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Saab MFI-17

Discussion, tutorials,hints and tips relating to designing military ai aircraft.
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Firebird
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Re: Saab MFI-17

Post by Firebird »

There will always be takers for flight plans.
Steve
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Re: Saab MFI-17

Post by jgowing »

I'm very sorry about the bouncy taxiing that some have experienced with my MFI-17. I am a total novice modeller, which undoubtedly doesn't help, but I am perplexed as to why some people have the problem and some do not.

Nevertheless, I want to get to grips with this, as I want to make more models, and I also want to be able to produce them one day for the more current sims. I know I can't stay with FS9, but that was the best place to start learning.

Currently I have a beta FS9 Saab 105 (taught me about gear animation) flying from Linz with the Austrian air force and, for the record, in my set up it again taxies smoothly.

Jon
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gavinc
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Re: Saab MFI-17

Post by gavinc »

JBD wrote: 16 Oct 2020, 13:05 I fixed the problem by replacing the general section of the config file by copying from the Bulldog. Works fine in my setup. This was using the original FS9 version. I just confirmed that the same problem is present in the FSX version - the same fix works with that too.
Would you post the changes that you made to the config file so that people who are having the issue can fix it?

thanks
Gavin
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John Young
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Re: Saab MFI-17

Post by John Young »

I'm not sure how substituting the [General] Section of the aircraft.cfg file will influence the flight/taxi characteristics, eg:

[General]
atc_type=
atc_model=
performance= For AI use only
editable=1
Category=airplane

There's nothing in there but identities.

I've usually found bouncing to be caused by the CG in the wrong position, the contact points - especially gear compression, or sometimes the wrong moments of inertia. Too low a frame rate can also magnify the problem.

Gavin, try your solution with your target frame rate set to 10 fps. Is the Saab still stable?

John
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Re: Saab MFI-17

Post by JBD »

Sorry John.
I meant the general section and everything below there.
In other words I replaced the whole of the config file ( except for the [Fltsim.xx] section) with the contents from the Bulldog. The Saab then performs perfectly in FSX. Not ideal probably but for me a pragmatic temporary fix.

John D.
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Re: Saab MFI-17

Post by John Young »

Aha, now that makes sense John.
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miljan
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Re: Saab MFI-17

Post by miljan »

Hello,
first of all this is a great addition to Sim world, especially being converted for FSX/P3D.
While painting this one I noticed that c_tire is not texturized to match both sides and bottom of cockpit area is going out of fuselage as it can be seen on photo as dark line under the cockpit. This are easy fixes and it can happen to everyone.

Cheers
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miljan
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Re: Saab MFI-17

Post by miljan »

JBD wrote: 16 Oct 2020, 13:05 I mentioned this FSX problem to Jon a while back. Didn’t put it in the forum as I’m hoping to set up retro flight plans for upload. Intended to raise it then.
I fixed the problem by replacing the general section of the config file by copying from the Bulldog. Works fine in my setup. This was using the original FS9 version. I just confirmed that the same problem is present in the FSX version - the same fix works with that too.
It really is a great model. Just out of interest would there be any takers for flight plans using the excellent Otto Knudsen FSX Avnoe scenery. The RDAF Flightschool was located there up to 1993.
Can you please share this line with us ? I have my RAFO jumping around like on trampoline.
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gavinc
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Re: Saab MFI-17

Post by gavinc »

Hi,
just noticed in my P3D content errors file the following error

error=Found Duplicate Key Name
File:E:\Prepar3D v4\Test AI\Aircraft\JGAI_MFI-17_RNoAF\aircraft.cfg
Section:contact_points
Key:gear_system_type

I haven't had a chance to test but I wonder if that is why the model is exhibiting bad behaviour when it taxis????

Same error is being thrown up for the RDAF aircraft.

Gavin
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Re: Saab MFI-17

Post by Joseph29 »

I have that also. one entry says gear_system_type = 0 and the other entry says gear_system_type = 1
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Re: Saab MFI-17

Post by JBD »

miljan wrote: 21 Oct 2020, 09:06
JBD wrote: 16 Oct 2020, 13:05 I mentioned this FSX problem to Jon a while back. Didn’t put it in the forum as I’m hoping to set up retro flight plans for upload. Intended to raise it then.
I fixed the problem by replacing the general section of the config file by copying from the Bulldog. Works fine in my setup. This was using the original FS9 version. I just confirmed that the same problem is present in the FSX version - the same fix works with that too.
It really is a great model. Just out of interest would there be any takers for flight plans using the excellent Otto Knudsen FSX Avnoe scenery. The RDAF Flightschool was located there up to 1993.
Can you please share this line with us ? I have my RAFO jumping around like on trampoline.
Miljan,
I will attemp to attach a temporary config file here. It is for use with the FS9 RDAF version.
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JBD
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Re: Saab MFI-17

Post by JBD »

OK. That's the first time I've uploaded anything. Next time I'll try not to upload it twice! Hopefully it will work. Note that it gets the FS9 version to work in my FSX setup.

Regards,
John D.
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gavinc
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Re: Saab MFI-17

Post by gavinc »

From the FSX SDK
gear_system_type This parameter defines the system type which drives the gear extension and retraction.
0 = electrical
1 = hydraulic
2 = pneumatic
3 = manual
4 = none

I would assume that since they have fixed gear it should be 4

Gavin
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Re: Saab MFI-17

Post by Joseph29 »

gavinc wrote: 22 Oct 2020, 22:21 From the FSX SDK
gear_system_type This parameter defines the system type which drives the gear extension and retraction.
0 = electrical
1 = hydraulic
2 = pneumatic
3 = manual
4 = none

I would assume that since they have fixed gear it should be 4

Gavin
I tried deleting one of the gear_system_type = lines then changing the other line to gear_system_type = 4 but the planes still bounce all over the place.
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gavinc
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Re: Saab MFI-17

Post by gavinc »

Sorry, can't help more than that. I don't see the behaviour in P3D. In FSX I see the behaviour when I am viewing AI with time sped up but the behaviour reverts to normal once I reset the time to 1x

Gavin
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John Young
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Re: Saab MFI-17

Post by John Young »

So that sounds like a frame rate issue. For those users who have the bounce, what frame rate do they have? The aircraft might bounce at 15 fps, but it might not at 30 fps.

John
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Re: Saab MFI-17

Post by JBD »

John.
Away from my pc (an ancient thing running on Vista) at the moment so can’t check my frame rate. I’d guess it’s well below 30 so that might indeed be part of the problem. The config file attached above certainly fixes the issue in my set up and I’d be interested to find out if it works for anyone else.

John D.
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gavinc
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Re: Saab MFI-17

Post by gavinc »

Hi,
can confirm that frame rates are a factor.
I set my target FR in FSX-SE to 10 and the Saabs started bouncing around like they had ants in their pants (even when parked). I waited till one started to taxi and then raised my target FRs to 30, the plane bounced around a little bit more and then settled down and started to behave normally.

No idea how to fix it (other than keep your FRs up)

Gavin
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John Young
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Re: Saab MFI-17

Post by John Young »

Gavin Is the frame rate being influenced by the aircraft or the complexity of the scenery you were testing in?

I still think the gear compression settings are a factor.

John
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gavinc
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Re: Saab MFI-17

Post by gavinc »

Hi John, the frame rates aren't being influenced by the aircraft or scenery - if I set Target Frame Rate to unlimited I am getting well over 100 FPs.
I set the damping ratio in the Aircraft.cfg to both 0 and 1 (separate tests obviously) and the behavior persists when I artificially restrict the FR to 10 FPs. Set target framerate to unlimited (or 30) and I don't see the behaviour.

I then raised the static compression ratio to 0.5. This seems to have solved the issue.

Looks like you were right.

Thanks
Gavin
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