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FSXA Prop Feathering

Heretic

Heretic

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Did anyone ever make the default prop feathering code work?

The switches are properly set up (lever_prop_feathern) and feathering is available in the aircraft.cfg (feathering_switches=1, prop_feathering_available= 1, min_rpm_for_feather= 0).
If I use the switches in-sim, however, they're immediately disengaging again.
If I add some code to force the switches on when off, I get constant button toggling.

So is there something I'm missing or is this a long standing bug?

There are other threads dealing with prop feathering and all end up with some custom code which would be my next step if I can't get the default stuff to work.
 
2016-3-26_7-8-55-501.jpg
B-17 Engine#2. Shut off fuel to kill engine, then pressed feather. Came ON then OFF, but prop feathered on that command
Roy
EDIT. Yes it looks like it is feathered, but I never animated that. Blade should be edge on to wind, not flat to it
 
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Is this with the same aircraft.cfg entries that I've posted above?

I might just have a fundamental logic flaw in my prop pitch animation. Will have to investigate tomorrow.
 
What variable are you using for your prop pitch?

PS. I had to use custom code.
 
Here is the stuff from the aircraft.cfg
prop_feathering_available= 1
prop_auto_feathering_available= 0
min_rpm_for_feather= 700.000
beta_feather= 88.500
power_absorbed_cf= 0.900
defeathering_accumulators_available= 1
prop_reverse_available= 0.000
minimum_on_ground_beta= 0.000
minimum_reverse_beta= 0.000
feathering_switches = 1

Again, I turned off the fuel to the engine and it kept windmilling (I think). Then poked the #2 feather button, tooltip said ON, then OFF and prop had stopped when I looked at it. There is no custom code all just bog standard. Made this thing a long time ago. The props were in high RPM at the time.
Roy
 
The default DC3 has prop feathering but it doesn't look like it works at all either. As you and Roy have found if you press the feather button it goes on and then turns off again. In the DC3 it will kill your RPM down to 1000 (even if the engine is running). I couldn't get the prop to stop rotating in the DC3 with feathering though.

It might be worthwhile monitoring the PROP BETA angle to see what happens when you press the feather button. Whether or not it goes to a high prop blade angle or not. FSX will run props down to a low blade angle when there is no power which makes them more edge on to the rotation of the prop. A high blade angle = edge on to the wind, low blade angle = edge on to the prop rotation which helps when starting.

The realair Duke has some nice prop feathering.
 
I'm normally fairly meticulous with flight test results and this was badly done. Sorry Guys.
In fact what Anthony described is exactly what happened.
2016-3-27_10-33-0-362.jpg
In this picture I have just pressed the Engine#2 Feather button (Red button just right of the VHF radio and left of the Ignition Master cut-off bar (Bright Red).
Engine #2 RPM has fallen to 1000 (gauge just above Throttle 1) Remaining engines are at 2500 RPM.
On the flight test gauge fuel flow for #2 is 269, but Feather says NO. That is
Code: 
(A:PROP FEATHERED:3, bool)
. Note the engine still has combustion.
During the feather the tool tip says On momentarily and it is TOOLTIPTEXT_PROP_FEATHER_SWITCH_1 "Prop 1 Feather Switch
Code: 
 (%((A:Prop feather switch:1,bool)) %{if}on%{else}off%{end})"
So the tool tip just describes the switch state, not whether the prop is feathered.
When I turn off the fuel valve for that engine, fuel flow goes to zero and combustion goes off, see next image
2016-3-27_10-28-1-673.jpg
The engine stops and that is what my original post showed, NOT feathered as I said, just shut down.
Bad input, must be getting lazy in my old age
Roy
 
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Thanks for the continued input.

I'll check the beta angle one I get back to this.
The animation for the feathering isn't much of a problem, but what good is a visually feathered prop if it still produces drag in the FDE?


tgibson said:
What variable are you using for your prop pitch?
Click to expand...

The one for the button. Which, in retrospect, is a stupid idea.
 
I think the feather switch is an on/off condition and if it is off... you wont be feathered.
 
OK despite my last post. Here is what is happening now to the B-17, which has everything stock, no custom anything.
I close the fuel cut-off on #2. Fuel flow drops to zero. Boost drops to ambient.
RPM stays the same. I'm not sure that is realistic, but it is, basically, windmilling.
Since air is now pushing the prop around instead of vice versa we have big drag from it.
Now if I press the feather switch, the engine slows down and stops. That's what it should do if the prop pitch is such that it does not rotate in the airflow.
In my model the prop feather is not animated, nor is pitch so it does not look feathered.
And, PROP FEATHERED:2, bool remains ZERO. It never seems to be a 1. Even when pressing the feather switch which temporarily becomes true.
So from the visual sense, the prop is stopped and it happened by pressing the feather switch.

It is probably worth stating that you would only feather an engine after it has been shut down so just feathering it and leaving the engine running is unlikely but the sim does drop the RPM to 1000. If the fuel is off the RPM goes all the way to zero
Roy
 
I use LEVER_PROP_PITCH0 through LEVER_PROP_PITCH3 for my prop pitch animation in FS9. But I need to control the prop pitch separately from the FEATHER variables in the feather gauge code.
 
Did another test with 2 different turboprops. Although I enabled everything feathering-related in the aircraft.cfg, the ARM AUTO FEATHER SWITCHES and FEATHER SWITCHES appear to do nothing at all. Not even toggling for a second.

I can however get the prop manually into feather by holding F2...


By the way, did you know that fully feathered DC-3 props still produce enough thrust to climb on? :D

 
The investigation continues and I can confirm Roy's findings. Feather switch -> cut combustion and ~750 RPM, mixture to idle cutoff -> RPM drops to 0.

AFSD shows the beta of a feathered prop as 17.40° which is the beta_min value defined in the aircraft.cfg. (Note: I use Alex Metzger's C-47 FDE.)
The feathered beta is defined at 89.5°.


- Edit:

I've animated the blades using "(A:PROP BETA:n, radians) rddg" (keyframe range 0 to 90) and a visual inspection confirms that the prop is definitely NOT feathered when the feathering button is pressed and the mixture is cut.

- Edit2:

The prop seems to go into a feathered state as long as it's windmilling and will reset to beta_min when coming to a halt. WTH Aces?
 
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WarpD said:
And this is with the feather switch staying in the ON condition?
Click to expand...
I cannot remember much about feathering on the only twin pistons that I was qualified on (Piper Navajo and Aztec), but my Pilots Notes for the Fortress GR.IIA says " Hold the button in only long enough to ensure that it stays in by itself then release it so that it can spring out when feathering is complete"
The B-17 F & G Manual says "Each propeller is feathered individually by one of four red push button switches. Pushing the switch in starts an electric pump in the nacelle which supplies hydraulic power for the feathering operation. When the propeller is fully feathered the push button automatically releases, stopping the pump"
Based on that I think the feather switch is behaving correctly by coming on temporarily. However the actual feather state variable PROP FEATHERED:Index does not seem to respond to the switch.

Roy
 
I think the procedure used by MSFS is mildly screwed up. The trick that is perpetuated around the web for the default aircraft is to nudge the prop levers below zero percent with CTRL+F2.
You can do this by using the "feather" button and CTRL+F2 or CTRL+F1 and CTRL+F2. If the corresponding throttle lever is then brought back to idle, RPM will drop to zero and AFSD shows the feathered prop beta defined in the aircraft.cfg.

If someone (Roy?) can indeed confirm this, it will solve the FDE part of the riddle. The rest is just some better gauge code for the feathering buttons.
 
Roy, I'm not asking about a real aircraft... I'm asking about what you're doing in the sim itself.
 
Prop #2 is feathered and the custom "prop beta, radians (to degrees)" driven animation reflects it.

prop1.png


prop2.png



Disadvantage: Moving the prop lever will put the prop beta out of feathering.
 
Disadvantage: Moving the prop lever will put the prop beta out of feathering.
Click to expand...
Could this be prevented by leaving "defeathering accumulators" at 0 in the cfg?

Also, by lowering prop_tc you can slow down the feathering process itself so that it's not that abrupt. Of course, this will slow down the reaction of the prop pitch at all the other rpms as well...
 
Custom coded feathering buttons can do this as well. And a pop lever that is disconnected from the actual prop pitch logic.



The accumulators seem to do nothing.
 
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