steep turns- 2 questions

[Jeanie]

a. Why do pilots need to know how to do steep turns?

b. Why is there a tendency to overbank?

 

[brcase]

a. I am sure there are a lot more reasons. Here are what I think off the top of my head.
1. They teach you how to control bank and pitch at the same time.
2. They teach you how to look inside and outside the airplane (when done properly VFR)
3. They teach you it is ok to bank the airplane, believe it or not some students don't want to bank more than about 20 degrees.
4. They help teach how bank affects pitch.
5. They help teach how pitch affect bank.

b. Gliders really demonstrate overbanking tendancy due to the long wings.
basically the outer wing has to travel faster than the inner wing, causing the inner wing to generate less lift than the outer wing. In a 2-33 at slow speed (thermalling) circling it is not uncommon to have the aileron against the stop to prevent the bank angle from increasing. This of course means that pretty much the only way to decrease the bank angle is to either increase speed or slip the glider with the rudder.

 

[bbchien]

Someday, you will be flying down a river and encounter decreasing ceilings. You will deploy half flaps and make a tight radius turn w/o loss of altitude, and thank your lucky stars that you were able to do so. That after exempting how dumb getting into that situation was, in the first place.

Think, Cory Lidle and Tyler Stenger, CFI.

Plus, is simply increases mastery of the envelope. The steep bank causes a slip unless the rudder follows.....low and slow, it's a death stall. at 45 degrees, the rudder also acts like the elevator....there is crossover. That is really why we have to master it.

 

[Matthew]

b. Gliders really demonstrate overbanking tendancy due to the long wings.
basically the outer wing has to travel faster than the inner wing, causing the inner wing to generate less lift than the outer wing. In a 2-33 at slow speed (thermalling) circling it is not uncommon to have the aileron against the stop to prevent the bank angle from increasing. This of course means that pretty much the only way to decrease the bank angle is to either increase speed or slip the glider with the rudder.

Yeah - first time I did a steep turn in a glider I was surprised at how much opposite aileron was required to keep it from feeling like it would roll over. Later, I noticed that my neck hurt. Then I remembered, a 60* bank is a 2G turn, and we'd been thermalling for about 40 minutes.

My CFI stressed steep turns - you will learn how a steep bank angle decreases the vertical component of lift. To keep a steady airspeed and altitude you will need to learn how to balance the back pressure, power, bank angle, rudder, and your feel for the plane.

Then, like the good doctor said, there may be a time when you'll need it.

 

[Mason]

Someday, you will be flying down a river and encounter decreasing ceilings. You will deploy half flaps and make a tight radius turn w/o loss of altitude, and thank your lucky stars that you were able to do so. That after exempting how dumb getting into that situation was, in the first place.

Hopefully, turning upwind rather than downwind.

 

[Areeda]

What about the reason for overbanking tendency. I'd also appreciate more insight.

My incomplete understanding is that roll stability is produced by several design characteristics like dihedral. It is not as good as pitch stability. Beyond certain limits it produces the opposite effect and hence the overbanking tendency.

Joe

 

[Doggtyred]

When I went for a checkout in subsequent rentals, many times the checkride consisted of steep turns in either direction and nothing else besides the takeoff and landing.. the older instructors considered it a good demonstration of aircraft mastery at the private pilot level.

Everything is interconnected - pitch, power, airspeed, visual reference inside the cockpit, outside the cockpit...

 

[wpierce]

And it is so cool when you fly back through your wake when done properly!

 

[Lawreston]

When I went for a checkout in subsequent rentals, many times the checkride consisted of steep turns in either direction and nothing else besides the takeoff and landing.. the older instructors considered it a good demonstration of aircraft mastery at the private pilot level.

Everything is interconnected - pitch, power, airspeed, visual reference inside the cockpit, outside the cockpit...

- - - your response is interesting. When I did my SODA flight(blind in left eye) the FAA examiner had me do a bunch of maneuvers. Then he asked me if I was afraid of steep turns. "If I am I shouldn't be here with you." He had me do one to the left and then one to the right. At the conclusion of those he said, "OK, take us back to the airport and show me some landings." Your observation(above) leads me to believe that my steep turns capped-off what he needed to know.

HR

 

[nosehair]

a. Why do pilots need to know how to do steep turns?

Even if you think you can do all your flying at 20 degrees or less, someday, just like a cross wind, a sudden gust of turbulence will suddenly throw you into a steeper bank, approaching 45 degrees, or even greater. As the pilot, you need to be trained to handle the airplane in a variety of situations that you do not necessarily intend to get into, mainly because of weather.

b. Why is there a tendency to overbank?

What tendency? Are you asking about the theory, or the actual tendency? I haven't really noticed much overbanking tendency in most of the popular 'training' airplanes on the market. And at 45 degrees, there usually isn't any. In the theory.

 

[somorris]

I think the principle reason for doing them is it teaches aircraft control nearer the envelope edges.

b. Gliders really demonstrate overbanking tendancy due to the long wings.
basically the outer wing has to travel faster than the inner wing, causing the inner wing to generate less lift than the outer wing.

I agree with Brian here.

 

[brcase]

<snip>What tendency? Are you asking about the theory, or the actual tendency? I haven't really noticed much overbanking tendency in most of the popular 'training' airplanes on the market. And at 45 degrees, there usually isn't any. In the theory.

True in most training aircraft the effect is small at the speeds we normally demonstrate steep turns. Also pilots usually compensate for it without thinking about it. Next time you do a steep turn, look where the stick/yoke is positioned once the turn is stablized. It probably won't be in the center. Trying the turn a bit slower will demonstrate the effect even better.

Brian

 

[timwinters]

a. Why do pilots need to know how to do steep turns?

Because they're fun! And, I too gain a sense of satisfaction when I "hit the bump" flying back through my own wake.

 

[poadeleted20]

For the "why" of overbanking, see http://www.av8n.com/how/htm/roll.html#sec-overbanking. As discussed in the Airplane Flying Handbook (Section 3, page 3-7/8), in shallow turns (20 degrees or less), the overbanking tendency is usually overridden by other factors, bringing the airplane back towards wings-level. In medium banks (20-45 degrees), the overbanking and underbanking tendencies are fairly equal, keeping the aircraft in approximately the same bank. In steep turns (above 45 degrees), the overbanking tendencies become dominant, with an increasing roll rate as bank increases.

As for why we do steep turns...

STEEP TURNS


The objective of the maneuver is to develop the smoothness, coordination, orientation, division of attention, and control techniques necessary for the execution of maximum performance turns when the airplane is near its performance limits. Smoothness of control use, coordination, and accuracy of execution are the important features of this maneuver.

 

[Dan Thomas]

True in most training aircraft the effect is small at the speeds we normally demonstrate steep turns. Also pilots usually compensate for it without thinking about it. Next time you do a steep turn, look where the stick/yoke is positioned once the turn is stablized. It probably won't be in the center. Trying the turn a bit slower will demonstrate the effect even better.

Brian

It's there, if you have the ball centered. Most people will let the airplane slip a little in a steeper turn and that diminishes the overbanking tendency. In coordinated flight most will need some top aileron.

Dan

 

[Dan Thomas]

Because they're fun! And, I too gain a sense of satisfaction when I "hit the bump" flying back through my own wake.

That means you descended a few feet. Tip vortices descend a little after the airplane passes, and to get the thump-thump you have to drop maybe ten feet.

Dan

 

[wpierce]

That means you descended a few feet. Tip vortices descend a little after the airplane passes, and to get the thump-thump you have to drop maybe ten feet.

Dan

I'll take it.

 

[Dan Thomas]

Hopefully, turning upwind rather than downwind.

Oh, no. Here we go

Try doing level steep turns, or any level turn for that matter, under the hood when the winds aloft are 30 knots or so, and see if you can feel or otherwise detect any airspeed fluctuation. (Carry a lookout pilot.) The earth's gravity works only in the vertical, not horizontally, and once in the air the airplane becomes part of the airmass and moves with it. To get an airspeed drop you would have to somehow make an instantaneous reversal in direction, and that's impossible with airplanes.

Dan

 

[flyingcheesehead]

That means you descended a few feet. Tip vortices descend a little after the airplane passes, and to get the thump-thump you have to drop maybe ten feet.

Au contraire - Yes, tip vortices descend, but if the drop is "ten feet" you'll hit the higher wing's vortex while maintaining altitude.

 

[Mason]

Oh, no. Here we go

Try doing level steep turns, or any level turn for that matter, under the hood when the winds aloft are 30 knots or so, and see if you can feel or otherwise detect any airspeed fluctuation. (Carry a lookout pilot.) The earth's gravity works only in the vertical, not horizontally, and once in the air the airplane becomes part of the airmass and moves with it. To get an airspeed drop you would have to somehow make an instantaneous reversal in direction, and that's impossible with airplanes.

Dan

That wasn't the point of my comment. I agree with you about the so-called "downwind turn."

My reference was to the fact that turning upwind you will cover less distance over the ground and therefore have a better chance of not hitting the buildings on the far side of the river. If the point of making the steep turn is to do a 180 while remaining over the river.

 

[Dan Thomas]

That wasn't the point of my comment. I agree with you about the so-called "downwind turn."

My reference was to the fact that turning upwind you will cover less distance over the ground and therefore have a better chance of not hitting the buildings on the far side of the river. If the point of making the steep turn is to do a 180 while remaining over the river.

Ah, you're right. In a valley, with a wind across the valley, you normally want to be on the upwind side. That would make a minimum-radius turn into the wind.

Dan

 

[nosehair]

It's there, if you have the ball centered. Most people will let the airplane slip a little in a steeper turn and that diminishes the overbanking tendency. In coordinated flight most will need some top aileron.

True, the flight controls will be positioned differently to stay 'coordinated'. As soon as you begin to pull back pressure to hold altitude, you are introducing increased AoA which increases P-Factor, and the need to hold right rudder during the turn, especially in the right turn. To stay coordinated in a right steep turn, you will be holding back elevator, significant right rudder and left aileron. But is this because of the overbanking tendency or P-Factor?
The left turn is different. Some airplanes (of the same make/model) need a slight touch of top rudder with some top aileron, but some are happy at neutral rudder/aileron during the left turn.

 

[MauleSkinner]

When I went for a checkout in subsequent rentals, many times the checkride consisted of steep turns in either direction and nothing else besides the takeoff and landing.. the older instructors considered it a good demonstration of aircraft mastery at the private pilot level.

Everything is interconnected - pitch, power, airspeed, visual reference inside the cockpit, outside the cockpit...

Darn...I'm an "older instructor" again!

It's true, though...there are certain maneuvers that tell a LOT about whether the pilot is the master of the aircraft or not, and steep turns is one of them.

 

[Doggtyred]

Ah, you're right. In a valley, with a wind across the valley, you normally want to be on the upwind side. That would make a minimum-radius turn into the wind.

Dan

Am I missing something here? If you are upwind, an upwind turn would be into the rocks not into the valley... right?

 

[MikeELP]

When I went for a checkout in subsequent rentals, many times the checkride consisted of steep turns in either direction and nothing else besides the takeoff and landing.. the older instructors considered it a good demonstration of aircraft mastery at the private pilot level.

Everything is interconnected - pitch, power, airspeed, visual reference inside the cockpit, outside the cockpit...

I use both steep turns AND slow flight. Show me good control of the airplane in those two areas and I'll have a very good idea of your overall ability in flying the airplane in different extremes.

Mike

 

[TangoWhiskey]

Am I missing something here? If you are upwind, an upwind turn would be into the rocks not into the valley... right?

I'm sure Dan meant to say that you normally want to be on the downwind side when flying up a valley with wind flowing perpendicular to the ridges, which allows you to fly in rising updrafts as well as being able to turn into the wind if a 180 becomes necessary.

 

[rottydaddy]

Am I missing something here? If you are upwind, an upwind turn would be into the rocks not into the valley... right?

Right. If the valley runs, say, north-south, and you are flying north, with the wind out of the west, you'd stay "to the right", on the leeward side. At least I would...

Two reasons:
First, yes, if you need to make a 180, you will turn into the wind, not downwind. This keeps you from being carried into high terrain. If it's really blowing hard, you open up the turn a bit, or sped up, or whatever. Much easier than compensating for a turn downwind between obstacles...

Second reason: generally speaking, when wind blows across a valley, or a canyon especially (steep sides), it tends to spill down on the upwind slope and rise up on the other side.

Glider pilots know this well... the rule of thumb when flying near rising terrain is to fly on the upwind side, and make all turns into the wind.

Gliders are more at the mercy of airflow, but power pilots can benefit from this knowledge, too. High, steep slopes and strong wind can be a trap for even very powerful airplanes with excellent climb performance.


Imagine, instead of a valley or canyon, there is only one ridge or slope, and you want to track along it, not very high above it. Let's say you want to fly below the highest part. Would you fly on the upwind side or downwind side?


Pretty easy to visualize that... now consider that a valley or canyon is usually a space between two ridges or slopes. The rising slope or canyon wall on the downwind side of the depression becomes your target area for flight, because the air is rising back up on that side, making it easier to maintain altitude above the terrain, should you have to get close to it.

In strong winds, with terrain producing powerful effects, you're better off battling updrafts than downdrafts, especially close to rocks.


Obviously, this means our pilot making a 180 into the wind across a canyon may encounter downdrafts as they approach the slope that is "behind" the wind, but having started on the far side, they can improve their chances of attaining that new heading before they get close enough to that side. If you do get into a downdraft, the headwind should still keep your turn tight (ground-track-wise), making it easier to turn around over the lower part of the valley, not near the walls.

 

[gismo]

Am I missing something here? If you are upwind, an upwind turn would be into the rocks not into the valley... right?

Right. So if there's wind from one side you need to move to the other side before turning back. If the corridor is really narrow you should already be there.

 

[Dan Thomas]

Right. So if there's wind from one side you need to move to the other side before turning back. If the corridor is really narrow you should already be there.

Right. Never in the center. No room to turn that way, especially if you come around a corner and find that the canyon is blind.

I did mean the downwind side when I mentioned staying to the side when there's a crosswind. Normally, if the valley is a busy corridor, traffic stays to the right, and if you have the wind from the right you'd want to be on th left side to take advantage of orographic lift, but the guy coming the other way also wants that lift and it's on his side so you'd better be watching.

In really deep, narrow places the wind could be crosswind in the opposite direction from that aloft above the peaks. It can form a rotor within the valley.

Dan

 

[dmccormack]

To the OP....

IMHO nothing provides such immediate evidence of the pilot's mastery of an airplane as a steep turn.

A Well-executed chandelle is a close second.

 

[Dan Thomas]

True, the flight controls will be positioned differently to stay 'coordinated'. As soon as you begin to pull back pressure to hold altitude, you are introducing increased AoA which increases P-Factor, and the need to hold right rudder during the turn, especially in the right turn. To stay coordinated in a right steep turn, you will be holding back elevator, significant right rudder and left aileron. But is this because of the overbanking tendency or P-Factor?

It's the overbanking tendency. The outer wing is faster than the inside, just a bit, and generates a little more lift. It's noticeable in either direction.

Dan

 

[gismo]

It's the overbanking tendency. The outer wing is faster than the inside, just a bit, and generates a little more lift. It's noticeable in either direction.

Dan

I think we can be pretty sure that the overbanking tendency in a sailplane isn't cause by P-factor.

 

[MauleSkinner]

I use both steep turns AND slow flight. Show me good control of the airplane in those two areas and I'll have a very good idea of your overall ability in flying the airplane in different extremes.

Mike

Better yet, show me both of 'em at once.

 

[Doggtyred]

I did mean the downwind side

Thanks... thats what I was clarifying...

I've been wrong more than once, myself, so I just wanted to make sure I understood ya..

 

[flyingcheesehead]

Better yet, show me both of 'em at once.

Actually, there *is* use in that exercise (slow flight + steep turn). It's the minimum radius turn possible (think Corey Lidle, or anyone who ends up in a box canyon). For normal category, 74 degrees bank with the stall horn screaming the whole way around. Probably not exactly how you want to practice it, but I think that after doing commercial steep turns, the next step as far as steep turns go would be 60-degree banked slow flight - 180 degrees at a time instead of 360. You'd be slightly above 1.414Vs1 (you're unlikely to be in landing configuration when you need this, after all) to do it right. Ideally, the exercise would also include a full-aileron-deflection roll-in, complete with proper rudder input (since, unless you've done tailwheel training, your brain is probably something like "Rudder? What's that?" most of the time.)

Don't try this at home, kids.

 

[dmccormack]

Actually, there *is* use in that exercise (slow flight + steep turn). It's the minimum radius turn possible (think Corey Lidle, or anyone who ends up in a box canyon). For normal category, 74 degrees bank with the stall horn screaming the whole way around. Probably not exactly how you want to practice it, but I think that after doing commercial steep turns, the next step as far as steep turns go would be 60-degree banked slow flight - 180 degrees at a time instead of 360. You'd be slightly above 1.414Vs1 (you're unlikely to be in landing configuration when you need this, after all) to do it right. Ideally, the exercise would also include a full-aileron-deflection roll-in, complete with proper rudder input (since, unless you've done tailwheel training, your brain is probably something like "Rudder? What's that?" most of the time.)

Don't try this at home, kids.

If you want to try it -- practice at altitude with someone competent aboard if you aren't proficient in spin recovery.

 

[bbchien]

Kent, see post #3

 

[SkyHog]

1) Excellent question, and one I've been arguing for a while. Steep turns, turns around a point and S-Turns belong in the commercial pilot PTS, not in the Private Pilot PTS.

2) I have no idea, except to say that it probably has something to do with the plane's stability after 45 degrees.

 

[poadeleted20]

Actually, there *is* use in that exercise (slow flight + steep turn). It's the minimum radius turn possible (think Corey Lidle, or anyone who ends up in a box canyon). For normal category, 74 degrees bank with the stall horn screaming the whole way around.

Beware of drag exceeding thrust in such a turn in a light plane. Fighter pilots are familiar with Ps diagrams providing data on excess power in various turning states, but light plane manuals don't have such information. Put this in a similar category to the "impossible turn" as something you don't want to be trying for the first time when the need occurs. Try it at a good safe altitude (like one from which you'd intentionally enter a spin) before considering it a usable tool to put in your aviation toolbox.

 

[flyingcheesehead]

Steep turns, turns around a point and S-Turns belong in the commercial pilot PTS, not in the Private Pilot PTS.

S-turns, I can somewhat agree, though I don't think they should be commercial maneuvers either (the comm ground-reference maneuvers are harder) - They're basically useless.

Turns around a point are a good way of demonstrating the effect of groundspeed on turn radius. I can see them not being part of the checkride, but they should be at least demonstrated and tried a few times (which is usually all it takes to master them anyway.) Unfortunately, as we know, there are enough bad CFI's out there that anything that's not on the PTS isn't going to be taught to everyone.

Steep turns, I vehemently disagree. Rolling in and out of a steep turn is about the only thing you really need rudder for in the private PTS, it demonstrates things like load factor and the fact that you can bank that much without stalling (think base-to-final spin, people are scared to bank!) plus it's about the only maneuver on the private PTS that requires you to demonstrate mastery about all axes of flight simultaneously. It's also a VERY useful maneuver. Why on earth would you not want private pilots to know how to do steep turns?