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3 Answers

C172S Range and Endurance profile chart in performance.

Asked by: 6276 views Aerodynamics, Aircraft Systems, Commercial Pilot, Flight Instructor, General Aviation, Private Pilot, Student Pilot

Hello everyone,

I fly C172S NAVlll model, and I came up with question on which chart to using while planning out XC flight.

With the skeletons figured out in the navlog sheet, I always open to 'Cruise Performance' section, choose altitude based on hemispheric rule, and then speed depending on how quickly I want to make this trip.

The next page, followed by Range and Endurance profile is where I was lost.

The range profile apparently displays speed, power, and range in nm which I think will be useful for long trip. On the other hand, the endurance profile allowed hours of flight time(endurance) to be deducible depending on altitude and power setting or vice versa.

My question is:-

  1. when do we use range or endurance profile chart?
  2. Any situation where I have to use both the chart to derive the cruise perf?
  3. Any situation where I have to use one of them only to derive the cruise perf?
  4. Do I have to use cruise performance chart in conjunction with range and endurance chart?
  5. I am planning a trip that is real far away from home airport, fuel topped off(53gallons), and I want to get there range permitting, and save as much as fuel. In this case, should I consider both range and endurance? what is your opinion?

Steve

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3 Answers

  1. Best Answer


    jay2712 on Jun 07, 2016

    For you trip I would suggest using the endurance calculations. Note that on the range chart there is a note which states “no wind”, which is not a likely situation for your real life trip. This can be a trap, as in a headwind, your fuel will burn down to nothing before you get the expected range, tailwind you will have more range.
    For cross country planning, calculate your ground speed based on weather conditions at the time of your trip and see how long this trip will take you and calculate your fuel requirements. We fly time and gallons burned, not range. The range will vary everytime.

    Remember to include your VFR Day reserve of an additional 30 minutes. I would suggest a personal minimum reserve of an hour until you are more experienced with fuel burn and flight planning in the aircraft you are flying. If its close, plan an interesting fuel stop at an airport en route and take a break. Never stretch fuel.

    Hope this helps and have a fun trip!

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  2. Steve on Jun 07, 2016

    so, can I deduce the endurance from altitude and power setting I want to use, and then get the groundnspeed from cruise chart, and then correct for windspeed, and get a range?

    Since the wind is in 0kt wind condition, how do I adjust or correct for it in order tomget endurance?

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  3. jay2712 on Jun 07, 2016

    I would not figure the max endurance as it really doesn’t help you in this case.
    Figure the time of your flight.
    Take out the trusty flight computer or use one of the flight plan tools online.
    On the day of the flight, get the winds aloft for the altitude you want to fly.
    Set up the wind on the dial, along with your deviation, heading ect. and use the airspeed from the power setting you are planning on using (should be bringing back memories of the private pilot exam? I hope…). With the wind dialed in, you can now read the ground speed you can expect for each leg. With the ground speed calculated, divide the mileage by the ground speed and get the total time required for the flight. Total time can then be used to determine fuel burn (gallons per hour). Add in the fuel for start, climb to altitude, descent and reserves like I mentioned above and you will have the fuel needed.
    If this exceeds what you can carry on board, plan a fuel stop.

    Use a flight log with checkpoints along the way to see if you calculated the time correctly and need to make adjustments. If its taking longer to get to a checkpoint then it will require more fuel.

    Hope this helps!

    JB

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