The Secret Boeing 737 Jet engine
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- Опубликовано: 31 май 2024
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Today I will be giving you another technical video describing the APU, the third Jet-engine of the Boeing 737. We will be discussing limitations, what it is used for and what happens if you DON´T have an APU available.
As always I would love to hear from you about the questions YOU are wondering about. Make sure to send in a comment below, give the video a like and subscribe to the channel.
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Please don’t make a habit of these clickbait titles. Believe it or not even the layperson could probably hang with an honest technical title. And even so most of us who watch your videos aren’t “the average” person.
@Mentour Pilot Just got a bit confused where you said the the ground start unit connects to the right hand side of the aircraft which means you can only start engine number one ..isn't engine number 2 on the right where the starter unit would be?
Also, how is the APU itself started? Since the jet engines need the power from the APU, what does the APU get its power from to start?
Lucifer Morningstar hi! What do you think should be the title of the video? Even though I agree this title is quite basic I think it would be very approachable for people that aren’t into aviation (yet).
Stephanie either the GPU power or battery power. On some military aircraft the APU is started by hydraulics.
‼️Help MENTOUR PILOT‼️ In X-Plane-11, when I manually start engines , while on takeoff roll with TOGA, the thrust percentage goes all the way till 103%, and turns red, it goes back to normal after rotating. Why does this occur only when I do a manual startup from cold and dark? Any switch I forgot to turn off/on or is it the 🌡️flex temperature in FMC?
Its the spare engine, In case of a engine failure in mid air they can pull over and install it
😂😂😂
Wait I got lost at the pull over step can you please explain?
@@zachary456 If the engine fails in mid air the plane pulls the side of the sky to change out the engine
Lmfao
They only need to land in one big cloud, exit and change it 😀 , if there are some angels on the cloud, they can ask them to change it, they are pretty good doing it 😉
I once had a somewhat interesting run in with an APU in Kansas City, we flew in on a 737 and all of a sudden the cabin filled with a thick white smoke that got so thick that you couldn’t see the seat in front of you, it was quite scary. We were all quickly evacuated by the flight atttendants and once safely in the terminal (which started to fill with the thick white smoke coming from the jet bridge) we found out that there was an oil leak with the APU and it hit the exhaust and started a small fire which was the source of the smoke. We got a new plane and after an hours delay we were on the way to Florida with free drinks!
You: APUs are important because ....
Me: Hey the dog moved. He is very sleepy.
APU: Most often used at JFK when the aircraft has to wait in the standby area for an hour because their IFR release got missed/delayed or after landing and there there is no gate available.
Ha, try LaGuardia. What the hell’s a gate?
Makes me wonder if the fuel supplier is paying off controllers to slow things down.
Do they still put you in holding patterns partway along the east coast routes causing you to need more fuel when you land like they used to.
@@waynep343 It's just a busy mess with JFK, LaGuardia and Newark all in close proximity and sharing the same airspace. Also, JFK has a lot of different international airlines, many of which don't have gate/stand leases so it's "first come, first serve" on gate availability. In both cases, planes often have to spend extended time waiting for their slot so they often shut down the main engines and run off the APU to conserce fuel.
@@waynep343 It's just a busy mess with JFK, LaGuardia and Newark all in close proximity and sharing the same airspace. Also, JFK has a lot of different international airlines, many of which don't have gate/stand leases so it's "first come, first serve" on gate availability. In both cases, planes often have to spend extended time waiting for their slot so they often shut down the main engines and run off the APU to conserce fuel.
@Mr Horse yep. I am a stupid car driver. Who never buys Chevron or standard fuels. Because of their history of overthrows of countries and covert wars to do so
I was on a plane at ATL, just before pushback, the APU went out and so did all the lights and electric power on the plane, they had to
wheel a portable power generator out and hook it up to the plane.
Dog: "Oh Geez, he is going to talk planes again."
Actually, it's muzik to his ears
I have been an APU mechanic for over 30 years and I have one thing to say to all pilots and mechanics............NEVER pull the circuit breaker to avoid the cool down period!! it wreaks havoc on the turbine bearing area and reduces the life of the hot section. Some of the newer engines have some very complex technology incorporated to extend hot section life and aborting the cool down will cause excessive stress and reduce hot section life. It will also cause excessive oil coking in the turbine bearing area. To give an idea, the cost to replace the first stage blades on a 331-500B (777-All), can exceed 250K USD. Take care of the APU like you would as the GE90s or CF6s. They are not cheap to repair/replace.
Great vid.
MJA6995 The fault history is always 30 pages (of 30) on the cdu mainly becauce pilots cut the power before the cool down period🤭
Ahh, those start carts. Using a turbine to spin a turbine when then starts another turbine, from which that turbine spins another turbine to start that turbine. You've gotta love aviation.
The start cart for an SR-71 uses two V8 chevvy engines.
Gordon Lawrence but they did end up switching to a turbine start cart later.
@@gordonlawrence1448 Yeah, they called it The Buick. I remember seeing something about that. Also, the SR-71 was unable to take off with a full load of fuel, it had to take off nearly empty and refuel in mid-air.
😂
Moon Moon TWA.... old Smokey... also Buick.... 😂 1011 start cart... tried and true!
I'm going to start calling APUs "secret engines" just to mess with people now
Same
Start calling all planes with APUs trijets, that will need with people even more
@@CaptainChrom So that means trijets were actually quad jets then if trijets had apu's.
@@markvolpe2305 and quadjets are (close to being "were" now) what? pentajets?
@@sh230968 I was thinking the same
Good job on keeping a straight face when saying "the big airhole" :)
Very good description of the APU and its function. One thing to remember about the APU, in response to some of the comments about using other types of engines, is this. The APU bleed air is by design close to 400F degrees. This is not by accident. As you pointed out, the APU is used as a bleed source to run the Air Conditioning Packs. Each pack has a component in it called an Air Cycle Machine. That device works on thermal expansion, using bleed air to drive a turbine, which in turn drives a compressor. The 737 bleed system controls bleed temperature between 390 - 440F, because that nominal temperature works most efficiently for the Air Cycle Machine. The APU providing a bleed air source at this temperature is right for the Air Conditioning Packs and the Air Turbine Starter efficiency.
If I remember correctly, one of the first things "Sully" did after the bird strike, was to start the APU.
Great video Petter, and an amazing pice of machinery.
That is correct! 👍
Yes because it gave him full electrical and hydraulic power and put the plane back into normal law so it wouldn’t stall
@@tomstravels520 the plane not being in normal mode doesn't automatically result in it stalling.
It results in you being able to stall it if you really wanted to. (and a lot of other things)
You are correct! On the Pakistan International crash PK8303 on 22.05.2020 the Airbus automatically deployed the RAT" RamAirTurbine" to produce the power. Good pilots save lives.
MadDog95 I didn’t say that. I said the plane being in normal law prevented the plane from accidentally being stalled and meant it wouldn’t exceed its flight envelope. Meant sully could fly the plane at minimum speed safely
I'm gonna need an APU installed at my house here in Texas to run my A/C so I can finally get my house cooled down
Still needing that secret engine?
@@johnbuyers8095 yes. You need to cool down the house even further
Little did That Guy know that one day his APU would be used to _heat up_ his Texas home...
You're just wearing too many clothes :)
Aged like milk
Thumbnail: secret engine.
Me: A P U, I know but I watch anyway.
Same
Same
Same
Same
Same
I just have to say I've watched almost all your videos. Your professionalism and positive attitude come through well in your presentation. I find aviation fascinating, but your personality sets your channel apart from the rest!
On the B-17 and other bombers during WWII the "APU" was a piston driven engine which the crew called a "putt-putt" because it sounded like a one cylinder motorbike.
Many of them were single cylinder air cooled motors no? One of my fav RUclipsrs got one and made a cool chopper style motorized bike from one.
I remember the first time I fly on a 737. (1976). I heard what I thought was an engine running, but as I learned later, it was the APU. I had no idea there was an APU in an aircraft. Certainly makes a lot of sense, though. You can be self sufficient while waiting for push-back. The amount of thought and engineering that goes into an aircraft is amazing. I've had the opportunity to fly in a 737-NG simulator. Very cool! With some practice, I was able to land by myself!
Love you videos!
Great stuff! Thank you!
His dogs are too adorable ... Sometimes i also gave attention to Aircraft stuff ☺️
They look tasty
I built a bunch of these APUs at the Garrett Honeywell gas turbine plant at Sky Harbor in Phoenix. A nice little turbine APU for military and civilian aircraft. Also spent a some time at Pratt & Whitney and at the U.S. Army engine plant in Stratford, CT building AGT-1500 turbines for the Abrams main battle tank...fun times.
Excellent video. I am a retired pilot with more than 6000 hours as PIC on B732 mostly, a few hundreds on the B734. I love the B737, magnificent airplane.
The Convair 580 had a "Secret" Engine inside the number 2 engine QEC (Quick Engine Change) nacelle. It's called the GTC (Gas Turbine Compressor) It's used for starting the Allison 501D13 turbo props.
On the Convair 580 the GTC could only give air pressure but not enough electric power for aircraft operation.
You are definitely a very good instructor. I hope you could be my CFI. I understood perfectly everything you said. Thank you. Educational RUclips. I checked everything and you gave also a hands on approach, practical view. Very good.
Y’all he’s talking about the Planus
Oh god you’re a Funny 😂
Amazing timing. My last flight, on a 321 neo, had an apu related issue as we were about to line up for take off. We sat for quite a while then had to return to the gate. After a 2 hour wait during which engineers came on board we were cleared to go without the apu functioning because of a valve related issue. We did need the big power unit to start the engine and went through the second engine start up exactly as described in the video.
The dog is listening carefully and studying up for the next dog fight with the Red Baron.
Dog "Silly hooman, talking with the empty air again....! Let's sleep some more, maybe he comes to his senses!"
I have been watching a couple of your posts and I am impressed by the professional way you are dealing with all the different scenarios that you are coming up with. And most impressing to me as somebody who is not a native speaker of English (German from Bavaria, grown up with American English), is that I feel that I get to understand even the subtlest hints when you deliberately want to be as diplomatically as possible. Please keep up that good work, for a flying buff like me your channel makes my day (sorry for citing Clint...) 🙂
It's ok there comes a time in every mans life when he learns there's two holes down there and not just one.
Technically girls have 3 the 3 ps
Men have just 2
😂😂
@@markmitchell450 This is beyond technical.
When I was younger I used to see the exhaust coming from the back of the plane and it really confused me because I wondered how the engine exhaust was coming out the back. Learned a few years ago that it was a separate engine in the tail.
I prefer to have a vissual representation of where you're talking about like pictures. great explaining though.
Yes
New follower here. It's a pleasure to listen to you, you are a natural born teacher. And since I don't know much about aviation but love engineering things, I marvel about everything. Thanks!
9:39. Coincidentally, at the same moment the picture of those B-52 engines showed up, the fan in my laptop ramped up to 100%. I think it's getting jealous of all the jet engine videos I've been watchin
Video idea - On the airplanes used for zero-G flights, are any modifications needed for any of the liquid handling systems: fuel, hydraulic, engine oil, toilets? I know this isn't your area of expertise, but I wouldn't be surprised if you have connections.
Interesting question. Now I'm wondering about the same. I presume at least the toilet will have had a bit of a redesign.
I guess it would be pressurised
@@Robvdh87 I did a little googling, and the only thing I found was a NASA paper from 1966. They were using an AJ2 aircraft that was powered by 2 piston engines and one jet engine. They said the fuel system didn't require any modifications. The oil system for the jet also didn't require modifications, but centrifugal air/oil separators were added for the piston engines.
Since I haven't found anything that says system changes are needed (on the current zero-G planes), I'm leaning toward them not being necessary. I personally suspect the toilets are the least likely to need any modifications. Unlike the other systems, they don't need to move any fluids while in zero-G. They only need to contain them. The toilets are undoubtedly already designed to keep things contained in rough air (including short duration negative and zero-g). A longer duration zero-g situation probably doesn't open up any new leak paths.
@@leonperry123 I'm not sure which system you are referring to being pressurized, but pressurization is not necessarily a solution.
For example, take a typical hand-portable water fire extinguisher -- you know, those silver ones on the wall that are about 7 inches (180 mm) in diameter and 2 feet (600 mm) tall. If you turn it up-side-down and squeeze the trigger, you will get almost no water out of it, just air. This is because the water pickup is at the bottom of the tank where gravity normally keeps the water. When up-side-down, there is air at the pickup.
In zero-G, you can't really predict where in the tank the water and the air will be. Regardless of how you hold the tank, you might get water, or air, or some of both when you pull the trigger on the fire extinguisher.
A bladder in the tank is one solution for this (basically a heavy balloon in the tank). The fluid is on one side of the bladder and the air (or other gas) is on the other side. The bladder keeps the air and fluid from mixing, so any time you draw off fluid, there is no chance of getting air. Some of the aerosol cans that can be used in any orientation use a this.
For inverted flight, military engines often have a weighted, moveable oil pickup tube inside the oil reservoir, such that the intake is always "down" regardless of aircraft orientation. Obviously, passenger type engines, don't have this system, but even Tex Johnston knew how to maintain a +1G barrel roll!
If you haven't already done a video on the following, please could you explain the APU, main engine start and AC configuration for airports above 10,000 feet.
When you are outside of a jet that is ready to start engines you hear a clicking or ticking sound, then the APU starts to spool up to full start speed, fuel is started into the APU. The APU finally fires and once up to speed the APU will force air into the main engines using the same basic startup procedure as the APU, spark, compressed air & then fuel. A huffer is the ground power starting unit.
Amazing so much mental and technical prep goes into piloting this and any aircraft.
Think the dogs have heard it all before. Thanks for the info. Stay safe. Mick🇬🇧
What about anti-gravity systems and zero point energy generators?
I hope this is just a joke.
sorry bro but we haven't found the stargate yet when we do we will wait for the right solar flair and send you back to your time period you came from.
A friend of mine who works in aviation told me the technical term for “anti-gravity system” is called the “wings”.
Jess Hull you’re a bit slow on the uptake.
@@Make-Asylums-Great-Again it seems you're likely the slow one. you're replying to comments that are over a month old.
As someone who once made aero parts that flew I loved your Informative video- Thankyou - IAN - UK.
Your videos are always full of interesting surprises. Thanks again!
I couldn't stop staring at the dog
Which of them?
I hate dogs.
You're a dog
@@stalinneger5029 They're called Patxi and Molly.
@@phorzer32 Sorry for your loss
Another great video mentour! I found this one very interesting! Keep up the good work !!
Thank you! I’m so glad you liked it!
Wow, lots of info. Love your channel! It helps me when I fly to sort of know what is going on.
Been watching for a little over a year. Your context is excellent!
The SR 71 used to use two buick V8s from race cars to start its engines.. It was the craziest thing you'll ever hear..
Brilliantly explained as ever. Thanks.
One other important thing that was not discussed: The APU provides bleed air to start the engines. For safety, turbofan engines also need bleed air to shut down. Why during shutdown? Well, during engine start or shut down a tailpipe fire can happen, which is unburned fuel reacting with the hot surfaces and igniting. This can damage the tailcone of the engine and even light the wing on fire if left unchecked. So having bleed air available lets you windmill the engine (spinning the engine with the bleed air starter, but ignition is turned off). The resulting air flow through the engine extinguishes the fire by "blowing" it out. The "start cart" provides this same safety measure. In the Navy, we called these "Huffers".
Not only does the APU keep the ship warm, it charges the batteries and all the lighting needed especially in winter. If I recall its a helicopter engine about 400 up.
But it also gave us techs if walking about on the ground a bit of relief with massive heat wave when 35 below zero. It's just not very good air filled with exhaust and some passengers more than likely smelled this exhaust when first getting on board as it enters cabin if wind helps it get into air vent ports up front.
One hole at the back means it's a boy plane. Two holes, it's a girl.
Big funny
😆😆😆😆😆 you made my day
And a 1+2 gets a little Cessna
@@iinotpxnda Remember, you may experience a delay getting to your destination during mating season.
Karens be like: STUPID PLANES DONT HAVE GENDERS DUMBASS
I can't even comprehend the engineering and then different manufacturer's that go into this process
Videos like this is why Mentour is the best
Hello sir, as u told there are two holes in the back, one is for APU exhaust and the other one is for cool air intake. But, it might be possible that the cool air vent can suck the hot exhaust, as both the holes are nearer to each other.
Love your dog just chilling out. Looks similar to my Cocoa........
I love your videos ... but I also love almost just as much how relaxed your two dogs are, every single time! I asume and hope you keep them running and busy on other instances during the day 😉
Thanks so much for that video on APU that answered quite a few questions I Had.
Great stuff!
It's an APU mainly used as a Back Up Generator!!! The air is a bonus and if it's broken it can be MEL'd ATA Chapter 49 or the Air can be MEL'd CHAPTER 36 or the Electrics can be MEL'd CHAPTER 24 there you go sorted
The air is a bonus!? 🤪 Its a must🤨It is a ATA 49 cat C MEL only☝🏻Is your MRO African or what?!😂🤚🏻
Great video, Petter! Can you do one on Fuel Imbalance. Do you check on the ground for this or in the air? Is there a memory item for Fuel Leak and/or Fuel Imbalance?
13:10 Omg, the puppy almost ate a fly!!
That puppy is so fast he put Bruce Lee to shame.
He just missed out on a little snack! ;)
Mentour pilot, your an awesome pilot man! I love your videos your explanations are great. Keep them up
And APU is used in flight on EDTO segments, as our company policy. Since 3 independent electrical sources are needed in an EDTO sector.
Theres always that one person when you boarding the aircraft
Lady: is the engine already on? We're not even on the plane
Me: no
Lady: then what's that engine sound
Me: the apu the power generater when the engines are off
Lady: NERD
@PETER ZARI you asked, deal with the answer
Lady: but the fan is rotating.
(wind rotates it)
No one says that lmao
@@yazzy4175 I sometimes here that lol😂
most of the time i'd say fuel pumps
Great now had flash backs of all the times the apu failed after it was started and then look at each other with the oh crap look. Now can't get the sound of the air start out of my head haha
Yeah, I know! 😂😂
@@MentourPilot I did 10 years on the ramp and some of things you mentioned about the apu I didn't even know but sure did love how quiet the 737-700s, 800s, and 900s apu were. MD80 apus sucked when decieing due the apu exhaust right below the tail facing up blowing the decieing fluid back in the face
Great one Peter, nice to see you often the last days!
Running APU also gives another 3.5kN additional thrust, with a minor Vmax increase. FYI for the speed freaks!
John Smith Please give the reference for that. The APU gives no additional thrust that is given in the Boeing 737NG AMM or the Honeywell 131-9 spec.
@@speedbird9313 If the APU was providing bleed air, the engines would have more power. I don't know if they would provide an additional 3.5 kN but there would be an increase in thrust. The APU itself won't provide thrust.
No, it's Apu the Indian jet engine!
Can you please ex-plane the joke?
Flipidy_Arif I could, but I’m not sure it would land
@@ScramasaxeRA ok ok I see what you did there
thats a pretty turbulent joke not gonna fly.
@@wzr3293 listen, with that kind of drag, we aren't going to get anywhere
Just curious, how often do you practice starting the #1 engine with a start cart while on revenue flights? Or is this something that is just practiced in the sim?
Also known as the world's most expensive kettle.😊😉
Great video as always Petter.
I just started up E195 with APU INOP using the Air Starter at work :)
Actually a jet engine is used for jet propulsion. An APU doesn't generate an appreciable amount of thrust because it converts heat into kinetic energy that either pressurized hydraulic and/or pneumatic lines and/or turns a generator.
Some non-jet engines do produce enough thrust to make a difference. The Lockheed L-188 Electra has short wings that rely on powerful turboprop engines to blow enough air over them to produce lift. The turboshaft motors that turn the propellers also make enough thrust that L-188 pilots have reported having to apply reverse propeller pitch to keep from overheating the brakes while on taxi.
Technically the jet engine in a APU would be called a Turbo Jet in that the jet engine part is powering turbine blades that are in turn providing the mechanical power that you need. Helicopters, Turbo-prop aircraft and APU's fall into this category. Most modern airliners are Turbo Jet's with their High Bypass Engines where the jet engine provides part of the thrust but the huge turbine blades also provide thrust.
@@johnknapp952 My understanding is that a turboshaft engine is what you call a turbine engine that uses most of its power for turning a PTO. A turbojet is something that was being phased out when I was little, those had no fans, only the thrust from the gasses coming out the tailpipe was used for propulsion. Turbofan engines have bypass fans that make thrust pushing some air around the engine core. A low bypass turbofan makes less than half its thrust from the fan, and high bypass makes more than half from the fan.
I had a chart of efficiency vs. various parameters, and turbojets aren't very efficient except at very high altitudes and speeds (like Mach 2+), which is why most military fighter jets use low bypass turbofans and afterburners. High bypass turbofans are ideal for jets that spend most of the time above 30,000 feet at close to Mach 1, and turboshaft is most efficient at everything below that. That's why a regional prop plane makes more sense than a jet of a similar size. And helicopters are mostly low and slow.
Doggo sleeping looking real cute
Yep. He always is. Cute that is. :)
@@EphemeralProductions usually sleeping too tbh
13:43 I'm sure it's been mentioned many times before, but it's mindboggling that smoking used to be tolerated on planes for so long. It's like running hurdles with an unsheathed knife in ones pocket!
I made and still make the molds for the multiple castings used in each of these units. The foundry where I used to work made thousands of these castings over the years. Interesting units. The engineering is amazing.
Can you do a video about what happens when you get "behind the power curve" and what circumstances would cause you to get there, and how to recover? You've never talked about it, so does that even affect heavy aircraft, or is only a phenomenon that private pilots need to be aware of?
Great idea!
I'm open to that.🙊
I'm not familiar with this slang terminology, what is "behind the power curve"?
@@mytech6779 It's not slang or jargon. It's something you'll learn (or should have learned) about in ground school. Your flight instructor may or may not have also talked to you about it. I'm not a CFI, so I'll defer to Petter to explain it...
MyTech google is your friend
The dog seems riveted by this discussion.
But love having him at home!
Which one?
I discovered this channel recently and have been binge watching it. The next time I fly (very soon I hope) is going to be much more interesting. I won't be able to look at the aircraft, airports and all the supporting equipment the same way again. I wish it were possible to book a jump-seat ticket! But I understand why that can never safely be a thing.
In 1995 my family flew to Tenerife, and my elder brother got to see the cockpit and said he was able to steer the plane by twisting a little knob. That never made sense to me until recently as I knew planes had control sticks or wheels. Since getting into flight simulators during lockdown I finally figured out that the captain must have let him adjust the heading adjustment knob one way then back again. I'm still jealous I never got to do that!
If I could start life over again I'd definitely train to be and hopefully become a pilot.
That was straight forward. Didn't know it provided the power on the ground for a/c.
0:47 Doggo experiences landing gear failure during taxi
There is nothing secret about an APU.
ssshhht, FAA is waching
Not everyone knows about it so let those who don’t know much about planes watch in peace
@@tomstravels520 Sure. Nobody is saying they can't watch the video. But the lack of knowledge is not the same as a secret so the title is clickbait. A critique is not the same as taking anything away from anyone.
All planes use AC power? Do they also have DC batteries?
Catalin Alb yes
At MSP for Delta, they run APUs when its 90F/32C or above since the jetbridge air cant keep up, and during the winter, they run them when its below 20F / -6C. During the winter is when they request APU fuel for overnight rons when they spend the night at the gate.... During the summer though, all that heat from the APU exhaust is annoying for workers like myself when the temp is already very uncomfortable, let along 400F+ air shooting out of the packs and APUs to add to that.... However, when its the winter, that heat is awesome to warm yourself up especially during the polar vortexes we get where temps drop below -40F/C. Yea, we get colder temps here in Minnesota than even Anchorage, Alaska.
Well that explains the exhaust in the rear I have always wondered what it was for.
Did the old tri-jets also have APUs? If so where, how, why?
727s had the APU located in the main wheel well.
I thought you are going to talk about the new warning over the older 737 engine failure by the FAA.
CNN: FAA issues emergency notice about Boeing 737
An advisory about the 5th stage compressor relief valve getting corroded while in storage. Not a big deal cool your jets K...Watch blancolirio on You Tube He explains it well... Ask @Mentour Pilot, he will agree about his friend being knowledgeable.. I dare ya...
@@paulsilva3346 LOL
@Mr Horse I feel the need-the need for speed! Oww!!
BLEED VALVE NOT ENGINE
Funny. I always thought the aft ports in the tail were to dump fuel. Thanks for the info!
Great podcast, very informative. Thank you!
737: Engines fail
Me: *panik*
APU generator: exists
Me: *kalm*
APU : fails
Me : *panik*
Im in heaven: *kalm*
but you actually aren’t : *panik*
When you walk up in bed: *kalm*
but you realize that it's your first class seat and the aircraft is nose-diving : *panik*
How much additional thrust do you get out of the main engines, when getting all bleed air from the APU? Are we talking about a 10% increase, or what?
What exactly is your question. The apu just powers things while the main engines are off and assists in starting the mains. It's not like a turbo that adds power to them while in operation.
@@MrTheWeedMan007 He's asking about the main engines. By not having the bleed air coming out of them, how much of a thrust boost is that? I don't think he's talking about the APU itself providing thrust.
I think I see what you're saying... 10% seems a bit generous, given the overall power of the mains. Interesting question, though.
@@samrobinson9110 the apu does not boost the engines lol it simply provides power to the aircraft when the mains are off and it provides the bleed air to start the mains. It isn't a turbo or anything like that it does not provide any thrust
BirdValiant i think the other way you can get a better idea would to be think , that what is the maximum thrust generated by the engines in optimal conditions and then just subtract the loss of thrust because of the bleed air intake which goes in power generation.
Your dog looks like it could use an APU. A little sleepy in this video.
Heck, I could use an APU myself, ha ha.
Thanks for the video. Great content.
Had a 738 scheduled to depart ENTO, had a known APU low oil situation but airport assured ground power would be available for start so both engines were shut down at gate. Turned out that the Dash-8 GPUs weren't powerful enough to get it started, and the only big unit was out of order... Had to get a spare plane flown in the next day to get the pax to destination, then wait another couple of days for someone to fix the starter (and the APU)
Mention of secret engine is just a click bait. Actually, this channel does not need click bait. I personally try to watch the video as soon as I get it.
Yeah it's a bit annoying because his videos are fantastic as they are. I am not the biggest fan of clickbait.
What would you have suggested as the title?
@@MentourPilot Boeing 737 APU Explained (for example).
for most ppl it was a secret
@@piotrkuler2474 Like I said: lack of knowledge is not the same as it being a secret. Come on now.
Petition to start calling the APU a Planus
Fantastic podcast as always! I would be great if You could do a podcast about crash of PLF101 (TU-154) flight in Smolensk.
I flew an EasyJet flight earlier this year where the pilot announced before takeoff that there was an APU problem but it's nothing to worry about. The flight was normal as far as I could tell too.
Yep, apart from the engine start it’s pretty much normal sailing.
Technically not a jet engine, since producing a jet is not its primary purpose, but generating torque as in turboprops, which would make it a turboshaft. (Still a gas turbine, though!) :)
I think you're right about classifying it as a turboshaft, though the dual purpose with supplying presurized bleed air makes it a little less clear cut.
@@FireStormOOO_ I think that does not really matter, since even if used for bleed air, it is still not generating a significant jet. But the term gas turbine always works in these cases.
@@Puukiuuki Yep, definitely a gas turbine, and with no nozzle not a jet. It is a turboshaft/turbine generator for the electrical part. Hypothetically what would you call a gas turbine acting exclusively as an air compressor though?
@@FireStormOOO_ Hmm, I guess in a way that is closest to a turbofan, but definitely not that though. I guess one would just have to call it a gas turbine, as no more specific term appears to exist. (Turbocompressor?)
@@FireStormOOO_ It would simply be a gas-turbine with a larger compressor. Commonly found in the form of a turbo-supercharger on piston engines.(the only job is to extract all exhaust energy with a turbine to power a compressor) The front half of any gas-turbine engine is already called the compressor section. The turbine is the part that converts exhaust energy into mechanical energy, which can be used for compressor or a shaft, this removes energy that could have created jet-thrust.
Rockets, ramjets, scramjets, turbo-ramjets, turbojets, turbofans(partly), and pulsejets are all jet engines. Some do not contain any turbine, but they all create a jet of fluid that can accomplish useful work.
A turboshaft is not a jet engine, neither is a steam turbine, nor is a turbo-supercharged piston engine(though it converts exhaust energy into mechanical which drives a compressor much like as a gas-turbine). A pressure washer might be considered a jet engine in some sense, certainly produces a jet that can accomplish useful work though that is very loose with the term engine. There was an early piston-jet for aircraft thrust which used a piston engine to drive the compressor section of the gas-jet, the hot section was essentially an afterburner as I recall.
Excellent and instructive video, thanks and greetings from Barcelona.
Greetings from Girona!
Rat Strut? Great info. I have done Engineering development work for APUs at Honeywell and UTC. The ignitors (spark plugs) must function "underwater'. Why? At altitude the APU gets colder than ice. After descending and opening the inlet in a warm moist coastal climate there is a LOT of condensation inside the APU. The ignitors need to work if you spray them with a fire hose, which is what the specs require. Crazy huh?
Lol all jetliners have APUs. The Lockheed Electra turboprop even has one.
Jessica Hall the Douglas DC-8 didn't have an APU.
I whent to see the final flight of queen jumbo Qantas
Oh I saw that on the internet
After the 380 debacle, they may wish they still had the "Queen of the Skies". Although the reality probably lies with acquiring more 787's.
Since you asked about improvements... I noticed some bright "flashes" throughout the video. I think that's your camera's auto exposure over-adjusting. Try manually setting exposure and white-balance.
Petter very well done sir! Excellent detail on the 737 APU and its use and limitations, I'm just a wee bit weary the "secret engine" term may trigger the fuel hoax clan 😝 👍.
DC8Combi 73😉😝
@@speedbird9313 👍