How Auxiliary Power Unit Works | Part 1 : Starting

[@SplashJohn]

I'm not in aviation, but I can recognize an excellent graphical and verbal presentation when I see one. Good work!

[@ryanreedgibson]

My dad and brothers worked on the industrial piping for the Honeywell plant that rebuilt these in Arizona. The plant did nothing but rebuild these APUs all day long. Awesome video!

[@SimonButler]

I work on 777s every day and still found this presentation informative and well made! Great job!

[@thabg007]

o man I remember the days on the flight line when I was in the Airforce having to listen to those screeching loud APU's 8-12 hrs a day, Yes I had (double) hearing protection. Its louder than the turbofan engine is (at idle). We used the APU to generate electrical & hydraulic pressure to load the gun system with ammo while at the same time removing the spent shell casings. There was a machine to connect to externally for electricity and hydraulics, it was taught to us in practice. But in real world use, it was never used, well at least not at the base I was at.

[@po1ly414]

A-10?

[@thabg007]

@@po1ly414 yea, how did you know?

[@aarond.8831]

A-10. One of the few that keeps its empties.

[@grumpyBSTRD]

Security forces and guarded c17’s and kc-135 refueler. Never knew wtf was screeching every damn day until I started getting into flight sims. It all made sense lol. Ear pro did nothing 😂

[@Greatdome99]

Military aviation equipment is exempt from federal emissions, noise and fuel efficiency stds, so they are usually loud, smoky and toxic. Commercial is not.

[@BSDLLC]

Love that this video is in "dark mode". So much easier on the eyes.

[@kellyfernandx]

I'm studying this to help my fiancé answer a test at work... omg this is so complicated lol the engineering behind airplanes is just insane... amazing

[@BlackFoxFalcon]

Masterpiece of engineering. Like pretty much everything in aviation.

[@flapjack413]

I've always wondered where the air intake for an APU was. Very cool!

[@주인공-m7t]

crazy quality I’ve ever seen about APU

[@DavK637]

this is a damn good animation for those that are visual learners. thank you aircraft science for taking the time to make this

[@demal1010]

Heading been a ramp agent for a certain amount of time for a regional carrier, who used CRJ200's that had the APU exhaust at ground level, you had to walk quickly past all the heat if you were walking back there. (However in frigid temps it was a nice heat source outdoors lol)

[@grantnaval4519]

Now this. Is improvement! Amazingly done as always. From GE90 engine start and now goin' to the APU! Amazing and great! Thank you for this. As an aircraft mechanic with this type training. YOU MADE EXPLAINING. Easy. Always here to watch and see you go!

[@AircraftScience]

Thanks a lot!

[@gepset]

Great video. Interesting to see the APU follow the traditional British jet layout.

[@CHOXON2CHOXOFF]

As usual, awesome animation and detailed. Keep going, we need such videos in our field for better understanding.

[@AircraftScience]

Thanks, will do!

[@oOSpecialProskillsOo]

i am probably never going to need this knowledge, but it was very well broken down and presented, great job

[@Denis_mkay]

This was excellent. Your videos are getting better with every release. Thanks heaps!

[@AircraftScience]

My pleasure!

[@XzX-7]

Good information / Good graphics

[@jeylful]

Fabulous animation and explanation! Thank you!

[@eneebarry6764]

It’s absolute and beautifully crafted animation and perfectly rendered here. Tombs up.

[@rhiannacoady8370]

I will be starting to make these in Honeywell in a few weeks!! So excited!

[@pdks7088]

Absolutely amazing work. So helpful video!

[@ccacrislan]

Absolutely brilliant, I really like and appreciate your job. Thank you. Always looking forward for more of your videos.

[@AircraftScience]

Many thanks!

[@spvillano]

I remember starting the APU back before all of that automation existed. Spin it up, wait for 5% speed to cut in fuel, 7 - 10% one hit the igniters, 50% cut off igniters, wait for it to spool up and stabilize then switch in the loads, all while monitoring pressure increasing in the chamber. Now, it's pretty much turn it to start, automation does the rest. Same basic sequence for any other turbine engine, be it a turboprop or fanjet. The primary difference is that the APU is smaller and speed governed. Ground air start, there it could get a bit more complicated. Don't get that hose connector properly seated and locked, you've got a massive coupler at the end of 3 1/2 inches of hose angry and flopping around on the ground trying to smash something or someone... Old air start carts had a regular piston engine that drove a compressor to pressurize a 8 - 10 foot long tank to around 400 PSI, governed down to 40 PSI output. Newer units use an APU for the engine and bleed air and are a lot smaller and also automated start. Turbine engines are simple in construction, complex in actually making them work, as any measurable runout on a bearing and the turbine or compressor will contact static components and shred the works. So, my hat off to the men and women that keep those spinny things spinning safely! Those simple devices are complex to keep them reliable, after all. And remember, Scully couldn't have put that airplane safely down without that APU.

[@john.enospahitamos3596]

Dont stop please. Thanks!

[@EleanorPeterson]

And to think: in the 1960s there was just a stewardess pedalling a static bicycle hooked up to a generator in a cubicle behind the toilets. (🚴

[@11snakePlayz]

This will be very useful for a project I'm working on in a game I play.

[@lmoraz]

Very good animation.. waiting for part 2, thanks

[@lunganzimande8056]

Awesome video! Better than most CBTs

[@seantaggart7382]

The apu is awesome Its more than just a starter Its backup power and Emergency pneumatic! Its nice

[@zlatimirzdravkov8940]

Thanks ! Useful video ! I guess it took you thousands of hours hard work!

[@matthaxx7137]

Thanks. Question: Does the pawl clutch run the ratchets continuously after starting or is there some sort of disengagement mechanism once the APU is up to speed? Seems that there would be a lot of wear otherwise.

[@AircraftScience]

The clutch disengages once the motor stops at 50% RPM. As the engine speed increases, the pawls move outward against their spring tension due to centrifugal force. This eliminates contact and thereby reduces wear.

[@ryanreedgibson]

When will part two be done?

[@AircraftScience]

Hopefully, late January.

[@alexkazzeo6208]

Fantastic graphics, excellent explanation. Superbly done. Better than the Boeing one. Teach them something.

[@garyroachester1500]

Great presentation! can't wait for part 2

[@troybowen3024]

You Really Haft To Be A Genius To Be A Pilot And Designer And Innovator Of These Jet Engines I Tip My Hat To Them

[@motionsick]

This complexity is the reason there are no competitors to Boeing and Airbus. Such a colossal undertaking building a single one of these aircraft.

[@alirezamkz9688]

It was nice explanation thank you

[@demal1010]

Would have been nice to see the pneumatic start option as well as the electric. It's not available till an engine or exterior air supply is running, so i hope it will be covered in an upcoming video.

[@AircraftScience]

I will cover the pneumatic start system in the APU bleed air section of the series.

[@russchadwell]

Are there any "APU" engines that might be rigged to fly some sort of small aircraft? A means for some hobbiest to get some inexpensive second hand "jet" engines.

[@naylinasha4719]

very helpful !!! thank you so much for this video 🙏🙏🙏

[@AircraftScience]

My pleasure 😊

[@ivanltrinidad8598]

exelent video wow!!! EXELENT!!!

[@AircraftScience]

Thanks!

[@dalemanolas5994]

Is the alternator permanently geared in or does it have an electric clutch to engage it once the APU gets up to speed? Presumably the APU drives a hydraulic pump as well. Does that have a clutch? I'm just wondering if the starter motor has to spin all that stuff or is all of that disengaged during starting?

[@humphrey.b]

Best visual video & best explanation ever!! ❤️❤️❤️

[@chrisalister2297]

First video watched, subscribed.

[@jiriprochazka9254]

What if it's raining and air inlet door are open? Is there some filter to prevent water getting inside the APU turbine?

[@JanV29]

Your videos are bonkers man !! Love them ❤

[@AircraftScience]

Thank you!

[@davecrupel2817]

So the 777 apu has a pneumatic start option. Interesting. Makes sense if it needs to crank at altitude, and you want to conserve bat power.

[@lilawaffel186]

Where is part 2? This is so good thank you!

[@AircraftScience]

I'm working on it!

[@udayakumar5348]

Small turbine works behind produce small amount of electricity and A/c to cabin and also bleed air to start engine

[@vishwajeet7806]

Very nicely explained ❤

[@Gabidulla-p6c]

it's good job, wonderful,brilliant

[@Djunturica]

Brilliant videos!

[@dilandias4018]

Awsome bro....thank you for such videos

[@AircraftScience]

My pleasure!

[@HurinisEbuega]

why igntion and fuel supply on APU take plase with 7%, but ignition and fuel supply on main engine on 21%?

[@chrisfox3161]

Single shaft turbo jet, no bypass, will idle at around the 30% mark. A large multispool will idle at at over 60% HP compressor speed. It's not so much the rpm % as the amount of air going through the core.

[@jaiyp77]

I'm very amazed with your animation videos, it really helps to fill my knowledge. But there's something I'm wondering about the engine, how does the fuel metering system work?

[@AircraftScience]

Hi, I have plans to cover this topic in the APU performance (part 3) video.

[@jaiyp77]

@@AircraftScience Thank you very much

[@Kirmo13]

is the RPM expressed as a percentage of maximum speed?

[@AircraftScience]

Yes!

[@richardbriansmith8562]

Awesome Video 😊

[@HurinisEbuega]

why compressor wheels look like centrifugal compressor, unlike compressor wheels of main engine?

[@chrisfox3161]

They far more robust than an axial flow compressor and cheaper/easier to produce.

[@kh40yr]

The Key Bird. After an extensive restoration in the frozen wasteland to fly home, once running was attempting to take-off on all 4, the restored 2 stroke APU rattled free, shorted out on the fuselage, and burned the craft to the ground. A volunteer mechanic lost his life during that restoration.

[@HurinisEbuega]

3:11 you say that fuel cluster consists of mech pump etc. Then you say that controller commands the fuel valve, and nothing about pump

[@r.robbie7918]

Great, ending this interesting episode without telling me HOW electricity and hydrolic pressure is generated... I assume it is coupled somewhere.

[@stachowi]

This channel is amazing.

[@rickybrazzell7348]

Nice presentation but where is the generator part of the APU?

[@AircraftScience]

Coming soon!

[@mubashirghani9344]

Please make video on APU bearings and seals..

[@AircraftScience]

Noted!

[@abdulla9042]

Hello, I can translate your video?

[@WhyHow-vn6fo]

What software did u use bro

[@AircraftScience]

Blender.

[@WhyHow-vn6fo]

Tq for ur reply and please upload some videos about modelling

[@southernpilot]

That was very well done.

[@mahmoodtariq7535]

Amazing video has been created...thanks a lot

[@AircraftScience]

Most welcome!

[@chitralisontakke7186]

Waiting for part 2!

[@Magan-lg4bc]

Absolute GREAT.

[@artysanmobile]

Superb video!

[@jepleas9159]

The dark shadows with the black background make the details difficult to see. KZbin animators like Jared Owen and AiTelly include more contrasting shades and colors to make the details more visible. Nice work. Your effort really shows.

[@BobSmith1980.]

I love the graphics

[@maheshanura5413]

Thank you very much sir.....🙏🙏🙏

[@AircraftScience]

Most welcome

[@sssaeedssahz.1434]

Excellent👌❤

[@marioecheverria5152]

Where is the generator?? You explain the mechanical turbine but… the electrical part?

[@AircraftScience]

Part 2!

[@AusticHardOfHearingSinger]

Nice!

[@Lx-photos]

Very dark. Nothing visible.

[@musiegirma2728]

Can you do for airbus apu

[@SticksTheFox]

The Video: Informative, technical, intresting The Music: Battlefield Butt Rock/ Command & Conquer

[@orunabho]

I always thought there is an internal combustion engine there, a motor at work there. O, a jet engine!!! Nicely explained. What about thrusts it generates?

[@justing42]

It is negligible. They shut it off after engine start.

[@josephjeno6709]

When will come next part video

[@agungdwif]

Part 2???

[@randygravel2057]

Ok this video ends where the apu is running. You forgot to tell how is the electricity made. Where is the “auxiliary power” made?

[@formatogrande397]

brilliant content

[@myheart-ok4ie]

We want a video of how to run the engine via the APU

[@AircraftScience]

The main engine start will be covered in the second part of the series.

[@MonkPetite]

And apu with an air starter as an option ? That’s a wrong stament. The igniters work before fuel is added. Fuel nozzles are mostly duplex. Meaning they have two stage function for starting and normal operations, you can’t dump all fuel less the 40 %.

[@PeterWu-n8s]

Nice education video ❤! How about pneumatic start! Never use on line ! Ha!😂

[@juggsauce]

Always wanted to find a timed-out, old apu and put it in an old truck. Power an electric motor. Wouldn't be very efficient but fuck would it be cool.

[@CybershamanX]

(0:23) Oooo... So shiny! 😉😎

[@tumurbaatarchinzorig273]

Landing gear pls

[@AircraftScience]

The next series will be on landing gear.

[@tumurbaatarchinzorig273]

@@AircraftScience Thank you so much!

[@apivovarov2]

turbine blades should be curved opposite to what is shown on the video . The angle is ok, but the curvature shape is not

[@n.s.shankar]

Brilliant❤

[@LezamaDamian]

Nice video. However, it's kind of too slow with long pauses, it would be way better if it were more dynamic. Also is it a human narrator or AI? A little more emotion would not hurt either 😊

[@AircraftScience]

Noted!

[@lordpickle8424]

Thank you, come again!

[@zachansen8293]

that was a REALLY well done video. I'm much more likely to downvote a bad video than upvote a good one but I had nothing bad to say about this other than I'm sad the next one isn't out yet.

[@keitha.9788]

Get rid of the black background. It will increase the contrast and makes your diagrams more visible....

[@Nurhadi98-e6t]

yes gud thank's

[@RounakKushwaha]

Sooo good

[@Takeitlightly6]

That plane looks very pimped