Re: [Jsbsim-devel] F-35 VTOL Engine Modeling

[Alan T. <ajt...@v-...>]

From: Sean McLeod 
Sent: Saturday, April 21, 2018 7:56 AM
To: Development issues 
Subject: Re: [Jsbsim-devel] F-35 VTOL Engine Modeling

Hi Alan

 

“I have just done this with my WIP and it seemed to have the desired effect.”

 

Yep, that’s why I was wondering why the F-22 model doesn’t use it.

 

How do you go about reducing the main thrust once you’ve calculated the loss due to flap blowing?

 

Do you tweak the throttle command going to the engine or is the max thrust in the engine file a property that you change during flight by subtracting the loss from flap blowing from it?

 

<turbine_engine name="CFM56">

  <milthrust> 20000.0 </milthrust>

 

Cheers

 

--------------------
Sorry Sean, I missed that step out in my last email. I multiply the thrust tables by propulsion/flapblow_Milthrust_loss and propulsion/flapblow_Augthrust_loss
The engine definition function(s) can contain any JSBSim xml code – they are not restricted to being just tables.

I had heard about the SA Lightning, but did not know about the Buccaneers. Thanks.

Alan

<function name="MilThrust">
        <product>
            <property>propulsion/flapblow_Milthrust_loss</property>  <!-- see TSR2_aero.xml -->
            <table>
                <independentVar lookup="row">velocities/mach</independentVar>
                <independentVar lookup="column">atmosphere/density-altitude</independentVar>
                <tableData>
          -10000       0   10000   20000   30000   40000   50000   60000
     0.0   1.2600  1.0000  0.7400  0.5340  0.3720  0.2410  0.1490  0
     0.2   1.1710  0.9340  0.6970  0.5060  0.3550  0.2310  0.1430  0
     0.4   1.1500  0.9210  0.6920  0.5060  0.3570  0.2330  0.1450  0
     0.6   1.1810  0.9510  0.7210  0.5320  0.3780  0.2480  0.1540  0
     0.8   1.2580  1.0200  0.7820  0.5820  0.4170  0.2750  0.1700  0
     1.0   1.3690  1.1200  0.8710  0.6510  0.4750  0.3150  0.1950  0
     1.2   1.4850  1.2300  0.9750  0.7440  0.5450  0.3640  0.2250  0
     1.4   1.5941  1.3400  1.0860  0.8450  0.6280  0.4240  0.2630  0
                </tableData>
            </table>
        </product>
    </function>

    <function name="AugThrust">
        <product>
            <property>propulsion/flapblow_Augthrust_loss</property>   <!-- see TSR2_aero.xml -->
            <table>
                <independentVar lookup="row">velocities/mach</independentVar>
                <independentVar lookup="column">atmosphere/density-altitude</independentVar>
                <tableData>
           -10000       0   10000   20000   30000   40000   50000   60000
     0.0    1.1816  1.0000  0.8184  0.6627  0.5280  0.3756  0.2327  0
     0.2    1.1308  0.9599  0.7890  0.6406  0.5116  0.3645  0.2258  0
     0.4    1.1150  0.9474  0.7798  0.6340  0.5070  0.3615  0.2240  0
     0.6    1.1284  0.9589  0.7894  0.6420  0.5134  0.3661  0.2268  0
     0.8    1.1707  0.9942  0.8177  0.6647  0.5309  0.3784  0.2345  0
     1.0    1.2411  1.0529  0.8648  0.7017  0.5596  0.3983  0.2467  0
     1.2    1.3287  1.1254  0.9221  0.7462  0.5936  0.4219  0.2614  0
     1.4    1.4365  1.2149  0.9933  0.8021  0.6360  0.4509  0.2794  0
     1.6    1.5711  1.3260  1.0809  0.8700  0.6874  0.4860  0.3011  0
     1.8    1.7301  1.4579  1.1857  0.9512  0.7495  0.5289  0.3277  0
     2.0    1.8314  1.5700  1.3086  1.0474  0.8216  0.5786  0.3585  0
     2.2    1.9700  1.6900  1.4100  1.2400  0.9100  0.6359  0.3940  0
     2.4    2.0700  1.8000  1.5300  1.3400  1.0000  0.7200  0.4600  0
     2.6    2.2000  1.9200  1.6400  1.4400  1.1000  0.8000  0.5200  0
                </tableData>
            </table>
        </product>
    </function>