dear friends and followers welcome back to my channel and lovely greetings from the EAA Air Venture here in Oshkosh at the Pratt and Whitney booth in today's video we'll be talking about one of the most reliable most powerful most advanced and most sold engine in its class the Pratt and Whitney pt6 turbo engine I'll explain how the engine works why it's so unique and what Dom toretto's Dodge Charger from The Fast and Furious movie has to do with it clear probe and let's get started today's video is brought to you by Pratt Whitney powering sustainable Aviation with Dependable engines let's first get a fundamental understanding of the pt6 engine now the pt6 works like most other gas turbine engine but is in one aspect uniquely different as it is a reverse flow free turbine turbo prop engine what that means you'll see in a minute as I'll mention each section individually now it follows the same principle of suck squeeze bang blow but the pt6 does not have a bypass compared to the standard jet engine on an airliner which makes up more than 80 percent of the forward pushing thrust now within the pt6 it's only the exhaust gases that make the propeller turn and instead of pushing the air through the engine from front to back the pt6 does it from back to front so we're not starting thing here instead we have to start at the back of the engine right here so initially the outside air gets sucked in via the inlet duct which on many pt6 driven planes you see below the propeller now the air is directed below the engine towards the inlet screen where the steel mesh protects the engine from large debris entering so in this part known as the cold section the outside air gets sucked in and then directed towards the compressor now the first part is the low pressure axle compressor which comprises three stages for the small pt6 engines or four stages for the larger pt6 engines but why low pressure now very basically speaking the inlet sucks in the outside air more or less like a powerful vacuum cleaner the first stage has the largest compressor blades which accelerate the air or put kinetic energy into it and right after the rotary blades are a set of stator veins meaning they are stationary or fixed in place and Aid in increasing the air pressure this accelerating and increasing of air pressure process repeats itself two or three more times as the air gets forced further inwards now at the same time the diameter Narrows with each axial compressor stage each followed by a set of stator blades now to give you a perspective the air entered at let's say 15 degrees Celsius at the inlet with one bar outside pressure and once it passed through the first four compressor stages the air got heated to 180 degrees Celsius and increased to 4 Bar in air pressure think of your bicycle pump remember how warm it gets as you pump air into your tires after the last set of stator veins the heated compressed and accelerated air enters the single stage centrifugal compressor now compare this to the spin wheel of the turbocharger in your car if you don't have a Turbocharger in your car this is what it looks like now at this point the air has a temperature of approximately 300 degrees Celsius and a pressure of roughly 10 bar that means it went in with one bar at the inlet and forcing it through a compressor which is not longer than 30 centimeters the pressure is 10 times higher now the already relatively hot and compressed air then gets guided around this Bend via a pipe diffuser which makes sense because initially the flow Direction was parallel along the compressor shaft then the centrifugal compressor changed its direction by 90 degrees to the shaft and after the diffuser it is yet again parallel as it enters the combustion chamber liner so this completes the end of the Cold section OD compressor stage we've sucked in the air squeezed it together and now the air enters the hot section as the air exits the diffuser and enters the combustion chamber liner it passes by the 14 fuel nozzles which inject jet fuel into the combustion chamber now the fuel air mixture then ignites instantly which leads to a controlled and vectored combustion meaning the hot expanding gases are confined in the combustion chamber and want to vacate the chamber as quickly as possible it is then guide around this Bend so briefly into the opposite direction it came from and then flows directly onto the high pressure compressor turbine so this is a single stage axial flow turbine and as you can clearly see here the turbine is the driving force of the compressor stages as they are both mounted on the same shaft spinning at approximately 39 000 revolutions per minute or 650 rounds per second so the three components I just mentioned the compressor the combustion chamber and the compressor turbine complete the gas generator does that make sense now two more things I need to mention in regards to the combustion chamber the combustion of the fuel air mixture is continuous from the engine start until shutdown meaning because of the hot compressed air entering the combustion chamber it will also self-ignite the mixture as long as fuel flow is given also there are no spark plugs as you would have in your car to ignite the fuel air mixture but during engine start you can hear that Infamous clicking sound those are a set of spark igniters on both sides of the combustion chamber assisting the engine's startup when the core is still relatively cold on to the next stage so we can estimate that a little more than half of the energy from the hot gas exiting the combustion chamber was absorbed or used to spin the compressor turbine now the remaining Gas Energy is then guided into the power turbine the gas passes yet again a set of stator veins which accelerate the gas velocity and then hits the first axial power turbine very simply speaking think of a hair dryer being the gas generator blowing onto a windmill which is our power turbine that converts air speed into kinetic or mechanical Power the extracted energy from the gas stream then turns the power shaft and Spins it up to 33 000 revolutions per minute the exhaust gases then Escape through these two side mounted ducts in the power turbine housing which are somewhat of the signature of the pt6 engine letting other Pilots know what this plane is powered by so now we have 33 000 revolutions per minute which is way too fast to drive a propeller now instead the power shaft is then connected to a two-stage planetary output reduction gearbox which turns the propeller at a speed of 1700 to 2200 revolutions per minute outputting a reduction ratio of approximately 15 to 1 which allows for the largest propellers within the general aviation industry to be mounted for example the Pilates Porter comes with a 2.7 meters in diameter propeller and at 1700 pounds of torque so the power turbine blades the power turbine shaft and the reduction gearbox make up the power section of the pt6 an important note I mentioned at the beginning that it's a free turbine what is meant by that now if you haven't noticed it yet the power turbine turns in the opposite direction of the compressor turbine why is that if you look closely in between the first axial power turbine and the compressor turbine you'll notice they are not connected with each other meaning the power turbine shaft spins freely and is not connected with the gas turbine shaft yet again think of a hairdryer blowing onto a windmill now the counter rotation also serves its purpose remember when Dom Toretto revved the engine of his tuned up Dodge Charger now the immense torque nearly bent the frame of his car so during excessive power changes for instance during takeoff and go around the excess torque could if the power turbine the gas generator and the propeller would all spin in the same direction potentially flip over your plane and all pilots flying the pt6 engine in a single-engine aircraft know how strong the torque forces still are despite the counter rotation but there are some great advantages that come with the free turbine reverse flow turbo prop engine design the overall length of only 1.8 meters of the power unit is relatively short compared to others and keep in mind the pt6 and various models can output from 550 up to 1700 shaft horsepower the reverse flow also allows for a shorter power shaft resulting in a lighter structure and fewer vibration problems and due to the fact that a compressor intake is at the back of the engine foreign objects can be diverted by inertial separators in the inlet making the engine ideal for rough Runway surfaces hence the Cessna Caravan or the Pilates Porter which are well known as Bush planes because they hardly ever land on a Tarmac Runway also the three turbine allows for both shafts to run at different speeds and during engine startup the starter has to accelerate only the gas generator making the engine easy to start particularly in cold weather also because both shafts are independent it aids in maintenance by allowing the entire power section to be removed along with the propeller exposing the gas generator section for easier access okay now that we've spoken about the main engine components I would like to direct your attention to the rear and front part of the engine at the rear part we have the accessory gearbox directly connected to the gas generator shaft reducing 39 000 RPM to as low as 4000 RPM to run the mounted accessories for instance the fuel control unit which controls the amount of fuel needed in accordance with the thrust and propeller lever position right in front of that is the high pressure fuel pump bringing up the necessary pressure for the fuel nozzles on the other side we have two scavenge oil pumps responsible for proper lubrication of the reduction gearbox both shafts and the accessory gearbox and the large thing here is the starter and Generator which is connected to the airplane's battery and then spins up the gas generator for engine start and then acts as an electric power generator once the engine is running then at the front we have the propeller interface unit which respectively controls the propellers RPM now here we have a glimpse of the Pratt and Whitney's latest p26e66x T engine model it's part of the pt6e series engine family the first to offer a dual Channel integrated electronic propeller and engine control system in general aviation in summary it has all the trusted components that have made the pt6 the iconic engine it is today plus many new features for the optimal combination of precision performance and efficiency and lastly this is a list of planes helicopters and other vehicles that trust the power and reliability of this engine and as you can see this is long and growing and this sums up my explanation of how the pt6 turbo pulp engine works I really hope you enjoyed this video and got a few takeaways from this incredible engine a huge thank you to Pratt Whitney and their team here at the standard Oshkosh for allowing us to record this video and on that bombshell here's your checklist for today subscribe to my channel and check activate the notification Bell check follow my Instagram account check and perform a touch and go at my website check and don't forget a good pilot is always learning especially at the air Venture here in oscos wishing you all the best your Captain Joe [Music] thank you