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Almost impossible to control speed on finals


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After leaving the Twin Otter in the hangar for a while, I used her quite extensively during the last weekend.

 

What I noticed was that the plane's speed was basically uncontrollable on finals. Trying to slow down to approach speed and maintaining it was absolutely impossible for me. Speed was more or less controllable down to about 100-110 kts. Anything below and the slightest change on the throttles would let the speed go up from e.g. 90 kts to 130 or down to 60 (or even below). I got the impression that there was an ever so slightly difference between a low power and a reverse power setting which resulted in the excessive change of speed. 

 

I'm using a Honeycomb Bravo throttle and have the controls set up via spad.next (but also tried the throttle settings within MSFS with no difference). Twin Otter version is 1.0.5.

 

Is this a known problem in conjunction with SU 9, is my setup wrong or am I simply not able to fly the Twin Otter appropriately? Any hints are appreciated...

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  • Aerosoft
1 hour ago, Belga said:

After leaving the Twin Otter in the hangar for a while, I used her quite extensively during the last weekend.

 

What I noticed was that the plane's speed was basically uncontrollable on finals. Trying to slow down to approach speed and maintaining it was absolutely impossible for me. Speed was more or less controllable down to about 100-110 kts.

Hi Belga,

 

Several questions : 
- 1 - Is the ASSISTANCE parameter set to TRUE TO LIFE ?

- 2 - Can you please make sure the Bravo is correctly calibrated in the Windows peripheral utility  
         and that the levers in the simulator and those on the Bravo move accordingly ?
- 3 - Can you make sure no other device has an axis assigned to the throttle function in MSFS or other third-party utility ?

- 4 - Can you apply this tutorial regarding the use of the Bravo with the Twin Otter ?
        https://forum.aerosoft.com/index.php?/topic/169524-basic-honeycomb-bravo-throttle-controls-with-the-msfs-aerosoft-twin-otter/

Thank you.

 

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Hi Belga,

 

there are a few posts regarding this behaviour and the possible cause by an invisible spoiler that should simulate the increased drag of the propellers under certain circumstances.

I too think that approach speed handling got a lot more difficult since SU9.

 

Unfortunately the devs can't reproduce the issue so it might be dependent on other settings or we perform the approach not in the right way.

 

There is a slight chance that this improves when the new propeller simulation of MSFS is better understood by the developers...

 

Anyhow: You are not alone. 🙂

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15 hours ago, SimWare said:

Hi Belga,

 

Several questions : 
- 1 - Is the ASSISTANCE parameter set to TRUE TO LIFE ?

- 2 - Can you please make sure the Bravo is correctly calibrated in the Windows peripheral utility  
         and that the levers in the simulator and those on the Bravo move accordingly ?
- 3 - Can you make sure no other device has an axis assigned to the throttle function in MSFS or other third-party utility ?

- 4 - Can you apply this tutorial regarding the use of the Bravo with the Twin Otter ?
        https://forum.aerosoft.com/index.php?/topic/169524-basic-honeycomb-bravo-throttle-controls-with-the-msfs-aerosoft-twin-otter/

Thank you.

 

 

1) All MSFS assistant options are turned off. 

2) Bravo is correctly calibrated and is working flawlessly with all other aircraft (including e.g. the Aerosoft CRJ 700).

3) There is no other device assigned to the throttle function. I checked that several times.

4) I've already done that after noticing the problems to make sure it's not a problem with spad.next or FSUIPC. Unfortunately following the tutorial made no difference.

 

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  • Aerosoft
27 minutes ago, Belga said:

 

1) All MSFS assistant options are turned off. 

2) Bravo is correctly calibrated and is working flawlessly with all other aircraft (including e.g. the Aerosoft CRJ 700).

3) There is no other device assigned to the throttle function. I checked that several times.

4) I've already done that after noticing the problems to make sure it's not a problem with spad.next or FSUIPC. Unfortunately following the tutorial made no difference.

 

Hi Belga,

 

1) All MSFS assistant options are turned off. 

----- > So the assistance profile is TRUE TO LIFE, right ?

2) Do the levers in the simulator and those on the Bravo move accordingly ?

----- > Can you check this please ?

 

2) Regarding FSUIPC : Can you please for the sake of test, temporary uninstall it to rule out any interaction 

     as it has already happened in the past. 

 

Thank you.

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  • Aerosoft
13 hours ago, TheMarvinX said:

there are a few posts regarding this behaviour and the possible cause by an invisible spoiler that should simulate the increased drag of the propellers under certain circumstances.

It may be also worth checking if no "rogue" spoiler assignment exists since every system update 

has a poential chance to reset some default assignments and since, eventhough some surfaces or controls may not

visually move, they can still be affected if a signal is given. 

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43 minutes ago, SimWare said:

Hi Belga,

 

1) All MSFS assistant options are turned off. 

----- > So the assistance profile is TRUE TO LIFE, right ?

2) Do the levers in the simulator and those on the Bravo move accordingly ?

----- > Can you check this please ?

 

2) Regarding FSUIPC : Can you please for the sake of test, temporary uninstall it to rule out any interaction 

     as it has already happened in the past. 

 

Thank you.

1) Actually it's "Custom", since I turned off the "Pause at end of flight" function and turned on "Software Tipps" for getting messages when flying on VATSIM network.

2) Levers move from end to end (i.e. from full forward to full reverse). I reassured by moving the Bravo throttle to full forward and full reverse and checked whether I could move the lever further by using the mouse.

3) I'll do and will report back, but most probably not before Thursday evening since I won't have the time to test this.

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  • Aerosoft
2 minutes ago, Belga said:

1) Actually it's "Custom", since I turned off the "Pause at end of flight" function and turned on "Software Tipps" for getting messages when flying on VATSIM network.

2) Levers move from end to end (i.e. from full forward to full reverse). I reassured by moving the Bravo throttle to full forward and full reverse and checked whether I could move the lever further by using the mouse.

3) I'll do and will report back, but most probably not before Thursday evening since I won't have the time to test this.

Hi Belga,

 

Thank you.
My goal here is to definitively rule out any hardware/third-party utility issue.

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Hopefully Aerosoft will spend some time correcting some of the "realism" changes they have made. I'm kinda like BELGA, planes have been grounded for awhile. Just too unpredictable.

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So I finally had some time to test with the settings proposed by @SimWare.

 

I switched off FSUIPC and solemly used the MSFS settings. Result: the aircraft was controllable at low speeds. I was wondering since I had already tested this setup. Activated FSUIPC and spad.next again. Aircraft was controllable. The only thing changed during the last week was the patch for SU9. Perhaps that's the reason, I don't know. I will do some further tests, but at the moment the problem seems to be resolved. Thanks for the support.

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Hi everyone!


I also returned to virtual flying, tempted by the new Twim Otter :)


I'm using CH Eclipse Yoke and I'm having the exact same problem - the Twin Otter becomes uncontrollable at low speeds.


It seems that at throttle settings below 20 PSI (torque press) something happens to the propellers, as if they suddenly go into idle mode. There is a distinct change in their sound (into a low buzz), the "Don't sink!" warning is activated and the plane stalls. As a result, it's almost impossible to reduce the speed to around 100kts, to the speed when you can extend the flaps.


I watched the tutorial on Youtube and I see that, at least with some people, the plane is perfectly controllable even with the throttle set to 10 PSI and the sound of the propellers is much different from mine and is completely normal. British Avgeek recommends doing the approach at 10 PSI, but with me at that throttle setting the plane stalls even if the flaps are set to 20!


I'm not using FSUIPC and I've checked the spoiler issue. I also set the throttle sensitivity settings on the yoke according to the manual.
Unfortunately in my case nothing helped :(

 

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The short explanation is to remain at 75pct prop rpm as long as possible during the approach - the POH says until 500 AGL. 

The long, more technical story: The YouTube videos you see may use an older version of the aircraft so they are of limited use since the prop modelling was changed to the new mode introduced in SU8. That resulted in a very slippery plane that was impossible to slow down (at least at full prop rpm) for a short landing. As torque is lowered and the constant speed prop changes to a finer and finer pitch and into beta, the prop simply continued to give forward thrust or at least not induce any drag as you would expect on a turbo prop plane. It was suggested in other posts on this forum that this could be remedied by adjusting the new propzerothrustdrag parameter related to the the prop modelling in the aircraft.cfg. Instead, the devs in 1.05 chose to make the prop draggy by adding an ‘invisible spoiler’ in the code. When the prop pitch goes below 11 degrees (at below c. 15 torque) a 60 degree spoiler kicks in immediately. It feels like hitting a brick wall and the plane will fall out of the sky. Some weeks ago a dev replied to this issue and stated he was looking into it, but nothing has materialised.

In the meantime some DIY fixes has been suggested on this and the MSFS forum. The easiest is to go into the config files and change the spoiler angle to e.g. 30 degrees.
 

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7 minutes ago, UnsealedKarma said:

In the meantime some DIY fixes has been suggested on this and the MSFS forum. The easiest is to go into the config files and change the spoiler angle to e.g. 30 degrees.

 

Yes... but that tweak makes simply does not provide the amount of drag that is needed, it exchanges one problem for another. As you say the POH has the answer, keep the prop setting up. 

It is a complex issue and we are just now testing a new tweak for that. 

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17 minutes ago, Mathijs Kok said:

It is a complex issue and we are just now testing a new tweak for that. 

Good to hear. I appreciate you strive to take advantage of the new features Asobo adds to the sim like the prop model even though it seems they leave you out to dry because of the incompleteness of the documentation and perhaps the features themselves.


The problem with the current spoiler tweak is the very binary on/off feel of the drag. 
 

FWIW I made a DIY script that induces a non linear increase in drag from each prop from 17 degrees beta to 10. Perhaps it can be of inspiration. The script needs to run continuously as A:SPOILERS·LEFT·POSITION really can’t be set and wants to go back to zero.

 

(A:PROP·BETA:1,·degrees)·17·<·if{·17·(A:PROP·BETA:1,·degrees)·-·sqr·50·/·(>A:SPOILERS·LEFT·POSITION,·Position)·}

And for the right:
(A:PROP·BETA:2,·degrees)·17·<·if{·17·(A:PROP·BETA:2,·degrees)·-·sqr·50·/·(>A:SPOILERS·RIGHT·POSITION,·Position)·}

 

 

 

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1 hour ago, UnsealedKarma said:

The short explanation is to remain at 75pct prop rpm as long as possible during the approach - the POH says until 500 AGL. 

The long, more technical story: The YouTube videos you see may use an older version of the aircraft so they are of limited use since the prop modelling was changed to the new mode introduced in SU8. That resulted in a very slippery plane that was impossible to slow down (at least at full prop rpm) for a short landing. As torque is lowered and the constant speed prop changes to a finer and finer pitch and into beta, the prop simply continued to give forward thrust or at least not induce any drag as you would expect on a turbo prop plane. It was suggested in other posts on this forum that this could be remedied by adjusting the new propzerothrustdrag parameter related to the the prop modelling in the aircraft.cfg. Instead, the devs in 1.05 chose to make the prop draggy by adding an ‘invisible spoiler’ in the code. When the prop pitch goes below 11 degrees (at below c. 15 torque) a 60 degree spoiler kicks in immediately. It feels like hitting a brick wall and the plane will fall out of the sky. Some weeks ago a dev replied to this issue and stated he was looking into it, but nothing has materialised.

In the meantime some DIY fixes has been suggested on this and the MSFS forum. The easiest is to go into the config files and change the spoiler angle to e.g. 30 degrees.
 


Thank you for these explanations. I now understand the essence of the problem.
What you described exactly matches the problem I encountered!
 

 

 

1 hour ago, Mathijs Kok said:

It is a complex issue and we are just now testing a new tweak for that. 


I'm glad and appreciate that the producer is already working on this problem.


Twin Otter is a great aircraft and I've spent many enjoyable hours with Twin Otter Extended for FSX.
Enough to say that the release of this single aircraft convinced me to buy MSFS and return to virtual flying in general :)

Twin Otter is a legend, both in reality and in Flight Simulator :D

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