I was only a kid when the 727 came into being. It was massive, sleek and all the rest, lol. Now it looks a little bigger than a business jet. How times change.
Does an APU idling at full speed (no shaft load, no bleed load) produce any measurable thrust? For instance, say you lost both engines at 35,000 ft. You pitch for best glide and calculate that you can glide 25 miles before reaching the ground. The nearest airport is just barely over 25+ miles away. ...Would running the APU potentially help extend your glide distance?? I know the APU is very tiny compared to the main engines and that it’s not made to produce a thrust effect, but it is still a gas turbine, and I would think that even a little thrust is potentially better than no thrust at all.
You would think so, but no. The exhaust duct may not even be pointed aft. It can also be pointed out to the side of the aircraft, that's how little thrust (zero) is produced. I believe that the APU turbine is designed to extract every bit of energy possible from the exhaust to do it's job which is to drive other equipment. If the APU produced thrust that would mean that it would be wasting energy 99.99% of the time on unwanted thrust while static on the ground. Although I do agree that any little thrust is better than no thrust at all, I think that in the case you posted about the multiple engine failure, you'd be better off dumping fuel(loosing weight) to extend your glide distance.
I have read on a 737 NG fuel system description that APU is suction fed if the AC fuel pumps are not operating, without any explanation. How is suction feed possible for the APU? Suction-feed is possible for the main engines because they have engine-driven pumps. But I couldn't find if the APU also has engine-driven pump.
Hi. Watched all of your videos. I think your channel is one of the best ways to discover how everything works in aviation from technical perspective. But I still have questions and dont understand some stuff. First of all let me say Im noob in technical things .... I like flight simulators and would like to discover how everything works. 1. When reading about APU control switch in the cockpit for MD-80 aircraft there is a saying, not copyrighted but close to the original, - when switch in AIR COND COLDER position that means it closes the turbine bypass to increase differential pressure across the turbine. Im not sure what it means from the pneumatic system perspective. I watched your videos about bypass jet engines, low-bypass and high-bypass, but there you say its made the way air passing bypass route will be mixed with the hot "thrust-air" (exhaust). But the APU does not produce thrust so how does it work in this case? Will the air passing bypass be mixing with the bleed air from compressor, therefore it will be more colder pneumatic air in the pneumatic system?? 2. Another confusion that I cannot understand is about having "RAM Door" and "NON-RAM Door" for the APU. What does it mean? To be honest I dont really get the term of "RAM". How to descrypt those letters? I think I get the basic idea when RAM Air means the air taken from outside, from atmosphere without any usage of fan that sucks air into. But Im not sure. And if Im not mistaken in basic idea of getting air from outside then what does "NON-RAM Door" mean? What is it for? It is not for exhaust I believe. I dont get the point. 3. Let me ask you to show or somehow teach me about the process of "bleed air" and pneumatic system. I watched all of your engine videos but you didnt say anything about bleeding air. I`ve read some manuals, I get the basic idea to take away compressed air from the compressor stage (on some aircrafts like MD-80 there are two bleed air points, 8th-stage and 13th-stage) but how does it look like? I know there are ducts, check-valve and augmentation valve .... I just would like to visually see how everything is connected and works. And I dont know anyone better than you in "showing how it works" business. PS: if it helps, the APU installed on MD-80 aircrafts is AlliedSignal (Garret) GTCP85-98D (Wikipedia says).
I wonder if a repurposed APU would be practical for augmenting an electric drive performance car? I mean one of the larger commercial ones is definitely going to be too big, to heavy, and way too expensive, but something salvaged from an old and no longer airworthy private jet could in theory work fine as a range extender, and could potentially improve traction and handling if ducted to draw air from beneath the vehicle to create a ground effect. I've actually been pondering the idea for a while now, but gas turbines aren't exactly my field of expertise
Hello You Name It Gaming, you are correct. An APU could certainly be used for that purpose. As a range extender, etc. It would be nothing more than a generator, a mechanical mean of converting chemical energy from a fuel into electrical energy. A piston engine could do the same, in fact that's what hybrid cars do. Advantages of the turbine engine(APU) would be perhaps a lighter/smaller package when compared to the piston counterpart but at a higher price tag. I like your idea of using the intake air to create down force, but think of the amount of debris that that APU would be inhaling, it's basically a vacuum cleaner. The engine life would be greatly reduced, but then again, top fuel dragsters replace engines every couple of runs. I guess it all depends on the budget. It would be a pretty cool project.
@@planesimple8514 indeed, any intake air from beneath is going to need some form of filtration. But in saying that, depending on how much surplus amperage the APU can generate, one could also run electric fans to draw underside air and circulate that air around the turbine to aid cooling whilst helping with aerodynamics and ground effect. If the APU used has a built in blow-starter for bigger engines, that could probably be used to help cool the batteries as well, or at the very least routed through an air accelerator (see Dyson bladeless fan) in the rear exhaust duct to draw more underside air around the turbine. With fans, or without, I think it could make a very noticeable difference in lap times as whilst it's unlikely that such a setup will come close to pulling a decent vacuum beneath the vehicle, any reduction in pressure will be multiplied across the surface area. I think we could be on to something here 👍
I work on these. Kinda the same concept with a helicopter. Converts gas turbine energy to a shaft to turn a gearbox which a generator, and other vitals are driven.
APU maintain Generator frequency by running at the constant RPM. as the load vary, fuel flow schedule will also vary but RPM remain constant. So, therefore what change in side APU?
Hello B 787, nothing changes inside of the APU, more fuel goes in, therefore more heat is created, which means that there's more power available for the turbine to extract, which means that the APU as a whole has more power to spin the generator. This means that nothing "changes" inside of the APU, it remains exactly the same, only burning more fuel and making more power.
No sir, it's an Auxiliary Power Unit. It does not provide any thrust, it provides pressure air, electrical power and a lot of times hydraulic power to the aircraft, full size aircrafts, not RC models.
Dude can you just assume anyone looking at this unserstands what internal combustion engines do and skip that bit and get into what this internal combustion engine does
H.P. There...that's one mention. Oh no, wait! Mason, you were the first one to bring it up,so I guess that makes mine the second mention oh H.P. And that's three times now...😂 Thanks for coming by Plane Simple.
@@planesimple8514 actually I’ve seen these rated from 100 and up to 400 hp. It wouldn’t hurt to mention it and it can be determined by kw. A 757 is rated by thrust but it can be in kw and yes hp. About 90000
Ground Power Units provide electricity. whether it's from the APU or GPU the main engines need electricity to start. So all of that BS you were saying about the starters being too heavy is complete BS. The weight of the batteries is the only difference, and the APU can be used for heavier loads in the cabin. The engines also have alternators/generators. I appreciate the video but you shouldn't be making them as some source of education when clearly you have no clue what you are talking about.
And yes. The 727 used to offer the APU as an option. But it already had 3 engines. So why would they need a 4th? And they got the plane without it. Then it wouldn't start? So they had to have in APU aftermarket install. In order to start the plane. Without a Start Cart. With a pair of V-8 engines in it. Running at full blast. And they couldn't take that one with them. Start the plane back up at another airport. That also didn't have one. And that's why they needed to get the optional APU installed. From an aftermarket company. Because they were stupid! Beyond, Stupid! And now they've got this bozo. Working on that plane! Everyone's lives are in jeopardy! RemyRAD
This guy just keeps showing the APU over and over again. Like a toddler pointing at it. Mommy daddy, lookee! It's an APU! See? It's an, APU! And batteries start it! It's got batteries! Lookee! It's an, APU! And it started with batteries! They have batteries on the plane! They can start it with batteries! Oh boy! I mean really? This guy is authorized to work on that plane? Who authorized him? Santa Claus? RemyRAD
This narrative description. Is an, oy vey, moment. The inarticulate is trying to describe a gas turbine powered Generator. And explaining how it burns fuel to do so. DUH. This dude did not get his degree in Public Speaking. That's for sure. And he doesn't know how to say gas turbine engine? He doesn't know what it is? It's a motor. Yes it is but it is an axial motor. And spins faster than the speed of sound. But makes a racket doing it. And so while the process is faster than sound. It makes a lot of sound,, just the same. These are designed to start jet engines. Frequently require,, two, V8 engines. To start a jet engine. And this is only a small, gas turbine engine. That can produce the power of 2, V8 engines. And is much smaller and more compact and lighter in weight. Which was important for an airplane. I would love to have one of these to power my entire house. But I think my neighbors would complain? That they didn't have one of their own. And have to pay the power company. When they could just spend more money for fuel instead. Instead of the lousy electric power company! Taking my money. I'd rather give my money to, GE or Rolls-Royce. So they can stay in business. So the US government doesn't have to. Jet engines are great in planes, cruise ships and trains. And a few, copper colored Chryslers. Not so good for off grid living. Unless you are Philip and 66? You probably don't want your own jet engine? They aren't what we call, fuel-efficient. Though they can burn anything that will burn. Like Donald Trump and Ron DeSantis. Marjorie Taylor Green et al. What human beings want to act like that? Politicians. Named Marjorie Taylor Green and Company. And they once attended school? How many decades ago? Did they graduate from kindergarten? With a college degree. And you just thought this was about jet engines? RemyRAD
I was shocked when I first learned of an APU...never knew it ever existed..what an ingenious creation!!
Hello Nilakantha Sadasiva, indeed they are quite ingenious.
until you got to repair them
Another great video! You're a treasure for future aircraft mechanics!!! Thank you!!
Thank you very much Sasha. I really appreciate it.
Good explanation! I understood very well. Thanks
I'm glad. Thank you very much!
Very well explained sir,couldn't have been better.
Thank you.
Wow! Thank you very much SH Khan, I appreciate it.
He was making shit up the whole time
Thank you sir. Valuable information and great explanation.
Thank you very much WAIRLOW. I appreciate it.
I was only a kid when the 727 came into being. It was massive, sleek and all the rest, lol. Now it looks a little bigger than a business jet.
How times change.
The A.P.U. in the Vulcan2 was powered by a turb[ne designed for the Rover Gas turbine car.
The A.P.U. was always referred to as A squared / P squared.
thanks got an exam about the APU this will help
Awesome! I'm glad to hear that you found my video helpful. Good luck on your exam.
Nice. I liked it. Very informative. Keep making such videos, your channel will grow for sure.
Thank you very much Indian Tony. I'm glad you. Like it and thank you for taking the time to let me know.
This was very informative. Thanks 👍
Thank you.
And thanks for taking the time to write in your nice comment.
Wow!!!! A great video again ......
Thank you very much!
Does an APU idling at full speed (no shaft load, no bleed load) produce any measurable thrust?
For instance, say you lost both engines at 35,000 ft. You pitch for best glide and calculate that you can glide 25 miles before reaching the ground. The nearest airport is just barely over 25+ miles away. ...Would running the APU potentially help extend your glide distance??
I know the APU is very tiny compared to the main engines and that it’s not made to produce a thrust effect, but it is still a gas turbine, and I would think that even a little thrust is potentially better than no thrust at all.
You would think so, but no. The exhaust duct may not even be pointed aft. It can also be pointed out to the side of the aircraft, that's how little thrust (zero) is produced. I believe that the APU turbine is designed to extract every bit of energy possible from the exhaust to do it's job which is to drive other equipment. If the APU produced thrust that would mean that it would be wasting energy 99.99% of the time on unwanted thrust while static on the ground.
Although I do agree that any little thrust is better than no thrust at all, I think that in the case you posted about the multiple engine failure, you'd be better off dumping fuel(loosing weight) to extend your glide distance.
Awesome 👍👍👌👌
I have read on a 737 NG fuel system description that APU is suction fed if the AC fuel pumps are not operating, without any explanation. How is suction feed possible for the APU? Suction-feed is possible for the main engines because they have engine-driven pumps. But I couldn't find if the APU also has engine-driven pump.
Hi. Watched all of your videos. I think your channel is one of the best ways to discover how everything works in aviation from technical perspective. But I still have questions and dont understand some stuff. First of all let me say Im noob in technical things .... I like flight simulators and would like to discover how everything works.
1. When reading about APU control switch in the cockpit for MD-80 aircraft there is a saying, not copyrighted but close to the original, - when switch in AIR COND COLDER position that means it closes the turbine bypass to increase differential pressure across the turbine. Im not sure what it means from the pneumatic system perspective. I watched your videos about bypass jet engines, low-bypass and high-bypass, but there you say its made the way air passing bypass route will be mixed with the hot "thrust-air" (exhaust). But the APU does not produce thrust so how does it work in this case? Will the air passing bypass be mixing with the bleed air from compressor, therefore it will be more colder pneumatic air in the pneumatic system??
2. Another confusion that I cannot understand is about having "RAM Door" and "NON-RAM Door" for the APU. What does it mean? To be honest I dont really get the term of "RAM". How to descrypt those letters? I think I get the basic idea when RAM Air means the air taken from outside, from atmosphere without any usage of fan that sucks air into. But Im not sure. And if Im not mistaken in basic idea of getting air from outside then what does "NON-RAM Door" mean? What is it for? It is not for exhaust I believe. I dont get the point.
3. Let me ask you to show or somehow teach me about the process of "bleed air" and pneumatic system. I watched all of your engine videos but you didnt say anything about bleeding air. I`ve read some manuals, I get the basic idea to take away compressed air from the compressor stage (on some aircrafts like MD-80 there are two bleed air points, 8th-stage and 13th-stage) but how does it look like? I know there are ducts, check-valve and augmentation valve .... I just would like to visually see how everything is connected and works. And I dont know anyone better than you in "showing how it works" business.
PS: if it helps, the APU installed on MD-80 aircrafts is AlliedSignal (Garret) GTCP85-98D (Wikipedia says).
I wonder if a repurposed APU would be practical for augmenting an electric drive performance car?
I mean one of the larger commercial ones is definitely going to be too big, to heavy, and way too expensive, but something salvaged from an old and no longer airworthy private jet could in theory work fine as a range extender, and could potentially improve traction and handling if ducted to draw air from beneath the vehicle to create a ground effect.
I've actually been pondering the idea for a while now, but gas turbines aren't exactly my field of expertise
Hello You Name It Gaming, you are correct. An APU could certainly be used for that purpose. As a range extender, etc. It would be nothing more than a generator, a mechanical mean of converting chemical energy from a fuel into electrical energy. A piston engine could do the same, in fact that's what hybrid cars do. Advantages of the turbine engine(APU) would be perhaps a lighter/smaller package when compared to the piston counterpart but at a higher price tag.
I like your idea of using the intake air to create down force, but think of the amount of debris that that APU would be inhaling, it's basically a vacuum cleaner. The engine life would be greatly reduced, but then again, top fuel dragsters replace engines every couple of runs. I guess it all depends on the budget. It would be a pretty cool project.
@@planesimple8514 indeed, any intake air from beneath is going to need some form of filtration. But in saying that, depending on how much surplus amperage the APU can generate, one could also run electric fans to draw underside air and circulate that air around the turbine to aid cooling whilst helping with aerodynamics and ground effect.
If the APU used has a built in blow-starter for bigger engines, that could probably be used to help cool the batteries as well, or at the very least routed through an air accelerator (see Dyson bladeless fan) in the rear exhaust duct to draw more underside air around the turbine.
With fans, or without, I think it could make a very noticeable difference in lap times as whilst it's unlikely that such a setup will come close to pulling a decent vacuum beneath the vehicle, any reduction in pressure will be multiplied across the surface area.
I think we could be on to something here 👍
You channel name is freaking awesome!
Thank you very much man!
I work on these. Kinda the same concept with a helicopter. Converts gas turbine energy to a shaft to turn a gearbox which a generator, and other vitals are driven.
APU maintain Generator frequency by running at the constant RPM. as the load vary, fuel flow schedule will also vary but RPM remain constant. So, therefore what change in side APU?
Hello B 787, nothing changes inside of the APU, more fuel goes in, therefore more heat is created, which means that there's more power available for the turbine to extract, which means that the APU as a whole has more power to spin the generator. This means that nothing "changes" inside of the APU, it remains exactly the same, only burning more fuel and making more power.
Apu engine more videos please 👍
I'm glad you liked it!
Hey sir ...I have question about how this aerodynamic Stall works ...I want to know in details.... please explain me when you'll be free ... thanks 😊
Is that a jet engine for a model RC toy ?
No sir, it's an Auxiliary Power Unit. It does not provide any thrust, it provides pressure air, electrical power and a lot of times hydraulic power to the aircraft, full size aircrafts, not RC models.
AH! RE220
Indeed! Good eye MJA6995!
Dude can you just assume anyone looking at this unserstands what internal combustion engines do and skip that bit and get into what this internal combustion engine does
Not one mention of hp
H.P.
There...that's one mention.
Oh no, wait! Mason, you were the first one to bring it up,so I guess that makes mine the second mention oh H.P.
And that's three times now...😂
Thanks for coming by Plane Simple.
@@planesimple8514 actually I’ve seen these rated from 100 and up to 400 hp. It wouldn’t hurt to mention it and it can be determined by kw. A 757 is rated by thrust but it can be in kw and yes hp. About 90000
Ground Power Units provide electricity. whether it's from the APU or GPU the main engines need electricity to start. So all of that BS you were saying about the starters being too heavy is complete BS. The weight of the batteries is the only difference, and the APU can be used for heavier loads in the cabin. The engines also have alternators/generators. I appreciate the video but you shouldn't be making them as some source of education when clearly you have no clue what you are talking about.
And yes. The 727 used to offer the APU as an option. But it already had 3 engines. So why would they need a 4th? And they got the plane without it. Then it wouldn't start?
So they had to have in APU aftermarket install. In order to start the plane. Without a Start Cart. With a pair of V-8 engines in it. Running at full blast. And they couldn't take that one with them. Start the plane back up at another airport. That also didn't have one. And that's why they needed to get the optional APU installed. From an aftermarket company. Because they were stupid! Beyond, Stupid!
And now they've got this bozo. Working on that plane! Everyone's lives are in jeopardy!
RemyRAD
This guy just keeps showing the APU over and over again. Like a toddler pointing at it. Mommy daddy, lookee! It's an APU! See? It's an, APU! And batteries start it! It's got batteries! Lookee! It's an, APU! And it started with batteries! They have batteries on the plane! They can start it with batteries! Oh boy!
I mean really? This guy is authorized to work on that plane? Who authorized him? Santa Claus?
RemyRAD
This narrative description. Is an, oy vey, moment. The inarticulate is trying to describe a gas turbine powered Generator. And explaining how it burns fuel to do so. DUH.
This dude did not get his degree in Public Speaking. That's for sure. And he doesn't know how to say gas turbine engine? He doesn't know what it is? It's a motor. Yes it is but it is an axial motor. And spins faster than the speed of sound. But makes a racket doing it. And so while the process is faster than sound. It makes a lot of sound,, just the same.
These are designed to start jet engines. Frequently require,, two, V8 engines. To start a jet engine. And this is only a small, gas turbine engine. That can produce the power of 2, V8 engines. And is much smaller and more compact and lighter in weight. Which was important for an airplane.
I would love to have one of these to power my entire house. But I think my neighbors would complain? That they didn't have one of their own. And have to pay the power company. When they could just spend more money for fuel instead. Instead of the lousy electric power company! Taking my money. I'd rather give my money to, GE or Rolls-Royce. So they can stay in business. So the US government doesn't have to.
Jet engines are great in planes, cruise ships and trains. And a few, copper colored Chryslers. Not so good for off grid living. Unless you are Philip and 66? You probably don't want your own jet engine? They aren't what we call, fuel-efficient. Though they can burn anything that will burn. Like Donald Trump and Ron DeSantis. Marjorie Taylor Green et al.
What human beings want to act like that? Politicians. Named Marjorie Taylor Green and Company. And they once attended school? How many decades ago? Did they graduate from kindergarten? With a college degree.
And you just thought this was about jet engines?
RemyRAD