How does the airoplane's engines get started?

Question

If a stoped airoplane is to be started as we start our vehicles then How does it willbe started?

Answer 1

It is a multistep process and it depends on the type of engine:

1. Usually with piston engines they are electrical turned just like a car's engine. As the engine is INITIALLY turned, fuel and and spark ignition is introduced into the cylinders. Just like a car, the engine usually becomes self-sustaining very rapidly. Much more rapidly than a turbine engine.

2. In the case of a small jet or turbo-prop engine (such as many corporate jets, turbo-prop commuters, etc.) they are typically started using an electric motor as well. The electric motor turns the engine and once the engine reaches a certain speed, fuel and ignition are then applied into the combustion chamber. The engine then becomes self-sustaining and the electric motor used to initially turn it is turned off.

3. In the case of large jet engines, they are typically started using pneumonics. Air from a different engine goes through a bleed air system and turns a set of turbines that in turn, rotates the engine's compressor. Once the compressor reaches a certain speed, fuel and ignition are introduced into the combustion chamber. Once the engine has self-sustaining combustion, pneumonic air is removed. Exhaust air from the combustion process in the large engine will then rotate one or more sets of turbine blades that continue rotating the compressor and begin rotating the fan. The fan is the first set of blades that you see as you view the engine from the front. Fans are different from compressors. Compressors consist of a set of blades that form the intake to the combustion chamber. In the case of the aircraft that I fly, for every 7.88 parts of air that goes through the fan, only 1 part goes through the compressor. All air that goes through the compressor gets combusted by the combustion chamber. However the air that doesn't go through the compressor (but does go through the fan) simply gets blown out the back of the engine, without being combusted, providing additional thrust. Anyway, after the first engine of a large aircraft is started, the aircraft then uses bleed air from the running engine to provide the bleed air for the remaining engine(s).

The air used to turn the compressor for engine start-up usually comes from one of two sources:

The APU: This is a very small jet engine that is usually somewhere along the aft fuselage, or in the very back of a large jet aircraft. Some airplanes, such as the one that I fly, have two APUs. It stands for Auxiliary Power Unit. APUs are used to supply the aircraft with bleed air, electrics, and hydraulics when the aircraft is not flying with the engines off, or as an emergency backup when the airplane is flying. In the case of the aircraft that I fly, the APU is started using hydraulic pressure. If the hydraulic pressure has bled down then it can be started using hydraulic pressure from a different hydraulic system in series through a device called a "Power Transfer Unit". If you have no same system hydraulic pressure or no hydraulic pressure from a different system in series, then the same hydraulic system has to be pumped up manually using a lever.

The GPU: This stands for Ground Power Unit. It is essentially the same thing as an APU except that it belongs to the airport, and is on a little cart that can be towed around from airplane to airplane. Just like an APU, a GPU can provide an aircraft with bleed air, electrics, and indirectly via the aircraft's systems, hydraulics.

Okay, now that you understand how an engine is started on the ground let's say that an engine has failed or was shut down by the crew while airborne and needs to be restarted. There are two ways:

Airstart: As the airplane moves forward, ram air against the propeller and/or compressor and/or fan will cause it/them to rotate. If the engine is rotating then fuel and ignition can be applied, and the engine will become self-sustaining unless their is a malfunction preventing it.

Starter assisted start: If the airplane is either above a certain altitude and/or below a certain speed, the engine won't be receiving as much ram air and might not be rotating fast enough to apply fuel and ignition to become self-sustaining. In this case, you first use the starter to get the engine rotating, and then apply fuel and ignition to make the engine become self-sustaining, unless there is a malfunction preventing it.

Wow, that was painful wasn't it?!? Want any other long explanations?!? ...lol

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Message to flyin_gsxr600: I am a U.S. Air Force C-5 Galaxy instructor pilot with almost 4,000 hours, degrees in both macro-propulsion systems engineering (a highly specialized branch of mechanical engineering) and transportation. On top of this education, I have also completed all of the course work required for a bachelor's degree in electrical engineering. I have two patents and several unpatented engineering designs - basically, I know how stuff works! I fly out of Dover AFB, Delaware. Perhaps you would like me to fax you a section out of the Dash 1 that explains APU use. Perhaps the aircraft I fly is way beyond your comprehension and skills as a pilot.

Actually moron, the APUs (plural, meaning more than one) on the aircraft I fly DO NOT have their own battery. Other APUs from different airplanes do. Just because you fly an aircraft and it works a particular way doesn't mean that all airplane systems work exactly the way that yours does. Did you notice how in my original message I said "Some airplanes, such as the one that I fly" Did you notice how I didn't say "All airplanes work like this..."? I did this so that pinheads like you can't then send me a message and say that this is not how your airplane works.

Sorry I spelled "pneumatic" incorrectly. You got me there. Unfortunately for you, that is the only thing that you got me at.

So, you've never seen a hydraulically started APU? Perhaps you have never flown an APU equipped aircraft that is more than 25 years old. Or perhaps you have never flown an aircraft that shuts down all power for several days at a time while it waits for cargo, sometimes in sub-zero temperatures, where a lead acid battery started APU would lose all of its charge. Why don't you open your eyes and look on the internet for such APUs, they're there. Or do you even know how to search for something on the internet? And by the way, when they need to be pumped up the pumps aren't located in the avionics bay, they're located at the hydraulic servicing center in the cargo bay. Also, yes, the C-5 DOES HAVE TWO APUs. Again, I will gladly fax you the section out of the C-5 Galaxy's Dash one, but you might not know how to read it.

Here you go. Check out this website: http://www.tpub.com/content/ahapache/TM-1-1520-238-23-1/css/TM-1-1520-238-23-1_357.htm. This appears to be a section in the dash-one of an Apache helicopter. I found it almost immediately on the internet. Regardless of the aircraft type, it proves that hydraulically started APUs exist. Read it and weep.

I hope you aren't a flight instructor. If so then God help the future of aviation! The fact that you are a pilot, if indeed you are a pilot, means that when you are out flying, some village somewhere is being deprived of an idiot!

Before you go making personal attacks on people on this, or at any other website, you better have your facts straight. Now go get lost - this is probably the only thing that you're an expert at when you fly!

Answer 2

Light aEroplane (please note the spelling) engines operate similar to an automobile/car engine.

The Cessna 152/172 uses a key just like an automobile. They have a battery and a starter/generator with something very similar to spark plugs [magnetos].

A jet engine is an engine that accelerates and discharges a fast moving jet of fluid to generate thrust in accordance with Newton's third law of motion. This broad definition of jet engines includes turbojets, turbofans, rockets and ramjets and water jets, but in common usage, the term generally refers to a gas turbine used to produce a jet of high speed exhaust gases for special propulsive purposes.

A turbojet engine is a type of internal combustion engine often used to propel aircraft. Air is drawn into the rotating compressor via the intake and is compressed, through successive stages, to a higher pressure before entering the combustion chamber. Fuel is mixed with the compressed air and ignited by flame in the eddy of a flame holder. This combustion process significantly raises the temperature of the gas. Hot combustion products leaving the combustor expand through the turbine, where power is extracted to drive the compressor. Although this expansion process reduces both the gas temperature and pressure at exit from the turbine, both parameters are usually still well above ambient conditions. The gas stream exiting the turbine expands to ambient pressure via the propelling nozzle, producing a high velocity jet in the exhaust plume. If the jet velocity exceeds the aircraft flight velocity, there is a net forward thrust upon the airframe.

Turbofan engines
Most modern jet engines are actually turbofans, where the low pressure compressor acts as a fan, supplying supercharged air to not only the engine core, but to a bypass duct. The bypass airflow either passes to a separate 'cold nozzle' or mixes with low pressure turbine exhaust gases, before expanding through a 'mixed flow nozzle'.

Forty years ago there was little difference between civil and military jet engines, apart from the use of afterburning in some (supersonic) applications.

Civil turbofans today have a low specific thrust (net thrust divided by airflow) to keep jet noise to a minimum and to improve fuel efficiency. Consequently the bypass ratio (bypass flow divided by core flow) is relatively high (ratios from 4:1 up to 8:1 are common). Only a single fan stage is required, because a low specific thrust implies a low fan pressure ratio.

Pneumatic air pressure is used from the auxiliary power unit to start some turbine engines.

Answer 3

with the push of a button. the energy from the batteries goes to the starter motors, that turn the motor, compression is built, and the engine ignites and continues and runs.
this is a very general description. not exact. this is also how car motors work. there are different types of airplane engines. prop, turboprop, and jet engines are all different.

Answer 4

there are as many different starting methods as there are engines. some have air starters, some are electric, some even start with shot gun shells.

Answer 5

It depends on the engine you are trying to start. Try cleaning up your english.

Answer 6

key.....hiihhieeeee