We bugged out in the C-310 to Moline IL. ( and a hangar) to avoid the pending weather….hope to return toOSH tomorrow (Thursday) to keep narrating the STOL Demo for Thursday and Fri. Night. Jb.
The fact that these engines are still in production and still in high demand with very little change to their design 60 years later shows what geniuses the folks were who designed them in the first place. You would think that a design that old without FADEC just wouldn't be able to compete, but you'd be dead wrong. They really are just that good.
The moment I saw the exhausts sticking out right behind the prop on the PC-9/PC-21/Texan, I wondered how that turboprop arrangement worked. A suitable amount of googling gave the answer, but this rotating cutaway makes the picture even clearer. Thanks Juan!
Good eye! That "backwards" airflow (and folding) design is the counterintuitive secret underlying the wonder and mysterious workings then of the PT6A's first appearance to people. Huh?! But it worx! like a charm to carry our sorry butts through the dumbest predicaments we "flying monkeys" can so unpredictably, (yet predictably now, as such) could find ourselves in. THAT's why I couldn't EVER quite get a clear idea of how those turbine fans all blend as they do. NOW I do and the understanding leaves me awed, humbled and thankful for the new standard of simplicity, affordability, flight safety and comfort it specifically ushered into the (general) aviation public, typically, in America and world-wide: the marvelous PT6A.
JUAN as a former BE 1900 driver I an tell you that the PT6A-6b powerplants were extremely pilot friendly. Felt snug as a bug in a rug climbing out of Lebanon NH in the summer with a full load.
The split spool turboprop engine is also referred to as a 'free turbine'. The propeller drive spool is not physically connected to the gas generator section but, rather, spins freely by itself and is driven solely by gas pressure. This is opposed to a geared turboprop engine like a Garrett (Rockwell Turbo Commanders et al) in which the propeller shaft is directly geared to turbine itself.
Good Job, Juan! I was looking forward to talking with you, but I was deemed non essential by the US borer guards in Montana. Various models of the -A go from 550 to over a thousand Hp, and your numbers are right in the ball park!
Just the guy I was thinking of watching this! Sorry about the inhospitable non-welcome... Any time you want to make a video explaining this "backwards" engine setup, I'll watch with great interest.
This doesn’t seem like an efficient design to power a prop. I sure I’m wrong cause I’m not an engineer. But the engine makes 3000hp. But outputs 1000? Would like you to do a video explaining why this is the design
Thank you Juan, from all the pilots who've flown their best hours comfortably with the wonderful, (old reliable) PT6A turboprop for halfa century! the best explanation of turboprop mechanics yet. Ya think ya know it like the back of your hand, but this cutaway and following yur finger: one disc driving 4, that's feeding compression to combine O2-loaded air with expanded/exploding fuel in the circular combustion chamber DRIVING the two propulsion discs UNLOCKED for me MUCH better understanding and appreciating where and how of the PT6A's smmooooth, but strong, delayed and sudden, instead of steadily rising and falling acceleration, yet always well-measured response behavior; of the physics, chemistry, math and metallurgy working wonders together, anew for all us old hands. After piston radials, it was a wild new adventure ta learn ta fly right with these sweethearts, but what joys all the new features of the PT6A first! brought with it in one small (completely new experience) turboproppelled package. The PT6A's performance heritage and the unique respect and regard the aviation community holds for this one engine are quite understandable, especially now in seeing it's wonderful design and craftsmanship.
My dad worked for PWC as a test engineer so as kids we got to see these cut-aways all the time at "family days". These looked complicated until years later the first PW100 series came out (3 co-centric shafts!!) - now the PT6A looks so simple!
The reduction gearbox is about 17:1. The Dash 65 model you show here is one of the larger models, smaller versions only have one power turbine disk not the two in this engine.
It looks like a vastly improved PT-6 with the higher compressor pressure ratio of 11, approximately 2.5 accross the 4 axial stages and 4.4 produced by the centryfugal stage and the spiral tube diffusor, remarkable are the cooled turbine inlet guide vanes and the gasgenerator cooled turbine blades. The turbine inlet temperature is probably around 2500 F, consistent with the high pressure ratio. This partly explains the increased power output and lower specific fuel consumption compared to previous PT-6 engines.
The Pilatus PC-12 has a 1200 hp engine. The compressor requires about 1600 hp to compress the inlet air (6.6 #/sec) by a factor of 11. The temperature rises from 80F to about 1280F compressor exit temperature (after the spiral diffusor). The combustion chamber increases the mean temperature to about 2400F with a slight pressure loss (no bang!) at the turbine inlet guide vanes. The heat produced is equivalent to about 3600 hp. The following gas generator high speed turbine produces a little more than 1600 hp to drive the compressor. The hot gas expands and reduces the temperature to about 1680 F. The pressure is reduced by a factor of 3.3 below the pressue in the combustor. The power turbine absorbs somewhat more than the 1200 hp required by the propeller The expanding gas in the turbine reduces the pressure to somewhat more than ambient, with an exhaust temperature of 1140F. The combustion chamber pressure at 100% N2 is 11 times the ambient pressure . The pressure ratio accross the power turbine is also about 3.3. These are the values typical for the PT-6A high performance engine
I went to East Coast Aero Tech at KBED, Hanscom Airport Massachusetts,back in 1988,we got to tear down,inspect,rebuild and run up a Jacobs R-755 and Hamilton Standard 2B-20 counter weighted propeller.That is my most fondest memory,because when I was a young "airport bum" A charter pilot gave me lots of right seat time in a Cessna 195.My first job was at a North East commuter airline running ATR 42's,Saab 340's, Beech 99's & 1900's. The PT6 was practically bullet proof,but was a bear to properly rig.
Centrifugal is large in diameter for it's power so it isn't great for turbojets or turbofans - but they do have incredible pressure ratios. That one stage has the pressure boost equivalent to 6-10 axial stages.
@@blancolirio An additional benefit of the axial/centrifugal mix is that their different flow rates guarantee plenty of excess air at the final stage to run bleed air services.
When I was a kid, I understood how all of that stuff worked because I was obsessed with flight and engines. Now I’ve forgotten all I knew and it’s very cool to get a refresher!
The Beech Starship and Piaggio Avanti finally mounted the PT6 the right way around! The design was an ingenious way to produce a small, free-turbine engine without concentric shafts (like the later PW100 series)
I think 4000 hp is the equivalent to the amount of fuel burned, not the amount extracted by the turbines. From what I recall from online reading, the compressor uses about 2300 hp, the power turbine extracts about 1000 hp from the gas flow, and about 700 hp are "lost" at the exhaust. Still a very efficient machine all things considered.
@@johnschreiber1574 well, a little over 20% is the mean thermodinamyc efficiency of the US's fleet of road vehicles, so that wouldn't break the case. The most efficient turbine engines today (static power generation units weighting several tens of tons) achieve about 45% efficiency without cogeneration, so 20% is not that bad for an airplane if the thrust to weight ratio is decent and it has a small footprint
@@makecba, Juan's a little shy on the horsepower. The -65s on our Be1900s put out an honest 1100 SHP, not counting exhaust thrust. Our SD30s had -67s which were essentially the same engine, but ran hotter and were rated somewhere north of 1400 HP.
And somebody had a great idea of building such a thing and figured out how to build it. Now that would be interesting to go back and look at some of the first turbo props and who came up with that idea.
We had a Turbine class (1 semester) for the PT-6 and the Allison 250. After 3 years of night classes (A&P) at OCC I will be done with my last class in 1 week. Then get to take the FAA exams. Those PT-6's and the Allison 250 are marvels of engineering.
Its basically a lot like a conventional turboprop engine like on a C-130 except for one major difference. A conventional turboprop engine has the turbines, compressor and the prop drive all connected together on the same shaft. But on this engine the shaft is split so one turbine powers the compressor while the other powers the prop. I talked to a pilot who flies one of these and he told me that the gas generator in the back and the prop don't always run at the same speed and that part of the run up test is to lock the prop while running the gas generator section to leak check the engine. I'm not sure exactly why they do it this way but there must be some advantage to it. I think it might have something to do with allowing the gas generator section in the back to always run all spooled up at full speed while the prop speed can be independently adjusted and adapted for the current flight conditions.
Correct your right on. Ive been told you could actually hold aPT-6 propeller until about 13% on startup not in real life ofcourse but shows the difference vs a Garret which needs much more amperage with micas battery to start.
One of the most versatile and reliable engines. My understanding is that it was designed to run as a pipeline engine (running continuously for very long periods of time). It has certainly found a home in aviation on everything from crop dusters to King Airs
Understood the theory and on a straight jet it is simple but this solution is so elegant and clean. I imagined it being an all inline one way flow with a offset shaft returning to drive the prop. Thanks for that Juan!
Pratt & Whitney Canada, eh. It’s actually a centripetal flow engine, as the final compressor rotor flings the compressed air out to the combustors and not straight through. I think the ratio you quoted is the difference in potential speed between the power turbine and Jet exhaust driven fluid drive for the propellor.
Wow very interesting. Didn't think they'd be back to front like that. I love your easy to follow explanation and love mechanical stuff also. Thankyou.😊
Wasn’t this display so cool? I asked one of the P&W guys to give me a “day in the life” of an air molecule. Took him a couple minutes and it made incredible sense. So amazing!
Nice video. The PT-6 is usually called a twin shaft turbine. It started out as an oil field pump engine. I spent many hours behind these. Don't cob the power on one for a go-around or you'll over torque or over temp it depending on the temperature.
Excellent show and tell. I've watched an AgentJayZ video which showed similar flow reversals so this was not too much of a surprise. The difference in power consumption was a surprise.
Great explanation. Next time if you look at the vanes or supports between air intake and accessory drive. They are hollow and there's holes (piccolo holes) in them that pre-swirl the intake air. Just something many don't know about. Keep up the good work 👍 Luke
Turbines are absolutely fascinating! Mind blowing how those 2 tiny discs can handle 1k HP ramming prop blades through the air. Crazy! I still can't really grasp how they work, since a cutaway only shows a tiny piece of the picture. Seems the price of those is not like most commodities - looks like it will never come down, keeping it way out of reach for us regular folks. Too bad. I'd love to play around with one!
My dad worked at PWC and hired my schoolmate out of engineering school to do product support. A PT6A showed up for 5000 hour overhaul with dry bearings so my friend's first job was to figure out why (oil feeds holes were drilled backwards as a CNC machine had been programmed wrong) and then find every engine out in the field that had backwards oil holes (actually easy, 100% tracking on every part) and get replacement engines out to them. Every bearing was cooked and had to be replaced but not a single engine failed in flight.
@@DominicRichens We had one seize on a Twin Otter. Thankfully, it was flying slow on a survey line at the time instead of developing full torque. Surprising for the crew, but a non-event in a sea level environment. Might have been a different situation in the mountains. Loss of oil pressure also results in self-feathering on a PT6. Not as responsive as Garrets or as fuel efficient, but still a great engine.
@@mannypuerta5086 Roger ALL and echoes of the praise for our old pal the PT6A. Her relative deficiencies to Garrets, throttle response and efficiency generally are only due to the earlier time element of state of the design's science/art of turbopropping generally, imho. My sentiments are just nostalgic really, loving a forgiving and reliable engine, like a forgiving aircraft; especially when we're green pilots, more often than not ALL flying PT6A's invariably at one time or another and ALL her built-in, inherent qualities, apparent here, was maybe the only thing that allowed us the common delights of eventually becoming old (happy, curmudgeon) pilots today.
Fascinating…I’ll be honest…I always wondered how those single turbo prop engines seemed so short between prop and exhaust…whole lot of engine behind. When you walk thru the explanation so clearly explained by Juan, one wonders why someone hadn’t already invented it. I always had to know how a torque converter worked on my automatic car. It almost gave me a migraine learning how an eight speed ZF epicyclic box worked.
in 1981 < that is many moon ago > i work at pratt & whitney in Longeuil Quebec i work as a grinder operator on PT6 and JT15D main shaft bearing diameter and flange face those motor are so precise and beatiful
Former A&P here. I worked on PC-12s for a decade. Also old King Airs. And a Bell 212 that all ran the PT6. It’s a solid engine. Especially when compared to the LTS-101. I still have nightmares about that model. 😖
The AF ones anyway are a 3000rpm constant speed prop, and your speed voting lever is simply your torque request...the turbine spins up to 100%RPM around 30% torque. Tons of power, it comes on fast (like ground loop, or go-around roll, fast...full boot of rudder). Having the intake below the turbine creates a heat soak issue for engine start... They are supposed to be very reliable systems...but the AF ones had problems with gearboxes and aerobatics.
Yes 1000HP from that small power turbine is impressive. But consider the space shuttle main engine fuel (liquid hydrogen) turbopump -- each turbine blade, approximately 1" x 2" in size, generates 700HP. Of course it only had to fly for 8.5 minutes before inspection.
Great job Juan I wish you was my instructor at A&P school and the engine class I tore down a Pratt and Whitney JT 12 turbine engine in school and reassemble.
Too bad the weather made everyone do a mass exit out of there. I must say, it was very impressive to see so many planes in the air at one time. Hundreds of planes left in the morning, and then hundreds more tonight. It was something to see so many green planes heading out of Oshkosh on FlightAwear.
That was very interesting. Nice job explaining. BTW; obviously don't know your flying itinerary but you have flash flood watches very close to your home. Some relief from the fires. Hopefully not too big of a pendulum swing in precip.
Just a bit of a nit-pick...the final compressor wheel is centrifugal, not axial, and that fact is a key element in the convoluted airflow of the design. Also key in the compactness and efficiency.
I think it’s interesting to note that you can feather the prop on a PT6 and the engine can still run providing electrical power…of course, you need at least another engine to continue flight.
That's good information on an engine for sure turboprop my dad worked at sweitzers he made Parts like that for Allison's engines that's really cool my friend thanks for the video I enjoyed that seeing how they work God bless 🙏I hope you're having fun hopefully we'll see you soon on video🛩
From what I hear the wrapping up planes and tying them down I hear you're having a bad storm coming that way be careful my friend I hope you're safe and your family God bless🙏
I would love to have heard the conversation the jet engine inventors had with their colleagues at the time... "That reciprocating stuff is nonsense. We can take two fans and light a fire between them and force it to go out one side, while we recover enough energy to keep the whole thing running and get some useful work out of it to boot. Awesome, what could go wrong..."
JB another thing you failed to mention is the absolute low number of moving parts to produce that 600+ horsepower. Now there are a lot of electronic parts that have to go right, but there is a lot less mechanical to go wrong in that engine.
No real electronics on most pt6as mostly still all hydromechanical, though Pratt is rolling out fades/EEC types which allow longer TBO partially due to more careful temperature handling of the engine. Less trust on pilots telling you if they have over temped the engine and for how long.
Juan, I work for P&W’s development shop & if I come across some interesting stuff on the PT6 I will get it to you. If you ever need any other info on our stuff, will see what I can do. Agent JayZ, good to see you old friend. I have a box I’m putting together to send up, glad all is well at Jet City.
Chrysler in the 1960's saw that simplicity and really wanted to make a turbine car. The prototypes were successful but they couldn't figure out how to get it under about $50K. (In 1960's money!)
Is aviation's Sasquatch the JET PACK MAN in the skies over LA? I dont know if I want to fly with pilots that report Sasquatch flying around at 5000 ft?
Power to Weight blows away radial and horizontal opposed piston engines. They also run much longer between TBO's and JET A is cheaper than AVGAS in most places around the world. In agricultural operations the PT6 can use Diesel Fuel below 8000 ft. Number 1 or Number 2 depending on the OAT. Placarded in the cockpit. The PT6 is a GREAT Engine but has the one big issue of all Turbine Engines -They are Fuel Pigs.
That "backwards" airflow (and folding) design is the counterintuitive secret underlying the wonder and mysterious workings then of the PT6A's first appearance to people. Huh?! But it worx! like a charm to carry our sorry butts through the dumbest predicaments we "flying monkeys" can so unpredictably, (yet predictably now, as such) could find ourselves in. THAT's why I couldn't EVER quite get a clear idea of how those turbine fans all blend as they do. NOW I do and the understanding leaves me awed, humbled and thankful for the new standard of simplicity, affordability, flight safety and comfort it specifically ushered into the (general) aviation public, typically, in America and world-wide: the marvelous PT6A.
Very good Juan, much different perspective then you get from a bunch of parts scattered on a bench. 3,000hp to run the compressor section? Don't know but I was thinking more like 300hp, but it's just a guess as I seem to recall about 30% as a rule of thumb for two stage turbine engines for the compressor. I also checked and it looks like the PT6 'E' model is a unique variant is used in the PC-12
I used that description to my daughter (about 9 at the time) while we were touring the Navy Aviation museum in Pensacola. She was embarrassed because other visitors heard me and laughed.
We bugged out in the C-310 to Moline IL. ( and a hangar) to avoid the pending weather….hope to return toOSH tomorrow (Thursday) to keep narrating the STOL Demo for Thursday and Fri. Night. Jb.
Elliot fix you up? Nice FBO.
Good Idea, You won't regret that decision.
Glad you all found some shelter! These mid west summer heat/humidity pop up storms can get pretty rough.
Good choice, Reed Timmer is doing a live update about the weather although the town names are tripping his tongue.
@@matthewgsimmonsms yep! Downtown layover is very nice too!
Thanks
PT6 , The Pride of PWC, design in the 1960's with paper and pencils and still one of the best engine today.
The fact that these engines are still in production and still in high demand with very little change to their design 60 years later shows what geniuses the folks were who designed them in the first place. You would think that a design that old without FADEC just wouldn't be able to compete, but you'd be dead wrong. They really are just that good.
A brilliant piece of engineering. These things will still be running in the next century.
The moment I saw the exhausts sticking out right behind the prop on the PC-9/PC-21/Texan, I wondered how that turboprop arrangement worked. A suitable amount of googling gave the answer, but this rotating cutaway makes the picture even clearer. Thanks Juan!
Always loved the PT6A... the backwards folded design is such an elegant solution to so many design constraints.
They say Union Pacific's Turbine Locomotives were powered by an Industrial PT6A.
Good eye! That "backwards" airflow (and folding) design is the counterintuitive secret underlying the wonder and mysterious workings then of the PT6A's first appearance to people. Huh?! But it worx! like a charm to carry our sorry butts through the dumbest predicaments we "flying monkeys" can so unpredictably, (yet predictably now, as such) could find ourselves in. THAT's why I couldn't EVER quite get a clear idea of how those turbine fans all blend as they do. NOW I do and the understanding leaves me awed, humbled and thankful for the new standard of simplicity, affordability, flight safety and comfort it specifically ushered into the (general) aviation public, typically, in America and world-wide: the marvelous PT6A.
@@RedArrow73 General Electric built the Turbine Engines for the UP locomotives.
JUAN as a former BE 1900 driver I an tell you that the PT6A-6b powerplants were extremely pilot friendly. Felt snug as a bug in a rug climbing out of Lebanon NH in the summer with a full load.
Your passion for the engineering of that engine is palpable. Love it Juan. 👍👍
The split spool turboprop engine is also referred to as a 'free turbine'. The propeller drive spool is not physically connected to the gas generator section but, rather, spins freely by itself and is driven solely by gas pressure. This is opposed to a geared turboprop engine like a Garrett (Rockwell Turbo Commanders et al) in which the propeller shaft is directly geared to turbine itself.
I worked for Pratt and Whitney in Montreal 1966-68 when they were developing the PT6, RB Nova Scotia.
Good Job, Juan! I was looking forward to talking with you, but I was deemed non essential by the US borer guards in Montana. Various models of the -A go from 550 to over a thousand Hp, and your numbers are right in the ball park!
Just the guy I was thinking of watching this! Sorry about the inhospitable non-welcome... Any time you want to make a video explaining this "backwards" engine setup, I'll watch with great interest.
Such hogwash!
So sorry Jay for the boarder hassle. Oshkosh is a great venue. Hope you get there in the future.
This doesn’t seem like an efficient design to power a prop. I sure I’m wrong cause I’m not an engineer. But the engine makes 3000hp. But outputs 1000? Would like you to do a video explaining why this is the design
Non-essential! Well just tell him you want asylum and they have to let you through!
Thank you Juan, from all the pilots who've flown their best hours comfortably with the wonderful, (old reliable) PT6A turboprop for halfa century! the best explanation of turboprop mechanics yet. Ya think ya know it like the back of your hand, but this cutaway and following yur finger: one disc driving 4, that's feeding compression to combine O2-loaded air with expanded/exploding fuel in the circular combustion chamber DRIVING the two propulsion discs UNLOCKED for me MUCH better understanding and appreciating where and how of the PT6A's smmooooth, but strong, delayed and sudden, instead of steadily rising and falling acceleration, yet always well-measured response behavior; of the physics, chemistry, math and metallurgy working wonders together, anew for all us old hands. After piston radials, it was a wild new adventure ta learn ta fly right with these sweethearts, but what joys all the new features of the PT6A first! brought with it in one small (completely new experience) turboproppelled package. The PT6A's performance heritage and the unique respect and regard the aviation community holds for this one engine are quite understandable, especially now in seeing it's wonderful design and craftsmanship.
My dad worked for PWC as a test engineer so as kids we got to see these cut-aways all the time at "family days". These looked complicated until years later the first PW100 series came out (3 co-centric shafts!!) - now the PT6A looks so simple!
The reduction gearbox is about 17:1. The Dash 65 model you show here is one of the larger models, smaller versions only have one power turbine disk not the two in this engine.
Reduction is 15:1 for propeller applications
It looks like a vastly improved PT-6 with the higher compressor pressure ratio of 11, approximately 2.5 accross the 4 axial stages and 4.4 produced by the centryfugal stage and the spiral tube diffusor,
remarkable are the cooled turbine inlet guide vanes and the gasgenerator cooled turbine blades. The turbine inlet temperature is probably around 2500 F, consistent with the high pressure ratio. This partly explains the increased power output and lower specific fuel consumption compared to previous PT-6 engines.
The Pilatus PC-12 has a 1200 hp engine. The compressor requires about 1600 hp to compress the inlet air (6.6 #/sec) by a factor of 11. The temperature rises from 80F to about 1280F compressor exit temperature (after the spiral diffusor). The combustion chamber increases the mean temperature to about 2400F with a slight pressure loss (no bang!) at the turbine inlet guide vanes. The heat produced is equivalent to about 3600 hp. The following gas generator high speed turbine produces a little more than 1600 hp to drive the compressor. The hot gas expands and reduces the temperature to about 1680 F. The pressure is reduced by a factor of 3.3 below the pressue in the combustor.
The power turbine absorbs somewhat more than the 1200 hp required by the propeller
The expanding gas in the turbine reduces the pressure to somewhat more than ambient, with an exhaust temperature of 1140F.
The combustion chamber pressure at 100% N2 is 11 times the ambient pressure .
The pressure ratio accross the power turbine is also about 3.3.
These are the values typical for the PT-6A high performance engine
Wow I loved this video. In all my years I’ve never seen a turbo prop engine explained. Great video!
I went to East Coast Aero Tech at KBED, Hanscom Airport Massachusetts,back in 1988,we got to tear down,inspect,rebuild and run up a Jacobs R-755 and Hamilton Standard 2B-20 counter weighted propeller.That is my most fondest memory,because when I was a young "airport bum" A charter pilot gave me lots of right seat time in a Cessna 195.My first job was at a North East commuter airline running ATR 42's,Saab 340's, Beech 99's & 1900's. The PT6 was practically bullet proof,but was a bear to properly rig.
Aha, you worked for Allyn Caruso, Frank Lorenzo's #1 disciple, didn't you? Bah Hahba Scayalines? My condolences. Did you go on to ConEx?
4 axial stages and one centrifugal stage!
Excellent point!
Centrifugal is large in diameter for it's power so it isn't great for turbojets or turbofans - but they do have incredible pressure ratios. That one stage has the pressure boost equivalent to 6-10 axial stages.
@@blancolirio An additional benefit of the axial/centrifugal mix is that their different flow rates guarantee plenty of excess air at the final stage to run bleed air services.
Yes indeed.Reminds me the early Rolls Royce centrifugal engines like The Derwent.The centrifugal compressors pack some PSI.
You gotta love that PT6…. Thank you for your post. You explained the operation correctly, your close on your numbers.
When I was a kid, I understood how all of that stuff worked because I was obsessed with flight and engines. Now I’ve forgotten all I knew and it’s very cool to get a refresher!
The Beech Starship and Piaggio Avanti finally mounted the PT6 the right way around! The design was an ingenious way to produce a small, free-turbine engine without concentric shafts (like the later PW100 series)
I think 4000 hp is the equivalent to the amount of fuel burned, not the amount extracted by the turbines. From what I recall from online reading, the compressor uses about 2300 hp, the power turbine extracts about 1000 hp from the gas flow, and about 700 hp are "lost" at the exhaust. Still a very efficient machine all things considered.
Your numbers look correct intuitively. Juan's numbers would indicate a thermodynamic efficiency of
@@johnschreiber1574 well, a little over 20% is the mean thermodinamyc efficiency of the US's fleet of road vehicles, so that wouldn't break the case.
The most efficient turbine engines today (static power generation units weighting several tens of tons) achieve about 45% efficiency without cogeneration, so 20% is not that bad for an airplane if the thrust to weight ratio is decent and it has a small footprint
@@makecba, Juan's a little shy on the horsepower. The -65s on our Be1900s put out an honest 1100 SHP, not counting exhaust thrust. Our SD30s had -67s which were essentially the same engine, but ran hotter and were rated somewhere north of 1400 HP.
While I’m impressed with the service these things have given to a wide variety of aircraft, that’s pretty miserable efficiency.
@@ben3989 even compared to a piston engine? I thought the best car engine was only about 24% efficient.
Glad Pete is getting involved and making friends. JB you and Jenny are doing a fantastic job, keep the kids involved.
And somebody had a great idea of building such a thing and figured out how to build it. Now that would be interesting to go back and look at some of the first turbo props and who came up with that idea.
We had a Turbine class (1 semester) for the PT-6 and the Allison 250. After 3 years of night classes (A&P) at OCC I will be done with my last class in 1 week. Then get to take the FAA exams. Those PT-6's and the Allison 250 are marvels of engineering.
Its basically a lot like a conventional turboprop engine like on a C-130 except for one major difference. A conventional turboprop engine has the turbines, compressor and the prop drive all connected together on the same shaft. But on this engine the shaft is split so one turbine powers the compressor while the other powers the prop. I talked to a pilot who flies one of these and he told me that the gas generator in the back and the prop don't always run at the same speed and that part of the run up test is to lock the prop while running the gas generator section to leak check the engine. I'm not sure exactly why they do it this way but there must be some advantage to it. I think it might have something to do with allowing the gas generator section in the back to always run all spooled up at full speed while the prop speed can be independently adjusted and adapted for the current flight conditions.
Correct your right on. Ive been told you could actually hold aPT-6 propeller until about 13% on startup not in real life ofcourse but shows the difference vs a Garret which needs much more amperage with micas battery to start.
One of the most versatile and reliable engines.
My understanding is that it was designed to run as a pipeline engine (running continuously for very long periods of time). It has certainly found a home in aviation on everything from crop dusters to King Airs
...also..note the bleed air lines and remember that rhe forward exhaust adds a small percentage of thrust to the engine performance (5-7% ?)
Understood the theory and on a straight jet it is simple but this solution is so elegant and clean. I imagined it being an all inline one way flow with a offset shaft returning to drive the prop. Thanks for that Juan!
Thanks for the overview of the turboprop. I had no idea how much power is used for compression WOW!!
Pratt & Whitney Canada, eh. It’s actually a centripetal flow engine, as the final compressor rotor flings the compressed air out to the combustors and not straight through. I think the ratio you quoted is the difference in potential speed between the power turbine and Jet exhaust driven fluid drive for the propellor.
Amazing how that works!
I understand compressor stall so much more now too.
Your numbers sound spot on! The TCDS gives 1,173 shp and a gear ratio of 0.0568:1. Considering prop RPM, the power turbines would be at 30,000 RPM
Wow very interesting. Didn't think they'd be back to front like that. I love your easy to follow explanation and love mechanical stuff also. Thankyou.😊
Beautiful things of working art.
Agree one million percent…..
Loved the explanation, JB, your the best at making difficult technical subjects easy to understand.
I always learn so much watching your videos. Thanks for everything you do! I hope to meet you someday.
Wasn’t this display so cool? I asked one of the P&W guys to give me a “day in the life” of an air molecule. Took him a couple minutes and it made incredible sense. So amazing!
Yours was pretty dang good too Juan 😉
Excellent! Got more out of this than if i were there and I can watch this again and show others.
Good reporting. Loved seeing Pete and Jacob. Good pair!
Cool explanation of how the turbo prop works! Amazing how much horsepower they have.
Very cool! I love & appreciate scaled down models, especially with cut-aways and motion.
Thanks Jaun. That is the best explanation on turboprops that I have ever seen !
Great job 'splainin'! Never knew turbo-prop worked like that.
a "Two Spool Turboprop Engine" is similar, but more straightforward.
Nice video. The PT-6 is usually called a twin shaft turbine. It started out as an oil field pump engine.
I spent many hours behind these. Don't cob the power on one for a go-around or you'll over torque or over temp it depending on the temperature.
Excellent show and tell. I've watched an AgentJayZ video which showed similar flow reversals so this was not too much of a surprise. The difference in power consumption was a surprise.
What an amazing piece of technology! I've had a general understanding of how turbine engines work, but this just blew my mind!
Great explanation. Next time if you look at the vanes or supports between air intake and accessory drive. They are hollow and there's holes (piccolo holes) in them that pre-swirl the intake air. Just something many don't know about. Keep up the good work 👍
Luke
Wow never knew how these engines worked. Great video!
Turbines are absolutely fascinating! Mind blowing how those 2 tiny discs can handle 1k HP ramming prop blades through the air. Crazy! I still can't really grasp how they work, since a cutaway only shows a tiny piece of the picture. Seems the price of those is not like most commodities - looks like it will never come down, keeping it way out of reach for us regular folks. Too bad. I'd love to play around with one!
One of they most reliable turboprop engines built.
My dad worked at PWC and hired my schoolmate out of engineering school to do product support. A PT6A showed up for 5000 hour overhaul with dry bearings so my friend's first job was to figure out why (oil feeds holes were drilled backwards as a CNC machine had been programmed wrong) and then find every engine out in the field that had backwards oil holes (actually easy, 100% tracking on every part) and get replacement engines out to them. Every bearing was cooked and had to be replaced but not a single engine failed in flight.
@@DominicRichens We had one seize on a Twin Otter. Thankfully, it was flying slow on a survey line at the time instead of developing full torque. Surprising for the crew, but a non-event in a sea level environment. Might have been a different situation in the mountains. Loss of oil pressure also results in self-feathering on a PT6.
Not as responsive as Garrets or as fuel efficient, but still a great engine.
@@mannypuerta5086 Roger ALL and echoes of the praise for our old pal the PT6A. Her relative deficiencies to Garrets, throttle response and efficiency generally are only due to the earlier time element of state of the design's science/art of turbopropping generally, imho. My sentiments are just nostalgic really, loving a forgiving and reliable engine, like a forgiving aircraft; especially when we're green pilots, more often than not ALL flying PT6A's invariably at one time or another and ALL her built-in, inherent qualities, apparent here, was maybe the only thing that allowed us the common delights of eventually becoming old (happy, curmudgeon) pilots today.
Fascinating…I’ll be honest…I always wondered how those single turbo prop engines seemed so short between prop and exhaust…whole lot of engine behind. When you walk thru the explanation so clearly explained by Juan, one wonders why someone hadn’t already invented it.
I always had to know how a torque converter worked on my automatic car. It almost gave me a migraine learning how an eight speed ZF epicyclic box worked.
Juan please do an analysis video of yesterday's crash in carpathian mountains killing 4
in 1981 < that is many moon ago >
i work at pratt & whitney in Longeuil Quebec
i work as a grinder operator on PT6 and JT15D main shaft bearing diameter and flange face
those motor are so precise and beatiful
I’ve always loved how the pt6 uses axial flow compressors then the final one is a centrifugal compressor
Former A&P here. I worked on PC-12s for a decade. Also old King Airs. And a Bell 212 that all ran the PT6.
It’s a solid engine. Especially when compared to the LTS-101. I still have nightmares about that model. 😖
The AF ones anyway are a 3000rpm constant speed prop, and your speed voting lever is simply your torque request...the turbine spins up to 100%RPM around 30% torque. Tons of power, it comes on fast (like ground loop, or go-around roll, fast...full boot of rudder). Having the intake below the turbine creates a heat soak issue for engine start... They are supposed to be very reliable systems...but the AF ones had problems with gearboxes and aerobatics.
Juan. How are you? I landed at Appleton about 10:30 last night. What a light show
Yes 1000HP from that small power turbine is impressive. But consider the space shuttle main engine fuel (liquid hydrogen) turbopump -- each turbine blade, approximately 1" x 2" in size, generates 700HP. Of course it only had to fly for 8.5 minutes before inspection.
I have built a few -28s they were always fun to build
minor correction 4 axial stages 1 centrifugal stage on the compressor.
You can hold onto the prop and start the motor. When you let go, get out of the way, fast
I can confirm, I have actually done it (for fun) when groundhandling a DHC6.
Great job Juan I wish you was my instructor at A&P school and the engine class I tore down a Pratt and Whitney JT 12 turbine engine in school and reassemble.
Wow. Thanks for showing that. That was interesting and definitely cured my curiosity on how the internals worked.
Man thanks Juan. I really enjoyed that. I didn’t know and even flew a few back in my day.
That was very cool JB. Always like to see what's behind the curtain.
Take care, have fun and fly safe. 🤟🏽🖖🏽
Too bad the weather made everyone do a mass exit out of there. I must say, it was very impressive to see so many planes in the air at one time. Hundreds of planes left in the morning, and then hundreds more tonight. It was something to see so many green planes heading out of Oshkosh on FlightAwear.
What a Great Video,,,, This Man Is Very Good At Providing Detailed Information,,,
Thanks Juan!! I have a lot of hours sitting behind a PT6, and never really got a good look before today!
Fascinating , thanks for posting 🤔 👍🏼 ✨
That was very interesting. Nice job explaining. BTW; obviously don't know your flying itinerary but you have flash flood watches very close to your home. Some relief from the fires. Hopefully not too big of a pendulum swing in precip.
Everything ok out there at Oshkosh? Haven't seen an update since the storms rolled through.
That’s one amazing engine! It’s not as complex as I first thought it was
I used to see these things everywhere in the army
Thanks Juan, I never understood how a jet prop worked, still dont but this helped
Just a bit of a nit-pick...the final compressor wheel is centrifugal, not axial, and that fact is a key element in the convoluted airflow of the design. Also key in the compactness and efficiency.
Thanks for your updates from the show. What stick and rudder hardware do you use on your flight sim?
I think it’s interesting to note that you can feather the prop on a PT6 and the engine can still run providing electrical power…of course, you need at least another engine to continue flight.
That was super cool! Thanks Juan 👍🏻
You always make it an interesting video Thanks
That's good information on an engine for sure turboprop my dad worked at sweitzers he made Parts like that for Allison's engines that's really cool my friend thanks for the video I enjoyed that seeing how they work God bless 🙏I hope you're having fun hopefully we'll see you soon on video🛩
From what I hear the wrapping up planes and tying them down I hear you're having a bad storm coming that way be careful my friend I hope you're safe and your family God bless🙏
A beautiful thing.
Very impressive, thanks Juan! I always wondered how that technology worked!
Juan,
The Turbine Section doubles as a Torque Converter.
That simple.
I would love to have heard the conversation the jet engine inventors had with their colleagues at the time... "That reciprocating stuff is nonsense. We can take two fans and light a fire between them and force it to go out one side, while we recover enough energy to keep the whole thing running and get some useful work out of it to boot. Awesome, what could go wrong..."
JB another thing you failed to mention is the absolute low number of moving parts to produce that 600+ horsepower.
Now there are a lot of electronic parts that have to go right, but there is a lot less mechanical to go wrong in that engine.
No real electronics on most pt6as mostly still all hydromechanical, though Pratt is rolling out fades/EEC types which allow longer TBO partially due to more careful temperature handling of the engine. Less trust on pilots telling you if they have over temped the engine and for how long.
@@threeparots1 true.
Juan,
I work for P&W’s development shop & if I come across some interesting stuff on the PT6 I will get it to you. If you ever need any other info on our stuff, will see what I can do.
Agent JayZ, good to see you old friend. I have a box I’m putting together to send up, glad all is well at Jet City.
I wasn't going to watch this video because I thought it wouldn't interest me, boy was I wrong! Thanks Juan.
Over half a million dollars for one of these and it's got less moving parts than my lawnmower.
Chrysler in the 1960's saw that simplicity and really wanted to make a turbine car. The prototypes were successful but they couldn't figure out how to get it under about $50K. (In 1960's money!)
@@matthewbeasley7765 Fuel consumption at low power rates could be an issue.
I worked for Beech when the first 200 left the factory loaded at under $2 million. But an A36 was under $100k then.
@@matthewbeasley7765 I really like the idea of a turbine car even though I don't think it would ever make sense.
It's an elegant design for sure
Juan is good at explaining ... I'm fascinated by planes 4 sure... should've been a pilot
Juan definitely has a gift for teaching!!
Is aviation's Sasquatch the JET PACK MAN in the skies over LA? I dont know if I want to fly with pilots that report Sasquatch flying around at 5000 ft?
Power to Weight blows away radial and horizontal opposed piston engines. They also run much longer between TBO's and JET A is cheaper than AVGAS in most places around the world.
In agricultural operations the PT6 can use Diesel Fuel below 8000 ft. Number 1 or Number 2 depending on the OAT. Placarded in the cockpit.
The PT6 is a GREAT Engine but has the one big issue of all Turbine Engines -They are Fuel Pigs.
Very interesting! Thanks
That "backwards" airflow (and folding) design is the counterintuitive secret underlying the wonder and mysterious workings then of the PT6A's first appearance to people. Huh?! But it worx! like a charm to carry our sorry butts through the dumbest predicaments we "flying monkeys" can so unpredictably, (yet predictably now, as such) could find ourselves in. THAT's why I couldn't EVER quite get a clear idea of how those turbine fans all blend as they do. NOW I do and the understanding leaves me awed, humbled and thankful for the new standard of simplicity, affordability, flight safety and comfort it specifically ushered into the (general) aviation public, typically, in America and world-wide: the marvelous PT6A.
JEEEEZ JUAN. COULDN'T YOU FIND ANYTHING COMPLICATED THERE !
Very good Juan, much different perspective then you get from a bunch of parts scattered on a bench. 3,000hp to run the compressor section? Don't know but I was thinking more like 300hp, but it's just a guess as I seem to recall about 30% as a rule of thumb for two stage turbine engines for the compressor. I also checked and it looks like the PT6 'E' model is a unique variant is used in the PC-12
Thanks for the laymans explanation. Well done
"Suck, Squeeze, Bang, Blow" greatest explanation of a turbine engine.
Really that’s a piston engine phrase but it works here also
Internal Combustion; Air, fuel, Spark, Boom.
I used that description to my daughter (about 9 at the time) while we were touring the Navy Aviation museum in Pensacola. She was embarrassed because other visitors heard me and laughed.
If there is a bang from your turbine engine something has gone wrong. I'd go with "Suck, Squeeze, Burn, Blow".
Seems like they are failure prone. Maybe it has something to do with things spinning opposite directions in there?
They most certainly are not failure prone.