i.e. Altimeter and EHSI).


Type of engine used to power space flights?

rocket engines,compared to jet engines


What energy source was used to power steam engines?

water


Steam engines were first used to power?

Machines in factories


Where did the term horse power come from?

Horse power is a measure of the power output of engines using the pulling capacity of a draft horse as its base unit. It was originally used to compare the power of steam engines compared to horses and was later extended to included petrol and diesel engines.


The fuel used to power most automobile engines comes from?

non renewable


Why is petroleum such a valuable resource to our society?

used to make plastic and power engines


What was used in the preelectronic period for power supply?

Steam engines, water wheels, etc.


What was steam engines first used to power?

Pumps, to remove water from coal mines.


What type of materials are engines made of?

Most engines are made of cast iron, some are aluminum alloys those are pretty much the primary materials used for engines. presently engines are designing with plastic. These engines are used in racing and high end cars.


Power for biplane?

2 wings, to determine which engine was used need to know what biplane


What kind of steam engines are used in power stations?

Coal fired steam driven power stations are still in use