feathering gremlins

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Masterius
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Joined: 30 May 2019, 14:36

feathering gremlins

Post by Masterius »

As a programmer in my (now-distant) past, I enjoy dabbling with scripts, and using LINDA and FSUIPC. I've encountered an oddity regarding the feathering feature.

I'd noticed this when testing out a new script I'd written, automating an emergency in-flight (or on the ground) engine shut-down. First was dealing with the prop pitch controls not functioning after running the shutdown procedure. A bit of tinkering fixed that but, while doing so, I ran across something that just doesn't make sense: Engines 1, 2, and 3 operate correctly . . engine 4 does not.

It isn't a matter of my having borked up something in my scripts, because even if I use the A2A B-17 provided scripts for feathering and unfeathering the same thing happens:

On the ground, engines off, engines 1,2, and 3, when I enable feathering, nothing happens (which is correct: no oil pressure, no feathering/unfeathering). Engine 4, however, when the feather button is pressed (or the script ran) at the 8 second mark both feathers the prop and pops the feather button back out. Pressing the feather button at that point, it depresses then immediately pops back out, as the blades then unfeather.

This behavior repeats with the engines running, except that #4 doesn't always unfeather.

Anyone else seeing this happen?
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alan CXA651
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Re: feathering gremlins

Post by alan CXA651 »

Hi Chevalier.
I dont recall any issues , only time i have deliberatly shutdown and restarted my engines was on a training flight i did when i first had the aircraft , to see what it was like shutting each engine down and restarting in flight , never tried with engines shut down .
Like you say nothing should happen with the prop if its shut down , due to lack of oil pressure , but i would expect the button to stay in if pressed untill pressed again , i will have to check mine.
regards alan. 8)
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alan CXA651
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Re: feathering gremlins

Post by alan CXA651 »

Hi Chevalier.
Just tried mine , engines off batt on and off eng 4 after 8 seconds feathers /feather button pops back out eng 1,2 and 3 react correctly button stays in but props dont move.
I think you have found a bug.
regards alan. 8)
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Masterius
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Re: feathering gremlins

Post by Masterius »

Hey Alan,

Thanks for looking into, and verifying that, for me.

Chevalier
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Gypsy Baron
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Re: feathering gremlins

Post by Gypsy Baron »

I just checked the code and found the differences between Eng 4 and the other 3 engines.
Will notify the powers that be.

Paul

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FireRescue85
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Re: feathering gremlins

Post by FireRescue85 »

Not sure if related, but I had E3 fail to feather after it failed and sent me into a flat spin the other day.

Granted, after the spin my electrical system was completely shot, so I’m not sure if that affected the failure to feather.

-Scott
Fire Marshall, Firefighter/Emergency Medical Tech.

B-17G
B377
L-049

alan CXA651
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Joined: 15 Mar 2016, 08:23

Re: feathering gremlins

Post by alan CXA651 »

Hi.
If the engine stops turning before the feathering is activated , then you have no oil pressure , and it will never feather , this will cause a lot of drag.
Also , if like me you have the vac mod , and you are on autopilot , the first thing to do on eng3 failure , is turn ap off , go through the shut down feather routine , then turn vac to eng2 then retrim aircraft then re engage ap.
Reason for this is the air driven gyro , this runs down if vac is selected to eng 3 and eng3 fails , ap has no referance , and starts to give runaway trim , resulting in a stall and or spin.
regards alan. 8)
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FireRescue85
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Re: feathering gremlins

Post by FireRescue85 »

Hi Alan,

AP was off at the time, I was under manual control. I also switched vacuum to E2 once E3 failed. The failure was my fault, mixture was slid up to cutoff instead of auto lean. Failure to restart was caused by the mag being turned off, but by the time I noticed it the spinning engine caused the aircraft to yaw right and go into a spin.

I’m still trying to figure out how the majors electrical failure occurred.
Fire Marshall, Firefighter/Emergency Medical Tech.

B-17G
B377
L-049

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FireRescue85
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Re: feathering gremlins

Post by FireRescue85 »

Was able to re-create this issue multiple times, I believe it's an error in the coding:

Take your fortress and fly up to around 5,000'AGL. Move the E3 mixture to cutoff, the engine will shutdown. Turn off fuel flow, fuel pumps, generator, and feather the prop. Everything shuts down as it should. If you start the engine (Start + mesh) it will start to rotate. At this time you can unfeather the prop and move the prop % from 0 to 100. I did this in an attempt to get some RPM's for an on air start. Leave the mag turned off. The engine fails to catch (due to the mag being turned off "accidentally", I'm re-creating my first flight where I noticed this). I shut down the starter and mesh, let them re-energize, and attempted to re-engage (prop was rotating slowly at this time due to airflow) Everything was fine until I moved the prop control back to 0%. This caused multiple anomalies I can't explain. The engine, while appearing to remain in a slow but steady RPM buried it's needle on the high side of 4,500RPM's. This caused the aircraft to yaw severely to the right, which is odd because if the game thought it was producing thrust the opposite should have happened. Severe vibrations were noted along with loss of control. Aircraft enters a flat spin and is unrecoverable. Also, even though E3 generator is turned off and is not producing, electrical variations are noted on all gauges (all generator and main amp meter) which will cause your other working generators and batteries to fry in a matter of seconds.
Fire Marshall, Firefighter/Emergency Medical Tech.

B-17G
B377
L-049

alan CXA651
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Re: feathering gremlins

Post by alan CXA651 »

Hi.
What was your major electrical problem exactly.
Was it a batt failure , gens turned off, ectra.
what was the volt / ammeters reading , or did things happen so fast that you cannot remember.
regards alan. 8)
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Gypsy Baron
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Location: San Francisco

Re: feathering gremlins

Post by Gypsy Baron »

There is an issue with the code. I have found it and reported it. It won't be addressed for awhile so
there is no point in delving in to this any further.

See my earlier post in this topic.

Paul

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FireRescue85
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Re: feathering gremlins

Post by FireRescue85 »

Alan,

Essentially the volt/ammeter rating vary sporadically, the needle surges from one end of the meter to the other. It does this on the main ammeter and all generators. Within approx 2 min, you have a complete electrical failure. On the ground, your batteries are shot (red) and all generators are shot as well (red) and need to be replaced. I was more concerned with the complete lack of control due to unintentional yawing, which makes the aircraft nearly unrecoverable. Even with nose down, full left aileron, and full left rudder, I was still in a flat spin and was unable to recover.

Paul, I agree we have all realized there are issues with the coding, however it could be worth fleshing out what issues with the flight dynamics one will encounter if they have this problem, rather than be taken by surprise as I was when the Fort suddenly starts spinning and dropping at a high rate of decent.

-Scott
Fire Marshall, Firefighter/Emergency Medical Tech.

B-17G
B377
L-049

alan CXA651
Senior Master Sergeant
Posts: 2438
Joined: 15 Mar 2016, 08:23

Re: feathering gremlins

Post by alan CXA651 »

A2A staff
Did you look into the code_r.xml file on the feathering section engines 1 to 3 are the same but engine 4 as a few extra bits in the code .
Engine 4 is the only engine that can be feathered and unfeathered when the aircraft is cold and dark , which is wrong .
This issue effects both FSX and P3D or has this issue slipped through the net .
Regards Alan. 8)
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hazzer111
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Re: feathering gremlins

Post by hazzer111 »

Hi all,

I have also experiencenced this flight spin encounter whilst shutting down the engines in flight. Still with a a decent airspeed no near stall the aircraft just spins and loses alt and is ushly unrecoverable.

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