Did you know that the APU intake is considerably louder than its exhaust.
@Hopeless_and_Forlorn
6 ай бұрын
Great strides have been made in lowering the noise generated by both the APU exhaust and the inlet. However, in past years the exhaust was painfully loud to ground personnel who were not wearing hearing protection, and much louder then the sound of the intake. Also, on the early Boeing 737s the exhaust from the air conditioning pack heat exchangers was painfully loud to ground personnel, as was the sound of the electrically powered hydraulic pumps to anybody who put their head into the main wheel well. All of those loud noises have been reduced in newer aircraft.
@ericdavidson9974
5 ай бұрын
@@Hopeless_and_Forlorn As an airplane mechanic that works on Boeing 767s and 747s, airplanes are still very loud. Especially the APU and air conditioning packs. Electric hydraulic pumps are loud but not as bad. Air driven hydraulic pumps are really loud too. But this is probably because all the airplanes I work on are over 16 years old. I have no experience working on any airplanes less than 10 years old.
@paulallen8329
Ай бұрын
Wait so that's the loud sound that can be heard when boarding a plane?
@DOOM_Nukem
Ай бұрын
@paulallen8329 yes.
@Dirt_Breaker
Ай бұрын
@@paulallen8329 yes, and also the air conditioning packs towards the middle/ front of the plane
@Errcyco
6 ай бұрын
The APU is what makes jets even possible.. arguably as important and interesting as the engines themselves
@andrijasaviccsavic1124
6 ай бұрын
What do you mean it makes the possible?? There Are ton of jet airplanes that do not use APU for startning, but if you are talking about airliners, yes they usually have APU
@Errcyco
6 ай бұрын
@@andrijasaviccsavic1124 commercial aviation and military might as well be night and day as far as how they work. Look up economies of scale lol. One is a business, one prints money to burn. They also gotta have something for all those dudes they pay to do. Hard to even compare the two even though both use jets.
@FinlandGuy747
6 ай бұрын
@@ErrcycoThe first generations of the DC-8 and 707 didn't have an APU. The 727 was the first airliner to use an APU.
@honor9lite1337
4 ай бұрын
Hmmm,, interesting 🤔
@xxafthabxx9346
Ай бұрын
It also starts the main engines
@frankperez1184
Ай бұрын
Nice explanation !
@MiniMC546
6 ай бұрын
waiting for more new educational and informative videos...
@Sarvitar
Ай бұрын
Like it's sooo simple..just three turbines and youv got an engine 😂. I think the engineers just took the quickest shortcut in making the last small engine.
@user-ju8ye5he7x
5 ай бұрын
it is not always at back a plane. Il76 airplane's APU is at a gearside.
@patrickoneill1011
5 күн бұрын
Then theres the R.A.T. (Ram Air Turbine which is also a power generator unit onboard many commercial aircraft.
@junahsong130
Ай бұрын
ARMORED PERSONNEL UNIT 😱😱
@syednaqvi6075
Ай бұрын
Thanks for sharing.
@BuzzMoves365
Ай бұрын
Our 747-400’s APU burns fuel at about 200 lbs/hr.
@GeneralGayJay
5 ай бұрын
I think the APU should maybe be used to deliver power to electric motors propelling the aircraft on the tarmac 🤔
@richardmillhousenixon
5 ай бұрын
Too much weight and complexity for a comparably small benefit
@Vini_anonymous
9 күн бұрын
Good idea,but it's too expensive and not practical for today, but maybe in the future...
@kyungtaekim6362
3 ай бұрын
Where does that pressured air go?
@BuzzMoves365
Ай бұрын
To the pneumatic systems and PACKs (Pressurization and Air Conditioning Kit)
@AKD96070
17 күн бұрын
Also to help start the engines, if the bleed valves are turned of the engines will receive this pressurised air
@markbolam1383
18 күн бұрын
you missed one of the apus main functions to start one of the main engines
@luisito6314
Ай бұрын
And the exhaust gives the plane another half lb of push lol
@gabutman6144
6 ай бұрын
Does the APU generate any thrust while the plane is stationary?
@Errcyco
6 ай бұрын
No.. well not exactly. Half goes to turbines that spin an alternator that runs a generator for powering the plane. The other half however would have some “thrust” to it.. but it stays IN the plane. It gets compressed and then that’s what is used to keep the cabin pressurized and the AC going for you at your seat. The APU in a jet is more like a giant powerbank/fan than it is a jet engine.. and it is a jet engine. Neat little enigma.
@andrijasaviccsavic1124
6 ай бұрын
Are you sure that apu exhaust air is used for heating and pressurizing? APU doesnt work in flight, unless emergency?
@Hopeless_and_Forlorn
6 ай бұрын
@@andrijasaviccsavic1124 APUs go back in history to small, piston engines used to generate electrical power in large aircraft in WWII. Many types and configurations have been used since then. The GTC (Gas Turbine Compressor) used on some turboprop airplanes was used only to provide air for engine starting, and was shut off before takeoff. The APU in the much-used Boeing 727 supplied both electrical power and compressed air for ground air conditioning and engine starting, but also had to be shut off before takeoff because of its location in the main wheel well. On the 737 and most later aircraft, the location of the APU in the tail means that the APU can supply electrical power and air on the ground, and electrical power in the air if needed. Also, the DC-9. and MD-80 aircraft had ram air doors for the APU inlet that meant that under the proper conditions the APU could be started in flight even when the aircraft battery did not have sufficient power for the APU starter motor.
@ericdavidson9974
5 ай бұрын
They probably make a few pounds of thrust while operating, but not enough to make a difference while flying or taxing.
@b2spirit86
5 ай бұрын
@@andrijasaviccsavic1124 That depends on aircraft models, but in this case of A220, it is correct that it provides heating and pressurizing, even in flight
@AKD96070
17 күн бұрын
It is not a back-up power my guy. It is impossible to start the APU mid flight. So there goes your 'back-up'. The only reason the APU exist is to power the plane if there is no ground power available. The more you know.
@bournemichael3227
12 күн бұрын
You are misinformed then, on the a320 for example the APU can be started up to 25k feet by batteries or 41k feet by transformer rectifiers, and it also can provide bleed air up to 20k feet. The more you know.
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