Taking off and landing the Cessna 172

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Hello,

So as the title suggests, I am having some trouble landing. I am still trying to work out the relationship between trim and the angle of the iPad to maintain elevation. I am finding it very frustrating. When it comes time to descend and land, the plane want to go to like 1000ft above ground, and the risk of overspeed increases, or a stall, or both…as I tilt the nose of the plane up high. Everything usually results in a bounce on the runway, the grass, a hill, or a crash. Short final puts me at just below 1000ft, as I try to land. Not a whole lot of success. I almost threw my iPad at the wall in frustration. My takeoffs are challenging too. Once I am in the air and above 1000ft (about 40% of the time, I can steadily cruise up to 7000-9000. If my rate of ascent is too fast I stall, and then lose altitude. I also tend to stall when the plane lifts off the ground at around 80knots (probably from the tilt of the plane) Still working out the rudder part.

Any pointers on how to stay in the air, and land safely when I want to to land?

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Hello there :waving_hand:

Don’t get frustrated. In my country is an idiom which says “No master has fallen from the sky”, which while I am writing it, is funny, because it touches our aviation subject here kind of. But actually the meaning is, nobody suddenly appeared on earth and has been skilled as a master from the beginning. So step by step learning.

First of all, find yourself a steady and comfortable position to fly at. For myself, I am always lying on my couch, have my elbows sat down next to me and my iPad is straight vertical, when I calibrate the position. So I definitely know, which position of my iPad is leveling out the plane.

When your aircraft bounces wildly up and down with its nose, maybe your inputs are too strong. Either reduce the pitch and yaw movement and use it more mildly, or else you have the possibility to go into settings/ preferences choose controls and at the lower right is a config button. There you can reduce the sensitivity of the iPad for your motions. Might be helpful at the beginning, when your input movements are a bit too harsh.

So after taking off, so sit or lay in your comfortable position holding your iPad and when you cruise at a certain altitude, you will find out, that the aircraft rises its nose, when you push the throttle for more speed and it will lower the nose, when you go slower. All without moving your ipad forth or back.

When the speed stabilizes at a certain point and the nose is e.g. still going up, then use the trim to level your aircraft at that certain speed and the position of your iPad. In real life for example, when you fly a plane holding the yoke and the nose always wants to drop down, you would have to pull the yoke always back to keep the nose up. But that’s not comfortable at all. So you trim up until the nose stays leveled at that speed without the need to touch the yoke.

In IF, when you touch the trim button and pull it down, the nose will go more up and vice versa.

So before trying to learn landings, you need to figure out, how to keep the aircraft in a stable flight.

So when you reduce your speed, naturally the nose drops, but thus resulting in acceleration and that lifts your nose again, slowing down your aircraft again, which lets your nose drop again, which means you will go in waves up and down. With subtle corrections counter wise you can control this oscillation.

When landing, do you use flaps? Flaps make your aircraft go much more stable at lower speeds and when on final your flaps should be extended. I am not flying the Cessna or any other smaller aircrafts much anymore, so I cannot tell you now the reasonable speeds for landing and which speed for which flaps setting- other can probably tell you better.

But first try to level out your aircraft in a stable flight position.

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Thank you so much for that feedback. I will try to use it next time. I do try to use flaps, and I think I understand how they work for flying. Though in real life when I have been a passenger on a plane, I usually see them activated for landing. I imagine its to push the plane down and prevent it from simply “gliding” on the air? Yes, I will have to monitor the trim a bit more.

I was just practicing last night of plotting a single point mid flight, to find a random air field or landing spot, and then worked the movement of the plane to get over to the track line. 30 minutes of flying to the destination, resulting in the aforementioned crash. :angry: :roll_eyes: I’ll keep working on it. This is also encouraging me to revisit the value and practice of patience - which I need, in order to practice it. :grinning_face_with_smiling_eyes:

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Flaps are increasing the surface of the wings and therefore also the lift. They also increase the curvature of the wings, which as well increases the lift. Bernoulli’s law says (simple), when air is flowing over a surface, where the airspeed is greater, is lower pressure.

Because of the curvature of the wings, the air coming from the front has to travel a longer way on the upper side of the wing, than underneath it. That means, the airflow ontop of the wing has to go faster, resulting in a lower air pressure ontop of the wing. That is the force, that actually keeps the plane in the air- not the air “pushing” under the wing. So actually the aircraft is “sucked” upwards due to the lower air pressure over the wings.

Flaps which point downwards increase this effect by making the way for the air over the wing even longer. But completely extended flaps also have a drag, which slows the aircraft down. So when you want to takeoff, you usually use a small flaps setting, which helps you to lift off the runway faster. When the flaps are extended too much, the drag will not let you accelerate so much.

On final, with your sink rate, the aircraft wants to get faster, but the fully or almost fully extended flaps have a drag that slows your plane down. But the increased wing surface lets your plane still fly stable at lower speed because of the stronger lift.

But in real life there is a maximum speed for each flap setting. If you extend your flaps at high speeds, they can get ripped off or get damaged. Doesn’t happen here though.

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I really appreciate that explanation. I will review it a bit more to absorb it. I had no clue about how planes use the air that way with the wings. Insane. Thank you for that additional help.

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Is it okay that I continue to be frustrated with landing this thing? :laughing: Whether its on a pattern turn (is that the right wording?) to land, or trying to do a landing on a short final I always seem to mess it up. Despite my best attempt to line up the plane to the runway, I am always veering off course. On short final it starts out dead center, but then starts to wobble in the air moving side to side. Then I get distracted because I am coming down to the runway too fast, then I bounce on the landing (sometimes with a crash), while I am also trying to hit the brakes and control the rudder to stop the plane.

I have had less trouble maneuvering a bicycle. :roll_eyes: :unamused_face:

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Hi,

For the 172, the landing set-up using the short final function in solo flight mode is pretty good.

You can easily keep doing that over and over, because you get back to the start short final position with a single button press.

So you can focus all your attention only on getting fluent at staying under control on that last bit of flight down to the ground.

Be sure to set wind to zero. I’d recommend keeping zero trim, and only controling with pitch and power (small movements). Very small bank if necessary to keep in the right direction.

Once you can get some fluency with this one goal, it will help the rest of your flying.

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Hello Adit,

I appreciate the kindness in your suggestions. I am not an avid flyer by any stretch, but I love planes. I get really frustrated and experience a severe lack of patience when it comes to the desire to do things correctly, Like I should be able to do this with a one and only try mentality (I mean, how hard can it be to land this thing in a computer game?). I’ll try the ideas offered, and see if it helps. :+1: :grinning_face:

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If you try it a dozen or few dozen repetions, and do that over a bunch of days, I don’t think you could help but improve: the muscle memory gets worked out and solidified.

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Hi, You made me think - putting lift in terms of the most fundamental classification of Newtonian mechanical forces is kind of interesting and revealing:

Contact forces: static or dynamic (like a book held up by a table, or friction from sliding the book)

Momentum exchange forces: discreet exchange or flow field (like cannon recoil, or jet engine exhaust)

If the force holding something up has to be one or the other: contact force or momentum exchange force, lift can only be a momentum exchange force.

That means in flight, you always need the downward momentum exchange.

A pressure difference cannot sustain an aircraft in flight unless it produces a momentum exchange force.

Pressure difference is the mechanism of the momentum exchange force that is lift.

Sorry, that was a digression from your point about a C172’s flaps changing the geometry as the cause of more or less pressure difference, which is of course adjusting lift for slower approach speeds.

And it makes this still true:

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Yes, you are right.

Actually, both explanations — Bernoulli and Newton — are right, they just describe the same thing from different angles.

Most of the lift (around two-thirds) comes from low pressure on top of the wing, which kind of “sucks” the plane upward.

The rest comes from higher pressure underneath pushing it up.

That low pressure isn’t magic though — it happens because the wing’s shape and angle of attack make the airflow speed up over the top and deflect the air downward (downwash)

So when the air gets pushed down, the wing gets pushed up (Newton’s third law), and the pressure difference that causes that is what Bernoulli describes.

In short: a wing flies because it both pushes air down and gets pulled up by lower pressure above it — same physics, just two ways of looking at it.

(Edit) @adit I pressed reply but somehow your name didn’t appear so I was not sure if you get a notification.

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But please correct me, or anyone else, in case I wrote something wrong

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Hi, yeah if you have a book on a table, gravity is obviously pushing the book against the table.

So to keep the book from moving down, the table has to push back up against the book with an equal but opposite force.

For the aircraft, weight is overcome by, as you said, low pressure above sucking the aircraft up, plus higher pressure below pushing the aircraft up.

But think about the reaction of the table pushing back on the book. Without that complementary opposing force, the book doesn’t stay put.

In the aircraft’s case the low pressure on top sucking the aircraft up, is “pulling on the sky” above.

So, that air above turns downward (because it’s not a solid mass that can stay put against a force of suction). That is one part of the downward change in momentum (Newton’s action-reaction, 3rd law).

And, the higher pressure pushing up on the bottom, “pushes against the sky” below.

And so, that air below also turns downward. That is the other part of the downward change in momentum (still Newton’s 3rd law).

So, the Bernoulli pressure change (top and bottom), must always completely compliment Newton’s 3rd law (both top and bottom).

Because, what Bernoulli actually represents is conservation of energy, while Newton’s 3rd law represents conservation of momentum.

And the above two conservation properties act everwhere and always, along with conservation of mass (flow continuity).

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Also, especially in a 172, you want to look for about 80 knots with 10 flaps, 75 with 20 flaps, and 65* with full flaps.

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Hello,

I want you all to know that while I might not respond to every post (I am not here all the time, and the email attached to this account is one I don’t check often), I do read the responses. I never really studied physics, so for me much of the conversation is outside my scope of knowledge - short of letting go of an egg and watching it drop to the floor :rofl: . Well, that’s gravity, but similar I suspect. These in-depth responses I am sure will be helpful, but I doubt I will be thinking about Bernouli or Newton as I am trying to land the plane. :laughing: :+1:

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@adit
I am completely with you- that’s also my feeling and understanding of forces: same amount of force in one direction needs the same amount of force in the other direction.

But what i wrote above is what I read about avionics and what I heard from rl pilots. I am really not sure, which one to believe more: my intuitiv equal force to each direction or the 2/3 law of avionics books.

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Thank you for this info :+1:

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Hi, sorry I didn’t mean to mix you up. Because I don’t think you are wrong in either case:

The “equal force” is really just the mirror response of downward flow, in response to pressure.

Those two have to be equal to each other, on both the top (comparing the top to itself) and the bottom (comparing the bottom to itself).

BUT:

is still correct (or often about right, depending on airfoil and flight conditions).

Just to be clear, about 2/3 of the lift from the top; 1/3 from the bottom.

But that 2/3 on top is represented by a pressure force, equal to the responding downward momentum force.

And the 1/3 on the bottom is a pressure force, equal to its downward momentum force.

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There’s kind of, to me, an amazing logical fallout from all this:

The only ingredient necessary for lift is asymmetry to the relative flow.

And the air doesn’t care if asymmetry is from AOA vs asymmetrical camber (or whatever combination of the two)…But:

Maximizing lift from the upper surface through camber asymmetry reduces reliance on AoA and therefore bottom-side pressure, minimizing drag from blunt-force dynamic pressure. This improves aerodynamic efficiency by encoding lift into dynamic pressure minimizing geometry rather than brute-force displacement, optimizing the L/D ratio.