Mishandling a forward slip

[Shiny Side Up]

Instructors I've found are generally not consistent on transmitting this supposed fear of bank you're talking about

Really? Well, you're doing a lot better out in Alberta
with flight instruction (as well as financially) as compared
to back east here in Ontario.

Every PPL I have ever flown with was crippled by his
ab initio instructor who sternly told him:

USE MAXIMUM X DEGREES OF BANK IN THE CIRCUIT OR YOU WILL DIE

I won't claim I've never heard it, only that I don't find that it is a consistent failing of instructors. I will say that you might find the problem more acute in your neck of the woods since I know that new class 4s are being made out that way by a couple of class 1s who are passing on this mentality. I will say the worst culprits I find making skidding turns are the ultralight guys - which sort of confirms my previous thesis - they spend a whopping seven hours before being "permitted" and most of that is starting off going around the circuit to figure out landings before anything else, then they go do just enough of the obligatory upper air practice to check off the boxes before the letter is submitted.

They think I am insane when I tell them to use as
much bank as they want in the circuit, but I want
the ball in the center.

I'll happily demonstrate this as well to students, but I also make clear that steep angles of bank aren't the solution for poor judgement (they're also good ways to make your wife never fly with you which might curtail your dreams faster too). You do a steep turn because you planned to do a steeper turn. Reading the wind is key to this, something a lot of people have trouble with, unsuprising since as I said, illusions is often the overlooked lesson. The "fix", if you really botched the turn onto final, isn't a suddenly increased angle of bank or a footful of bottom rudder to skid the turn, but rather an overshoot and go around and try it again. The other tactic I advise, is to begin with a gentle angle of bank and if it looks like its not working then to increase to a greater one, try to plan for the gentler one off the start though. If you're uncomfortable with how steep you must make the bank to make the turn, then see above. This is mostly for style sake, its easy to make a turn tighter by steepening the turn if it looks like you're going to overshoot the corner, than it is to make it look good if you start with a steeper bank and try to shallow it out part way through the turn, not that you can't, but even the layman in your passenger seat can tell when you make this error in judgement. Either way, that's less important than both the coordination of the turn and the judging of its resulting path of flight.

Students should also note that increasing the angle of bank is going to increase the rate of descent if the airspeed is maintained, so something to think about on the final turn. Cranking a steep turn on final without a thought to this has probably also filled a few drawers on new CPLs and contributed to their general fear of angles of bank. Its unfortunate that many pilots are afraid of the steeper bank angles, and slips more so than they are of skids.

[photofly]

Losing focus here.

And where better to do it than Avcanada.

You certainly start out ballistic
in the descent than as your speed builds the drag
from the prop, airframe, etc builds until some
equilibrium is reached.

Ok.

But that's missing the point entirely. The point is
that during the descent, the wings are not working.
They are not producing any lift. They have no AOA.

It's not entirely missing the point. If I'm going to stop generating aerodynamic force from the wings, I want to know what other forces I can use to keep me safe from the 1920fpm/second force of gravity.

At cisco, we used to call "rathole!" during
design meetings, when people would diverge off
into other topics of discussion that could not be
easily (or ever) resolved, and were orthonogal
to the topic at hand.

Did you have something someone could yell if they thought it wasn't a rathole? "Mole-hill"?

[Colonel Sanders]

SSU: the important thing is that people can see
a steep turn. Bank frightens them. They naturally avoid
it. I have never met a PPL who was comfortable using
59.9 degrees in the circuit.

But the exact opposite is true of a skidding turn. You
can't see it. No one does it on purpose. It is insidious.
And far more dangerous than a brief steep descending
turn with a low AOA.

[Colonel Sanders]

If I'm going to stop generating aerodynamic force from the wings, I want to know what other forces I can use to keep me safe from the 1920fpm/second force of gravity

Go see Gerry. He's quite a character. He will show you.

I think everyone in Canada ought to fly with Gerry at
least once. Builds character!

[Shiny Side Up]

SSU: the important thing is that people can see
a steep turn. Bank frightens them. They naturally avoid
it. I have never met a PPL who was comfortable using
59.9 degrees in the circuit.

But the exact opposite is true of a skidding turn. You
can't see it. No one does it on purpose. It is insidious.
And far more dangerous than a brief steep descending
turn with a low AOA.

Hence why people should see these things, preferrably at altitude before they start taking stabs at them near the runway. You can't see a skid, but your ass sure can feel it if one is in tune with such things. I suppose people aren't shown how a skidding turn is a surefire way to get into a spin either. don't get me wrong, I fully agree with you on most of it, I just think we need to look a bit farther back than the circuit training to find the ultimate source of the problem.

[Colonel Sanders]

You can't see a skid, but your ass sure can feel it

I don't even need to look at the ball. With my
@ss firmly belted to the seat, as my shoulders
move back and forth, my back will tell me if we
are in unco-ordinated flight.

Often, in the right seat, I will be pinned to the door
by the side force. I have to put out my hands against
the window, to try to oppose it. That's how badly
unco-ordinated we are. At that point, I might suggest
a little right rudder. I don't need to look at the ball.

The problem is that the guy in the left seat is so
tense, he can't feel his shoulders shift back and
forth. He is totally physically exhausted after a
45 minute flight, and it's not hard to see why.

It takes a while before you get completely relaxed
in the cockpit, and start to notice the side force.

I try to keep things really simple for people. For
example, after takeoff, I tell them to put the nose
on the horizon, level the wings, and step on the ball.

In the turns onto base and final, I like to see 80 mph
and the ball centred. After wings level on final, then
back to 70 mph.

Esp with a high-winged aircraft, the descending turns
to base and final can almost be IFR exercises. 80
and ball. 80 and ball. That gets rid of illusions created
by drift.

the worst culprits I find making skidding turns are the ultralight guys

I don't want to talk about ultralights. Ever.

[Shiny Side Up]

It takes a while before you get completely relaxed
in the cockpit, and start to notice the side force.

True, hence why students need more time just flying before they enter the circuit rush. If they haven't relaxed a bit after some of the basics, they sure aren't doing repeated ground rushes for hour after hour as one frequently sees in PTRs. More time spent on stuff before the circuit almost universally reduces time spent in the circuit before people do that much pursued solo, but no one ever believes that. Plus everything else after that is a breeze. Forced approaches? No problem, we already spent time pretending to be a glider and doing slips and not fearing steep banked turns relatively close to the ground. Now just tell me the story TC likes to hear while you do it.

I don't want to talk about ultralights. Ever.

That would be fine and dandy if some of those fellows weren't trying to graduate into private pilots and bringing hours of bad habits with them. One of these such students isn't an easy job for a new instructor. I do want to talk about ultralights since the rules concerning them are really outdated, they aren't just hangliders with briggs and strattons attached anymore.

[Beefitarian]

As you say many of these guys are trying to graduate to PPLs. I suspect a lot of them worked up to ultralights via model planes. Some of the elementary ones did not used to have ailerons at all. Nearly every turn was done by skidding.

[akoch]

What's the deal with the ultralights? I beg pardon, I'm really ignorant what's going on there.

[Beefitarian]

Basically ultralights are getting better all the time. Unfortunately the rules are not improving along with the airframes.

This is good and bad. It allows you to do whatever you want to a degree. Problem being most of us want to save money differing maintenance. This is bad enough in a car, you can't just pull over in an ultralight.

[cgzro]

As you say many of these guys are trying to graduate to PPLs. I suspect a lot of them worked up to ultralights via model planes. Some of the elementary ones did not used to have ailerons at all. Nearly every turn was done by skidding.

Ive not seen a single channel rc plane in nearly 40 years. In fact almost all rc pilots turn without rudder using aileron and elevator only at bank angles and g loads that would make CS proud.

[digits_]

Every PPL I have ever flown with was crippled by his
ab initio instructor who sternly told him:

USE MAXIMUM X DEGREES OF BANK IN THE CIRCUIT OR YOU WILL DIE

Where X is some random number. Might be 30. Might
be 40. Might be 20.

I don't tell it that extreme, but I do urge them to keep the bank angle at max 20° in the circuit, especially the final turn. I'm talking about students who are working towards their first solo. Why ? Because for some reason, in the beginning, they have the tendency to make the nose go up and lose all the airspeed in that turn. If you combine this with angle of bank of 45 degrees and the nervous student, I don't consider it a good mix. Of course you can recover from such things easily and safely without loosing altitude, but we're talking about students who are taking their first 10 hours of instruction. This behaviour of the nose going up is of course corrected every time, and after a few times they fly it in a normal way. However, I don't find it unlikely that , when the first solo is there, they are quite nervous and might fall back into old habits. Thus my 'demand' that they keep the bank angle at max 20° in the circuit. It's what they taught me in 3 different schools as well though. So to me, it doesn't sound all that farfetched.

If I make an error in this reasoning, feel free to point it out !

Simplify it and put the ball in the center. With
80 degrees of bank and ZERO G on the meter,
I am not asking the wings to do any work. In
fact, I could fly at zero airspeed and not stall
the wings, because the AOA is zero.

True, and what you write in your other posts looks correct as well, but at some point you have to exit your zero G flight. This will most likely increase the G load and thus the stall speed.

[photofly]

It's not actually zero-g flight; it's just zero g in the direction normal to the wings, which is, with 80 degrees of bank, nearly horizontal.

[Colonel Sanders]

Thus my 'demand' that they keep the bank angle at max 20° in the circuit.

You're teaching people to skid airplanes through their turns
to base and final. That's how people accidentally enter
spins.

I spend a lot of time, fixing students of instructors like you.

It's what they taught me in 3 different schools

Doesn't means it's correct. For example, "everyone" used to
think that stomach ulcers were caused by stress. Then a couple
of Australian researchers discovered that they were caused by
bacteria, which "everyone" knew couldn't exist in the stomach.
Well, "everyone" was wrong. And the poor Australians were
viciously attacked by the status quo.

Plus ca change, plus c'est le meme chose.

I could have ONE MILLION people email you that they thought
2+2=5. Does that make it so?

EVERYONE used to think the earth was flat. Do you, still?

Physicists used to think at the end of the 19th century
that Newtonian mechanics was all there was. Do you
agree with that?

EVERYONE used to think that the sun rotated around
the earth. When a guy spoke up and said, Gee, I think
it might be the other way 'round they tossed his @ss
in jail.

at some point you have to exit your zero G flight

Go fly with Gerry Younger in his S-2A. You probably think
you know more about flying than him, but he's probably
competed at more WAC's than you He flies the
entire final approach with the wing unloaded.

Do you understand what "the wing unloaded" means?
It is providing no lift. Since it is providing no lift, it is
impossible for you to stall at any bank angle or airspeed.

You straight and level guys like to attack aerobatics
as stupid and childish and irrelevant, but it you that
hasn't got a clue about how an airplane flies.

[digits_]

It's not actually zero-g flight; it's just zero g in the direction normal to the wings, which is, with 80 degrees of bank, nearly horizontal.

Yes, but in this case, on which other axis would there be non-zero g forces ? He would be flyin ball center (well, in zero g more like 'ball floating') so no forces in that direction either. Then all that remains are the forces generated by the engine and/or drag. But those are not relevant for the stall discussion here, since the effect would be possible to achieve as well with as without engine power. No ?

[digits_]

Thus my 'demand' that they keep the bank angle at max 20° in the circuit.

You're teaching people to skid airplanes through their turns
to base and final. That's how people accidentally enter
spins.

No, I want them to make bigger turns with less bank angle. I will pay extra attention to it next time, but as far as I can recall they don't skid.

It's what they taught me in 3 different schools

Doesn't means it's correct.

Of course not. It was not meant as an argument, I added it as an illustration to explain where the reasoning came from.
But also note that (some) examiners are not happy with 'steep' turns in circuits as well. So don't put all the blame with the instructors, only a part of it...

at some point you have to exit your zero G flight

Go fly with Gerry Younger in his S-2A. You probably think
you know more about flying than him,

I do not. Nor have I ever claimed to do so.

He flies the
entire final approach with the wing unloaded.

Do you understand what "the wing unloaded" means?
It is providing no lift. Since it is providing no lift, it is
impossible for you to stall at any bank angle or airspeed.

So you can basically replace an unloaded wing with a broomstick with ailerons on , right ? I don't claim it is impossible to fly such an approach, only that at one point he has to leave this 'wing unloaded' equilibrium. Or does he land with an unloaded wing as well ? I don't see how this would be physically possible.

You straight and level guys like to attack aerobatics
as stupid and childish and irrelevant, but it you that
hasn't got a clue about how an airplane flies.

Again: I do not. Nor have I ever claimed to do so. Critical questions are not an attack.

[Colonel Sanders]

as far as I can recall they don't skid

and there's your problem. They don't know they
are skidding, either. But you have crippled them
with your arbitrary and silly "MAX 20 BANK" which
causes then to pull the nose around with the inside
rudder - because you've told them to turn the
aircraft without using any bank. You won't let
them incline the lift vector. This is madness.

Don't teach people to turn aircraft flat.

The cure is worse than the disease. Every
year, people die from this. If you are cool
with killing your students, carry on.

I don't see how this would be physically possible.

Sigh. Go fly with Gerry. Lots more stick. Less chalk.

[Colonel Sanders]

Apart from keeping the ball centered (no skidding turns)
if I could teach ONE thing to people it would be:

DON'T FEAR THE BANK ANGLE

Everyone fears bank angle. If you try to turn an aircraft
with bank, they will tell you that you will stall. You might
even accidentally pull infinite G, with enough bank, and
that's not good. With infinite G, your aircraft will implode
into a size less than a grain of sand.

Utter hogwash. Time for a little chalk. A "normal" turn
for me is 60 and 2. That is, 60 degrees of bank and +2G,
which is about what you experience when you stand up.
+2G will not make you black out. It will not make the
wings fall off. Or even the tail.

But what about the stall, you wail?

Well, the stall speed at +2G is:

Vs(G) = Vs(1G) x sqrt(G)

Let's take your airplane with a 50 mph stall speed,
flaps up. In a level, 60 degree turn with the ball in
the center, we will pull +2G:

Vs(+2G) = 50 mph x sqrt(2) = 70 mph

So if you can keep your speed up above 70 mph
in maneuvering flight (flaps up) you will not stall
in a co-ordinated, level 60 degree banked turn.

I would hope that you guys don't routinely fly
around at less than 70 mph. It is only with
great effort and persuasion that I am able to
make people spend any time here at all in
slow flight at 3000 AGL.

What we have learned from our little chalk
exercise above is

DON'T FEAR THE BANK ANGLE

Now let's look at specific turns. The ones
I want to look at are the turns from downwind
to base, and from base to final.

When I turn base, or final, I am generally in
a descent. I am NOT performing the level
turn above, which resulted in the fearsome
stall speed of 70 mph with 60 and 2.

During these turns, I unload the wings. That
means that I am not asking them to produce
as much lift. That means that even though I
have 60 degrees of bank on, with the ball in
the center, there is not actually +2G on. That
means that the wings are operating at a lower
AOA. That means that the stall speed is actually
less than 70 mph.

DON'T FEAR THE BANK ANGLE

tl;dr An aircraft turns by inclining the lift vector.
This is not dangerous. The number of people
who accidentally spin an aircraft with a bootful
of inside rudder, is at least 100x as many as
the number of people who stall an airplane with
excessive G and the ball in the center.

Edit -- Does Weird Al Yankovic do requests? We
really need him to do a parody of BOC's "Don't
Fear The Reaper". He can use as much cowbell
he wants:

[Colonel Sanders]

Tangent: another really valuable lesson people
need to learn:

YOUR FLIGHT INSTRUCTOR IS NOT GOD

You'd be amazed at how often people will tell me
something that's quite silly.

I will reply, "That's quite silly". And they get really upset.

I ask them "Why you think (or do) that?".

The reply, "My flight instructor told me so".

And this really shakes the foundations of their
universe - that their 250TT class 4 instructor
might have been wrong about something. This
is a big psychological problem for them.

And it doesn't really matter what's right or not -
it's the cracks in the foundation of their belief
system (i.e. that the flight instructor was infallible)
that is the big problem for them.

Lesson:

YOUR FLIGHT INSTRUCTOR IS NOT GOD

[trampbike]

...but he has 4 bars on his shoulders, very nice Ray Ban shades and a HUGE flight bag!

[photofly]

So you can basically replace an unloaded wing with a broomstick with ailerons on , right ? I don't claim it is impossible to fly such an approach, only that at one point he has to leave this 'wing unloaded' equilibrium. Or does he land with an unloaded wing as well ? I don't see how this would be physically possible.

There's a teensy weensy bit of exaggeration going on, on both sides, I think.

Interesting how you can develop all sorts of forces from things other than the wing though:
http://www.youtube.com/watch?v=ZId2oiK1pr8

[Colonel Sanders]

It's too bad you guys are too young to have ever
seen Delmar Benjamin fly:



Delmar didn't have a Phd in Aerodynamics
but gosh he could sure fly that Gee Bee Racer.

Probably almost as good as an airline pilot

I don't know why, but I find it amusing when a
collection of esteemed PhD's explain why an R-985
with a pair of handlebars could never fly, then
a high school dropout demonstrates how it's done.

[Colonel Sanders]

Here's a guy that simply could not keep up
with the theory on AvCan:



Talk to me about his wing loading, and his stall speed.

He probably doesn't fly as well as the expert
flight instructors here, but he's trying.

[pdw]

A little bit of everything is "loading" up there

(engine thrust ... the wings ... .. fuselage for sure ... a bit of a V-tail going there at the tail ... heck even the wheel pants must be in on it)

[photofly]

Here's a guy that simply could not keep up
with the theory on AvCan:

That was the one I was looking for!