A flaw with aircraft slow flight characteristics (especially during landing)

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So I’ve been doing my flight training (using the Cessna 172) and have been using MSFS to practice during the days where I don’t have any flights. This is the long explanation, but the summary of the issue is posted below.

Now, for the most part, the flight characteristics are fine. It’s only during landing that I saw the differences in real life and in MSFS. These differences, if not corrected, could encourage “negative training” as it did with me.

Slow flight and region of reverse control:

In a scenario where you are flying in slow flight (let’s say 60-65kt on the C172), to slow down you would need to bring out your flaps (if necessary), and to maintain altitude you would need to increase your angle of attack by raising the nose. Either cases would increase the angle of attack.

You might have seen some landing tutorial videos on youtube where they would say “pitch for airspeed, power for altitude”. At high angles of attack, that is how the airplane behaves and you would most likely have your flaps out during landing thus you’d have a high angle of attack.

In our specific 172, this behaviour occurs as early as flaps 10. In MSFS, I have found it to be in effect during flaps 20 and beyond but I’m just assuming each plane is different.

Though in MSFS I have found that even with flaps 20 out, increasing the power will increase the airspeed a lot. In my experience, increasing the power will not increase the airspeed or at least won’t increase it that much especially with that much drag. What would happen is that the airplane will climb instead of going faster.

Now, as my experience is only on the Cessna 172, I cannot confirm for other aircraft on the slow flight characteristics. I have flown the 152, and the slow flight characteristics do seem to occur at flaps 20 during landing. But the concept still remains: “pitch for airspeed, power for altitude”. And adding power shouldn’t add too much speed.

I have found that some addons do have this kind of model, but I’m hoping that this behaviour could also be implemented with other aircraft as well.

Crosswind landings and rudder control:

This is the most annoying and frustrating one.

During my training, on final I was taught to use the rudder for steering and alignment and the ailerons just to level the wings. Though as my training progressed I have found my style of using the ailerons for tracking the runway early on in the final and then slowly transition to using the rudders, but well each pilot has their own style I guess.

That aside, rudder control in the sim is bad. There are times wherein no matter how much rudder I put in, the aircraft won’t go where you point it and sometimes would even head in the opposite direction!

If I apply left rudder, the airplane should go left! And if I apply right rudder, the plane should go right!

Yes, the plane will YAW into where you put it, but it won’t really head into that direction and instead continue on its previous trajectory or drift with the wind, which is not what happens, unless maybe if you exceed the crosswind limitations. But even with a light crosswind in the sim, the plane would still tend to drift.

The plane MIGHT inch toward the direction you put the rudder in, but in a lot of cases the plane would drift into the opposite direction. And especially on short final and on the flare during crosswinds, the rudders become absolutely useless unless it’s for de-crabbing. I noticed the drifting becomes really bad just before touchdown as well.

This behaviour would really discourage me from using the rudder in real life hence encouraging negative training.

The one good thing it’s taught me is to practice the wing-low technique in a crosswind since even a full deflection on the rudder won’t do anything.

Well, that’s enough of my rant. I am hoping this gets fixed in MSFS 20204.

If you guys are real pilots out there whether you are flying general aviation aircraft or maybe even a 747, I want to know your experiences too.

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Brief description of the issue:

Behavior during landing, especially crosswind landings are incorrect.

Especially during crosswind landings, no matter how much rudder I put into the wind, the aircraft will still drift causing a crabbed landing or a landing away from the centerline

Detailed steps to reproduce the issue encountered:

Just to a normal landing or a crosswind landing

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6 Likes
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I’m in agreement with this. I have often felt like the rudder in the sim really doesn’t actually do very much. In the sim, you can easily fly light aircraft with absolutely no rudder input but that just doesn’t work in the real world. But I suspect this is a simplification to make the sim more accessible to those without a twisty stick/rudder pedals?

At low speeds in a single engine aircraft, the ailerons don’t do much other than keep the wings level. You can bank all you like but doing so won’t change the direction of the aircraft due to the drag on the higher wing - you pretty much just keep going straight while banked

But if we press the rudder while keeping the wings level in the sim, sure, the aircraft will rotate around it’s centre axis but it doesn’t cause it to change course. Instead it simply slips along in the direction you were travelling before you applied the rudder. Once you release the rudder, it springs back to the heading it was on before. This isn’t what would happen in a real aircraft

One thing that it does do is that if you are flying along in a single engine aircraft, you can apply rudder on the pedals with your hands off with stick/yoke. This causes the outer wing to travel faster than the inner wing which increases lift on the outer wing while decreasing it on the inner wing and so causes the aircraft to bank, putting it in a turn. I remember flying this way when I did the gold rush achievement in the Savage Cub. You can then do the opposite and it will level the wings

It does also allow you do do tighter turns when used properly - just doesn’t do anything on it’s own. So it’s those low speed characteristics that are the problem

3 Likes
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there are good reasons to expect an improvement in this regard in msfs 2024,
only 2 months away at the time of writing

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Yeah there was something about improved physics for FS2024 so here’s hoping

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I’m hoping for improvements in MSFS 2024 as well.

As for the plane springing back when you release the rudder, I found that it does happen in the real airplane as well but not as violently as in MSFS. And even if the airplane does spring back, the trajectory will be where the airplane’s nose is pointed at instead of drifting all over the place. When the nose is pointed in one direction, it tracks toward that direction.

Oh and yeah now that you mentioned it, I realized that these are slow flight characteristics in general. I should update the title too.

Anyways, thanks for your input!

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Just remember that the forces and magnitude of control deflection you impart on the controls in the sim have nearly zero tactile feedback other than spring re-centering. Thus, it’s really easy to overcontrol. Conversely, note how much more difficult it is to deflect the rudder in a real plane. You also have the seat of the pants feel and 3-dimensional perception telling you “that’s enough.”

That said, I don’t really have too much difficulty maintaining centerline in a sideslip in the sim unless it’s really strong (likely near or exceeding the max demonstrated crosswind component anyway). The biggest differences between that scenario and real life are the lack of tactile and perceptual cues mentioned above, but those can be overcome in the sim if you know what to look for.

As far as yaw and roll coupling, the poster after you got it right. You’re basically describing uncoordinated flight. If I yaw in the sim, it will still roll and the nose will eventually follow as the new relative wind is established. But the amount of yaw and whether it’s instantaneous and/or sustained should matter. I’ve never experienced it not do that in the sim.

For the region of reverse command - how’s your trimming? If I’m at flaps 20, trimmed out, and give it the goose, it’s going to pitch up pretty rapidly and try to maintain that airspeed (this is why we see so many stall/spins on go-around). Again, this can be pretty easily overcome in the sim by pushing our light sim yokes forward - versus the much more difficult forces to overcome in the real plane. That can impart acceleration, even in the region of reverse command. It also might make a difference what model 172 you’re flying in real life (the SP has quite a bit of go to it), the weight/CG, and density altitude.

That said, I feel like there was someone else describing a similar issue a while back it turned out they were using the classic flight model?

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My biggest concern here is that it looks like the OP is assosciating the slow flight regime with flap settings as opposed to the airspeed range below L/Dmax.

That being said, based on testing best glide before and after the 172 was changed to a CFD model, the current model has excess lift and/or a shortage of drag at L/Dmax with flaps up and idle power. So I would anticipate it would enter slow flight regime a few knots slower than otherwise anticipated.

It’s been quite a while since I’ve done slow flight in the real thing, but everything about resuming normal cruise from a full flaps slow flight regime feels about how I remember it.

1 Like
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Absolutely, it’s an unintentional red herring.

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Thanks for your input!

I do have my aircraft trimmed out at flaps 20 and could maintain 60-65kt on the approach. However I can’t exactly remember if the plane in MSFS would pitch up if you add power but I do remember gaining a lot of speed if I add a lot of power.

I have found out by testing other aircraft that the region of reverse command does depend on the implementation of the flight model on a per-aircraft basis. Perhaps the 172 that I’m flying in real life has more drag than it does in the sim (?)

As for the rudder control, I have talked to some of my friends at my flight school and even they would have a hard time with rudder control during landing because of the drifting. I try to do a sustained input on the rudder, but even in a light crosswind the plane will still drift away.

Lately when get serious, I’ve been using X-plane to practice instead of MSFS since the plane kinda does what I would expect it to.

Also I would like to know where the “classic flight model” settings that you say is. I have set it in my settings to use the “modern” one if that’s what you’re referring to.

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Modern is the correct setting.
The other setting is Legacy, and very often will cause issues.

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That’s it, had the names messed up (never change it but have heard of the issues). Thanks for the clarification!

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You need to use more aileron. In a cross-controlled, sideslip landing, aileron corrects for drift, rudder points the nose.

But if you have to bank so much that you’re going to drag a wingtip and/or you run out of rudder authority to put the nose where you want it, you need to find a different place/runway to land.

Going back and correlating this with your original post, I think you might have a misunderstanding of how the rudder, coordinated flight, slips, and skids all work. Please work with your CFI and straighten that out before worrying about the accuracy of it in the sim.

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My interpretation of the original post was that at low speeds in a light aircraft on approach you don’t use the ailerons to bank in order to keep aligned with the runway. Instead you use the rudder to steer left and right while keeping the wings level. But this doesn’t really seem to do anything in the sim as you apply rudder and it rotates the aircraft on it’s axis and points where you’ve applied the rudder but it doesn’t cause a change in course and instead continues to slip in the direction that it was travelling before you applied rudder. Releasing the rudder will cause it to rotate around the axis back to where you started having had no impact on the course of the aircraft

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This is incorrect; that’s exactly what you do for a sideslip landing method. Versus landing in a crab, where the nose is not pointed in the direction of movement, which causes sideloads on the gear that most small, light aircraft don’t tolerate well (airliners, large, military aircraft can land in a crab and “kick out”).

If you use rudder alone (or maybe too much) without the commensurate bank angle in the same direction, you will be uncoordinated, skidding. The outside, high wing will be traveling faster due to the rotation and will tend to continue to overbank. The relative airflow will be coming from the outside of the skidding turn, which, if you were to suddenly release the rudder, will weathervane the nose back momentarily toward the outside of the turn (as long as the airplane has positive stability).

However, if you enter a skid like that when you don’t have a lot of energy, as often happens during a base to final overshoot, the overbanking wing tends to lead pilots to incorrectly apply opposite aileron. This increases the drag and angle of attack on the low wing, which is being partially blanked by the turbulent airflow around the fuselage in the skid. Because of that and the increasing load factor, along with all that extra yaw, this kind of cross-controlled situation can lead to an unrecoverable stall/spin in the direction of the bank.

Whereas a sideslip is generally safer because the airplane is not overbanking, it’s generally not a situation where the load factor is increased, and the airflow is blanking the high wing, leading to a situation in which that wing should drop first in a stall, which restores level flight (assuming proper stall recovery and no pro-stall/spin inputs are made).

That said, an airplane can stall at any airspeed and attitude, as long as it reaches the critical angle of attack. I cannot overstress how important it is for real-world pilots to understand how all this works, so again, if that describes you, consult your CFI.

Meanwhile, the sim is a fun place to play with all this, but it doesn’t quite get the overbanking tendencies and spin entry correct, much less the control forces I mentioned above.

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The crab method always concludes with a kick, unless you are flying a B-52 or C-195 with crosswind gear STC.
The aircraft is flown down into ground effect while still in the crab position, the runway axis going diagonally under the aircraft.
Usually once in the ground effect region the real crosswind experienced is less than even a few feet higher. So you correct aircraft alignment accordingly while starting the transition into the landing flare.
And that is where the difficulty really is in this approach to crosswind landing. To land the aircraft axis, travel direction over the ground and runway centerline should of course be parallel.
That means the aircraft must be rotated in the yaw axis, the upwind wing must be lowered at that point to compensate the crosswind effect and importantly that upwind main wheel placed on the runway first, all in one smooth motion.
Done correctly, as I said you can easily land a Piper Warrior in 32-34 kt direct crosswinds. I have done that multiple times during the Santa Ana winds in SoCal.

But this technique does need lots of practice to get that timing right. As you know, there is a limit to how much side loading a GA main gear can handle.
Though looking at what some students repeatedly did with the -161s I never had heard of a single failure. But if the air boss was watching and she did not like what she saw CFI and students got some hot ears.

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FWIW, regardless of real world technique; I’ve always found that the crosswind, cross control, and transition from slow flight to ground effect during landings (think flare) flight regimes are MSFS’s weakest performance where flight dynamics are concerned. This stuff has been beaten to death in so many other threads over time, but if I were to locate the flight regime where my real world flight training is most challenged in MSFS, it would be here. Which is not to say I’ve given up on trying to do it the right way in the sim; it’s just so often disappointing how proper technique is not always rewarded in kind with the expected flight performance. Sometimes it works, sometimes the sim just does not deliver exactly as expected. The lack of sensory input (sound, seat of pants, peripheral vision, etc.) in these flight regimes no doubt amplifies the often odd outcomes, but MSFS is just not real strong here for me after 950+ hours in it, GA to Jets.

1 Like
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I just wanna give another example with the rudder control issue.

One of my landings during my pre-solo days, just above the runway threshold I was starting to drift way left of the centerline. My CFI slammed the rudder (“slam” might be a bit of an exaggeration) toward to the right and then re-aligned the plane with the runway and the centerline; so it was basically a big right rudder input to steer the plane back on to the centerline, then left rudder to straighten out the plane. He only did those with the rudder and just kept the wings level. I can’t do that in MSFS as the plane would continue to drift to the opposite direction.

I guess he also slammed it “wake me up” as these early morning flights can be really exhausting (woke up at 4am, departed at 6 and arrived at about 10am).

Anyways, regardless of technique and based on my experience, you really should be able to have directional control even if you use rudder alone.

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Yeah everyone is going on about crosswind landings but what I am referring to is simpler than that. If there isn’t a breath of wind and you’re lined up with the right hand side of the runway at approach speed, the rudder alone should be enough to correct you back onto the centreline. But in the sim it can be done with aileron alone which wouldn’t work in real life

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What you’re describing could be several things - it really depends on how the aircraft was prior: how uncoordinated, how much alignment (or not), how much drift, etc. If you yaw alone and end up in a skid, yes the airplane will slowly turn (“drift”) that way, but the momentum is to and airflow is coming from the outside of the turn. So you’ll eventually get there, but it’s inefficient and can be dangerous, as I described above.

It almost sounds like you were in a crab and the instructor kicked the nose over just before touchdown. Sure, that can work itself out that your path and nose is aligned down the runway, but more often than not, if you don’t also use some bank, you’ll be drifting off centerline. It doesn’t necessarily take much bank, so maybe it was just perception that your wings were level?

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Are you saying that a coordinated turn or even a slip can’t align you with the runway? I mean, I just demonstrated all of this on Wednesday’s stream, same as I’ve done countless times in real life.