Thanks CarsonXL, I appreciate it.

Hey, thank you very much man! I really appreciate that. Thank you for taking the time to give me some positive feedback.

Thank you very much DoggishEarth, that means a lot.

You are quite welcome So ShiroYami. I'm glad you liked it.

Awesome!! The A-10 is not only one of my favorite airplanes but I'm also familiar with it's engines, well, the civilian version of them, the CF34, vs the TF34 from the A-10. The CF34 version I'm familiar with are from the Bombardier Challenger 604, 605 and 650 family of airplanes. I'm glad you liked my simple video and thank you for taking the time to write in your positive feedback.

Good! I'm glad you liked it. Thank you.

Hello Rolandemartin, wow! What a privilege to have worked on the B52's. Such an iconic aircraft! I hope the government agrees to dedicate the budget to modernize it with the new engines and keep it alive for another generation. I made it a point to take a picture of me and my kids inside the wheel well and the bomb bay of a B52 that came to a local airshow. Anyway, I'm happy to hear that you liked my video. Thank you for taking the time to write in. Welcome to Plane Simple.

I thoroughly enjoyed working on the BUFF. Only had four years of it. Actually got to fly on them a few times. That proved to be a real experience in itself.@@planesimple8514

Hello coodudeman, thank you for taking the time to give me some positive feedback. I appreciate it. I'm glad you liked my simple video.

Awesome! Thank you.

My pleasure John, I'm glad you found my video helpful. Good luck with your cooling system.

Thank you very much Dakshesh Rawat, I appreciate it.

Thank you very much Carlos Sampayo, I am glad you found my video helpful. Good luck with your A&P.

Hello, thank you. I appreciate it. I'm glad to hear you found my simple video helpful.

Cool. That's a cool idea. Thank you.

Thank you MDSBock, I appreciate the positive feedback.

Thank you very much William Wallace. Much appreciated.

Thank you Maria Robert. I appreciate the nice comment.

Thank you Eugene.

Hello Chris Boseley, thank you very much for the correction and for the positive feedback. I appreciate it.

@@planesimple8514 yes I just finished reading the Biography of Sir Stanley Hooker “Not much of an engineer”. And looked to you to expand my understanding of his book. And that you did.

My pleasure, thank you for your nice comment.

Hello Evan Olsen, that's a really good question. I never really thought about that. Perhaps the size of ducting needed to re-direct the air into the intakes was too large to be hanging out on a wing without it becoming another fuselage itself. I really don't know, but I would like to know the answer so if you do find out, please share it here. Thanks for watching and welcome to Plane Simple.

@@planesimple8514 yes sir it could be size meter but I saw it on the fuselage of mini jet aircraft (single seat). Lot of thanks dear sir for the nice helpful video and so beautifully illustrated both types of compressor.

@@muhammadkamran851 the Gloster Meteor, Britain's first jet fighter used the Rolls Royce Welland and later Derwent engines in a twin engine configuration, with large engine pods embedded in the middle of the wing. Both of those are centrifugal turbojets and competed against the axial Junkers Jumo 004 in the Me 262, also with wing pods suspended below the wing. The reason many jet planes have the engines embedded in the fuselage, no matter the compressor type, is because they are often military aircraft designed to be agile and powerful. Placing the engine(s) as close to the center of gravity as possible has many flight characteristic benefits. One example is if a twin engine fighter had an engine out, the remaining functional engine will induce less yaw due to a short moment arm between the engine and the center of gravity. Engines located in the fuselage also give weight benefits, as the airframe in the wings doesn't need to be reinforced to support the mass and thrust of the engines (although many wings get reinforced for hard points and payload). Engines in the fuselage are also more stealthy, although that didn't really apply when centrifugal engines were used. I am a 4th year mechanical engineering student and love aviation! Aerospace is one of the most fascinating fields in my opinion.

Instead of an axle down the centre of an axial flow, why not bolt the blades to an annulus ring so it could be a ram jet as well. Just an idea I'd like to see happen.

why push more large drag surfaces through the air, when you are already pushing the fuselage, more efficient to make that slightly larger instead of having multiple! hope this makes sense! (btw, i am not an engineer and this is admittedly a guess!) @@planesimple8514

Hello Shooter's Ready Channel, Thank you for the nice words and my apologies for taking so long to reply... 1) I may have misspoken about the relative RPM's. One of the biggest factors limiting RPMs is the materials themselves. The metals or composites have a tensile limit that cannot be exceeded, therefore you cannot spin the engine any faster than the revolutions where the centripetal force is the same as the tensile limit of the material, at that point the engine would self destruct. Having said that, the diameter of the engine is what determines ultimate RPM and not what type of compressor it is. I hope that makes sense. 2) I don't have any numbers to back up any claims, but I'd be willing to bet that they are very efficient, given that the trend has been to go to bigger and bigger fan engines and those altitudes are where those engines spend the vast majority of their lives operating at. 3) Again, I may come up empty handed with this question too. I do agree that the prices are "what the market will bear", but consider two things: One, the technology and precision required to manufacture modern jet engines is outstanding(and expensive) and Two, those prices have only a limited life to make up for all of the R&D, designing, prototyping, testing, etc. that has to happen ahead of time to develop a new engine. There's a lot riding on new engines, sometimes the whole future of the engine manufacturer is riding on their newest engine being a financial success. If you were the one in that position, what would you charge for your engines? Again, thanks for your kind words and thanks for the questions.

Speed of sound is a limit. Though axial compressors which try to utilize most of their area ( close to the hub ) just accepted supersonic velocity on the tips. Also temperature rises along the axis, so later stages want to run faster. An inefficient first stage at least rises the temperature and makes the next stage more efficient Centrifugal compressor tips are slightly supersonic. The vortex effect in the gap brings it back down. This is for the elevated temperature due to compression. The wedge shaped diffusers shock any supersonic flow down. Amateurs tend to forget to measure the temperature after the compressor on their home built engine. They don’t know their inefficiency. 5000 $ for a jet engine for an RC plane. I guess that radial-5 piston engine is more expensive

Yes, the air path and the compressor stage itself gets smaller because it is now dealing with a mass of air that had already been compressed and therefore takes a smaller volume. As a good representation of this, look up pictures of piston engine compound turbos. Those are sequential centrifugal compressors on independent shafts. You'll see that the second compressor is physically smaller, and yet it deals with higher pressures.

You are absolutely correct. Thank you very much for pointing that out. Reverse flow is common on very successful engines like the venerable PT6. I think those direction changes do have a little drag penalty, but are small enough to be justifiable in order to fold and shrink an engine into a much smaller package. Even the TFE731 that I mentioned on the video reverses its flow in the combustors two consecutive 180 degrees to fold back in on itself and make the engine shorter and lighter, so yes, you are correct and I gave those 90 degree bends too much importance. Again, thank you for the comment and I love to have knowledgeable people like you engaged on my channel and adding to the knowledge! I think it's great. Thank you.

How much thrust have you seen on a turbocharger turbine?? And what was the turbochargers size??

There is no thrust from a turbocharger, regardless of the size of the turbo. The speed of the exhaust gases might even be less that a naturally aspirated engine since the point of the turbine in the turbo is to transfer that exhaust energy to the intake compressor.

@@planesimple8514 i mean a turbocharger converted to a centrifugal turbine Meaning the turbocharger is not attached to an engine instead it has a combustor between compressor and exhaust

Thank you for taking the time to let me know and congratulations on passing your exam...!!

Hello Peter Mallia, you are correct. Since I made that video I have received a number of comments from people that know a lot more about engine aerodynamics than do and you all agree on the same point. I have also read more about modern engines and the centrifugal compressor is a lot more common that I thought it was. You can see another example of this in the video I made looking into the Honeywell AS907. That is a very modern engine and also has a centrifugal compressor coupled with an axial compressor in front of it. Anyway, I think it's great to have people like you that take the time to write a comment adding to the knowledge base of this channel and all that come here. Thank you.

With a name like "Life under TheMicroscope" I can see why you made a connection between a jet engine and a maple leaf. I like it! Thank you for that comparison and thanks for watching my video.

You are welcome. My pleasure. I'm glad you liked it.

My pleasure. BTW...that's an awesome name DQ!

Hello Lloyd Evans, I'm not a WWII aircraft expert, hell, I'm not an expert at anything, really. But I believe those engines used one single stage compressor as the supercharger. By "single stage" I mean one single rotor. They had multiple "stages" in the sense that they had multiple gears to spin the rotor at different speeds to make up for lower density air at altitude to maintain power output of the engine. In jet engines, stages mean multiple disks stacked one after the other. Have you heard of "Greg's aircrafts and automobiles" KZfaq channel? It's awesome and has a few excellent videos dedicated to this topic.

P-38 has turbo in the fuselage plus the compressor mounted in the engine fab.

Hello Dylan, that's a difficult task you are undertaking. First off, for an axial compressor you should be running alternating stages of rotating blades and stator vanes, not impellers. Motors' locations, I'll leave the designing to you. Wires, you could use struts like the actual jet engines use. Good luck.

The drive shaft comes from the back from the turbine. Put your electric motor there. The last stage as centrifugal compressor naturally feeds pipes with compressed air. Can route wires between them.

Hello Rethman, thank you for pointing out my mistakes in a very respectful manner. Criticism like yours is always welcome here at Plane Simple. Those mistakes are a result of speaking and generating the ideas on the fly, without a script. I don't often get the chances to record those videos and when I do I only have a limited window of time, so I have to take advantage of the opportunities as they come up on the spot, that's why the are so off the cuff and prone to errors. Thank you again for being respectful and welcome to Plane Simple.

Hello shade rudland, I don't think just the annulus would convert the engine into a ram jet. Remember that there's already a duct all around the blades.

We call it a "Shroud". You would not believe the clearances between the shrouds and impellers that they would actually work to compress the air, but they do. Usually around 1 millimeter at assembly, and some even greater. Then with heat generated by compression the gap shrinks from expansion, and the curved blades want to "stand up" under compressional forces making them taller, as well as a little centrifugal force on those blades. So that gap shrinks a lot under normal operation. We also repair shrouds and impellers from FOD and or rub. Not by welding though but another type of material additive process. Then we re-machine them into the correct contour of the impeller we call the "Profile". Impellers get up to around 400 degrees 'F' while in operation so they expand several thousands of an inch just from heat alone. The smallest air-gap we call the Squash at the platform OD is called the Exducer. That is the most important part of the entire function.

You could suspend the whole engine on its front and rear tip and rotate opposite. Fuel line is in the center of rotation. FADEC over WiFi.

Super thank you man!

Hello mikepattison, no worries. I am far from perfect,as are my videos. I have made mistakes here and there mostly from being a novice at recording the videos and for not editing a script before recording like a professional would do. Any corrections that come respectfully and with the interest of betterment of the topic will always be welcome here at Plane Simple, so feel free to chime in at any time. Thanks for watching and taking the time to write in.

Hello MrLuvtheUSA, critiques like yours will always be welcome here at Plane Simple. When it is done with proper information, in a respectful manner, in the interest of clarity and education, comments like yours should and will always be accepted and respected. Thank you for taking the time to chime in and add to the topic. Would you like to add any specific centrifugal type turboprop engine application here for those interested? That way anyone looking to keep going down the rabbit hole has another lead to follow and read up on. Most modern engines that I've been exposed to that use a centrifugal compressor are a combination of a few axial compressor stages first followed by a centrifugal stage.

Hello martymckinney, those were mistakes on my part, good catch. You were paying attention, and apparently I wasn't...🤪. That was supposed to be a single stage CENTRIFUGAL compressor , but I have a feeling you already knew that. Thank you for the correction and for staying respectful about it.

Hello Dogukan KAMBAZLAR, I don't think the speed limit is in the combustion chamber. I think it's in the rest of the engine. All the rotating bits (compressor and turbine blades) would generate shock waves with supersonic flow, this would massively increase drag in the engine and slow down it's rotating speed and needing more fuel to run. Therefore it would act as a self regulating rpm limiter. As far as the air path, i have since learned that it really does not add much in the way of drag or increase inefficiency in any significant way.

@@planesimple8514 I got it, by the way good video :)

Thank you

Flame front has a speed. Over the speed limit you flame out. We try to fold the flame front. The turbulence from the mixing is used for this, but is a statistical process. So the engine just randomly dies? I guess that in an annualar chamber the gaps between the injectors hold the flame. With this huge centrifugal compressors can’t I have a huge diameter combustion chamber?

Hello, that is a very valid point. Thank you for mentioning that. I love your username by the way!

Mostly axial, although there are some turbofan engines that have several stages of axial compressor and then one single centrifugal stage. Look at another one of my videos about a AS907 or HTC7000 engine and you'll see an example of such an engine.

@@planesimple8514 why are most of them axial? Since axial need more stages as well.

The short answer is: Because you can achieve higher pressures with axial compressors. Centrifugal compressors give you a great pressure increase for a single stage, but as far as I know are limited to a max limit of two stages. Also, they present a bigger frontal area to the air stream, worse aerodynamics, than their axial counterparts. If you combine the two types, now you can have an axial compressor with many stages giving you a higher pressure than a single centrifugal compressors. Then, add a single centrifugal compressors behind that and you basically double the pressure in a single step. You can see an example of that in a video I did about a Honeywell AS907 engine.

@@planesimple8514 thanks for replying really appreciate it. Most turbofans in commercial planes are strictly axial only. Why isn’t centrifugal included inside them?

@@LordBagdanoffin those huge engines the axial compressor seems to have a conical shroud as the air gets compressed. It is anti centrifugal. I wound if it would help if we spin the shroud with stator vanes in the opposing direction to eliminate all centrifugal forces. But how would I deliver the fuel?

Hello Royal Wilson, sorry but my abilities don't go as far as to make an animation. Thanks for watching my video though.

@@planesimple8514 its cool...taking my power plant in a few days and need a little clarity

Wow...congrats! That's a huge milestone. Good luck.

Hello Bob G. Thank you for keeping your comment polite. I appreciate the criticism, but the reality is that this channel is not a high production value channel, as is plainly obvious. This is me just taking a few minutes here and there and squeezing in a few minutes of an impromptu, off the cuff, mini lesson for beginners. Most of my videos are recorded after classes are over in school, or after work. In both cases I only have a limited time window in which to capture and share a bit of knowledge as the opportunities present themselves. This environment is not conducive to pre-planned scripts and long setups. The goal of the videos is to transmit core ideas as simply as possible, hence the name of the channel, Plane Simple, and not the decorations that may be more enjoyable to watch but don't add or build on the concept. At the end, I hope that even if it is painful to listen to me talk, curious people can walk away having learned something new. Thank you for coming by Plane Simple.

@@planesimple8514 Thanks for the reply. I still use your vids to update my own knowledge before facing my online aviation students. Keep up the good work

Oh my...!! GEFanuc21t welcome to Plane Simple! As a primary source of information you are welcome to correct me any time you see fit. I'm surprised to learn that double sided centrifugal impellers like that are still being manufactured. What are they used on now? As far as grinding the blade tips on the CFM 56 and CF 6... That is awesome and yes, I can only imagine the noise that came from that. How big was the jig or stand to have the compressor partially assembled like that to spin and grind away? Do you use a form, gauge or template as a guide to grind down to? Or is it done stage by stage individually, each stage ground to a specific dimension? Man, you have hit the curiosity button in my brain! I'd love to see a video by you where you describe all these processes, even if it's just on pen and paper without revealing any trade secrets, etc. Would you consider doing something like that? I'd love to learn more about what you do. Thank you for taking the time to chime in here and again, welcome to Plane Simple.

@@planesimple8514 Love it. I'm not here to correct you. I'm here to give you alternate views that we use in the actual MFG process you may not be aware of. Can't show vids or pictures of proprietary processes. That can get people into trouble. LOL We presently weld repair impeller blades in an argon filled weld booth and repair impellers using 5-axis machining, and recut curvics, etc.. and I spin them in a vacuum pit daily. Extremely few ever fail spin pit testing even at 1.5 times the rated RPM. Maybe 1 in a 100 fail from an internal flaw. When they do fail it is usually from an operator error in assembly of the tooling. I used to high-speed grind axial flow compressor spools at GE in the late 1970's and 1980's. Yes it was friggin' loud. Big Norton manual grinder that spun the compressor spool loaded with blades at 5000 rpm to force the blades against the dovetails then we plunge ground each stage of blades at a different angle matching the Stator case. Took about 8 hours to set up for grind then another full shift to grind all stages. Each stage was ground to a radial dimension based on the centerline of the blade at a datum from a dial gage. Each stage angle had to be set by the Machinist per a chart by the engineering section for that actual assembly. That may change for every compressor spool a bit.

WOW...!!! Wow...!!! I can't say it enough....WOW!!! That's awesome! Thank you very much for all the explanations. That is all a small bit of awhile other side of this industry. And I find it all fascinating!

@@planesimple8514 For your question as to the compressor spool itself. They were all made of Titanium forgings and each stage was machined as a separate hollowed out disk. We called them a 'BLISK'. Short for Bladed Disk. Then the stages of blisks were "Inertia Welded" together into one piece called a spool. That's a whole other process I used to do. The machine tool to do that was about as big as a city bus. Imagine several auto tires welded together as one tire with the sidewalls and the rim beads connected. Thats the best way to describe a compressor spool. The smallest bore on the ID was around 10 inches in diameter. That would be like the rim beads of the tire. That design was to offer strength yet to keep rotating mass at a minimum. There was a fixture that expanded against the 10 inch ID of the spool webs called a "Hydrolock", with a drive coupling at one end and bearings pressed on each end. Several 'Runout' checks had to be performed well before it was ready to drop into a cradle of the grinder. Half-Moon style blocks cradled the bearings in the grinding fixture, as you engaged the drive coupler with the drive motor. Half-Moon top clamps over the bearings and oil was pumped to the bearings at 30 PSI. Now you were ready to start the beast up. Big electric motor slowly ran the whole spool up to 5000 rpm. The 4 foot diameter grinding wheel loaped along at 500 rpm. The speed of the blades cooking along at 5000 rpm did most of the grinding action. Took about a minute to get up there to 5000 rpm. None of this is secret. They still make them this way today. But they may be using CNC grinders instead which change blade angles fast and position the grinding wheel quickly. We had to do it manually back then by changing gage block stacks against pins on the machine table. Plus we had to do our own Trig calculations to get the angle engineering demanded for each stage of blades.

Hi, could you make a "Tesla Turbine Jet Engine"? Thanks

Thanks shkhan for the positive feedback.

Hello Ben A. E, thank you for keeping your comment respectful. I do listen to criticism and suggestions and do take them into consideration. As it should be painfully obvious, I am not too digitally savvy, I don't have a website to post on or add articles to, I make simple videos. I discuss concepts is a simple way, hence the name of the channel "PLANE SIMPLE". Think of the hand drawings as an impromptu, informal one on one discussion with a friend, or perhaps a teacher on a white board. Also, I don't know the legalities and limitations of using other people's pictures and drawings and would rather not get in trouble, besides, the point of the video is not super duper graphics, it's the concepts that's going after. Anyway, thank you for taking the time to give me some feedback and thanks for watching my video.

@@planesimple8514 Sir, if I can learn how to work with a software to illustrate content, anyone else can too. I understand if you don't like to spend a week to get a hang of such softwares, but I would not understand settling down for this low quality presentation. P.S. you can filter out images on google based on the ones whose rights are publically available for use.

Alright, that is very helpful, thank you. I never thought of that option for searching images. Do you have any software suggestions? If it's not too hard or time consuming I'll give it a shot. And thanks again for your suggestions.

@@planesimple8514 I didn't mean I know a particular software for this. I was referring to how difficult it was to take computer science and go to college when I was 30. I'm not a sharp guy, but still I stuck it out.

Understood, thank you. I'll look into it and see what I come up with.

I imagine it's not the turbines but perhaps the compressor disk. That'd be a cool re-use of them. I've never heard that before. If you can find a place where they have done that, share it here. I'd like to see that. Thanks.

That would be the world's most beautiful diamond!!! And yes, it'd solve all those limitations.