How do i calculate/get the fuel used?

[FlyingCoder]

Hi,

Is there any offset that i can get fuel used? If there aren't any, what is the formula to calculate or get the fuel used for the flight? Thank you!

 

[John Dowson]

You can try the following offsets which hold the GENERAL ENG FUEL USED SINCE START indexed simvar for 4 engines: 0x090C. 0x09A4, 0x0A3C. 0x0AD4

[FlyingCoder]

  On 4/3/2023 at 8:08 AM, John Dowson said:

You can try the following offsets which hold the GENERAL ENG FUEL USED SINCE START indexed simvar for 4 engines: 0x090C. 0x09A4, 0x0A3C. 0x0AD4

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Hi John,

What is the expected result? I'm flying the PMDG 738. Do i have to get value of all engines then add them up?

[John Dowson]

  On 4/3/2023 at 1:05 PM, FlyingCoder said:

What is the expected result?

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How can I possibly answer that?

  On 4/3/2023 at 1:05 PM, FlyingCoder said:

Do i have to get value of all engines then add them up?

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Yes.

  On 4/3/2023 at 1:05 PM, FlyingCoder said:

I'm flying the PMDG 738.

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These may or may not hold the correct value - try monitoring those offsets, using FSUIPC's offset monitoring facilitis, as you fly and see if the values increase from 0...
If they don't work, you can use the PMDG offsets (from the Offset Mapping for PMDG 737 document - should also apply to the 738):

6494	4	FLT32	FUEL_QtyCenter	LBS
6498	4	FLT32	FUEL_QtyLeft	LBS
649C	4	FLT32	FUEL_QtyRight	LBS

You would need to initially read and save the quantities at the start of the flight, and then whenever you want to know how much fuel has been used simply read them again and subtract that number from the initial values.

 

[FlyingCoder]

  On 4/3/2023 at 1:15 PM, John Dowson said:

How can I possibly answer that?

Yes.

These may or may not hold the correct value - try monitoring those offsets, using FSUIPC's offset monitoring facilitis, as you fly and see if the values increase from 0...
If they don't work, you can use the PMDG offsets (from the Offset Mapping for PMDG 737 document - should also apply to the 738):

6494	4	FLT32	FUEL_QtyCenter	LBS
6498	4	FLT32	FUEL_QtyLeft	LBS
649C	4	FLT32	FUEL_QtyRight	LBS

You would need to initially read and save the quantities at the start of the flight, and then whenever you want to know how much fuel has been used simply read them again and subtract that number from the initial values.

 

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Hi John,

 

Sorry, i am using your Offset and getting 115503102 and increasing.

I forgot about PMDG 737 offsets. I will take a look at it and see if these solution work. Thank you

[John Dowson]

  On 4/3/2023 at 1:34 PM, FlyingCoder said:

Sorry, i am using your Offset and getting 115503102 and increasing.

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It is a 32-bit float (as documented), not an integer, so I suspect that you are reading them incorrectly - monitor them as FLT32.

Just checked in the PMDG 737 and they seem to be working correctly, starting at 0 and increasing:

  Quote

      1703 Monitor IPC:090C (FLT32) = 0.0000
     1703 Monitor IPC:09A4 (FLT32) = 0.0000
     1719 Monitor IPC:0A3C (FLT32) = 0.0000
     1719 Monitor IPC:0AD4 (FLT32) = 0.0000
...
   251938 Monitor IPC:090C (FLT32) = 0.2448.
   251938 Monitor IPC:09A4 (FLT32) = 0.2448
...
   252375 Monitor IPC:090C (FLT32) = 0.4900
   252375 Monitor IPC:09A4 (FLT32) = 0.4900
...
   253313 Monitor IPC:090C (FLT32) = 0.7369
   253313 Monitor IPC:09A4 (FLT32) = 0.7369
...
   254266 Monitor IPC:090C (FLT32) = 0.9828
   254281 Monitor IPC:09A4 (FLT32) = 0.9828
...
   255266 Monitor IPC:090C (FLT32) = 1.2284
   255266 Monitor IPC:09A4 (FLT32) = 1.2284
...

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Of course, only two offset changing as there are inly two engines.

John

[FlyingCoder]

I'm using c# for my application. 32-bit float i believe is float or double? Which one should i use for the FLT32. There is no FLT32 type in c#.

Example code
 

public Offset<Int32> Engine1fuelUsed = new Offset<Int32>(0x090C);// Engine 1

Hope to get some clarification thank you

[John Dowson]

  On 4/4/2023 at 10:53 AM, FlyingCoder said:

I'm using c# for my application. 32-bit float i believe is float or double? Which one should i use for the FLT32. There is no FLT32 type in c#.

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float - a double would be 64-bits. FLT32 is what is used in FSUIPC's offset monitoring facilities and is not a language data type.

  On 4/4/2023 at 10:53 AM, FlyingCoder said:

public Offset<Int32> Engine1fuelUsed = new Offset<Int32>(0x090C);// Engine 1

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I don't use C#, but maybe try:

public Offset<float> Engine1fuelUsed = new Offset<float>(0x090C);// Engine 1

 

[FlyingCoder]

Hi John,

I just tested with float data type. It works now. Thank you!

[John Dowson]

👍