Turbofan model from the video: www.enginediy.com/products/1-20-turbofan-engine-diy-assembly-turbofan-frighter-ws-15-engine-model-kit-150-pcs?ref=d4a Turbojet model from the video: www.enginediy.com/products/1-3-turbojet-engine-model-kit-build-your-own-turbojet-engine-that-works-wp-85-turbojet-diy-aircraft-engine-model-100-pcs?ref=d4a Use code "d4a" to get 10% off on anything here: www.enginediy.com/?ref=d4a Support the channel by shopping through this link: amzn.to/3RIqU0u Patreon: www.patreon.com/d4a Become a member: th-cam.com/channels/wosUnVH6AINmxtqkNJ3Fbg.htmljoin
If I may suggest ... we could say that PISTONS separate the 'strokes' in time ... whereas in a Jet, they occur simultaneously, but are separated in space. You also called the consequence of a common shaft (in video 1) a "vicious cycle" ... but, I hope most of us are comfortable with your usage of phrases like, _"positive feedback loop"_ ... however, I believe some TurboFan (P&W I think worked on it) use planetary gears to "sync" the differing rotational rates as well as increasing torque ... Thanks again ... and I for one CANNOT overstate just how awesome I think you are. EXCEPTIONALLY intelligent. Bc the ability to make the complex accessible enough to the lay person absolutely MUST be intelligent ... and your consistent success in doing so serves as a proof of that intellect. Likewise, I think most of us are here out of our reverence for your ability to simplify the complex and share with us your enthusiasm ... and thus, it's entirely okay for you to veer off your conventional topic. And if ever your 'veerings' are in error, then, we'll forgive a misadventure. Because I assure you ... none of us are perfect either.
About the only thing he didn't mention was the average exhaust velocity which has to be higher than vehicle speed and is why low bypass jet engines are used for fighter jets and not high bypass and why Concorde used turbojets.
@@johnstudd4245 I don't think it was. He said that low bypass jets were used by fighters, and he said that they were less efficient, but gave higher thrust, but he never really said why they were chosen, and in fact pretty much implied it was just a weight thing.
@@BooBaddyBig Yea, the key word would have been specific thrust. They certainly don't produce higher thrust in general. Just compare the F135 of the F35 to the GE9X on the B777X.
I worked for Rolls-Royce for 32 years and have experience on a whole range of engines from Speys (A 'leaky-turbojet' more than a turbofan) to BR-700's. I think you did a marvelous job explaining the basics. Obviously it is far more complicated when it comes to practical applications!
@d4a you should do a video on some driving turbines 😎 Some of cars that have used turbine engines and some future concepts like that turbine hybrid garbage truck
As an aviation guy who watches your channel because cars are cool, I love to see you tackling stuff about aircraft. You have an incredible talent for explaining things my dogg.
I used to be a Harrier mechanic. I’m impressed that you know this about our Rolls Royce engine! Additionally, the Harrier uses 4 nozzles with a single engine. The two “cold” nozzles come from the Low pressure compressor and the “hot” nozzles from the high pressure compressor, combustion chamber and all the turbines. You can walk up to a running Harrier and put your hand in front of the LP cold nozzle and the air was only slightly warmer than ambient. But even at idle it is a LOT of volume of air at a pretty high speed. You wouldn’t want to put your face in front of it!
1:02 Wrong. No forward thrust is generated by the exhaust gasses exiting via the tailpipe. In fact some reverse thrust is usually produced by the tailpipe section. For the Harrier VTOL jet aircraft for example when the exhaust gasses & compressor air flow are turned through 90° reverse thrust = max thrust is generated & upwards thrust = max thrust is generated (f = ma) yet the aircraft doesn't accelerate backwards due to the max forwards thrust still existing & countering the vectoring nozzles full reverse thrust as all forward thrust is generated forwards of the turbine section. In Fact, the main features of the typical turbojet tailpipe is to be straight & have a big hole that allows the exhaust gasses out in the direction of general flow without getting in the way of or changing the direction of the exhaust gasses. Ideal Airliner thrust reversers 10 ton thrust engine - first 90° exhaust gasses turn - generates 10 ton reverse thrust countering the 10 ton forward thrust so no net thrust & 20 ton tension on engine casing, next 90° turn creates 10 tons tension across the reverser bucket & another 10 tons reverse thrust giving max reverse thrust of 10 tons net worth of braking effect, lovely jubbley.
As you said, turbofan engines of higher and higher bypass ratios have been developed to improve efficiency and reduce noise. To add a bit of engineering and physics to the discussion I offer the following: Noise - A significant source of jet engine noise is the shearing/mixing of high speed flow from the core with the lower speed flow surrounding it. In a turbojet engine, all the high speed core flow is interacting with the low speed flow around the outside of the engine, creating one very strong shear/mixing zone. With a turbofan engine the high speed core flow is mixing with the slower fan flow (still much faster than the overall flow over the engine) and the fan flow is mixing with the slower overall flow creating two less intense shear zones and therefore spreading out the mixing zone resulting in a gentler energy exchange and less noise. Fuel Efficiency - The job of the engine is to produce thrust. When thrust exceeds drag the aircraft accelerates. At cruise, thrust = drag. Thrust comes from increasing the momentum (mass flow rate X change in velocity) of the air flow. Fuel requirements are driven by energy considerations however, not momentum. Jet fuel is a storage medium for energy and is about 43Mj/Kg. Kinetic energy of the flow is (1/2 X mass flow X velocity squared). So, if we want an engine that produces say 1000 units of thrust, we can chose a low air flow rate/high airflow speed change solution (turbojet) or a high airflow rate/low airflow speed change solution (turbofan). But in either case, the fuel flow will be proportional to the kinetic energy change of the flow. So, suppose we want 1,000 units of thrust. We could choose a turbojet engine that processes 250 units of air flow and accelerates it 4 units of speed. Multiplying those parameters for momentum change/thrust we get 250 x 4 = 1,000 units of thrust and for kinetic energy change we get 2,000 units (0.5 X 250 X 4 X 4). Now we choose a turbofan engine that can process 500 units of air flow and accelerate it 2 units of speed. Multiplying again for momentum/thrust we have 500 X 2 = 1,000 units of thrust. However, the kinetic energy change required is now 0.5 X 500 X 2 X 2 = 1,000 units of kinetic energy...half of what the turbojet would require for the same thrust. In practice we can't get all that improvement and the resulting turbofan engine will be more complex, heavier and more expensive, but you can easily see why engineers pursue them!
Thank you for this clarification. I have another question that I didn't understand from the video. The author of the video mentioned that we can't have the bypass air (or end of the tips) exceed the speed of sound, but how come there are low-byepass supersonic airplanes? This confused me quite a bit...
@@tijljappens7953 on any kind of jet engine, only place where gas is faster than speed of sound is exhaust, but because that gas is hot, it has high speed of sound so maybe on some aircraft , at supersonic flight, hot gas does not need to be on supersonic speed because of itself hot temperature it still is more faster than true airspeed of ac(for ex Ma1 for air at 15C deg is 1200km/h but for gas at 800C deg it is at 2370km/h) sa exhaust gas at 800C deg, can flow through nozzle at 2300km/h and it is still below Ma 1
Absolutely fantastic, I work for an aircraft engine manufacturer and this has a far better explanation than any of the courses or literature the company has to offer. Thank you
Yes! And even when I watch them again, I still learn some more. Of course, my memory’s short and I don’t have a long one, I get distracted easily, and if/when I go an look for more info to clarify something, I’ll end up in another six-hour rabbit hole - kinda how I ended up here in the first place!
I’m a 30+ year aircraft technician, this is a very good video! One guy I knew who worked on aircraft from the 1950s to the 1990s told me those old turbojets were “designed to do two things: eat gas and haul ass!” He added fuel efficiency was just something that was not thought of back then.
Your ability to explain complex ideas is unsurpassed sir. Better yet, you also add a little humor but not so much it becomes a distraction. You are an inspiration. Never change.
I’m 24 and have worked on automobiles for about 6.5 years now, restoring my own collection of older trucks. I’ve always figured airplanes and their technology were out of my reach so I never gave them much thought. Until about mid December (‘23) I watched one recommended YT video of a C17 Globemaster III accidentally lane at the wrong airport that happened to be much smaller and it reversed back and still took off to the shock of the crew behind the camera. Ever since, I’ve done so much research of what kind of aircraft the US military and others have around the world and their capabilities and support roles. Now I’m going thru the process of enlisting in the Air Force and by watching this one video I’ve realized that their engines aren’t too complicated and that I can pretty easily comprehend how they function, just like how I learns how automotive engines work. I will forever help my future children in understanding that they can achieve anything in this world and that nothing is out of their reach as long as they have some kind of interest in it. Passion can really be incredible.
Or if you don’t want to do a military contract you can go to a A&P course for airplane maintenance and power plants. They also service Airline and government contracts with their aircraft. Especially here in Houston there’s a lot of Jobs and Military airports close.
This guy is amazing. From maybe three videos on turbine engines, he's (re)taught me 90% of the layman's understanding of turbines that it took me a decade to glean from AgentJayZ videos. No knock on AgentJayZ whatsoever, he just goes into way, way, way more depth. It takes more time to process. The high level view presented here condenses the core principles wonderfully.
And for those tolerant of his personality. Although he seems to have reeled it in after YT and viewers yanked his chain. His misplaced criticism of Bill Sweetman and Bill Gunston were particular sore spots for me, for example. In fairness, his deep dives motivated me towards adding a jet cert to my A&P, and doing a lot of reading and research.
This is one of the absolute best explanations of how and why the components of these engines work the way they do that I've ever come across. As someone who has zero background in mechanical engineering, this was readily understandable and a joy to watch!
As a person who loves internal combustion engines in both cars and planes, the fact that you started taking up jet engines too because I finished watching all of your car engine related videos long back is a HUGE win for me! Please continue making videos not just about car engines but also about jet engines. I feel like you dont get as much information in youtube about them as you get in car engines.
Brilliant. Was trying to explain to a colleague how the evolution of engine diameter & ground clearance had impacted the 737 against the A320 & the disastrous results.
The 737 was designed as a regional jet for small airports and needed to be low for on board air stairs. The A320 was designed as a mainliner and to only go between serviced airports (or use a ground airstair on unserviced ones). The 737 woudnt have had a problem if it was designed like the 727 or DC-9 or CRJ with the engines on the tail. But Boeing wanted lighter weight and more payload capacity so the engines went under the wings. As the 727 could not be modernized with newer engines because of its centre tail mounted engine, Boeing designed the 757 to replace it. It also designed the 757 with a massive amount of growth potential that the 727 as well as the 737 and 707 lacked by having very tall landing gear, very powerful engines, and very beefy structure. But the plane was too big in comparison to the A320… so they had to make the 737 into something it wasn’t designed to be.
Went to school for two years to learn to fix planes and want you said made so much more since than what some of my professors were saying lol keep up the good work.
Well done! Need to add a nitpick regarding gyro "cancellation": counter-rotation can only cancel the precession effects; it does not eliminate the inertia of the spinning rotors.
First video on your channel I have seen. Loved every second of it. You "dumb down" the explanations enough so a simpleton like myself can understand it, using just enough techno-speak. The graphics (with the assist to Animagraffs on this one) are simple and easy to follow. Thumbs up, and I am now subscribed!
Every one of your videos , I learn something new. I actually take notes, so I don’t forget. You have a natural skill in teaching. Longtime subscriber. Keep up the great work!
Excellent video, with clear explanations of gas turbine (jet engine) operating fundamentals, & basic differences between turbojet & turbofan engine design & operation. The model turbojet & turbofan engines are outstanding in their detail & functionality, & greatly aided your explanations with a visual reference! Superior presentation!
i cannot thank you enough D4A, i can attribute your videos mostly into pushing me to become a car mechanic, which has been my dream career since...pretty much ever, i just didn't know it beforehand :P, this next march i will begin my course to become a Car Mechanics engineer, and i will definitely remember everything you have taught us here
@@d4a I remember reading somewhere that Pratt & Whitney were now using a gear-box so that the fan would turn slower than the jet engine that it was connected to & that this would mitigate the problem of the fan blade tips going supersonic.
this video is truly testament to your quality of content. i honestly have very little interest in planes and their engines [no offence Aerospace Enthusiasts] but i loved watching this video and found it super interesting [as with all your others :D]. gotta be one of the best [mostly] Automotive Channels out there, if not THE best 👍🏻
Literally perfect presentation of very complicated fundamentals associated with aviation and jet engine technology/history. Also, am I the only one addicted to this guy’s speaking voice? His pronunciation, prose, pauses, volume, tone/pitch, everything is like an expertly crafted piece of machinery humming in perfect order. No moments where his voice is too loud or shrill or uncomfortable in any way! I’m genuinely in shock at the literal perfection of this video and audio. He’s the ideal teacher/human speaker dammit! I am spending far too much time listening to/watching his videos because they satisfy my need for perfection in some component of my life.
12:50 The Losi dirtbike R/C and its 2 counter spinning internal flywheels make it dang near impossible to tip over. This part of the video reminded me of it and similarities to how the engine + wheels affect the bike.
I had an RC motorbike as a kid with an internal flywheel. It makes a HUGE difference to model bikes, otherwise you have to maintain very high speeds to keep the gyroscopic except of the wheels high enough... Not something that's easy to do with a model bike, without the gyro you'd need a massive perfectly flat parking lot to run it and take long sweeping turns. With the gyro it was possible to turn it on a 2 lane street with ease.
@@volvo09 yea they used to come with training wheels.. hah thats the kind we had.. very slow, with training wheels, but it was an R/C motorcycle!! Sewper Kewl! Not.
@@umakemerandy3669 yeah I remember taking them off. Gave up on the body real quick. The riders foot was all worn away from crashing and sliding when I finally stopped using it.
Looked up how jet engines work after reading "Where's my flying car?" by J. Storrs Hall and I couldn't have been luckier. Your video explains everything I wanted to know with great precision, while still being easy to comprehend for a layman. Bravo!
I don't know about your childhood but your adulthood is totally awesome with those jet engine models. thanks for beautifully explaining such a complicated subject.
A couple of things to add: Commercial jets use high bypass turbofans because moving more air slightly faster than you are flying is a more efficient transfer of energy than moving less air much faster like in a low bypass turbofan or a turbojet. The downside to this is that the fan portion cannot accelerate air to supersonic speeds, so for fighter jets or supersonic transports you need to have most of your power coming from the jet core of the engine.
@@АлакПатрова yeah, a concept back in the mid 60's if I remember correctly. Turbine engine ran an auto transmission through a gear reduction. Goal of the car was to have a car that could run on multiple fuels. It wasn't fuel efficient, wasn't exactly quiet (but wasn't too loud either) so it never made it past a handful of test cars. The testers loved it though.
Even with a CVT a turbine is garbage,@@АлакПатрова, because response to power changes is poor and low-load efficiency is even worse than the low efficiency at ideal load. A turbine engine is only close to viable for a modern road vehicle in a series hybrid configuration. The US Army M1 Abrams tank is turbine-powered, with an ordinary mechanical transmission. The engine is the Honeywell AGT1500. It works well, except that it consumes far too much fuel. There are lots of web pages and TH-cam videos about it.
This was an outstanding lesson on jet engines! I always wondered why military jet engines were so different from those on commercial planes. Now I know. Thank you!
6:26 the blades at the back end (on the right) of the engine model are shaped the exact opposite way as they should - it's not a compressor driving the gas, but it's a turbine extracting the energy from the gas, so it should be shaped with the curved side up (towards the right).
Very good! Ive been a Flight Engineer / tech instructor for over 30 years. Ive seen engines evolve from RR Spey all the way to PW1000 series on my current aircraft type. They become more and more complicated but the basics remain the same. You did a great job here but I would have discussed inlet guide vanes and variable stators rather than outlet guide vanes. But that's a minor point, your descriptions here would be a great reminder for some of my students.
Not sure how you could have done this any more perfectly. I have learned this as a student about three times and could detect no error in your presentation. Those models are spectacular, by the way.
I am a maintenance engineer in steam turbine, but this presentation has given wings to my knowledge in gas turbine. I was reading from books but this is a clear shot and boom..!!
As someone who knows nothing about engineering, it’s still striking that jet engines seem to have far fewer parts than their piston predecessors. No wonder they are so much more reliable. It’s a remarkable difference, and a seemingly much simpler machine. Amazing!
Excellent episode that helped fill in a few jet engine/fan knowledge gaps. The Ducati example was something I’d never even considered. The more you know. 👍
It's not strictly true. Diesels usually run well below stoichiometric and ultra-lean homogeneous charge engines have been attempted. Peak temperatures are actually the result of ideal stoichiometry, if my understanding is correct. It's something like a bell curve in which temps drop above and below 14.7:1. I would say the diesel process has a great deal in common with the gas turbine in the way that they operate constant-air, variable fuel and rely on internal heat to initiate combustion (at least after igniters/glow plugs are off).
Although this is probably the actually most detailed an explanatory bid on the subject I've seen on TH-cam the truth is I still want more details. Like exactly how to build it. For example how many blades exactly of each type should there be. And there are size ratios in comparison to each other based on what amount of cubic mass etc. they can move. And what's the smallest you can build an engine two. For example you said engines can only go so big but how small can they get?
You have stepped out into others territory and done and explained better than anyone who was already in that space . A better explanation than all the aviation and engineering channels … fantastic work 😅
I started in your channel last year with a general interest in car piston engines. Now I begin my position in aircraft engines and I’d never forget how you light up my passion toward the engines 😊 a great thanks to you for landing my dream career.
I clicked on this video entirely by accident, but watched it out of idle curiosity. Absolutely totally glad I did because it really was fascinating. Thank you so much.
3:13 now this I didn't actually know. Never would've figured that the bypassed air produced most of the thrust Propeller plane with extra steps moment right there.
Absolutely brilliant. Re Pegasus engine. When I was young and the British RAF and Navy used Harriers it was common to see them at airshows and other events. They would always show off their verticle take off and hovering. And this being the 1980s the crowd would be literally 20 yards away. Ill never forget the sheer noise and the blast of a Harrier hovering 100 feet away.
Great Explanation! 👍 Nothing like the feeling of being pushed back into your seat after they release the brakes during takeoff! 😁🥰 After more than 50 years of flying, I Still enjoy it every single time! 🛫 Mike in San Diego. 🌞🎸🚀🖖
Loved This Vid. I'm an aviation Nut. This explained the Whole Bypass thing so well.I shall now binge watch all your vids. You explaine things that seem complex so well.
Bloody effin excellent video! Knew practically everything but I've never seen it explained so well. Not a word too many nor too little, the models are effin great and the presentation fantastic. That's all the compliments you'll get from me, I don't want to overdo it.
To really understand why an evolution from turbojets to turbofans happened, you have to look at propulsive efficiency and thrust calculations. The propulsive efficiency is the forward speed of the aircraft divided by the rearward speed of the jet. Thrust is proportional to the mass of air through the engine multiplied by the difference between the rearward speed of the jet and the forward speed of the aircraft. One important thing to notice is that the thrust produced by an engine running at 100% propulsive efficiency is exactly zero. For a high bypass turbofan, the fan drives a huge mass of air to the rear at only slightly faster than the aircraft's forward speed, so the thrust is enough to maintain cruising speed, while the propulsive efficiency is very high. Before the kinks were worked out of turbofan designs, the only way to improve propulsive efficiency was to improve the aerodynamics, so the aircraft flew faster, with a smaller amount of thrust, but greater propulsive efficiency (this is why airliner speeds peaked in the early 1970s and then declined. Speeds rose as aerodynamics improved and then went down as turbofans were introduced and the bypass ratios got larger and engines moved greater masses at lower speeds). Turbofans gave aircraft designers the ability to aim for lower cruising speeds for best propulsive efficiency.
very good presentation you’ve gotten down into the nut and bolts of it. A lot of people just gloss over this stuff but really people. need to understand the critical parts in the process and you’ve done very well applause.
Another excellent video - well done! You manage to get across all of the important concepts in a beautifully simple way - the hallmarks of a good teacher!
I was hooked with your Volvo red block video. Keep them coming. This video does a great job describing the differences. I believe one other advantage with the high bypass (but don't trust me without verifying) is that the momentum of the core exhaust is more efficiently transfered to the bypass exhaust because the bypass has a velocity that is closer to the core than the freestream velocity. And the same holds for the bypass exhaust momentum to freestream. Basically it's just a smoother transitiion from core to freestream. Hope I described that correctly.
😊🙏 Very informative video tutorial indeed! Love the TurboJet & TurboFan models! Thank You So Much Driving 4 Answers channel! Many Happy Good Blessings in Return to You! 🌷🌿🌏✌💜🕊
Many thanks for this brilliant elucidation of the operation of jet engines and the factors involved their design. The brief snippet about motorcycle engines and the gyro effect was a nice homely touch. Great stuff!
These videos are why I love this channel. Such intricate and interesting topics explained so well. Never really thought much about jet engines and until now thought that turbo jets were the "never" ones, because turbo fan didn't make "sense" to be better. Now I know better and understand why. And the example with the Ducati was interesting too.
Very well explained. Thank you! I've been watching some channels about aviation where countless times the terms turbofan, turbojet and high/low bypass ratio came across and you managed to answer all the questions I had in only 13 minute video.
Dude…… you get a like, a subscribe, and a standing ovation and dual air high five from me! Taking my Poweplant written tomorrow and this clears up so many questions I had!!!!!! Thank you
This video by far the only video that I found in youtube that explain how jet engine works. I plan to make a Gas turbine engine that is similarly used by modern MBT using RC stuff just for fun.
Although this is probably the actually most detailed an explanatory bid on the subject I've seen on TH-cam the truth is I still want more details. Like exactly how to build it. For example how many blades exactly of each type should there be. And there are size ratios in comparison to each other based on what amount of cubic mass etc. they can move. And what's the smallest you can build an engine two. For example you said engines can only go so big but how small can they get?
Turbofan model from the video: www.enginediy.com/products/1-20-turbofan-engine-diy-assembly-turbofan-frighter-ws-15-engine-model-kit-150-pcs?ref=d4a
Turbojet model from the video: www.enginediy.com/products/1-3-turbojet-engine-model-kit-build-your-own-turbojet-engine-that-works-wp-85-turbojet-diy-aircraft-engine-model-100-pcs?ref=d4a
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0:20 So the jet engine would be a true 1 stroke motor, right?
No, it's a zero-stroke motor, because there are no strokes,@@gustavmeyrink_2.0.
modified bypass and combust chamber shape, what will happen?
@@jdwdfw
Sorry, all the jet-powered Ducatis are located at the bottom of that cliff over there:
If I may suggest ... we could say that PISTONS separate the 'strokes' in time ... whereas in a Jet, they occur simultaneously, but are separated in space. You also called the consequence of a common shaft (in video 1) a "vicious cycle" ... but, I hope most of us are comfortable with your usage of phrases like, _"positive feedback loop"_ ... however, I believe some TurboFan (P&W I think worked on it) use planetary gears to "sync" the differing rotational rates as well as increasing torque ...
Thanks again ... and I for one CANNOT overstate just how awesome I think you are. EXCEPTIONALLY intelligent. Bc the ability to make the complex accessible enough to the lay person absolutely MUST be intelligent ... and your consistent success in doing so serves as a proof of that intellect. Likewise, I think most of us are here out of our reverence for your ability to simplify the complex and share with us your enthusiasm ... and thus, it's entirely okay for you to veer off your conventional topic. And if ever your 'veerings' are in error, then, we'll forgive a misadventure. Because I assure you ... none of us are perfect either.
The best description of how a jet fan works that I have ever heard
You are not subscribed to Agent JayZ?
Indeed... very compressed desciption. I loved it.
@@meleardil excuse the pun?
D4a is a phenomenal teacher lol I find my self thinking this with every one of his videos
Excellent.
As an aeronautical engineer I affirm that this material is of good quality. super recommended for all audiences.
About the only thing he didn't mention was the average exhaust velocity which has to be higher than vehicle speed and is why low bypass jet engines are used for fighter jets and not high bypass and why Concorde used turbojets.
@@BooBaddyBigI think that was sort of implied in other words by some of the other related things he said.
@@johnstudd4245 I don't think it was. He said that low bypass jets were used by fighters, and he said that they were less efficient, but gave higher thrust, but he never really said why they were chosen, and in fact pretty much implied it was just a weight thing.
and u didnt noticed blades of them jet models are all wrong?? & The turbine is in wrong direction in first jet at the start.
@@BooBaddyBig Yea, the key word would have been specific thrust. They certainly don't produce higher thrust in general. Just compare the F135 of the F35 to the GE9X on the B777X.
I worked for Rolls-Royce for 32 years and have experience on a whole range of engines from Speys (A 'leaky-turbojet' more than a turbofan) to BR-700's. I think you did a marvelous job explaining the basics. Obviously it is far more complicated when it comes to practical applications!
Nice. RB engine Trent engine XWB
I love the trent 900 from RR engine❤
Would you mind sharing some recommended sources for learning about turbo engines? I'd greatly appreciate any suggestions you may have.
I remember the RR Spey well, hearing them taking off with a 111 or an F28 , they sure had a sharp crackle and Roar to them, wonderful noise 💯
You can thank your lucky stars sir, 32 years with RR.
Flying 4 Answers!!! I'm here for it :D
@d4a you should do a video on some driving turbines 😎 Some of cars that have used turbine engines and some future concepts like that turbine hybrid garbage truck
😮 I want 🚀 4 Answers 🎉
Also riding for answers
But the Answers flew over my head
@@ddd.777- Y2K Baby!!! Man I want one so frickin bad.
A financial improbably at this point, but not impossible.
As an aviation guy who watches your channel because cars are cool, I love to see you tackling stuff about aircraft.
You have an incredible talent for explaining things my dogg.
I used to be a Harrier mechanic. I’m impressed that you know this about our Rolls Royce engine! Additionally, the Harrier uses 4 nozzles with a single engine. The two “cold” nozzles come from the Low pressure compressor and the “hot” nozzles from the high pressure compressor, combustion chamber and all the turbines. You can walk up to a running Harrier and put your hand in front of the LP cold nozzle and the air was only slightly warmer than ambient. But even at idle it is a LOT of volume of air at a pretty high speed. You wouldn’t want to put your face in front of it!
I just love the way you describe things in such a logical manner
Thoroughly understands and teaches. Thank you!
…and quietly!
1:02 Wrong.
No forward thrust is generated by the exhaust gasses exiting via the tailpipe.
In fact some reverse thrust is usually produced by the tailpipe section.
For the Harrier VTOL jet aircraft for example when the exhaust gasses & compressor air flow are turned through 90° reverse thrust = max thrust is generated & upwards thrust = max thrust is generated (f = ma) yet the aircraft doesn't accelerate backwards due to the max forwards thrust still existing & countering the vectoring nozzles full reverse thrust as all forward thrust is generated forwards of the turbine section.
In Fact, the main features of the typical turbojet tailpipe is to be straight & have a big hole that allows the exhaust gasses out in the direction of general flow without getting in the way of or changing the direction of the exhaust gasses.
Ideal Airliner thrust reversers 10 ton thrust engine - first 90° exhaust gasses turn - generates 10 ton reverse thrust countering the 10 ton forward thrust so no net thrust & 20 ton tension on engine casing, next 90° turn creates 10 tons tension across the reverser bucket & another 10 tons reverse thrust giving max reverse thrust of 10 tons net worth of braking effect, lovely jubbley.
100% these are fantastic vids.
As you said, turbofan engines of higher and higher bypass ratios have been developed to improve efficiency and reduce noise. To add a bit of engineering and physics to the discussion I offer the following:
Noise - A significant source of jet engine noise is the shearing/mixing of high speed flow from the core with the lower speed flow surrounding it. In a turbojet engine, all the high speed core flow is interacting with the low speed flow around the outside of the engine, creating one very strong shear/mixing zone. With a turbofan engine the high speed core flow is mixing with the slower fan flow (still much faster than the overall flow over the engine) and the fan flow is mixing with the slower overall flow creating two less intense shear zones and therefore spreading out the mixing zone resulting in a gentler energy exchange and less noise.
Fuel Efficiency - The job of the engine is to produce thrust. When thrust exceeds drag the aircraft accelerates. At cruise, thrust = drag. Thrust comes from increasing the momentum (mass flow rate X change in velocity) of the air flow. Fuel requirements are driven by energy considerations however, not momentum. Jet fuel is a storage medium for energy and is about 43Mj/Kg. Kinetic energy of the flow is (1/2 X mass flow X velocity squared).
So, if we want an engine that produces say 1000 units of thrust, we can chose a low air flow rate/high airflow speed change solution (turbojet) or a high airflow rate/low airflow speed change solution (turbofan). But in either case, the fuel flow will be proportional to the kinetic energy change of the flow. So, suppose we want 1,000 units of thrust.
We could choose a turbojet engine that processes 250 units of air flow and accelerates it 4 units of speed. Multiplying those parameters for momentum change/thrust we get 250 x 4 = 1,000 units of thrust and for kinetic energy change we get 2,000 units (0.5 X 250 X 4 X 4).
Now we choose a turbofan engine that can process 500 units of air flow and accelerate it 2 units of speed. Multiplying again for momentum/thrust we have 500 X 2 = 1,000 units of thrust. However, the kinetic energy change required is now 0.5 X 500 X 2 X 2 = 1,000 units of kinetic energy...half of what the turbojet would require for the same thrust. In practice we can't get all that improvement and the resulting turbofan engine will be more complex, heavier and more expensive, but you can easily see why engineers pursue them!
This is a good, insightful description.
that is speed/velocity efficiency
Very good explanation. I haven't thought in terms of momentum vs. kinetic energy before but it makes perfect sense now.
Thank you for this clarification. I have another question that I didn't understand from the video. The author of the video mentioned that we can't have the bypass air (or end of the tips) exceed the speed of sound, but how come there are low-byepass supersonic airplanes? This confused me quite a bit...
@@tijljappens7953 on any kind of jet engine, only place where gas is faster than speed of sound is exhaust, but because that gas is hot, it has high speed of sound so maybe on some aircraft , at supersonic flight, hot gas does not need to be on supersonic speed because of itself hot temperature it still is more faster than true airspeed of ac(for ex Ma1 for air at 15C deg is 1200km/h but for gas at 800C deg it is at 2370km/h) sa exhaust gas at 800C deg, can flow through nozzle at 2300km/h and it is still below Ma 1
Absolutely fantastic, I work for an aircraft engine manufacturer and this has a far better explanation than any of the courses or literature the company has to offer. Thank you
Every video of yours where I “know” the topic, I come away realizing there’s so much more to learn.
Yes! And even when I watch them again, I still learn some more.
Of course, my memory’s short and I don’t have a long one, I get distracted easily, and if/when I go an look for more info to clarify something, I’ll end up in another six-hour rabbit hole - kinda how I ended up here in the first place!
I’m a 30+ year aircraft technician, this is a very good video! One guy I knew who worked on aircraft from the 1950s to the 1990s told me those old turbojets were “designed to do two things: eat gas and haul ass!” He added fuel efficiency was just something that was not thought of back then.
Whittle had given a great deal of consideration to fuel efficiency & the efficacy of the turbofan engine before 1936.
Your ability to explain complex ideas is unsurpassed sir.
Better yet, you also add a little humor but not so much it becomes a distraction.
You are an inspiration.
Never change.
…and also as you speak you do not wake up your roommates…!
I’m 24 and have worked on automobiles for about 6.5 years now, restoring my own collection of older trucks. I’ve always figured airplanes and their technology were out of my reach so I never gave them much thought. Until about mid December (‘23) I watched one recommended YT video of a C17 Globemaster III accidentally lane at the wrong airport that happened to be much smaller and it reversed back and still took off to the shock of the crew behind the camera. Ever since, I’ve done so much research of what kind of aircraft the US military and others have around the world and their capabilities and support roles. Now I’m going thru the process of enlisting in the Air Force and by watching this one video I’ve realized that their engines aren’t too complicated and that I can pretty easily comprehend how they function, just like how I learns how automotive engines work. I will forever help my future children in understanding that they can achieve anything in this world and that nothing is out of their reach as long as they have some kind of interest in it. Passion can really be incredible.
Or if you don’t want to do a military contract you can go to a A&P course for airplane maintenance and power plants. They also service Airline and government contracts with their aircraft. Especially here in Houston there’s a lot of Jobs and Military airports close.
Now i know edactly what i should swap in my Vw Golf
Haha, do it!
I’ve taken my Scirocco down the Guildford bypass and it works!
Ed Zachary!
This guy is amazing. From maybe three videos on turbine engines, he's (re)taught me 90% of the layman's understanding of turbines that it took me a decade to glean from AgentJayZ videos. No knock on AgentJayZ whatsoever, he just goes into way, way, way more depth. It takes more time to process. The high level view presented here condenses the core principles wonderfully.
AgentJayZ is for the technical minded.
And for those tolerant of his personality. Although he seems to have reeled it in after YT and viewers yanked his chain. His misplaced criticism of Bill Sweetman and Bill Gunston were particular sore spots for me, for example.
In fairness, his deep dives motivated me towards adding a jet cert to my A&P, and doing a lot of reading and research.
This is one of the absolute best explanations of how and why the components of these engines work the way they do that I've ever come across. As someone who has zero background in mechanical engineering, this was readily understandable and a joy to watch!
I just can't get enough of your videos! Looking back at my days in school, wishing I had teacher like you.
As a person who loves internal combustion engines in both cars and planes, the fact that you started taking up jet engines too because I finished watching all of your car engine related videos long back is a HUGE win for me! Please continue making videos not just about car engines but also about jet engines. I feel like you dont get as much information in youtube about them as you get in car engines.
Brilliant. Was trying to explain to a colleague how the evolution of engine diameter & ground clearance had impacted the 737 against the A320 & the disastrous results.
The 737 was designed as a regional jet for small airports and needed to be low for on board air stairs.
The A320 was designed as a mainliner and to only go between serviced airports (or use a ground airstair on unserviced ones).
The 737 woudnt have had a problem if it was designed like the 727 or DC-9 or CRJ with the engines on the tail. But Boeing wanted lighter weight and more payload capacity so the engines went under the wings.
As the 727 could not be modernized with newer engines because of its centre tail mounted engine, Boeing designed the 757 to replace it. It also designed the 757 with a massive amount of growth potential that the 727 as well as the 737 and 707 lacked by having very tall landing gear, very powerful engines, and very beefy structure.
But the plane was too big in comparison to the A320… so they had to make the 737 into something it wasn’t designed to be.
In the mid 1960s I was a jet engine mechanic in the Navy. Your video was well done.
This guy is one of the best teachers I've seen in the last 20 years.
Went to school for two years to learn to fix planes and want you said made so much more since than what some of my professors were saying lol keep up the good work.
Just told myself I want to learn how jet engine works days ago and here it come, from a automotive TH-camr I like❤
Well done! Need to add a nitpick regarding gyro "cancellation": counter-rotation can only cancel the precession effects; it does not eliminate the inertia of the spinning rotors.
First video on your channel I have seen. Loved every second of it. You "dumb down" the explanations enough so a simpleton like myself can understand it, using just enough techno-speak. The graphics (with the assist to Animagraffs on this one) are simple and easy to follow. Thumbs up, and I am now subscribed!
Every one of your videos , I learn something new. I actually take notes, so I don’t forget. You have a natural skill in teaching.
Longtime subscriber.
Keep up the great work!
Excellent video, with clear explanations of gas turbine (jet engine) operating fundamentals, & basic differences between turbojet & turbofan engine design & operation. The model turbojet & turbofan engines are outstanding in their detail & functionality, & greatly aided your explanations with a visual reference!
Superior presentation!
i cannot thank you enough D4A, i can attribute your videos mostly into pushing me to become a car mechanic, which has been my dream career since...pretty much ever, i just didn't know it beforehand :P, this next march i will begin my course to become a Car Mechanics engineer, and i will definitely remember everything you have taught us here
Happy to hear, I wish you the best of luck 💪🔧
@@d4a I remember reading somewhere that Pratt & Whitney were now using a gear-box so that the fan would turn slower than the jet engine that it was connected to & that this would mitigate the problem of the fan blade tips going supersonic.
If someone can explain a very complex topic in a easy way it means that that's a professional who knows what he's talking about. Thanx for sharing.
this video is truly testament to your quality of content. i honestly have very little interest in planes and their engines [no offence Aerospace Enthusiasts] but i loved watching this video and found it super interesting [as with all your others :D]. gotta be one of the best [mostly] Automotive Channels out there, if not THE best 👍🏻
Literally perfect presentation of very complicated fundamentals associated with aviation and jet engine technology/history. Also, am I the only one addicted to this guy’s speaking voice? His pronunciation, prose, pauses, volume, tone/pitch, everything is like an expertly crafted piece of machinery humming in perfect order. No moments where his voice is too loud or shrill or uncomfortable in any way! I’m genuinely in shock at the literal perfection of this video and audio. He’s the ideal teacher/human speaker dammit! I am spending far too much time listening to/watching his videos because they satisfy my need for perfection in some component of my life.
This has got to be the best explaination of turbine engines I've ever heard. Thank you!
Excellent explanation! I’m studying AGK for ATPL and this video helps me a lot to clarify other few minor but important aspects of turbofan.
Thanks
12:50 The Losi dirtbike R/C and its 2 counter spinning internal flywheels make it dang near impossible to tip over.
This part of the video reminded me of it and similarities to how the engine + wheels affect the bike.
I had an RC motorbike as a kid with an internal flywheel. It makes a HUGE difference to model bikes, otherwise you have to maintain very high speeds to keep the gyroscopic except of the wheels high enough... Not something that's easy to do with a model bike, without the gyro you'd need a massive perfectly flat parking lot to run it and take long sweeping turns. With the gyro it was possible to turn it on a 2 lane street with ease.
@@volvo09 yea they used to come with training wheels.. hah thats the kind we had.. very slow, with training wheels, but it was an R/C motorcycle!! Sewper Kewl! Not.
@@umakemerandy3669 yeah I remember taking them off. Gave up on the body real quick. The riders foot was all worn away from crashing and sliding when I finally stopped using it.
We had this discussion last week and your timing and video is impeccable
Thank you very much
This is an incredibly well made video. You, sir, have an incredible speaking voice, as well. Keep making this high-quality content
Looked up how jet engines work after reading "Where's my flying car?" by J. Storrs Hall and I couldn't have been luckier. Your video explains everything I wanted to know with great precision, while still being easy to comprehend for a layman. Bravo!
You're the best "explainer" in the biz! Thanks for this excellent vid!
Fantastic video! Super-clear explanation of bypass and turbojet vs turbofan. Bravo!!!
Absolutely brilliant coverage of the topic!
I don't know about your childhood but your adulthood is totally awesome with those jet engine models. thanks for beautifully explaining such a complicated subject.
A couple of things to add: Commercial jets use high bypass turbofans because moving more air slightly faster than you are flying is a more efficient transfer of energy than moving less air much faster like in a low bypass turbofan or a turbojet. The downside to this is that the fan portion cannot accelerate air to supersonic speeds, so for fighter jets or supersonic transports you need to have most of your power coming from the jet core of the engine.
yes
Ok, now we need a vídeo about the chrysler turbine car!
Wow that was a thing?
@@АлакПатрова yeah, a concept back in the mid 60's if I remember correctly. Turbine engine ran an auto transmission through a gear reduction. Goal of the car was to have a car that could run on multiple fuels.
It wasn't fuel efficient, wasn't exactly quiet (but wasn't too loud either) so it never made it past a handful of test cars. The testers loved it though.
@@volvo09 a turbine on a CVT would probably work really well.
Even with a CVT a turbine is garbage,@@АлакПатрова, because response to power changes is poor and low-load efficiency is even worse than the low efficiency at ideal load. A turbine engine is only close to viable for a modern road vehicle in a series hybrid configuration.
The US Army M1 Abrams tank is turbine-powered, with an ordinary mechanical transmission. The engine is the Honeywell AGT1500. It works well, except that it consumes far too much fuel. There are lots of web pages and TH-cam videos about it.
@@АлакПатрова well, check out the "Marine Turbine" MOTORCYCLE too :) Based on an Helicopter modified turbine.
This was an outstanding lesson on jet engines! I always wondered why military jet engines were so different from those on commercial planes. Now I know. Thank you!
Absolutely amazing explanation. It was so clear and so engaging.
6:26 the blades at the back end (on the right) of the engine model are shaped the exact opposite way as they should - it's not a compressor driving the gas, but it's a turbine extracting the energy from the gas, so it should be shaped with the curved side up (towards the right).
So, it's kinda like they took plane propellers, gave them more blades. Stuck it in a housing in front of a jet engine. And boom, turbo fan lol.
Very good! Ive been a Flight Engineer / tech instructor for over 30 years. Ive seen engines evolve from RR Spey all the way to PW1000 series on my current aircraft type. They become more and more complicated but the basics remain the same. You did a great job here but I would have discussed inlet guide vanes and variable stators rather than outlet guide vanes. But that's a minor point, your descriptions here would be a great reminder for some of my students.
Was there a baby sleeping in the next room during filming? I felt you had been trying so hard not to wake someone up.
Newgen
It's fine, you're just going deaf.
😂😂😂
Turn your volume up lol
i don't know how you keep all the info from all the subjects you cover in your head........you're a smart young man. thx for sharing your knowledge.
i enjoy these telling its just so much passion and clear pronunciation same time
Not sure how you could have done this any more perfectly.
I have learned this as a student about three times and could detect no error in your presentation. Those models are spectacular, by the way.
I am a maintenance engineer in steam turbine, but this presentation has given wings to my knowledge in gas turbine. I was reading from books but this is a clear shot and boom..!!
As someone who knows nothing about engineering, it’s still striking that jet engines seem to have far fewer parts than their piston predecessors. No wonder they are so much more reliable. It’s a remarkable difference, and a seemingly much simpler machine. Amazing!
Excellent episode that helped fill in a few jet engine/fan knowledge gaps. The Ducati example was something I’d never even considered. The more you know. 👍
Its funny how a piston engine will melt itself if ran too lean, but jet engines are the extreme opposite. Awesome video btw, I love the aviation stuff
It's not strictly true. Diesels usually run well below stoichiometric and ultra-lean homogeneous charge engines have been attempted.
Peak temperatures are actually the result of ideal stoichiometry, if my understanding is correct. It's something like a bell curve in which temps drop above and below 14.7:1.
I would say the diesel process has a great deal in common with the gas turbine in the way that they operate constant-air, variable fuel and rely on internal heat to initiate combustion (at least after igniters/glow plugs are off).
That was an incredible and fascinating explanation of the differences and similarities between the two engine types. Thank you!
Although this is probably the actually most detailed an explanatory bid on the subject I've seen on TH-cam the truth is I still want more details. Like exactly how to build it. For example how many blades exactly of each type should there be. And there are size ratios in comparison to each other based on what amount of cubic mass etc. they can move. And what's the smallest you can build an engine two. For example you said engines can only go so big but how small can they get?
Production, explanation of the physics, modern applications= stellar. I really wish I had your presentation skills dude. Cheers, boss
You have stepped out into others territory and done and explained better than anyone who was already in that space .
A better explanation than all the aviation and engineering channels … fantastic work 😅
Agent Jayz has entered the room.
I started in your channel last year with a general interest in car piston engines. Now I begin my position in aircraft engines and I’d never forget how you light up my passion toward the engines 😊 a great thanks to you for landing my dream career.
I clicked on this video entirely by accident, but watched it out of idle curiosity. Absolutely totally glad I did because it really was fascinating. Thank you so much.
3:13
now this I didn't actually know.
Never would've figured that the bypassed air produced most of the thrust
Propeller plane with extra steps moment right there.
Absolutely brilliant.
Re Pegasus engine. When I was young and the British RAF and Navy used Harriers it was common to see them at airshows and other events. They would always show off their verticle take off and hovering. And this being the 1980s the crowd would be literally 20 yards away. Ill never forget the sheer noise and the blast of a Harrier hovering 100 feet away.
Great Explanation! 👍
Nothing like the feeling of being pushed back into your seat after they release the brakes during takeoff! 😁🥰
After more than 50 years of flying, I Still enjoy it every single time! 🛫
Mike in San Diego. 🌞🎸🚀🖖
I have been wanting to know/searching for this exact information for 25 years. I cannot thank you enough so here it goes ... thank you!
Loved This Vid. I'm an aviation Nut. This explained the Whole Bypass thing so well.I shall now binge watch all your vids. You explaine things that seem complex so well.
This video was highly educating. I've learned a lot!
Bloody effin excellent video! Knew practically everything but I've never seen it explained so well. Not a word too many nor too little, the models are effin great and the presentation fantastic. That's all the compliments you'll get from me, I don't want to overdo it.
This guys passion for mechanics is inspiring. Im really happy to have found the channel
woaaa well done, the blades look like they should at last
Yes! Thanks for noticing. Enginediy sent me new blades and fixed it for future models
To really understand why an evolution from turbojets to turbofans happened, you have to look at propulsive efficiency and thrust calculations. The propulsive efficiency is the forward speed of the aircraft divided by the rearward speed of the jet. Thrust is proportional to the mass of air through the engine multiplied by the difference between the rearward speed of the jet and the forward speed of the aircraft. One important thing to notice is that the thrust produced by an engine running at 100% propulsive efficiency is exactly zero. For a high bypass turbofan, the fan drives a huge mass of air to the rear at only slightly faster than the aircraft's forward speed, so the thrust is enough to maintain cruising speed, while the propulsive efficiency is very high. Before the kinks were worked out of turbofan designs, the only way to improve propulsive efficiency was to improve the aerodynamics, so the aircraft flew faster, with a smaller amount of thrust, but greater propulsive efficiency (this is why airliner speeds peaked in the early 1970s and then declined. Speeds rose as aerodynamics improved and then went down as turbofans were introduced and the bypass ratios got larger and engines moved greater masses at lower speeds). Turbofans gave aircraft designers the ability to aim for lower cruising speeds for best propulsive efficiency.
Could you also cover turboshafts and turboprops? I'm loving this series so far
very good presentation you’ve gotten down into the nut and bolts of it. A lot of people just gloss over this stuff but really people. need to understand the critical parts in the process and you’ve done very well applause.
Another excellent video - well done! You manage to get across all of the important concepts in a beautifully simple way - the hallmarks of a good teacher!
It is such a simple addition yet the performance increase defies intuition.
ASMR sound, quite understandable English and a fantastic technic explanation. This video is a gem.
I'm in awe of the fact that you made me understand this complex topic so easily. You've earned my subscription!
I was hooked with your Volvo red block video. Keep them coming. This video does a great job describing the differences. I believe one other advantage with the high bypass (but don't trust me without verifying) is that the momentum of the core exhaust is more efficiently transfered to the bypass exhaust because the bypass has a velocity that is closer to the core than the freestream velocity. And the same holds for the bypass exhaust momentum to freestream. Basically it's just a smoother transitiion from core to freestream. Hope I described that correctly.
yes
😊🙏 Very informative video tutorial indeed! Love the TurboJet & TurboFan models! Thank You So Much Driving 4 Answers channel! Many Happy Good Blessings in Return to You! 🌷🌿🌏✌💜🕊
Many thanks for this brilliant elucidation of the operation of jet engines and the factors involved their design. The brief snippet about motorcycle engines and the gyro effect was a nice homely touch. Great stuff!
I don't know how I can enjoy a new D4A video series without my daily explanation of primary and secondary imbalances.
😂😂
Sweet video :) you should do a whole video on turboshafts and some of the racecars/tanks/helicopters they’re put into
Thank you for your time friend. Always wanted to know the difference.
These videos are why I love this channel. Such intricate and interesting topics explained so well.
Never really thought much about jet engines and until now thought that turbo jets were the "never" ones, because turbo fan didn't make "sense" to be better.
Now I know better and understand why. And the example with the Ducati was interesting too.
Amazing way to explain complicated things in an easy-to-understand manner... Kudos!
wow great explanation, never think of the effect of that difference in jet engines before
I never understood how jet engines compressed air, here is the answer on a car channel. I do like the way you explain how things work.
I've watched a lot of videos on turbofans but this one pulled everything together wonderfully.
Fantastic job!
Very well explained. Thank you! I've been watching some channels about aviation where countless times the terms turbofan, turbojet and high/low bypass ratio came across and you managed to answer all the questions I had in only 13 minute video.
So the giant fan is sort of like a super efficient propeller driven by a jet engine. Brilliant!
I've looked into this stuff before, and kinda understood it, but this presentation really drove it home for me. Thanks!
Dude…… you get a like, a subscribe, and a standing ovation and dual air high five from me! Taking my Poweplant written tomorrow and this clears up so many questions I had!!!!!! Thank you
this video was soo complex yet soo simple to understand. Thank you for the explanation.
I love the fact that you've gotten into jet engines. You are one of my top 5 channels 🏆🏆🏆
As a Mechanical ⚙️ Engineer I can say that this video is extremely well done!
Excellent job explaining this.
I can’t believe it, but I actually understand jet engines now! Obviously half joking but this was a great video. Thank you! You are a talented teacher
This video by far the only video that I found in youtube that explain how jet engine works. I plan to make a Gas turbine engine that is similarly used by modern MBT using RC stuff just for fun.
This is the best description I’ve ever seen. Wish I would have seen this before my interview
Although this is probably the actually most detailed an explanatory bid on the subject I've seen on TH-cam the truth is I still want more details. Like exactly how to build it. For example how many blades exactly of each type should there be. And there are size ratios in comparison to each other based on what amount of cubic mass etc. they can move. And what's the smallest you can build an engine two. For example you said engines can only go so big but how small can they get?