Board index FlightGear Support Flying

Stability when landing

Controlling your aircraft, using the autopilot etc.

Stability when landing

Postby Stick&rudder » Tue Dec 24, 2019 12:10 am

Have been a pilot off and on for 55 yr. - single & twins, commercial - unrated jet experience. Lots of time with many simulators. FG is a fun FS light singles & twins but, for any jet it sucks during landing. Near the ground, aircraft becomes very unstable with yaw & roll. Smooth flare and touchdown impossible using joystick.
Stick&rudder
 
Posts: 5
Joined: Tue Nov 12, 2019 2:04 am

Re: Stability when landing

Postby enrogue » Tue Dec 24, 2019 12:12 am

Which Jets have you tried? It's likely to be flight dynamics model related (there are 2 commonly used in FG: JSBSim & YASim)
User avatar
enrogue
 
Posts: 232
Joined: Mon May 19, 2014 6:40 pm
Location: London (UK)
Callsign: enrogue
OS: OS X, Ubuntu

Re: Stability when landing

Postby SurferTim » Tue Dec 24, 2019 11:02 am

I found the B777 series was really stable.

The Citation-X I fly is a bit skittish near the ground, especially since I have real weather and advanced weather selected.

If you don't like skittish on landing, don't try my DHC6-300+ Twin Otter with the same weather settings. She will dance with you.

Edit: I forgot to mention my equipment.
Saitek/Logitech Yoke, throttle, and pedals.
The yoke has been modified to eliminate the dead zones and detents.
Those mods made this a whole different experience.
None of the other popular yokes has the dead zones.
Fly low, fly slow, land on a dime. Twin Otter DHC6-300+. https://github.com/SurferTim/dhc6p
PirateAir videos at https://www.youtube.com/user/SurferTim850
User avatar
SurferTim
 
Posts: 932
Joined: Sun Dec 09, 2018 5:49 pm
Location: Miramar Beach, FL
Callsign: Pirate
Version: 2019.2.0
OS: Ubuntu 18.04

Re: Stability when landing

Postby Stick&rudder » Tue Dec 31, 2019 11:13 pm

The Citation, 737, any military. Doesn’t matter if some throttle or closed with full flaps or none.
Stick&rudder
 
Posts: 5
Joined: Tue Nov 12, 2019 2:04 am

Re: Stability when landing

Postby SurferTim » Wed Jan 01, 2020 7:11 am

The Citation-X is a pretty stable aircraft if you aren't using real weather.
Military aircraft will be a bit unstable. That is what makes them maneuverable.

What input device(s) are you using to fly these?
If you try to fly a helicopter with a simple joystick and keyboard, you're probably gonna crash. I would.
Fly low, fly slow, land on a dime. Twin Otter DHC6-300+. https://github.com/SurferTim/dhc6p
PirateAir videos at https://www.youtube.com/user/SurferTim850
User avatar
SurferTim
 
Posts: 932
Joined: Sun Dec 09, 2018 5:49 pm
Location: Miramar Beach, FL
Callsign: Pirate
Version: 2019.2.0
OS: Ubuntu 18.04

Re: Stability when landing

Postby Knüppelrührer » Wed Jan 01, 2020 10:02 am

Small addition, as SurferTim has already given some ideas:
You can try the 777 for Yasim and the 737-300 for jbsim.
In principle there is an effect on lift and drag, but not on roll and yaw axis (as far as I know. Would make sense to have something small on roll).
User avatar
Knüppelrührer
 
Posts: 220
Joined: Thu Oct 25, 2018 9:06 pm
Version: 2019.1.1
OS: ubuntu 18.04

Re: Stability when landing

Postby tdammers » Thu Jan 02, 2020 12:11 pm

My money is on the input devices. It's impossible to make models feel the same across different joysticks/yokes; if your device is inaccurate, or provides the wrong amount of resistance, it'll feel wrong. Too much resistance, and it'll be like flying in molasses, too little and you'll be all over the place. The better ones have adjustable resistance, so if yours does, maybe play with that.

Frame rate is another common culprit - the lower your frame rate, the more latency you will experience, and you will subconsciously make larger control inputs, because you don't see the effect of the smaller ones immediately. If you get less than 10 fps, then this is the most likely explanation; 30 fps and up should be no problem though.
tdammers
 
Posts: 293
Joined: Wed Dec 13, 2017 10:35 am
Callsign: NL256
IRC name: nl256

Re: Stability when landing

Postby Stick&rudder » Wed Jan 08, 2020 7:24 pm

Thanks for your inputs. My joystick has been a good controller for MS FS gold and Plane X. With my FG experience, I guess I will have to wait till the new MS fs is released. I understand it is very impressive with updated cockpits, scenery, and realistic handling. Unfortunately, it is to be expensive compared to...
Stick&rudder
 
Posts: 5
Joined: Tue Nov 12, 2019 2:04 am

Re: Stability when landing

Postby asr » Mon Jan 13, 2020 11:05 pm

The problems with jets you describe sound like Yasim to me, it tends to bounce easily and act wild during flare, at least the jets I tried.

I suggest you give the 737-800YV a try, it's the most realistic landing jet I've seen in FG.

Now, if you're not familiar with the 737, I suggest you try landing flaps-30 first. Getting flaps-40 landings right requires more practice (in real world and in flightgear too)
asr
 
Posts: 84
Joined: Mon Sep 15, 2014 7:55 pm

Re: Stability when landing

Postby tdammers » Tue Jan 14, 2020 11:00 am

Yasim doesn't simulate ground effect, and ground effect tends to stabilize the aircraft during the flare and touchdown (wing lower to the ground generates more lift), which would explain why Yasim aircraft are more difficult to handle in that phase of the flight. I definitely notice a difference between the CRJ700 (Yasim) and the A320 (JSB), the latter is much easier to keep stable, thought that could also be due to the FBW system.
tdammers
 
Posts: 293
Joined: Wed Dec 13, 2017 10:35 am
Callsign: NL256
IRC name: nl256

Re: Stability when landing

Postby Richard » Fri Feb 07, 2020 1:07 am

Stick&rudder wrote in Tue Dec 24, 2019 12:10 am:Have been a pilot off and on for 55 yr. - single & twins, commercial - unrated jet experience. Lots of time with many simulators. FG is a fun FS light singles & twins but, for any jet it sucks during landing. Near the ground, aircraft becomes very unstable with yaw & roll. Smooth flare and touchdown impossible using joystick.


The aerodynamic model quality varies considerably.

Also the quality of your flight control hardware can make quite a difference as different sims have different methods of handling the input and obviously this can make quite a difference as to how the aircraft feels in flight.

The F-15, F-14, F-16, Viggen all have excellent aerodynamic models and I would recommend trying these.
Richard
 
Posts: 765
Joined: Sun Nov 02, 2014 10:17 pm
Version: Git
OS: Win10

Re: Stability when landing

Postby Stick&rudder » Mon Feb 10, 2020 7:51 pm

I have played with f-14,15, &16. No
smoothie with any fighters or a-10 and most commercial. Fighters can be landed in a control crash or a flop like on a carrier. MS FS should be soon & I think it is worth the wait.
Stick&rudder
 
Posts: 5
Joined: Tue Nov 12, 2019 2:04 am

Re: Stability when landing

Postby Thorsten » Tue Feb 11, 2020 7:17 am

I have played with f-14,15, &16. No smoothie with any fighters or a-10 and most commercial.


In that case the problem would be on your side (inside your control definitions perhaps?) - I have done plenty of hours on both the F-14 and the F-16 (for some reason I've never grown warm with the F-15...) and they can do smooth landings with a long flare phase as well as the controlled smash you need to make a carrier landing in gusty winds on a moving deck.

The F-16 or the Viggen are supported by excellent aero data, so there's no reason to assume they would react in any way unrealistic.

So this can definitely be done with these planes - if you can't do it, the fault is not with the plane but elsewhere.
Thorsten
 
Posts: 11577
Joined: Mon Nov 02, 2009 8:33 am

Re: Stability when landing

Postby Richard » Wed Feb 12, 2020 11:44 am

Thorsten wrote in Tue Feb 11, 2020 7:17 am:
(for some reason I've never grown warm with the F-15...)


Possibly because I messed up the flight controls when I did the original implementation; but after Josh and I fixed this and the current version flies a lot better.

Also there have been aero model changes recently; such as I fixed ground effect and tuned the performance to match some data I found on the DCS forums for both acceleration, turn rate and max speed. So aerodynamically the latest version is also better aerodynamically.
Richard
 
Posts: 765
Joined: Sun Nov 02, 2014 10:17 pm
Version: Git
OS: Win10

Re: Stability when landing

Postby Stick&rudder » Fri Feb 14, 2020 1:12 am

I have both download 2018 & 2019 disk set. Are you saying there is an updated ver or there is self patch that I need to install.
Stick&rudder
 
Posts: 5
Joined: Tue Nov 12, 2019 2:04 am

Next

Return to Flying

Who is online

Users browsing this forum: Google [Bot] and 2 guests