We’ve found consensus
I think your discussion was more or less based on semantics rather than what you do (stall vs too slow to maintain that altitude)
If you actually stalled the aircraft in the flare you’d plop into the runway very hard, and nose-first (in a plane that has CG before CL). Also how would you keep the nose off if the wings stopped flying? What we do is slow enough for the wings not to generate enough lift to maintain the level you want it to which results in a descend onto the runway. You could stall it of course with enough AoA but that isn’t the point
Bounces always have too much speed, but high speed won’t cause a bounce by default (hamfisted control inputs will)
A question to the pros… why are airliners landed with a much higher margin above stall speed than props?
I always thought it was because a prop essentially delivers power instanteneously (especially in relation to the light weight of the aircraft) hence a go-around can be successfully achieved at a much lower margin whereas a turbine will take a while to develop go-around power… is that actually true?
I also agree that the piston props in MSFS feel like they float longer than they should (feel, not necessarily are), but certainly they keep the nose up until almost standstill which is not what I ever saw IRL (granted, cherokees and diamonds are my experience, not a cessna)
I think this is mainly due to missing drag (certainlybprop drag is missing, maybe also tire rolling resistance?)
(Yes a quality yoke/stick is a given, without that nothing is realistic anyway)
So I still think something is off on landings in MSFS (although probably not to the degree usually portrayed here)
Exactly, you have to understand that the “pivot point” changes from being the CG to the main gear, so upon touchdown will nearly always cause a pitch-down effect.
The opposite is possible, I have flown an aircraft type where a lot of elevator input was required to rotate the aircraft but as soon the main gear left the ground you had to relax backpressure as not to over rotate.
Why don’t you take the landing gear into consideration in your arguments. Any carrier aircraft has a pretty sturdy landing gear able of absorb the energy from the touchdown and prevent bouncing back up…
I doubt you ever landed an aircraft by physically stalling it out if the air, part because the stall speed reduces in ground effect as the effective angle of attack increases.
The aircraft should naturally pitch down in the ground effect as the downwash angle on the horizontal stabilizer shallows. So if not touching the trim (and you shouldn’t) you always need to apply backpressure in ground effect in the flare, relaxing backpressure upon touchdown means the aircraft is definitely not bouncing back up.
Bouncing (in real life) is usually due to poor pitch / power coordination. Touching down with excessive vertical speed, beyond what the landing gear can absorb will bounce the aircraft back into the air (note that this will happen whether the aircraft is stalled or not). Otherwise pilot induced occilations, landing on the nose landing gear (wheelbarrowing) or a gust of wind upon or just before touchdown can all cause bounces.
The lack of an accurate flight model and drag simulation is probably not making it easier although I haven’t had such problems in MSFS other then the extensive floating due to inaccurate ground effect and drag modelling. But stalling an aircraft during flare? This does not seem like a proper technique to me, I have never heard of this before…
It is true that spoilers extend as soon as the touchdown occurs on most aircraft but this is not primarily done to prevent bounces, this is done to firmly place the weight of the aircraft onto the wheels and make the braking more effective. Thrust reverse is not going to prevent bounces as it takes time for those to deploy and spool up.
Depending on the aircraft touchdown normally occurs between Vat -5 to -10 kts when using the right technique (at least on the aircraft I have flown) which is above the normal stall speed and even further above the stall speed in ground effect. As said before, upon touchdown a natural nose down pitching moment occurs for multiple reasons:
The aircrafts inertia upon touchdown as the aircraft tends to keep following the original flight path when the ground is suddenly in the way, the CG is infront of the main gear so this causes the nose to pitch down, decreasing AOA. When making a very smooth touchdown close to zero vertical rate this effect will be non-existent.
As speed continues to decrease, more weight is transferred onto the wheels, also elevator / stabilator effectiveness reduces, reducing the nose-up pitching moment from the tailplane, lowering the nose.
As more and more weight is transferred from the wings to the main gear the nose down moment increases since the aircrafts CG is located in front of the main landing gear. The moment arm from the horizontal stabilizer to the aircraft “pivot” point becomes shorter as well as the aircrafts pivot point changes from the CG to the main wheels upon touchdown, the nose-up moment from the stabilizer reduces, lowering the nose.
The thrust vector acts below the CG for most aircraft creating a nose up pitching moment in normal flight, cutting thrust / power during the flare causes drag from a windmilling prop, this will cause a nose down effect. Also drag created by the wheels upon touchdown will cause a nose down pitching moment.
As discussed before the aircraft isn’t in trim to start with upon experiencing ground effect, causing a nose down pitching moment from the start.
The capacity of the landing gear to not only absorb, but also dampen the touchdown. This is depending on the vertical rate at touchdown, the type and condition of the landing gear. Some landing gear types are more “bouncy”, the springs on a Cessna for example compared to a trailing-link landing gear system. The nitrogen in an oleopneumatic shock absorber absorbs the forces during touchdown while the oil causes a dampening effect.
There are some dynamic effects when touching down with a high vertical speed creating a nose down moment, beyond that what the nose landing gear can absorb bouncing it back into the air, landing on the nose gear before touching on the main gear (wheelbarrowing) usually due to too high approach speed, wind gusts, PIO etc.
In short following a normal landing technique, touchdown at an acceptable vertical rate at a speed 5/10 kts below threshold speed should not result in any bounce. Even when not releasing the backpressure there should be a natural nose down pitching moment reducing the angle of attack as soon as the touchdown occurs, keeping the aircraft on the ground.
Note that on the Asobo Airbus A320 neo and Boeing 747 flight dynamics are completely reversed which might aid in the floating and bouncing:
BTW I did some touch ‘n goes today (there was a nice 9kts full crosswind so a rare and good training opportunity)
Remembering this thread I did pay careful attention to where the plane set down on the runway compared to MSFS in the same conditions (granted I flew a cherokee vs the 172 in sim but they are quite comparable).
Glide on final and main gear touchdown point were well inside a reasonable margin of error (actually they were very close, closer than I thought)!
Surprisingly so was weathervaning and torque effects! I think the turn coordinator (the ball specifically) is wrong but the physics are quite good!
Where the sim breaks down is after touchdown. In the sim the Cessna will not drop the nose until very very slow (almost a standstill) which of course doesn’t happen IRL). Drag seems to be an issue at slow speeds (in the air it seems to be correct even with a power-off landing, the plane sets down exactly where you’d expect it to)
The Cessna does experience less ground effect due to the high wings.
But I think the problem lies primarily in the missing propeller drag, apart from causing drag it should also partly spoil the airflow over the wing root and the stabilizer.
It sounds to me like the stabilizer + elevator are in undisturbed airflow and therefore more effective compared to real life.
I do have to say the Socatas I flew can “wheelie” down to very low speed, maybe 40 kts or something? Lower when adding some power, but they do have a stabilator instead of an elevator. So it might also be Cessna vs Cherokee? Doesn’t the Cherokee also have a stabilator instead of a elevator? Should be effective down to pretty low speed.
It does, and it does keep the nose up to quite a low speed but not like the cessna in sim (which should drop sooner rather than later)
I agree on the prop, I was just surprised how close it is to RL when paying attention. I think that was the same found by @N6722C when looking at stability
So I think there is something else inherent to simming that gives the impression of being way different where it actually isn’t?
Probably because it feels so sterile and effortless due to there being no forces in any direction whatsoever other than 1g into the chair, whereas real flying has a dramatically richer amount of sensations! Maybe that explains a lot of the complaints about “to far this-or-that” (I am not a real simmer, still trying to get the hang of it).
I am after today a lot more impressed with MSFS than I was before. Not perfect in any way but very good nevertheless!
Just as I anticipated. Take phrases out of context to prove you are right and every one else is wrong.
If the student pitches the nose up excessively while carrying extra speed the aircraft will bounce.
You obviously have a solid understanding of med/hvy aircraft landing procedure but have forgotten the effect of small light aircraft handled poorly by inexperienced pilots using bad technique. Stall landings have been used to teach proper/safe landing technique since the first student climbed into the cockpit. As a professional pilot I am pretty sure your instructor also taught you to arrest your descent rate and hold the aircraft off the ground until the loss of lift allowed the aircraft to settle onto the wheels. Tricycle are easier because the CG ahead of the wheels will pitch the nose down, reducing lift and helping keep the aircraft on the ground. Tailwheels are much harder as CG behind the wheels will cause a pitch up, if not in a three point touchdown, resulting in and increase of lift and increasing the tendency to bounce when carrying extra speed.
Flying onto the ground is a skill developed slowly. That’s why students don’t learn on DC-3s or King Airs. The simulator physics are off, but poor technique will merely aggravate the problem for inexperienced pilots trying to learn. Don’t make it harder for them by trying to apply advanced aircraft landing techniques to a 150/172 trainee.
I really don’t get the phrase “stall” or “stall landing” in relation to landing procedures. I can’t speak about tail draggers but on tricycle aircraft I have never heard about stalling an aircraft above the runway in order to land. And I have been an instructor for 5 years.
Leveling off a few ft above the runway, maintaining backpressure and let the aircraft settle is not the same as stalling an aircraft.
Your description is perfect and is exactly what we have all been saying. I think the use of the word ‘stall’ is a difference in era and location. I have talked with plenty of European trained pilots in particular that use “stall” only to describe the moment of airflow separation, while it is common in north America to teach new pilots that the moment the stall horn starts to chirp, treat it as a stall. We tend to use more generalizations over here. While you guys are very technically precise. I think the key here is that we want the student to understand that planes are designed to fly, not drive. Therefore, get it off the ground at the slowest safe speed and set it down at the last moment of lift. (obviously, runway conditions, wind, and pilot proficiency are all factors as well)
Going back to when I was learning, terminology of taildraggers was still used interchangably with students. Most tailwheel light aircraft have the wings in a stall AOA when sitting on all three wheels and the recommended technique in most is to ‘stall’ a three point landing.