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EPR in fs9

L

lh777

Messages
126
Country
italy
As we all know the EPR in FS9 is done badly.
To simulate some programmers do depend on the N1.
Is there a way to do it in a more realistic, then create it as a function of pressure and temperature?
 
EPR simulation for a JT8D-15.

Code: 
(A:TURB ENG CORRECTED N1:1, percent) 31.50   <               
if{ (A:TURB ENG CORRECTED N1:1, percent) 0.0013 *   1.00 + (>L:EPR E1, enum) }

31.50 80.80 (A:TURB ENG CORRECTED N1:1, percent) rng             
if{ (A:TURB ENG CORRECTED N1:1, percent) 31.50 - 0.0103 *   1.04 + (>L:EPR E1, enum) }
   
80.80 83.60 (A:TURB ENG CORRECTED N1:1, percent) rng         
if{ (A:TURB ENG CORRECTED N1:1, percent) 80.80 - 0.0357 *   1.55 + (>L:EPR E1, enum) }

83.60 86.15 (A:TURB ENG CORRECTED N1:1, percent) rng           
if{ (A:TURB ENG CORRECTED N1:1, percent) 83.60 - 0.0392 *   1.65 + (>L:EPR E1, enum) }

86.15 88.60 (A:TURB ENG CORRECTED N1:1, percent) rng           
if{ (A:TURB ENG CORRECTED N1:1, percent) 86.15 - 0.0408 *   1.75 + (>L:EPR E1, enum) }

88.60 91.20 (A:TURB ENG CORRECTED N1:1, percent) rng           
if{ (A:TURB ENG CORRECTED N1:1, percent) 88.60 - 0.0385 *   1.85 + (>L:EPR E1, enum) }

91.20 94.15 (A:TURB ENG CORRECTED N1:1, percent) rng               
if{ (A:TURB ENG CORRECTED N1:1, percent) 91.20 - 0.0339 *   1.95 + (>L:EPR E1, enum) }

94.15 97.65 (A:TURB ENG CORRECTED N1:1, percent) rng           
if{ (A:TURB ENG CORRECTED N1:1, percent) 94.15 - 0.0286 *   2.05 + (>L:EPR E1, enum) }

(A:TURB ENG CORRECTED N1:1, percent) 97.65   >               
if{ (A:TURB ENG CORRECTED N1:1, percent) 97.65 - 0.0240 *   2.15 +   (>L:EPR E1, enum) }
 
Ok, but these are fixed values.
I would like variables FS9 static pressure and temperature to try to shape it to vary from these
 
The static EPR table I'm using is the easiest method for getting reasonably accurate values from real cruise tables as published in the aircraft manual.


You could, of course, also try to determine the dynamic pressure at the exit of the engine and divide it by the dynamic pressure in front of the engine. But this requires some knowledge of the inner workings of a turbofan engine and might not be feasible to do in XML.
 
I have almost finished my studies in aerospace engineering, so I mean enough to jet engines. The only problem is I do not know the variables xml FS9 I need.
What I need it is:
Outside temperature, static pressure, and if it is possible the pressure at the outlet from the turbine.
I can get considering the egt and unfortunately if one believes some assumptions because of FS9.
 
But this

Code: 
(A:TURB ENG CORRECTED N1:1, percent) 31.50 <
if{ (A:TURB ENG CORRECTED N1:1, percent) 0.0013 * 1.00 + (>L:EPR E1, enum) }

31.50 80.80 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 31.50 - 0.0103 * 1.04 + (>L:EPR E1, enum) }

80.80 83.60 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 80.80 - 0.0357 * 1.55 + (>L:EPR E1, enum) }

83.60 86.15 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 83.60 - 0.0392 * 1.65 + (>L:EPR E1, enum) }

86.15 88.60 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 86.15 - 0.0408 * 1.75 + (>L:EPR E1, enum) }

88.60 91.20 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 88.60 - 0.0385 * 1.85 + (>L:EPR E1, enum) }

91.20 94.15 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 91.20 - 0.0339 * 1.95 + (>L:EPR E1, enum) }

94.15 97.65 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 94.15 - 0.0286 * 2.05 + (>L:EPR E1, enum) }

(A:TURB ENG CORRECTED N1:1, percent) 97.65 >
if{ (A:TURB ENG CORRECTED N1:1, percent) 97.65 - 0.0240 * 2.15 + (>L:EPR E1, enum) }
[\code]




I must add between
<Value Minimum="1.0" Maximum="2.25">.........<\value>?
 
But this what?

A list of available variables for FSX/ESP/P3D is here:
https://msdn.microsoft.com/en-us/library/cc526981.aspx

Most of these are also in FS9. Still, you do not have any readily available variables for p_Exhaust and T_Exhaust (EGT is calculated in the same way by FS9 as EPR).


If you want to calculate p_Exhaust, you'll have to make a simple thermodynamic model of a jet engine and translate it into XML-readable equations.
But as this model is simplified and thus will be prone to errors compared to the real engine, sticking to the fixed table is the easiest option.
You certainly have a cruise table for a 747-200 with RB211 engines somewhere. Use it to create said table.
 
I must add between
<Value Minimum="1.0" Maximum="2.25">.........<\value>?

Code: 
(A:TURB ENG CORRECTED N1:1, percent) 31.50 &lt;
if{ (A:TURB ENG CORRECTED N1:1, percent) 0.0013 * 1.00 + (&gt;L:EPR E1, enum) }

31.50 80.80 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 31.50 - 0.0103 * 1.04 + (&gt;L:EPR E1, enum) }

80.80 83.60 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 80.80 - 0.0357 * 1.55 + (&gt;L:EPR E1, enum) }

83.60 86.15 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 83.60 - 0.0392 * 1.65 + (&gt;L:EPR E1, enum) }

86.15 88.60 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 86.15 - 0.0408 * 1.75 + (&gt;L:EPR E1, enum) }

88.60 91.20 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 88.60 - 0.0385 * 1.85 + (&gt;L:EPR E1, enum) }

91.20 94.15 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 91.20 - 0.0339 * 1.95 + (&gt;L:EPR E1, enum) }

94.15 97.65 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 94.15 - 0.0286 * 2.05 + (&gt;L:EPR E1, enum) }

(A:TURB ENG CORRECTED N1:1, percent) 97.65 &gt;
if{ (A:TURB ENG CORRECTED N1:1, percent) 97.65 - 0.0240 * 2.15 + (&gt;L:EPR E1, enum) }

[\code]
 
No.
Code: 
<Element>
<Select>
<Value>
(A:TURB ENG CORRECTED N1:1, percent) 31.50 &lt;
if{ (A:TURB ENG CORRECTED N1:1, percent) 0.0013 * 1.00 + (&gt;L:EPR E1, enum) }

31.50 80.80 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 31.50 - 0.0103 * 1.04 + (&gt;L:EPR E1, enum) }

80.80 83.60 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 80.80 - 0.0357 * 1.55 + (&gt;L:EPR E1, enum) }

83.60 86.15 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 83.60 - 0.0392 * 1.65 + (&gt;L:EPR E1, enum) }

86.15 88.60 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 86.15 - 0.0408 * 1.75 + (&gt;L:EPR E1, enum) }

88.60 91.20 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 88.60 - 0.0385 * 1.85 + (&gt;L:EPR E1, enum) }

91.20 94.15 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 91.20 - 0.0339 * 1.95 + (&gt;L:EPR E1, enum) }

94.15 97.65 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 94.15 - 0.0286 * 2.05 + (&gt;L:EPR E1, enum) }

(A:TURB ENG CORRECTED N1:1, percent) 97.65 &gt;
if{ (A:TURB ENG CORRECTED N1:1, percent) 97.65 - 0.0240 * 2.15 + (&gt;L:EPR E1, enum) }
</Value>
</Select>
</Element>

The gauge needle is driven with.
Code: 
<Value Minimum="1.0" Maximum="2.25">(L:EPR E1, enum)</Value>
 
According to the SDK "rng returns True if the third operand lies between values one and two" Anyone know if that's correct?
 
0.002 (A:TURB ENG1 JET THRUST,pounds) 10000 / 4 pow * 0.008 (A:TURB ENG1 JET THRUST,pounds) 10000 / 3 pow * - 0.032 (A:TURB ENG1 JET THRUST,pounds) 10000 / * + 0,997 +

I tried the following formula, writing the EPR function of the thrust.
Still it seems to be all right, but when the plane accelerates EPR begins to decrease rapidly. Why?
 
Through an interpolation of points, data from cordinates X (jet trhust in pounds) and Y (EPR)
 
mgh said:
According to the SDK "rng returns True if the third operand lies between values one and two" Anyone know if that's correct?
Click to expand...

Is correct, and because of the way Heretic wrote his code, it works ok for him.

lh777 said:
0,997
Click to expand...

You must use 0.997 , or perhaps you have written it ok in the code?

BTW, are you shure about linking EPR to Jet Thrust ???

Tom
 
taguilo said:
Is correct, and because of the way Heretic wrote his code, it works ok for him.
Click to expand...

Code: 
1.50 80.80 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 31.50 - 0.0103 * 1.04 + (&gt;L:EPR E1, enum) }

80.80 83.60 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 80.80 - 0.0357 * 1.55 + (&gt;L:EPR E1, enum) }

Neither of those if-statements would evaluate if A:TURB ENG CORRECTED N1 = 80.80?
 
mgh said:
Code: 
1.50 80.80 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 31.50 - 0.0103 * 1.04 + (&gt;L:EPR E1, enum) }

80.80 83.60 (A:TURB ENG CORRECTED N1:1, percent) rng
if{ (A:TURB ENG CORRECTED N1:1, percent) 80.80 - 0.0357 * 1.55 + (&gt;L:EPR E1, enum) }

Neither of those if-statements would evaluate if A:TURB ENG CORRECTED N1 = 80.80?
Click to expand...

Both wil evaluate, and the second if{ will assign the value, overwriting the first.

rng includes first and second operands in the calcs. Normal use would be like

0-0.99999
1-1.99999
etc.

but as to include the most fractional value, it may be written like

0-1
1-2
etc

as Heretic did, with proper care, of course.

Tom
 
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