quest kodiak g1000

[johnboy007007 0]

Can anyone tell me why the g1000 glass cockpit`s engine management display shows a torque guage at the top and not a manifold pressure guage. This is frustrating me in my quest to learn to correctly fly in ms fsx deluxe, with the aid of ms flight simulator`s real world training manual. Am I missing something as From what I`ve read so far, you need to be able to adjust your manifold pressures to achieve the correct performance configerations. Any help or advice would be good. John

[WarpD 824]

If this is a payware aircraft... you'd be best served by asking the developer(s).

[Jim Robinson 122]

Because the Kodiak is turbine powered, and turbines don't have manifold pressure gauges or even manifolds for that matter. Torque is the turbine counterpart of manifold pressure, meaning both are used as an indication of power output, engine stress, etc.Manifold pressure is actually vacuum in most cases (the exception being turbo-charged or super-charged engines), this vacuum is measured on the engine side of the throttle butterfly. When the butterfly is closed (idle) the vacuum will be low because the engine is trying to draw air through a restricted opening. When the butterfly is open (full throttle) the restriction is less so the vacuum decreases (read in the cockpit as an increase in MP). Manifold pressure is measured in inches of mercury, as is barometric pressure. When the engine stops drawing air (shut down) the pressure equalizes and that's why you see the manifold pressure gauge jump up to 29.92 in/hg (or so) when the engine stops; because your manifold pressure gauge is now effectively a barometer.Torque in turboshaft engines is simply the amount of "twisting" force measured in foot/lbs being exerted on the high RPM shaft between the power turbine and the gear reduction that drives the propeller (or transmission in a heli). Since the RPM is high (maybe 30,000 RPM) the measured force is low, for example a person could easily apply 75 ft/lbs of torque to a stationary shaft by exerting a 75 lb pull on a 12" lever (or 37.5 lbs on a 24" lever). Maintaining this force on a shaft spinning at 30,000 RPM is where turbines come into their own. Now take that 75 lb pull at 30,000 RPM and reduce the speed through gearing to 2000 RPM or so and you get an idea of the kind of power that can be produced by simply moving hot air through a set of fan blades :( .Jim

[cnault2 3]

Jim,I'm an avionics tech for 30+ years. I'm not a jet troop but I've always wanted to completely understand the technical and operational aspects of systems I work with (in this case, engine instruments are part of my technical responsibilities). You just provided the best explanation I've ever heard of turbine ops. I appreciate it! In the past, I've always nodded my head in false understanding whenever a jet guy took the time to confuse me with an explanation of his systems. Today was a "light bulb" moment for me. Thanks very much!Mark Nault

[fly_a_mig17 0]

Because the Kodiak is turbine powered, and turbines don't have manifold pressure gauges or even manifolds for that matter. Torque is the turbine counterpart of manifold pressure, meaning both are used as an indication of power output, engine stress, etc.Manifold pressure is actually vacuum in most cases (the exception being turbo-charged or super-charged engines), this vacuum is measured on the engine side of the throttle butterfly. When the butterfly is closed (idle) the vacuum will be low because the engine is trying to draw air through a restricted opening. When the butterfly is open (full throttle) the restriction is less so the vacuum decreases (read in the cockpit as an increase in MP). Manifold pressure is measured in inches of mercury, as is barometric pressure. When the engine stops drawing air (shut down) the pressure equalizes and that's why you see the manifold pressure gauge jump up to 29.92 in/hg (or so) when the engine stops; because your manifold pressure gauge is now effectively a barometer.Torque in turboshaft engines is simply the amount of "twisting" force measured in foot/lbs being exerted on the high RPM shaft between the power turbine and the gear reduction that drives the propeller (or transmission in a heli). Since the RPM is high (maybe 30,000 RPM) the measured force is low, for example a person could easily apply 75 ft/lbs of torque to a stationary shaft by exerting a 75 lb pull on a 12" lever (or 37.5 lbs on a 24" lever). Maintaining this force on a shaft spinning at 30,000 RPM is where turbines come into their own. Now take that 75 lb pull at 30,000 RPM and reduce the speed through gearing to 2000 RPM or so and you get an idea of the kind of power that can be produced by simply moving hot air through a set of fan blades :( .Jim

loved the explanation, very well done :)

[raymar 969]

Thanks for the insight, Jim. Very good.Ray