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Cannot properly increase propeller pitch and engine throttle  Topic is solved

Good sims require good FDMs (the "thing" that makes an aircraft behave like an aircraft).

Re: Cannot properly increase propeller pitch and engine thro

Postby S&J » Sun Oct 17, 2021 9:12 pm

yes
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Re: Cannot properly increase propeller pitch and engine thro

Postby TheEagle » Sun Oct 17, 2021 9:13 pm

I do have to comment out the drag and lift functions ! But funny to get lifted up and fly on one place ! :)
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Re: Cannot properly increase propeller pitch and engine thro

Postby S&J » Sun Oct 17, 2021 9:14 pm

Also it looks like there's been some changes to the fuel mixture. Set the mixture to give an AFR of 12.8
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Re: Cannot properly increase propeller pitch and engine thro

Postby TheEagle » Sun Oct 17, 2021 9:22 pm

Sorry - I can't make 204 kts wind - I've entered that, but I get only 160 kt.
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Re: Cannot properly increase propeller pitch and engine thro

Postby TheEagle » Sun Oct 17, 2021 9:29 pm

Sorry - I cannot do this test - the engine just won't spin up. If I activate the starter long enough, the engine rpm goes up to 1100, but as soon as I release s, it slowly goes back down to 0.
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Re: Cannot properly increase propeller pitch and engine thro

Postby S&J » Sun Oct 17, 2021 10:12 pm

You're not trying to start the engine at 17kft are you ?

If so that would be a problem
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Re: Cannot properly increase propeller pitch and engine thro

Postby TheEagle » Sun Oct 17, 2021 11:38 pm

Well, what else ?
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Re: Cannot properly increase propeller pitch and engine thro

Postby S&J » Mon Oct 18, 2021 8:50 am

Start the engine at sea level conditions and then adjust for alt
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Re: Cannot properly increase propeller pitch and engine thro

Postby TheEagle » Mon Oct 18, 2021 11:37 pm

I've set my orientation heading to 0, then created 200 kt wind from heading 0. Then, I started the engine, moved throttle to full, prop pitch to 0.27. But changing the VE changed nothing on the MP or HP ! Only the fuel consumption changed. But why should the VE changed depending on airspeed, anyways ?
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Re: Cannot properly increase propeller pitch and engine thro

Postby S&J » Tue Oct 19, 2021 8:38 am

VE doesn't change from what you've worked out for static conditions with change in speed below the static condition critical alt However with ram effect the engines critical alt will increase from 17kft to somewhere around 23kft. What we're attempting to do now is understand the changes in VE between these two alt
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Re: Cannot properly increase propeller pitch and engine thro

Postby TheEagle » Thu Oct 21, 2021 12:07 am

VE with wind from bearing 0°

Code: Select all
Altitude      VE
0             0.704
1000          0.6979
5000          0.67
10000         0.6375
15000         0.6069
17000         0.5949
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Re: Cannot properly increase propeller pitch and engine thro

Postby TheEagle » Thu Oct 21, 2021 9:57 am

I'm still getting
Code: Select all
Malformed function name with number: 0 and property name: volumetric-efficiency but no "#" sign for substitution.

for
Code: Select all
   <function name="VolumetricEfficiency">
       <table>
           <independentVar>atmosphere/density-altitude</independentVar>
           <tableData>
                 0           0.7037
                1000     0.698
                5000     0.67
                10000   0.637
                15000   0.6069
                17000   0.5962
            </tableData>
        </table>
   </function>

Please tell me what's wrong … :x :x
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Re: Cannot properly increase propeller pitch and engine thro

Postby S&J » Thu Oct 21, 2021 10:05 pm

by increasing the speed you're simulating the plane creating the ram effect of air being forced into the turbo charger. This means the turbo charger does less work than when stationary and as such results in it being able the maintain the manifold pressure to the higher alt.

Code: Select all
   
               899.5520995   0.6876   0.6496
               926.2933474   0.6876   0.6496    <----
               937.2115576   0.6876   0.6514
               976.1173913   0.6876   0.6578
               1016.283985   0.6876   0.6644
               1057.801324   0.6876   0.6708
               1100.646743   0.6876   0.6774
      ---->    1145.005868   0.6876   0.684
               1190.796667   0.6907   0.6907


Here's a table of pressure against qbar (dynamic pressure).
at 0 qbar (stationary) the critical alt is at 1145 resulting in a VE of 0.6876
at 72.461qbar (going some) the critical alt is at 926.29 resulting in a VE of 0.6496
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Re: Cannot properly increase propeller pitch and engine thro

Postby TheEagle » Fri Oct 22, 2021 9:39 pm

I have done what you said (aircraft aligned with the wind and wind to 200 kts, set pressure, temps, mixture, according to your tables, and tested at 17000 ft, 10000 ft. 5000 ft and 0 ft, and the vol eff values I got were all almost the same (differing at max by 0.0002). Did I do anything wrong ?
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Re: Cannot properly increase propeller pitch and engine thro

Postby S&J » Fri Oct 22, 2021 11:00 pm

Keep going higher untill the manifold pressure starts to drop
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