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larshgf

Flying By The Numbers

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Can somebody tell how to define/determine the values for MP (Manifold Pressure), RPM (Rotation per minute), Config. (Flaps+gear), KIAS (Knots IAS) for any aircraft (mainly GA aircrafts) in the following situations:Cruise ClimbHigh Speed CruiseCruise DescentLow Speed CruiseApproach LevelApproach DescentDoes rules exist for defining these values for instance based on the different velocities of the aircraft (Vs, Vs0, Vx, Vy, Vno, .. etc) as defined in the POM (pilot's op. manual)?Best RegardsLars

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Typically, these are outlined in the aircraft's operating handbook. Things like manifold pressure and RPM are generally listed in the procedures section and broken down by things such as Economy and Best Performance. Often, they will list the ideal climb speeds also. For cruise, the numbers for speed and RPM setting come from tables or charts in the POM. Generally in light aircraft, all these speeds are given for the aircraft at max-gross and there really is no way specified to adjust for weight differences. Having never seen any of the POMs for aircraft larger than 6-seater multi-engine planes, I couldn't tell you about how they look with jets.

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Hi Lars and everyone.There are many Thumb rules / approximations that you can use in real or simulated flying. There is a real problem transferring Real numbers from Real flying to MSFS because of the inaccuracies in the sim. I have yet to find a single model that I can transfer from Real life to the Sim, especially when you try to use the sim in a totality of the real flight envelope. That said, you can still use the sim as a tool, if you know it's limitations.The biggest limiting factor, in MSFS, is the AI when used in Performance / Numbers flying, which basically is defined as Attitude and Power=Performance.You can find All the data you need in the Pilot Operating Hand book of the aircraft, or better yet the Owner's manual if you really want to be exact.I posted some info for you, in the pics and some of the Checklists that use with SpeechBuddy2, that can call / speak the phrases to you, and you do not have to memorize them.The 172 table is what I recommend to my students, and it works for Most GA aircraft, you can find / substitute the numbers that work with your Model.For approaches the best way is to simplify things as much as possible, and fix one thing at the time. I try to get set up 90 KIAS, or better yet GS if I can, before the OM, Straight and Level trimmed, that removes a lot of the load, configuration changes when things get busy later. At the OM, I get the Gear down, or where the Glide slope intercept starts, that normally requires no power change in an RG, or just reduce power to 90 KIAS Down 500 settings from the previously determined settings. This procedure is very quick / efficient and requires No trimming for most aircraft. Now you can concentrate on Flying the Approach, some minor trim may be needed, but the majority of the work is done. Most of the peoples cannot fly the Approach because they get too busy with adjusting, airspeed, descent rate etc.To get the numbers it's easy, you should know them before you get in, but if you don't get them long before you get in the System. In most GA Fast / Max cruise is top of green Clean, the more complicated steps / settings are VFR full Airport Pattern work. That can also be made easy by just setting your Performance to be within the Full flaps down range, around 85 KIAS for most Low GAs and Gear Down, first notch of Flaps, Abeam. Stay at 1000 AGL 'till ready to turn Base and 10 more flaps, descend to about 500 AGL, turn final and 10 more, if you have more flaps use them later when the Runway is made.The most important thing during Pattern work, that most important that even real pilots do not know / remember, is the Reverse Command Control at most of those airspeeds, especially on Final. Control / fix your Airspeed with Pitch and your Altitude with Power, pick an Aiming point on the Runway stay stabilized at the proper Airspeed and most airplanes will land themselves. On Take off, at Rotation pitch for 10 on AI and wait for the bird to peel off, fly Vy, unless Vx needed for obstacles, Clean and you are done. There is more to flying, but these simple steps should help. To help with the Look around, left, right, assign your Normally used Rudder axis to the Left Right view, if not used, and just twist in the direction you want to see. TV;Cessna 182Q 1979 Checklist.; Actual Check list from Cessna Manual and used in real flight.; The C in item 3 "Preflight inspection" stands for Compass ; Deviation card; ;NORMAL PROCEDURES, see EMCY. on another Checklist[Preflight inspection]0=Preflight checklist activated1=Cabin, -- ARROW, C2=Ampenage3=Right wing Trailing edge4=Right Wing5=Nose6=Left wing7=Left wing Leading Edge8= Left wing Trailing edge[before Starting Engine]0=Before Starting Engine checklist activated1=Preflight Inspection, -- COMPLETE2=Seat belts, -- Adjust and lock3=Fuel selector Valve, -- On Both4=Avionics, -- Off5=Brakes, -- Test and set6=Cowl Flaps, -- Open7=Circuit breakers, -- All in8=Beacon, -- On[starting Engine]0=Starting Engine Checklist activated1=Mixture , -- Rich2=Propeller , -- High RPM3=Carburetor Heat , -- Cold4=Throttle , -- 1/4 In. Open5=Prime , -- As Required Warm, 2 to 3, Cold 4 to 66=Masters Switch, -- On7=Propeller Area, -- Clear8=Ignition Switch, -- Both9= Starter, -- Engage10=Oil Pressure, -- Check 30 to, 60 Seconds11=Lights, -- As Required[bEFORE TAKEOFF];RUNUP0=BEFORE TAKEOFF checklist Activated1=Cabin Doors and Windows , -- Closed and Locked2= Parking Break , -- Set3= Controls , -- Free and Correct4= Trim , -- Takeoff5= Flight Instruments , -- Check and Set6= Avionics , -- Check and Set7= Auto pilot , -- Off8= Fuel Selector , -- Both9= Mixture , -- Rich10= Throttle , -- 1700 RPM11= Left Magneto , -- Check 150 RPM12= Magneto on Both13= Right Magneto , -- Check 150 RPM14= Magneto on Both15= Propeller , -- Exercise16= Carburetor Heat , -- Check for RPM Drop17= Engine Instruments and Ammeter , -- Check18= Suction Gauge , -- Check19= Throttle , -- 1,000 RPM20= Friction Locks , -- Adjust21= Flaps , -- 0 to 20, As REQUIRED 22= Parking Break , -- Release[NORMAL TAKEOFF];On Runway0=NORMAL TAKEOFF checklist Activated1=Flaps - 0, TO 20, As REQUIRED2= Carburetor Heat , -- Cold3= Power , -- Full Throttle, 2400 RPM4= Elevator Control , -- Lift Nose at 50 Knots5= Climb Speed , -- 80 knots, with flaps up[sHORT FIELD TAKEOFF]0=SHORT FIELD TAKEOFF checklist Activated1=Wing flaps , -- 20 degrees2=Carburetor heat , -- Cold3=Brakes , -- Apply4=Power , -- Full Throttle and 2400 RPM5=Brakes , -- Release6=Elevator control , -- Maintain slight tail low7=Climb speed , -- 57 knots, until all obstacles arecleared8=Wing flaps , -- Retract slowly, after reaching 70knots[CLIMB]0=CLIMB checklist Activated1=Air Speed , -- 85 knots 23 In. 2450 Rpm2= Power , -- Full Throttle and Maximum Rpm3= Fuel Selector Valve , -- Both4= Mixture , -- As Required5=Cowl Flaps , -- Opened As Required[CRUISE]0=CRUISE checklist Activated1=Power , -- As Required 15 to 23 In. 2200 to 2450Rpm2= Elevator and Rudder Trim, -- Adjust3= Mixture, -- As Required4=Cowl Flaps, -- Closed[NORMAL DESCEND]0=NORMAL DESCEND checklist Activated1=Power, -- As Required2= Carburetor Heat , -- As Required3= Mixture, -- Rich4= Cowl Flaps, -- Closed5= Wing Flaps, -- As Desired 0-10 to 140, 10-40 below95[bEFORE LANDING]0=BEFORE LANDING checklist Activated1=Seat Belts, Harnesses, -- Adjust and Locked2= Fuel Selector, -- Both3= Mixture , -- Rich4= Carburetor Heat, -- On Full5= Wing flaps, -- As Desired6= Propeller, -- High Rpm7= Autopilot , -- Off8= Landing light, -- As Required9= Airspeed, -- 60 to 70, with full flaps[bALKED LANDING]0=BALKED LANDING checklist Activated1=Power, -- Full Throttle2= Carburetor Heat, -- Cold3= Airspeed, -- As Required4= Wing Flaps, -- Retract5= Cowl Flaps, -- Open[sHORT FIELD LANDING]0=SHORT FIELD LANDING checklist Activated1=Wing FLAPS , -- 40 degrees below 95 Knots2=Airspeed , -- Maintain 60 knots3=Trim ,-- Adjust4=Carburetor heat , -- On5=Power , -- Reduce to Idle after obstacle is cleared6=Touch down , -- Main wheels first7=Brakes , -- Apply Heavily8=Wing Flaps , -- Retract for maximum brakeeffectiveness[AFTER LANDING];and clearing runway0=AFTER LANDING checklist Activated1= Taxi Light, -- As Required2= Wing Flaps, -- Up3= Carburetor Heat, -- Cold4=Cowl Flaps, -- Open5=Transponder ,-- Off[sHUTDOWN]0=SHUTDOWN checklist Activated1= Brakes, -- Set2= Radios and Lights, -- Off3= Throttle, -- Idle4= Mixture, -- Idle Cutoff5= Ignition Switch, -- Off6= Master Switch, -- Off 7= Control Lock, -- Install8= Fuel Selector Valve, -- Right9= Install Wheel Chocks and Release Brakes10=Tie Down11= Pitot Cover, On12= Lock Aircraft; TBM700 FS9 Checklist.; Speeds (KIAS); V r 85; V x 100; V y 124; V s0 128; V s1 178; V a 158; V l e 178 (extension); V l o 122 (retraction); V f e 122 (Landing / Full); V f e 178 (T O / 1 st Detent. ) ; V M O / V n e 266; Best glide 110 (clean config); Max T O 6579 lbs; Actual, but simplified, DATA from TBM Manual.; The "C" in "Preflight inspection" ; stands for Compass Deviation card ; NORMAL PROCEDURES, see EMCY. on another Checklist;DO NOT USE FOR REAL FLIGHT[Preflight inspection]0= Preflight checklist activated1= Cabin, -- ARROW C2= Ampenage3= Right wing Trailing edge4= Right Wing5= Nose6= Left wing7= Left wing Leading Edge8= Left wing Trailing edge[before Starting Engine]0=Before Starting Engine checklist activated1=Preflight Inspection, -- COMPLETE2=Seat belts, -- Adjust and lock3=Fuel selector Valve, -- Auto4=Avionics, All switches -- Off5=Brakes, -- Test and set; press CTRL+PERIOD key 6=Landing gear control, -- Down7=Circuit breakers, -- All inn8=Beacon, Strobes, -- Onan9=Electrical Equipment , -- OFF10=Power Lever, -- IDLE; press F2 until Idle 11= Condition Lever, -- FUEL CUTOFF; press CTRL+SHIFT+F2 until fully out 12= Fuel Quantity , -- CHECK 13= Anti-ice, -- Onan14= Anti-ice Annunciators, -- ILLUMINATED; press SHIFT+5 to display annunciator panel [starting Engine]0=Starting Engine Checklist activated;Press CTRL+E to initiate engine autostart sequence1=Auxilliary B P switch , -- Onan; press CTRL+SHIFT+F4 2=Propeller , -- High RPM; press CTRL+F3 until fully in 3=Ignition switch , -- Auto4=Propeller Area, -- Clear 5=Starter , -- Onan; click and hold until engine starts 6= At, N G

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I think what Lars was asking wasn't so much what the "numbers" are or where to find them for an aircraft, but where they COME FROM.Power settings are determined based on the engine and how it's installed. Aircraft engines are designed, or "rated" to give a certain amount of power at certain settings. For simple aircraft, like a Cessna 172, with a fixed-pitch prop, the only real measure of how hard the engine is working is the RPM. For example, the 172R is rated for 160 hp at 2400 rpm, or something. The 172SP has basically the same engine, but it is less "de-rated" and provides 180 hp at 2550 rpm. Don't quote me on those exact numbers, but I think you get the idea.Add a constant-speed (variable-pitch) propeller, and it gets trickier. When you move the propeller lever, you change the reference for the governor and set how fast the propeller will turn. If you apply more power (MP), the propeller will increase its pitch so it takes a bigger bite out of the air, requiring more torque, and slowing itself back down to the desired RPM.A fast propeller setting is like a low gear on a car. Great for acceleration, not so much for cruise.What I've just said is probably not news for most people here, but it helps you understand where "the numbers" come from.For high-performance piston engines, it's common to have some thermal limitations in addition to the MP/RPM limits of the powerplant. You can have a maximum power setting with the caveat "for takeoff" or "5 minutes" or something. That's to avoid frying the engines. More heat for more time is more bad for metal under pressure.So, for takeoff, you generally have max prop RPM, max MP, and try not to hold it for any longer than you have to.Cruise climb is typically faster than best rate-of-climb airspeed. This allows for more cooling air to pass over the engine cylinders and helps keep temperature down. Usually cruise climb settings will also specify a reduced RPM and MP setting that is higher than cruise but lower than takeoff."Fast Cruise" or "Max Cruise" goes back to temperature limitations. How bad do you want to be to your engines?"Normal Cruise" is a nice, conservative setting, but is usually still fast than max range airspeed."Max Range" cruise is an aerodynamic consideration. It is based on L/Dmax for the airfoil and varies with aircraft weight.POHs for most complex piston aircraft specify roughly "square" numbers. That means keeping MP less than 1/100 of RPM. 2300 RPM, 23" MP. 2500 RPM, 25" MP, etc. It seems to be pretty unusual to have MP more than that, although there are aircraft that do, particularly turbos. But you pay for it with a lower TBO on the engine(s).Another consideration when selecting prop RPM is noise. Knocking a couple hundred RPM off the prop could cut your cabin noise level in half, which might be very important to you or your passengers. It's also easier on the propeller since all sorts of bad vibrations happen when the tips go supersonic.Sorry this isn't very specific, but I just wanted to throw out some of the considerations that go into determining "the numbers" as far as I know.

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