37 years of working on these things and I learned something today, Pixie Dust, I knew Pratt and Whitney were with holding critical information on all those expensive training courses.
Thank you! This is the most easy to understand explanation I've found (I can now interpret the more complicated explanations with this as background context).
i'm in school right now learning about all the magic pixie dust that makes that engine work. And in class we're also disassembling/inspecting/reassembling a PT6A-20
Magic Pixie dust really happens in the combustion chamber thanks to the axial compressor stages, compressor bleed valves, centrifugal compressor stage and the CT wheel. All of the other whizzy stuff, going in the opposite direction, is just drag. BUT I catch UR drift :-)
I've always considered this ShOcK & AWE Alien Technology.... no mattery how many times it is described. Like a SpaceX launch, it never gets old and is a thing of beauty and a joy that lasts forever. Thank you for the overview. I hope it never gets taken for granted. Cheers!
I was hoping to hear the magic 4 words of turbine operation in there! nicely done--amazing to think that a bunch of folks that that up, drew it by hand, and then machined it.
And the exhaust also provides a little bit of jet thrust. I'm wondering if a turbopropeller or a turboshaft like this can provide greater efficiency of combustion into kinetic energy comprared to piston engines, and better power to weight ratio, why don't they make smaller size of it and use it to power cars. We can add more fan to eliminate the jet thrust and convert it into fully kinetic.
The only real surprise is how small and simple they are compared to an internal combustion engine of similar power. And how reliable, except for the occasional one like Mike Patey's on Turbulence. It's not perpetual motion because of the fuel burned in the combustion chamber, obviously. Modern turbocharged engines are also little gas turbine engines, but with the power taken out during combustion. My turbo diesel does nothing until the turbine spins up.
All pilots need to know is basic operation and engine limits and all mechanics need to know is re&re, tolerances, and rigging. Unless you’re the guy designing the thing, it’s all academic.
Hi Daniel, I'm a student at the University of Cincinnati working on an engine design project for my senior capstone. I was wondering if you might know the dimensions of the centrifugal compressor impeller- the diameter at the outlet, inlet, and hub. Thanks!
34,000 rpm would sound like a race car, I've seen a turbo propeller in flight, the propeller's blades were visible so it couldn't be higher than about 3,000 rpm
propellers can't go much faster than 3,000rpm, turbine engines can't go much slower that 30,000rpm. I'm sure you can figure out the solution to the problem...
andrew jowett Well, I'm glad you were able to enjoy it at least that far. The point of this video was not a detailed discussion, but a general idea of how it works. Once you study the PT6A a bit more, I'd love to hear your thoughts again. :)
Cool explanation, my knowledge in mechanics is very basic and i have a dumb question : -It seems to me that this engine has been build upside down: why air intake is not on the side of the propeller (front) and exhaust on the back ? (logical to me) thank you
Two reasons. 1). This makes the engine much simpler and easier to work on. No concentric shafts for the free turbine. Engine is easily split apart on the wing without even removing the propeller for hot section work. 2). Having the intake at the back allows for a very long inlet. Most have a particle separator so that gravel and ice don’t go into the engine and it can also slow down and pressurize the air going into the engine far more than a short inlet. An added bonus is the exhaust is easily dumped out the sides far ahead of the wing or cockpit which means you don’t have to have a long and cumbersome exhaust pipe out the back like most other turboprops have.
You can have the air intake anywhere,it makes things simple to have it on the rear on this engine.Same with exhaust pipe.Theres no physical connection between compressor drive shaft and propeller drive shaft.You could even do away with propeller drive shaft and drive propeller from compressor shaft.The RR Nene had air intake in center off engine cause it used a double sided centrifugal compressor while the DeHavilland designs were single sided .
ای کاش زبون مادریه خودم فارسیا بلد نبودم ولی مثل همه انگلیسی زبونها تسلط کامل به زبان بین الملی انگلیس داشتم واقعا نونم تو روغن بود خوش به حالتون که زبون انگلیسی زبان مادریتونه.
Hi Daniel, great vid! May I download it and maybe add Spanish subs, just for educational purposes. Thank you!! (I'll make the reference to your channel of course).
No. A torque converter uses an impeller to drive fluid through a turbine. This uses a gas generator to drive a turbine. The biggest difference is that the CT wheel that drives the compressor isn’t adding any energy to go to the power turbines. It’s actually taking away 2/3 of it to drive the compressor.
I get it. I kind of look at it like smoking... As long as people are willing to flip the bill, they'll command their price. One day maybe someone will build an equally good engine at half the price. Until then, I'll find find an alternate.
Daniel Geaslen Actually, it was designed in the late 1950s. Incredible how a 60 year-old design lasted this long. At the same time, nozzle-propelled axial turbines in mainline civilian applications have gone through 3 major revisions... turbojets, low-bypass turbofans, then high-bypass turbofans.
Sure it is. You’re welcome to try and make a better engine. General Electric-one of the largest aircraft engine makers in the world-just made a competitor for this engine but they sure didn’t make it cheaper. Just the engineering in the hot section alone is almost priceless. And unlike cars that can have R&D and tooling amortized over a million unit production run inside of 5 years... they’ve produced 5% of that total in ten times the amount of time.
@@Bartonovich52 Lol... I didn't even remember posting this comment (more than 2+ years ago), but suggest you reread it. OR Maybe your reply was intended toward another post? My post said the engine is a fantastic engine. So, I wouldn't have need to build a better engine. My comment only referenced the price tag.
P&W don't make airscrews. Others do. P&W only make the spinny Torquey thing that twirls the prop. en.wikipedia.org/wiki/List_of_aircraft_propeller_manufacturers
At least, the PT6C-67C engine on the AW-139, the main gearbox connected at the end of the output shaft is capable of running without oil for 30 minutes straight.
Car engines don’t have the superalloys that are used for the nozzle guide vanes and turbine wheels. The compressor turbine is spinning at 39,000 RPM at maximum RPM (104% Ng) and each blade has roughly one ton of force pulling on it... all while being blasted by combustion gases in excess of 2000°C.
Instead of using the terms ''cute little fan'', I would much rather prefer you say: ''axial compressor section'', ''centrifugal compressor'', ''gas generator'', ''power turbine'', and so forth. Simplified is good, but simplistic is not.
"Here's the complicated explination" then follows with the simplest explination there is. Maybe throw a technical term or two in there and it'll be more "complicated" with people still knowing what you're talking about. Like instead of "air goes in here" say "there is an Annular Intake on the rear of the engine, meaning air is drawn in from 360 degrees around the engine" and maybe name the different sections while you point at them like Centrifugal Compressor Blades and Compressor/Power Turbine Wheel. And maybe throw in some stats instead of saying "spins really fast" say "the power turbine wheel spins at 33,000 rpm" this kinda sounds like a highschool presentation, not a complicated breakdown of the engine.
The high camber blades puzzle me. Seems counter intuitive to force the air to change direction that much in a short blade. Imagine a wing like that, sure it would work but it would have an awful lift to drag ratio. Am I wrong?
A single decently priced small turbofan product in the world could dramatically change aviation. Everything is dragged down when idiots think super high price.
It is a million dollar engine when you think of the engineering that just went into that CT wheel you are so confused about. They spin at 39,000 RPM (104% Ng) and at that speed have roughly 2000 lbs of force pulling on each blade. This is all while being bathed for thousands of hours in combustion gases that exceed 2000°C. This is where the state of the art in superalloys lie. Alloys with low creep and that can withstand thousands of thermal and stress cycles without deforming or cracking. The rest is in the gas flow and fluid dynamics. What you have to understand is that the CT wheel is an impulse-reaction turbine. Unlike an aircraft wing.. we don’t need a high “lift” to “drag” ratio because we can turn the “drag” into useful motion. A reaction turbine is like an aircraft wing or a propeller. Also like a fore-and-aft rigged ship.. or a helicopter sprinkler. It turns the gas flow and that pushes the wing/sail/turbine. An impulse turbine is a post-stall turbine and uses pure momentum transfer. Also used in water wheels, paddle wheels, square rigged sailing ships.. as well as kites and fighter jets that can perform very high alpha maneuvers. So it isn’t really camber. It’s to capture some of the gasses to push it. The rest of the blade turns the gasses and gets more of a push. Impulse-reaction. That’s just part of why it’s worth $1,000,000. There are many more absolutely ingenious things about this engine that cannot be made easily or cheaply but are absolutely essential to its function.
@@Bartonovich52 the blades are not in 2000c, inconel is long gone at 1000c. try not to defend status quo without thought. look at how tiny the compressor and turbine parts are. How crude it looks. Like it was built in 1950s because it actually was. It first ran in 1960. So don't tell me it's state of the art. Imagine how dramatically different GA would be with LSAs having two tiny jets instead of a lame rotax. They would only weigh 10kg or so. And the plane could go 700km/h with better fuel economy.
No way. This is awesome! I’ve done hot sections on these and have several thousand hours behind them flying and this is by far the best explanation ever!
