Approach/Landing uncontrollable

[robbo3066 1]

Can someone help me with doing something to my setup in order to avoid the loss of control when landing.

Never had this problem with previous flight sim software (P3D & FSX etc), yet still have the same hardware, Logitech Extreme 3D Pro Joystick

and Thrustmaster pedals, whilst using MSFS2020.

If I am on an ILS approach, the aircraft remains steady until touchdown when it requires alot of effort to stay on or close to the the runway.  Without an ILS, the aircraft becomes uncontrollable on approach maybe 2-5 miles from touchdown. 

I tend to use the A320 in MSFS2020, the Flybywire version, although I have tried the Microsoft version, also the A330 and Boeing 747 aicraft.  I tend to get the speed down to landing speed on full flaps a couple of miles out in order to get things stable for landing, but almost all the time, it doesn't work.  Just reading back through this sentence, it points to hardware setup, am I right?

I have the freebie version of FSUIPC.  I have MSFS Take off Auto-rudder set on, Assisted Landing on and assisted takeoff as Off.  I have tried messing with the sensitivities of the joystick but don't seem to improve matters.

Would appreciate some suggestions.

 

Rob

[enright 496]

26 minutes ago, robbo3066 said:

Can someone help me with doing something to my setup in order to avoid the loss of control when landing.

 

 

 

If I am on an ILS approach, the aircraft remains steady until touchdown when it requires alot of effort to stay on or close to the the runway.  Without an ILS, the aircraft becomes uncontrollable on approach maybe 2-5 miles from touchdown. 

 

 

 

 

If it helps, it's not just you. I have a similar issue with the A320 and the Aerosoft CRJ. I find that the final 2-3 miles requires the elevator trim to be almost maxed out - and thus the AC becomes unstable. Also similar to your experience: with auto pilot enabled on an approach, it's not as much of an issue - perhaps because the AP is auto-trimming the aircraft up until the last minute?

I could be that I'm simply coming in too slow, although I'm no where near stall speed at any point. Curious to see other replies on this issue.

I'm using a TM Warthog setup. 

Edited March 24, 2021 by enright

[Bobsk8 12,584]

13 minutes ago, enright said:

If it helps, it's not just you. I have a similar issue with the A320 and the Aerosoft CRJ. I find that the final 2-3 miles requires the elevator trim to be almost maxed out - and thus the AC becomes unstable. Also similar to your experience: with auto pilot enabled on an approach, it's not as much of an issue - perhaps because the AP is auto-trimming the aircraft up until the last minute?

I could be that I'm simply coming in too slow, although I'm no where near stall speed at any point. Curious to see other replies on this issue.

I'm using a TM Warthog setup. 

What is your speed and flap setting?

 

[robbo3066 1]

9 minutes ago, Bobsk8 said:

What is your speed and flap setting?

 

Laatest one today was speed @ 150, full flap setting

 

Rob

[Chock 17,769]

Some info which might help, with some things to try...

Full flaps is potentially an issue when going slow. Flaps create a lot of lift, but they also create a massive amount of drag when at large angle settings; this large amount of drag is good for slowing you down when on a descent, but it's less helpful if you need a burst of power to ease you down because there's a ton of inertia to overcome even if you firewall the throttle when the flaps are full. Potentially this can mean you are lacking in power as you come in, because you may already be at quite high power settings with a large amount of flaps hanging out, and the spool up time and subsequent thrust effect of jet engines is not instantaneous of course.

This is exactly why you tend to not use full flaps in gusty conditions, because if the headwind drops and you lose airspeed, you want less inertia to overcome from big draggy flap settings if you suddenly drop below your reference speed for approach. Of course the fact that flaps can go to full settings means there is nothing wrong with using those settings, if there was, they wouldn't be there in the first place, but it is as well to be aware of this limitation with them and so it's sometimes better to go with a slightly higher landing speed on less flaps; because you will be on a lower throttle setting, so you've got more power available and can speed up quicker if you need to, and with increased speed already, your elevators and ailerons are more effective as well.

I don't know whether it is modeled in the sim, but the real Airbus A320 (and many other airliners too) have a system which automatically limits the aileron deflection to approximately half its normal throw the moment the system detects any weight on the wheels. This is there to prevent large aileron deflections from causing an engine pod strike or even a wingtip if you got really out of shape. Because of this, the moment you touch down, if you are laying off against the wind with some aileron, you may well have to considerably increase the aileron throw just to maintain the angle you were at before touchdown, because it will reduce when there's contact with the ground.

Something else to be aware of on short final: If you are coming into the wind on approach, be aware that you are quite often descending through a wind gradient. This is because the lower down you get, the lower the oncoming winds speed often is, owing to friction with the ground. It's easy to forget this and think that your 'perfect' throttle setting for your flap configuration when three miles from touchdown, will be something you don't have to touch, when quite often it will require a bit more thrust even to simply slow down at a desired rate as you come over the fence.

A good example relating to flaps and drag on airliners, is the belly landing of the British Airways Boeing Triple Seven at Heathrow in 2008. At the point where the engines both failed on it when on finals, it was in the landing config with 30 degrees of flaps. Problems began occurring at about 2.5 miles from touchdown, when the engines did not respond to increased throttle settings, caused by ice particles in the fuel system clogging intake filters. The speed dropped to just 108 knots when the aeroplane was only 200 feet above the ground and it wasn't going to make the airport. But at 150 feet, the co-pilot (who was P1) disconnected the autopilot and took over manually, pitching the nose down to maintain speed. The Captain, monitoring the instruments and operating the other controls, reduced the flaps from 30 degrees to 25, which significantly reduced the drag and enabled the aeroplane to stretch its glide a little so that it just cleared the ILS antennas before coming down on the grass just short of the runway. This shows you how much drag high flap settings cause.

A useful example of keeping the nose down, is when landing a glider on a hilltop landing site. These have no engine at all and no option to go around either (as with that BA Triple Seven, all of the power is from gravity). When coming into the wind, especially over the slope of a hill, the oncoming wind is dropping away from you following the contour of the land, so the headwind is also getting progressively slower, as the friction with the ground slows the windspeed down, but you are also in an air mass which is descending. Because of this, you tend to come in at almost twice the stall speed of the glider (about 70 knots, when it stalls at maybe 35) and often very steep. The high speed and the steep angle gets you down through the wind gradient quickly and the excess speed drops off as you go through it too. Anything left on the clock after that, is bled off by a fairly aggressive flare. Now of course this is not how you land an airliner - unless you are coming into Kandahar or Khe Sanh and trying to minimise exposure to SAMs - but it is kind of an extreme illustrative version of the physics going on as you come in for a landing, so conceptually it is a help in understanding how to manage things.

 

Edited March 24, 2021 by Chock

[Ixoye 1,813]

2 hours ago, robbo3066 said:

If I am on an ILS approach, the aircraft remains steady until touchdown when it requires alot of effort to stay on or close to the the runway.  Without an ILS, the aircraft becomes uncontrollable on approach maybe 2-5 miles from touchdown. 

Rob

You are not alone, those problems have keep me away from Airliners.

[marsman2020 1,310]

On the MSFS Forum someone noted that elevator trim doesn't actually seem to work correctly.  The elevator does not deflect due to the trim setting - trim seems to just add extra elevator authority that magically appears from nowhere.  

The consequence of this is that you need your trim setting during roundout and flare to match whatever was used to tune the aircraft flight model, in order to have the same elevator authority the person doing the tuning had. 

In a real aircraft being mistrimmed might increase the control force required significantly (for aircraft without fly by wire) but in MSFS it seems like having the wrong trim setting might make it impossible to flare properly at all.

 

[lzamm 143]

3 hours ago, marsman2020 said:

In a real aircraft being mistrimmed might increase the control force required.....

That is the case with light aircraft, but in most airliners the trim moves the horizontal stabiliser not the elevator, and can certainly lead to reduced or insufficient authority if badly out of trim. 

[robbo3066 1]

My solution.......

Having never managed to control these the Airliners in MSFS, I removed all the configuration of the joystick and thrust pedals and following a series of videos on the subject by Huddison on setting them back up again.  Whilst not complete, I can now control the aircraft manually, take off in a straight line without veering off course and land either via autopilot or manually wihout loosing control.

Huddison is not the only author of such youtube videos on the subject, but thanks to him anyway.

I am now enjoying flying again.  It is not perfect but hopefully with practice, it will improve, the remaining issues are down to me.

Rob