• Which the release of FS2020 we see an explosition of activity on the forun and of course we are very happy to see this. But having all questions about FS2020 in one forum becomes a bit messy. So therefore we would like to ask you all to use the following guidelines when posting your questions:

    • Tag FS2020 specific questions with the MSFS2020 tag.
    • Questions about making 3D assets can be posted in the 3D asset design forum. Either post them in the subforum of the modelling tool you use or in the general forum if they are general.
    • Questions about aircraft design can be posted in the Aircraft design forum
    • Questions about airport design can be posted in the FS2020 airport design forum. Once airport development tools have been updated for FS2020 you can post tool speciifc questions in the subforums of those tools as well of course.
    • Questions about terrain design can be posted in the FS2020 terrain design forum.
    • Questions about SimConnect can be posted in the SimConnect forum.

    Any other question that is not specific to an aspect of development or tool can be posted in the General chat forum.

    By following these guidelines we make sure that the forums remain easy to read for everybody and also that the right people can find your post to answer it.

Shorten the landing roll

  • Thread starter Thread starter GHD
  • Start date Start date
GHD

GHD

Messages
12,244
Country
england
One particular AI aircraft uses almost the whole of the runway before stopping.

I increased toe_brakes_scale from the default 0.427259 to 1.5 and it had absolutely no effect :eek:

How do I shorten the roll other than by changing toe_brakes_scale?
 
No, setting the spoiler_limit to 90 didn't work. Even setting toe_brakes_scale to 5.0 had no effect on the roll-out.

It seems that there is no braking until the speed is below about 40 knots, by which time it is almost at the end of the runway.
 
Hi,

You need to increase the reverse thrust, which is used at speeds *over* 40. In the GeneralEngineData section, make this more negative:

min_throttle_limit=-0.100000


Hope this helps,
 
No, George, 90 does not help.
Be generous in your changes.
I set it it to 1000 to have AI stop on a carrier.
Nio braking until speed is down to 40 is correct.
That is why I use the spoilers.
 
Tom, the min_throttle_limit is already at -1.250000.

No, George, 90 does not help.
Be generous in your changes.
I set it it to 1000 to have AI stop on a carrier.
Click to expand...
According to the SDK help, spoiler_limit is the angular limit of the spoilers. I have no idea what 1000 degrees means :confused:
 
True, I know.
But anyway that is what I do and that is what makes the aircraft stop almost on the spot. I do not think the number you put in there are degrees.
 
Well, setting spoiler_limit= 1000.000 sort of worked :)

The initial roll was quite long but at 40 knots it almost sat on its tail and then taxied to the exit.

I really need to shorten the inital part of the roll-out to be more realistic.

There is a reference to minimum_reverse_beta which I can change to a more negative value.
 
Last edited:
Apparently the spoliers become active on this aircraft quite late.
Then the only thing I can think of that is left is to increase the drag of the flaps when fully deployed.
Dependent on your aircraft you can do that in the cfg or else you will have to edit the .air file.
I am not sure reverse beta will change things because I do not think that is taken into consideration for AI.
Just one more thing perhaps, that I am not sure about at all, but what about decreasing the static thrust a tiny bit. I mean, once your AI has touched the runway the engines should be running at idle. If the thrust at idle is too high, then the aircraft will not slow down enough because its engine thrust is too high still. Just a thought.
It would help if you told us which AI you are talking about (like what we would advise to novices on this site as well:D).
 
Sorry Roby :o

It is a payware AI twin turbo-prop.

I have just about got it to stop at a reasonable position.

Tom was on the correct lines with reverse thrust, but, seeing as it is a prop, the equivalent is the 'minimum_reverse_beta' which is the pitch at minimum throttle. I set this to -16.25 degrees.

I also kept your 'spoiler_limit' set to 400 and 'toe_brakes_scale' to 5.0.

The interesting thing is that a 737 lands at a higher speed but slows down acceptably. This thing lands at 100 kts but the initial deceleration is abysmal.

My thanks to you and Tom for sticking with me.
 
Last edited:
Glad you got it sorted. That is definitely an odd bird, alright.
 
Hi,

If you are satisfied with its behavior now, fine. If not:
Is 100 kts realistic or could it also be 90?
You could then lower the landing and stall speed in the cfg. That would help as well.
 
If I understand you correctly, it touches down rather late or the front wheels stay off the runway too long?
Then maybe try another AI .air file for the same type of aircraft, if you can find one, because I am not sure there is anything more you can change in the cfg without influencing its flying characteristics.
If you have changed thrust at idle, braking strength, spoiler limit, full flaps stall speed and maybe reverse thrust and it is still not OK, then I would start looking at drag coefficents, lift, etc. in the .air file but that is going to be complicated, affect its flight dynamics and will more or less become a trial and error affair.
 
robystar said:
If I understand you correctly, it touches down rather late or the front wheels stay off the runway too long?
Click to expand...

Yes, that is the situation together with very slow deceleration.

I have finished tweaking and the values I have changed are:

min_throttle_limit
spoiler_limit
minimum_reverse_beta
flaps_up_stall_speed
full_flaps_stall_speed
drag_scalar
toe_brakes_scale

However, they all seem to be coupled :(
 
Of course they are coupled, at least some of them are, like stall speeds and drag scalar.
Do you have a thrust at idle entry? I mean, once the AI reaches the runway threshold its engines are set to idle and reducing that thrust may help.
I am only guessing as this is way above my experience. I only tweaked AI for carrier ops and that involved playing with moi, lift, drag, pitch and AOA in the 1101 and the aforementioned cfg tweaks.
 
The only thust entries are thrust_scalar and static_thrust, it is a turbo-prop.
 
Then the static thrust is the one to decrease.
You may have to increase the scalar a bit to compensate for the lesser static thrust.
(for carrier ops it would be the reverse to mimic catapult launch, also for turboprops).
 
Last edited:
You must log in or register to reply here.
Back
Top