Can you depart and spin from coordinated flight? Specifically a coordinated
climbing turn?

Several weeks ago I chimed in on an otherwise awful thread suggesting that
if the ball was in the center
the airplane would not spin. One of the posters
) responded that the difference
in relative wind between the inside/outside wing during a climbing turn
would result in an assymetrical stall
and wing drop even in coordinated flight. He had several
Canadian/Australian citations to back it up.

He posted summaries of them originally and my apologies for re-constructing
them:

Full power stalls in a balanced climbing turn tend to result in the outer
wing stalling first, because of the higher aoa of the outer wing, with a
fairly fast wing and nose drop (particularly so if the propeller torque
effect is such that it reinforces the roll away from the original direction
of turn and the aircraft is a high wing configuration) and likely to result
in a stall/spin situation that any pilot lacking spin recovery experience
may find difficult to deal with. If the climbing turn is being made with
excessive bottom rudder then the lower wing might stall first with the
consequent roll into the turn flicking the aircraft over. Recovery from a
stall in a climbing turn is much the same as any other stall - ease the
control column forward to about the neutral position, stop any yaw, level
the wings and keep the power on.

http://www.auf.asn.au/groundschool/umodule11.html#climb_turns

When the aircraft stalls in a climbing turn, the high wing is at a greater
angle of attack than the low wing and therefore stalls first, which results
in a rolling motion toward the high wing, creating asymmetric lift and drag.
The down-going wing will stall further as a result of less lift and more
drag than the up-going wing. A deeper stall, generated by aft C of G, will
aggravate these asymmetries, increasing aircraft rolling and yawing moments
into the down-going wing. In addition, the aft C of G reduces the distance
from the C of G to the centre of pressure of the vertical fin, thus reducing
directional control authority, making recovery more difficult

http://www.tsb.gc.ca/en/reports/air/1994/a94o0316/a94o0316.asp?print_view=1

In a climbing turn, the outside or upgoing wing is meeting the relative wind
at a slightly higher angle of attack than the lower wing. If we pull on
the column to the stalling bite, then the upgoing wing will reach it
first...The upgoing wing suddenly drops and the wing falls away from the
original direction of turn.

http://www.casa.gov.au/fsa/2000/sep/FSA34-35.pdf

The Transport Canada Guidelines on Stall Training and Spin Awareness
specifically requires demonstrations in coordinated climbing turns:
http://www.tc.gc.ca/civilaviation/general/Flttrain/TP13747/stalltrain.htm


I would have thought that the hamfisted chandelles I perform would have
flirted with disaster if this were the case. However while I have had to
demonstrate accellerated stalls from 20 degree banks, I cannot recall having
to deliberately stall the airplane from a climbing turn.

My question to uunet is; can you spin from coordinated flight? Regardless
the previous dialog did get me thinking:

The convergence of insufficient right rudder and a slipping turn, the left
turning tendencies and the
assymetrical stall could gang up on our hapless pilot resulting in a quick
snap and
spin during a climbing right turn away from obstacles in the departure path.

Regards
Todd

--
"Instrument flying, I had concluded, is an unnatural act, probably
punishable by God."
--Gordon Baxter

There is only one thing you have to know about spins. To enter one you
need 2 things to be present; stall and a yaw rate. All the rest is
simply stating different ways to make these two things happen.
You can spin a spin capable airplane from any flight condition,
coordinated or uncoordinated, straight and level, a turn, a climbing
turn, a descending turn; it doesn't matter. Just induce a stall either
at 1g or accelerated above 1g, introduce a yaw rate at that stall, and
you will have a spin.
Don't get all bogged down in specifics trying to explain whether an
airplane will spin from this or that. It simply confuses the issue.

The answer to your question is simple aerodynamics. Yes, you can spin an
airplane from coordinated flight and yes, you can spin an airplane from
a climbing turn. All that is needed from ANY flight condition is to
induce a stall and at that stall, induce a yaw rate.






Todd W. Deckard wrote:
> Can you depart and spin from coordinated flight? Specifically a coordinated
> climbing turn?
>
> Several weeks ago I chimed in on an otherwise awful thread suggesting that
> if the ball was in the center
> the airplane would not spin. One of the posters
> ) responded that the difference
> in relative wind between the inside/outside wing during a climbing turn
> would result in an assymetrical stall
> and wing drop even in coordinated flight. He had several
> Canadian/Australian citations to back it up.
>
> He posted summaries of them originally and my apologies for re-constructing
> them:
>
> Full power stalls in a balanced climbing turn tend to result in the outer
> wing stalling first, because of the higher aoa of the outer wing, with a
> fairly fast wing and nose drop (particularly so if the propeller torque
> effect is such that it reinforces the roll away from the original direction
> of turn and the aircraft is a high wing configuration) and likely to result
> in a stall/spin situation that any pilot lacking spin recovery experience
> may find difficult to deal with. If the climbing turn is being made with
> excessive bottom rudder then the lower wing might stall first with the
> consequent roll into the turn flicking the aircraft over. Recovery from a
> stall in a climbing turn is much the same as any other stall - ease the
> control column forward to about the neutral position, stop any yaw, level
> the wings and keep the power on.
>
> http://www.auf.asn.au/groundschool/umodule11.html#climb_turns
>
> When the aircraft stalls in a climbing turn, the high wing is at a greater
> angle of attack than the low wing and therefore stalls first, which results
> in a rolling motion toward the high wing, creating asymmetric lift and drag.
> The down-going wing will stall further as a result of less lift and more
> drag than the up-going wing. A deeper stall, generated by aft C of G, will
> aggravate these asymmetries, increasing aircraft rolling and yawing moments
> into the down-going wing. In addition, the aft C of G reduces the distance
> from the C of G to the centre of pressure of the vertical fin, thus reducing
> directional control authority, making recovery more difficult
>
> http://www.tsb.gc.ca/en/reports/air/1994/a94o0316/a94o0316.asp?print_view=1
>
> In a climbing turn, the outside or upgoing wing is meeting the relative wind
> at a slightly higher angle of attack than the lower wing. If we pull on
> the column to the stalling bite, then the upgoing wing will reach it
> first...The upgoing wing suddenly drops and the wing falls away from the
> original direction of turn.
>
> http://www.casa.gov.au/fsa/2000/sep/FSA34-35.pdf
>
> The Transport Canada Guidelines on Stall Training and Spin Awareness
> specifically requires demonstrations in coordinated climbing turns:
> http://www.tc.gc.ca/civilaviation/general/Flttrain/TP13747/stalltrain.htm
>
>
> I would have thought that the hamfisted chandelles I perform would have
> flirted with disaster if this were the case. However while I have had to
> demonstrate accellerated stalls from 20 degree banks, I cannot recall having
> to deliberately stall the airplane from a climbing turn.
>
> My question to uunet is; can you spin from coordinated flight? Regardless
> the previous dialog did get me thinking:
>
> The convergence of insufficient right rudder and a slipping turn, the left
> turning tendencies and the
> assymetrical stall could gang up on our hapless pilot resulting in a quick
> snap and
> spin during a climbing right turn away from obstacles in the departure path.
>
> Regards
> Todd
>


--
Dudley Henriques

Dudley Henriques schrieb:

> There is only one thing you have to know about spins. To enter one you
> need 2 things to be present; stall and a yaw rate. All the rest is
> simply stating different ways to make these two things happen.

While I agree that this is a correct and simple recipe and therefore
quite useful in practice, I don't agree that it helps to *understand*
the situation, because *reason* for the spin is not the yaw rate. The
reason for the spin is an asymmetric angle of attack, i.e. one wing is
more stalled than the other. Of course this situation can only occur if
there is some yaw, which leads us to the recipe given above.

Recipe: As there is always some yaw in a coordinated turn (otherwise it
wouldn't be coordinated), you can perfectly enter a spin from a
coordinated turn. Aerodynamic reason: The inner wing has a higher angle
of attack than the outer, so it stalls first or, if both wings stall, it
is more stalled. Asymmetric stall condition -> spin.

On Dec 27, 1:42 pm, "Todd W. Deckard" > wrote:
> Can you depart and spin from coordinated flight? Specifically a coordinated
> climbing turn?
>


Well, yeah, prolly, but it'd have to be pretty tight. We used to spin
some glider types "over the top" as you suggest, but it's kind of
splitting hairs to suggest what you are suggesting.

And courting disaster doing a chandelle? If you're going to do a
commercial ticket you should be familair with spins intimately. An
incipient spin shouldn't even make you break a sweat.


BTW, stalls in a climbing turn are pretty much standard standard stuff
even for Private pilots.

Bertie

Stefan wrote:
> Dudley Henriques schrieb:
>
>> There is only one thing you have to know about spins. To enter one you
>> need 2 things to be present; stall and a yaw rate. All the rest is
>> simply stating different ways to make these two things happen.
>
> While I agree that this is a correct and simple recipe and therefore
> quite useful in practice, I don't agree that it helps to *understand*
> the situation, because *reason* for the spin is not the yaw rate. The
> reason for the spin is an asymmetric angle of attack, i.e. one wing is
> more stalled than the other. Of course this situation can only occur if
> there is some yaw, which leads us to the recipe given above.
>
> Recipe: As there is always some yaw in a coordinated turn (otherwise it
> wouldn't be coordinated), you can perfectly enter a spin from a
> coordinated turn. Aerodynamic reason: The inner wing has a higher angle
> of attack than the outer, so it stalls first or, if both wings stall, it
> is more stalled. Asymmetric stall condition -> spin.


You can argue this until the cows come home but the answer is always the
same. To spin an airplane you need stall and a yaw rate...period! All
the rest of it, the difference in aoa, the dynamics of autorotation, the
whole magilla, is nothing but explaining in aerodynamic terms what
happens AFTER the stall and yaw rate are introduced.

As you say, understanding these things is essential, but they are the
EFFECT of what causes spin.
Look at it this way. Without stall and without a yaw rate being
introduced, you will have none of the things happening that you have
mentioned. None will be present until stall occurs and a yaw rate
introduced.

They are relevant of course, but not the single answer a pilot needs to
know when addressing the subject of spins.

When I ask a student what causes a spin, I don't want that student to
tell me what happens to each wing of the airplane as the spin is
developing. If I get that answer I'm immediately going to ask that
student how the airplane was placed in a position to cause these effects
to happen.

When someone asks what causes a spin, or whether or not an airplane can
be spun from this flight position or that one, the correct answer is
that stall and yaw rate must be present to produce a spin; and that spin
can be entered from ANY flight condition.
If you then ask a student to explain the aerodynamics in play as a spin
develops, it's THEN you want the auto rotational aerodynamics.

--
Dudley Henriques

I have a limited exposure to spins (I've demonstrated spins or received spin
instruction in 5 different airplanes on
six different occasions). I have a commercial certificate (although you
wouldn't think so from my demonstration
of a chandelle). Maybe I did have to demonstrate a power on stall while
in a climbing 20 degree bank, once.
As I recall, we survived it.

I return to the original question: if the ball is in the middle will it
spin?

Becuase I believe snowmobile suits are for snowmobiling and not for flying I
won't have a chance to explore it
with an aerobatic instructor and an appropriate (but drafty) airplane for a
few months -- so I thought I would
put the question in a bottle and throw it in the ocean.

Regards
Todd



"Bertie the Bunyip" > wrote in message
...
> On Dec 27, 1:42 pm, "Todd W. Deckard" > wrote:
>> Can you depart and spin from coordinated flight? Specifically a
>> coordinated
>> climbing turn?

> And courting disaster doing a chandelle? If you're going to do a
> commercial ticket you should be familair with spins intimately. An
> incipient spin shouldn't even make you break a sweat.
>

"Dudley Henriques" > wrote in message
...
> There is only one thing you have to know about spins. To enter one you
> need 2 things to be present; stall and a yaw rate.

So to corner your answer to my question: you cannot? spin from coordinated
flight.
The airplane must be yawed during the stall break (thus the inclinometer
ball slips or skids
to one side).

My question is not to seek out practical advice in spins, or recoveries. It
is to explore two
academic debates: Can a certificated airplane depart if the ball is
precisely in the middle
and is there something telling in the emphasis from the foreign sources
cited that exposes a
gap in our US training practices and material.

Thank you for your response.

I'll be making a new years resolution to try it out in the neighboorhood
Decathalon (with an appropriate
chaperone) but as it is cold and snowy I thought I would put it to the
uunet.

Best regards,
Todd

> Can a certificated airplane depart if the ball is
> precisely in the middle[?]

If the airplane is changing heading, then it is yawing, irrespective of the ball's position.

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

Todd W. Deckard wrote:
> I have a limited exposure to spins (I've demonstrated spins or received spin
> instruction in 5 different airplanes on
> six different occasions). I have a commercial certificate (although you
> wouldn't think so from my demonstration
> of a chandelle). Maybe I did have to demonstrate a power on stall while
> in a climbing 20 degree bank, once.
> As I recall, we survived it.
>
> I return to the original question: if the ball is in the middle will it
> spin?
>
> Becuase I believe snowmobile suits are for snowmobiling and not for flying I
> won't have a chance to explore it
> with an aerobatic instructor and an appropriate (but drafty) airplane for a
> few months -- so I thought I would
> put the question in a bottle and throw it in the ocean.
>
> Regards
> Todd
>
>
>
> "Bertie the Bunyip" > wrote in message
> ...
>> On Dec 27, 1:42 pm, "Todd W. Deckard" > wrote:
>>> Can you depart and spin from coordinated flight? Specifically a
>>> coordinated
>>> climbing turn?
>
>> And courting disaster doing a chandelle? If you're going to do a
>> commercial ticket you should be familair with spins intimately. An
>> incipient spin shouldn't even make you break a sweat.
>>
>
>
The answer to the ball question is no. It won't spin. A ball centered
airplane in a climbing turn is compensated by rudder and is considered
coordinated (in the classic sense).

If you introduce a climbing turn stall with the ball centered, you might
get a temporary wing drop at the break but unless you introduce a yaw
rate as the stall breaks; no yaw rate...no spin!




--
Dudley Henriques

"Dudley Henriques" > wrote in message
...
> Todd W. Deckard wrote:
>> I have a limited exposure to spins (I've demonstrated spins or received
>> spin instruction in 5 different airplanes on
>> six different occasions). I have a commercial certificate (although you
>> wouldn't think so from my demonstration
>> of a chandelle). Maybe I did have to demonstrate a power on stall
>> while in a climbing 20 degree bank, once.
>> As I recall, we survived it.
>>
>> I return to the original question: if the ball is in the middle will it
>> spin?
>>
>> Becuase I believe snowmobile suits are for snowmobiling and not for
>> flying I won't have a chance to explore it
>> with an aerobatic instructor and an appropriate (but drafty) airplane for
>> a few months -- so I thought I would
>> put the question in a bottle and throw it in the ocean.
>>
>> Regards
>> Todd
>>
>>
>>
>> "Bertie the Bunyip" > wrote in message
>> ...
>>> On Dec 27, 1:42 pm, "Todd W. Deckard" > wrote:
>>>> Can you depart and spin from coordinated flight? Specifically a
>>>> coordinated
>>>> climbing turn?
>>
>>> And courting disaster doing a chandelle? If you're going to do a
>>> commercial ticket you should be familair with spins intimately. An
>>> incipient spin shouldn't even make you break a sweat.
>>>
>>
>>
> The answer to the ball question is no. It won't spin. A ball centered
> airplane in a climbing turn is compensated by rudder and is considered
> coordinated (in the classic sense).
>
> If you introduce a climbing turn stall with the ball centered, you might
> get a temporary wing drop at the break but unless you introduce a yaw rate
> as the stall breaks; no yaw rate...no spin!


My thought is that we're splitting hairs in this thread. If the airplane is
in coordinated flight and stalls straight ahead (no wing drop), a spin can't
happen. But on most aircraft, one wing will drop first even if the ball is
centered. This wing drop creates a yaw, opening up the possibility for a
spin.


>
>
>
> --
> Dudley Henriques

I think you got me here, I cannot gin up a reference frame alibi. Let me
try this:

The airplane turns due to the horizontal component of lift. If the
horizontal component of lift
is exactly equal and opposite the apparent centrifugal force (a coordinated
turn) can the airplane
depart?

Regards
Todd

"Jose" > wrote in message
. net...
>> Can a certificated airplane depart if the ball is precisely in the
>> middle[?]
>
> If the airplane is changing heading, then it is yawing, irrespective of
> the ball's position.
>
> Jose
> --
> You can choose whom to befriend, but you cannot choose whom to love.
> for Email, make the obvious change in the address.

Todd W. Deckard wrote:
> "Dudley Henriques" > wrote in message
> ...
>> There is only one thing you have to know about spins. To enter one you
>> need 2 things to be present; stall and a yaw rate.
>
> So to corner your answer to my question: you cannot? spin from coordinated
> flight.
> The airplane must be yawed during the stall break (thus the inclinometer
> ball slips or skids
> to one side).
>
> My question is not to seek out practical advice in spins, or recoveries. It
> is to explore two
> academic debates: Can a certificated airplane depart if the ball is
> precisely in the middle
> and is there something telling in the emphasis from the foreign sources
> cited that exposes a
> gap in our US training practices and material.
>
> Thank you for your response.
>
> I'll be making a new years resolution to try it out in the neighboorhood
> Decathalon (with an appropriate
> chaperone) but as it is cold and snowy I thought I would put it to the
> uunet.
>
> Best regards,
> Todd
>
>
You are correct; IF coordinated flight is being defined as ball
centered. This is indeed what is taught to most new students as they
begin flight training.....that is until they start doing slips :-))

When and if you get into aerobatics or begin flying with advanced
instructors with deep aerobatic backgrounds you learn quickly that
coordinated flight can mean cross controlled flight as well as the usual
definition with everything going ball centered in the same direction :-)
I once flew a Pitts Special the full length of a major airfield holding
it in knife edge flight. In the TRUE sense of coordinated, holding the
aircraft in knife edge would be considered as coordinated flight.

Depending on the instructor, you either learn that coordinated flight is
with the ball always in the center, or you can be taught that you are
coordinated when the control pressures are applied in the exact amount
necessary to place the airplane in the sky at the exact configuration
required at any instant in time.
I prefer the latter definition and have taught my students this way for
many years.


--
Dudley Henriques

Thanks for this, this is consistent with what I believe (however I would be
eager to be rebutted).

Todd

"Dudley Henriques" > wrote in message
> The answer to the ball question is no. It won't spin. A ball centered
> airplane in a climbing turn is compensated by rudder and is considered
> coordinated (in the classic sense).
>
> If you introduce a climbing turn stall with the ball centered, you might
> get a temporary wing drop at the break but unless you introduce a yaw rate
> as the stall breaks; no yaw rate...no spin!
>
> --
> Dudley Henriques

Todd W. Deckard wrote:
> I think you got me here, I cannot gin up a reference frame alibi. Let me
> try this:
>
> The airplane turns due to the horizontal component of lift. If the
> horizontal component of lift
> is exactly equal and opposite the apparent centrifugal force (a coordinated
> turn) can the airplane
> depart?
>
> Regards
> Todd
>
> "Jose" > wrote in message
> . net...
>>> Can a certificated airplane depart if the ball is precisely in the
>>> middle[?]
>> If the airplane is changing heading, then it is yawing, irrespective of
>> the ball's position.
>>
>> Jose
>> --
>> You can choose whom to befriend, but you cannot choose whom to love.
>> for Email, make the obvious change in the address.
>
>
It can if you introduce an accelerated stall and a yaw rate from this turn.

--
Dudley Henriques

"Kyle Boatright" > wrote in message
> My thought is that we're splitting hairs in this thread. If the airplane
> is in coordinated flight and stalls straight ahead (no wing drop), a spin
> can't happen. But on most aircraft, one wing will drop first even if the
> ball is centered. This wing drop creates a yaw, opening up the possibility
> for a spin.
>

But the links that Dan_Thomas sent me indicated that the airplane would not
stall "straight ahead" if you were in a climbing turn. The outside wing
has a higher AoA
which diverges even further as it initially drops.

It was intriging to me as our vacation strip demands a short field takeoff
into a hedgerow of trees
and you'd want to be mindful of this if you stumbled into a maximum
performance evasive manuever
thru errors in planning or execution.

Kyle Boatright wrote:
>
> "Dudley Henriques" > wrote in message
> ...
>> Todd W. Deckard wrote:
>>> I have a limited exposure to spins (I've demonstrated spins or
>>> received spin instruction in 5 different airplanes on
>>> six different occasions). I have a commercial certificate (although
>>> you wouldn't think so from my demonstration
>>> of a chandelle). Maybe I did have to demonstrate a power on stall
>>> while in a climbing 20 degree bank, once.
>>> As I recall, we survived it.
>>>
>>> I return to the original question: if the ball is in the middle will
>>> it spin?
>>>
>>> Becuase I believe snowmobile suits are for snowmobiling and not for
>>> flying I won't have a chance to explore it
>>> with an aerobatic instructor and an appropriate (but drafty) airplane
>>> for a few months -- so I thought I would
>>> put the question in a bottle and throw it in the ocean.
>>>
>>> Regards
>>> Todd
>>>
>>>
>>>
>>> "Bertie the Bunyip" > wrote in message
>>> ...
>>>
>>>> On Dec 27, 1:42 pm, "Todd W. Deckard" > wrote:
>>>>> Can you depart and spin from coordinated flight? Specifically a
>>>>> coordinated
>>>>> climbing turn?
>>>
>>>> And courting disaster doing a chandelle? If you're going to do a
>>>> commercial ticket you should be familair with spins intimately. An
>>>> incipient spin shouldn't even make you break a sweat.
>>>>
>>>
>>>
>> The answer to the ball question is no. It won't spin. A ball centered
>> airplane in a climbing turn is compensated by rudder and is considered
>> coordinated (in the classic sense).
>>
>> If you introduce a climbing turn stall with the ball centered, you
>> might get a temporary wing drop at the break but unless you introduce
>> a yaw rate as the stall breaks; no yaw rate...no spin!
>
>
> My thought is that we're splitting hairs in this thread. If the
> airplane is in coordinated flight and stalls straight ahead (no wing
> drop), a spin can't happen. But on most aircraft, one wing will drop
> first even if the ball is centered. This wing drop creates a yaw,
> opening up the possibility for a spin.
>
>
>>
>>
>>
>> --
>> Dudley Henriques
>

The wing drop at a 1g stall is on the roll axis not the yaw axis . You
need rudder to induce the yaw rate at the stall necessary to cause entry
into auto rotation.




--
Dudley Henriques

For the purposes of my question I am referring to coordinated as:

If the horizontal component of lift is exactly equal and opposite the
apparent centrifugal force (a coordinated
turn). The pilot flying by the "seat of his or her pants" feels no skid or
slip with the seat cushion.

In your knife edge demonstration you could measure this if you rotated the
ball inclinometer 90 degrees.
I *believe* it would show you were in coordinated flight.

The Websters definition has merit for you when trying to reinforce a
fundamental learning objective
but I was trying to drive to a very specific question. Apparantly with that
I mis used "yaw"

Todd




"Dudley Henriques" > wrote in message
news:QMqdnYyufd3QT->

> Depending on the instructor, you either learn that coordinated flight is
> with the ball always in the center, or you can be taught that you are
> coordinated when the control pressures are applied in the exact amount
> necessary to place the airplane in the sky at the exact configuration
> required at any instant in time.

> I prefer the latter definition and have taught my students this way for
> many years.
>
>
> --
> Dudley Henriques

I reviewed the current copy of the Private Pilot PTS and it references
"maintain heading +/- 10 degrees in straight ahead flight, *or* not to
exceed 20 degrees ... in turning flight"
It would appear that the power on stalls may be demonstrated from straight
ahead *or* climbing turns.
They are not manditory, at least in the US at the private pilot level.

Todd


"Neil Gould" > wrote in message
...
> Standard, and _required_ for the practical. I had to do both climbing and
> descending turning stalls for my checkride. Possibly because I chose to do
> my checkride in the middle of winter with an 18 kt. breeze and the
> examiner didn't want to die... ;-)
>
> Neil
>
>

Dudley Henriques wrote:
> Todd W. Deckard wrote:
>> I return to the original question: if the ball is in the middle will
>> it spin?
> If you introduce a climbing turn stall with the ball centered, you might
> get a temporary wing drop at the break but unless you introduce a yaw
> rate as the stall breaks; no yaw rate...no spin!

There is a possibility that a flip to the outside can occur in a low
speed but large bank climbing turn, since the angle of attack of the
outboard wing is greater than that of the inboard wing. Thus, in a left
climbing turn of 30 degrees or maore bank, the right wing experiences a
higher angle of attack, and will stall first if the airspeed drops low
enough, and especially if an accelerated stall is induced. I have had
this demonstrated tome in a C150. The result is dramatic. The craft
flips to the right, as in a half snap roll, ends up upside down, and one
is obliged to recover by certain mens. My instructor then practiced much
back stick to get back to right side up, managing the zoom safely. It's
a bit more of a thrill and happens quicker than a conventional spin. It
can be done in both directions, plenty of altitude, please....

NOTE: If you analyze angles of attacks in urns, level, descending,
climbing, using a spiral helical surface as reference, you will see that
in turning descent, the inner wing experiences a greater angle of attack
and will fall safely to the inside of the turn, but when climbing the
oppsite wing stalls first. Te flip to upside down is a total surprise.
Hence in climbing steeply out of a takeoff, the speed, turn rate and
bank must all be carefully managed. Usually, the less the turn rate, the
better, the ball must alwys be kept centered and the airspeed must be
kept always at least 1.2 Vso or more.

A further hint is that in a cross-wind condition, especially when
higher level winds are of a changing direction (usually rotates to the
right on ascent in the northern hemisphere), it is best to make the
first turn into the wind; If you take off of RY270 and the surface wind
is from 300, the wind at 200 feet AGL will be from 310 and that at 400
feet AGL will be at 320 degrees, and likely of a higher wind speed. A
gradual right turn (10 degrees bank) will present you with increasing
airspeed and a more rapid rate of climb; wery safe and very efficient.

On descent to landing, opposite things happen. As you descend, the head
wind speed diminshes, and in the northern heispere it shifts a bit to
the left. Here in Ohio, if there is any significant surface wind, I
usually keep about 10 knots extra on early final (if Vso is 60 kts, I
carry 70 or 80 kts. When about a half mile from touchdown, I often see a
5 to 10 konot drop in airspeed with no action on my part. Crosswind
components accordingly dimiish in speed and shift a bit to the left. A
crab angle serves on the first part of final descent. If any significant
crosswind remains below 200 feet, a shift into a side slip, where
fuselage is aligned with the runway while the upwing wing is down is
best for touchdown, often on one wheel for a moment.

Angelo Campanella

That is to say "stall reocover while turning and climbing is not mandatory"

"Todd W. Deckard" > wrote in message
...
> They are not manditory, at least in the US at the private pilot level.
>

Dudley Henriques wrote:
> Todd W. Deckard wrote:
>> I return to the original question: if the ball is in the middle will
>> it spin?
> If you introduce a climbing turn stall with the ball centered, you might
> get a temporary wing drop at the break but unless you introduce a yaw
> rate as the stall breaks; no yaw rate...no spin!

There is a possibility that a flip to the outside can occur in a low
speed but large bank climbing turn, since the angle of attack of the
outboard wing is greater than that of the inboard wing. Thus, in a left
climbing turn of 30 degrees or maore bank, the right wing experiences a
higher angle of attack, and will stall first if the airspeed drops low
enough, and especially if an accelerated stall is induced. I have had
this demonstrated tome in a C150. The result is dramatic. The craft
flips to the right, as in a half snap roll, ends up upside down, and one
is obliged to recover by certain mens. My instructor then practiced much
back stick to get back to right side up, managing the zoom safely. It's
a bit more of a thrill and happens quicker than a conventional spin. It
can be done in both directions, plenty of altitude, please....

NOTE: If you analyze angles of attacks in urns, level, descending,
climbing, using a spiral helical surface as reference, you will see that
in turning descent, the inner wing experiences a greater angle of attack
and will fall safely to the inside of the turn, but when climbing the
oppsite wing stalls first. Te flip to upside down is a total surprise.
Hence in climbing steeply out of a takeoff, the speed, turn rate and
bank must all be carefully managed. Usually, the less the turn rate, the
better, the ball must alwys be kept centered and the airspeed must be
kept always at least 1.2 Vso or more.

A further hint is that in a cross-wind condition, especially when
higher level winds are of a changing direction (usually rotates to the
right on ascent in the northern hemisphere), it is best to make the
first turn into the wind; If you take off of RY270 and the surface wind
is from 300, the wind at 200 feet AGL will be from 310 and that at 400
feet AGL will be at 320 degrees, and likely of a higher wind speed. A
gradual right turn (10 degrees bank) will present you with increasing
airspeed and a more rapid rate of climb; wery safe and very efficient.

On descent to landing, opposite things happen. As you descend, the head
wind speed diminshes, and in the northern heispere it shifts a bit to
the left. Here in Ohio, if there is any significant surface wind, I
usually keep about 10 knots extra on early final (if Vso is 60 kts, I
carry 70 or 80 kts. When about a half mile from touchdown, I often see a
5 to 10 konot drop in airspeed with no action on my part. Crosswind
components accordingly dimiish in speed and shift a bit to the left. A
crab angle serves on the first part of final descent. If any significant
crosswind remains below 200 feet, a shift into a side slip, where
fuselage is aligned with the runway while the upwing wing is down is
best for touchdown, often on one wheel for a moment.

Angelo Campanella

> The answer to the ball question is no. It won't spin. A ball centered airplane in a climbing turn is compensated by rudder and is considered coordinated (in the classic sense).

Ok, now I'm confused again. If "stall plus yaw" is all that's necessary, and all (normal) turns involve yaw, then why won't it spin? Do I have the wrong definition of "yaw"?

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

Todd W. Deckard wrote:

> But the links that Dan_Thomas sent me indicated that the airplane would not
> stall "straight ahead" if you were in a climbing turn. The outside wing
> has a higher AoA
> which diverges even further as it initially drops.
>

Dan isn't wrong.
Climbing turn stalls are a bit complicated to nail down to a strict
behavioral pattern as each airplane and indeed each stall entered in a
specific airplane will probably be exhibiting slightly different stall
behavior due to varying control inputs by the pilot. The result of this
is that climbing turn stalls can produce different results depending on
what the pilot is doing with the airplane up to and at the instant of
the stall break.
Basically, if you are (as we say) coordinated, the top wing will stall
first and the airplane will roll off in that direction. The reason for
this is that as the stall is approached both wings start losing lift
causing the airplane to mush into a slip. The highest wing gets
interference from the fuselage and usually quits first. If you watch the
ball as this happens, as you get near to stall, you'll probably notice
that if you can't hold it centered, and a slip develops, that high wing
will usually be the one to go first.
This doesn't always happen however :-)) and if you skid the airplane,
the bottom wing can break first.
The bottom line is that in most climbing turn stalls, you will get a
roll off as the stall breaks, but remember, this is a ROLL OFF, not a
yaw rate!! Just reduce the angle of attack and use aileron to raise the
lowering wing and no pro spin forces are present.




--
Dudley Henriques

Stefan,

I am currently chanting the "ball centered = no spin" mantra. However
I am very sympathetic to your explaination that its a difference in AoA.
In the end, that may be the purest way to explain the spin.

If this thread sustains I'll listen in and see what I can sift out.

Todd

"Stefan" > wrote in message news:4bb62$4773ba89

> While I agree that this is a correct and simple recipe and therefore quite
> useful in practice, I don't agree that it helps to *understand* the
> situation, because *reason* for the spin is not the yaw rate. The reason
> for the spin is an asymmetric angle of attack, i.e. one wing is more
> stalled than the other. Of course this situation can only occur if there
> is some yaw, which leads us to the recipe given above.
>
> Recipe: As there is always some yaw in a coordinated turn (otherwise it
> wouldn't be coordinated), you can perfectly enter a spin from a
> coordinated turn. Aerodynamic reason: The inner wing has a higher angle of
> attack than the outer, so it stalls first or, if both wings stall, it is
> more stalled. Asymmetric stall condition -> spin.

Todd W. Deckard wrote:

> In your knife edge demonstration you could measure this if you rotated the
> ball inclinometer 90 degrees.
> I *believe* it would show you were in coordinated flight.

Didn't even have a ball indication in that airplane. You don't use them
in aerobatics. Even for primary instruction, it's best to get the
student's head outside the cockpit and away from the ball as soon as
possible and concentrated on nose attitude where it belongs.
Personally, I feel the ball is the least necessary instrument on the
entire panel :-)


--
Dudley Henriques

Your right, a string taped to the canopy is much better. Hah!
Todd

"Dudley Henriques" > wrote in message
I feel the ball is the least necessary instrument on the
> entire panel :-)
>
>
> --
> Dudley Henriques

Jose wrote:
>> The answer to the ball question is no. It won't spin. A ball centered
>> airplane in a climbing turn is compensated by rudder and is considered
>> coordinated (in the classic sense).
>
> Ok, now I'm confused again. If "stall plus yaw" is all that's
> necessary, and all (normal) turns involve yaw, then why won't it spin?
> Do I have the wrong definition of "yaw"?
>
> Jose

A "normal" turn is accomplished by splitting the lift vector, NOT by
holding in yaw. Yaw should only be present in the turn dynamic during
the entry into the turn and exit from the turn. Once stabilized in the
turn, there should be no yaw present. There could be however if the turn
was a slipping turn or a skidding turn.


--
Dudley Henriques

On Dec 27, 5:42*am, "Todd W. Deckard" > wrote:
> Can you depart and spin from coordinated flight? *Specifically a coordinated
> climbing turn?

You have to have yawing motion. However, its very common for students
to not be able to maintain coordination during a climbing stall to the
right; which is why its a common way to introduce unexpected spins (I
don't do that though).

-Robert, CFII

Todd W. Deckard wrote:
> Your right, a string taped to the canopy is much better. Hah!
> Todd
>
> "Dudley Henriques" > wrote in message
> I feel the ball is the least necessary instrument on the
>> entire panel :-)
>>
>>
>> --
>> Dudley Henriques
>
>
Actually, the horizon line is the best yaw indicator on the planet. In
lieu of that, a wingtip in a vertical climb, or the sight picture
directly over the nose in a vertical dive.


--
Dudley Henriques

In my experience, a stall break while straight and level or in a 60 degree
bank if perfectly coordinated will drop the nose straight down.
The kicker is that 98% of the pilots have lazy feet and don't really keep
the aircraft coordinated. If power is ON, the aircraft will need more
rudder to control yaw and that amount of rudder will increase as speed is
decreased approaching the stall. Some airplanes may not have enough rudder
to stay coordinated to the stall, most pilots will not use the rudder that
is available.
Some airplanes will not spin, even wit yaw supplied by maximum rudder input
at the stall in a pro-spin direction. The Beech Skipper [BE77] requires
that the stall be entered, just before the stall, full pro-spin rudder is
applied to induce a roll. At a 90 degree bank angle, sudden and full
aileron in the opposite direction as the rudder is necessary to stall the
wing crisply at the outer half. That will cause the airplane to roll
rapidly and enter a spin. If not timed or done correctly, the aircraft will
enter a spiral.

In the accidental spin, the pilot is likely to do exactly the same thing,
just not with thought and skill. The plane is stalled while yawing
[uncoordinated] and when the break happens, the poorly trained and
non-current pilot's reaction will often be to try to pick-up the wing that
is falling and the nose with aileron and up elevator. The natural reaction,
which training and experience correct, is to "fight" the falling nose, the
falling wing, with normal control input.

IF the aircraft is coordinated perfectly, the difference in lift vector is
due slightly to the radial airspeed difference between the L&R wings, but
more my the dihedral built in the airplane. The problem is that flight is
very dynamic, control forces are changing, humans have reaction times, and
the control authority created by the aerodynamic surfaces rapidly falls with
a small decrease in airspeed [lift equation] and the other forces, such as
P-factor and engine torque involve inertia and mass.



"Todd W. Deckard" > wrote in message
...
|
| "Dudley Henriques" > wrote in message
| ...
| > There is only one thing you have to know about spins. To enter one you
| > need 2 things to be present; stall and a yaw rate.
|
| So to corner your answer to my question: you cannot? spin from
coordinated
| flight.
| The airplane must be yawed during the stall break (thus the inclinometer
| ball slips or skids
| to one side).
|
| My question is not to seek out practical advice in spins, or recoveries.
It
| is to explore two
| academic debates: Can a certificated airplane depart if the ball is
| precisely in the middle
| and is there something telling in the emphasis from the foreign sources
| cited that exposes a
| gap in our US training practices and material.
|
| Thank you for your response.
|
| I'll be making a new years resolution to try it out in the neighboorhood
| Decathalon (with an appropriate
| chaperone) but as it is cold and snowy I thought I would put it to the
| uunet.
|
| Best regards,
| Todd
|
|

> A "normal" turn is accomplished by splitting the lift vector, NOT by holding in yaw. Yaw should only be present in the turn dynamic during the entry into the turn and exit from the turn.

Ok, then what exactly is "yaw"? My understanding is that it is a change of direction of the longitudinal axis of the aircraft in the plane that is roughly coplanar with the wings.

Splitting the lift vector serves to change the direction of flight, but not to change the heading. To do that you need what I was calling yaw, and if you want to stay in a coordinated turn, you need to continually change the heading as you continually change the direction of flight. You would have a steady change in heading (which will include a steady yaw) with no acceleration in the yaw direction.

You seem to be defining yaw as a rotational =acceleration= of the longitudinal axis of the aircraft in the plane that is roughly coplanar with the wings.

Do I have that right?

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

99% of the pilots will never have the ball centered all the way to a stall
break, it might look good 1/4 of a second before the break, but most pilots
stop actively flying when they start to feel the onset of the buffet. The
skilled pilot never stops making control adjustments.

I'll cite a comment made by a DPE after he had passed a student I sent him
for the private pilot practical test...
"That airplane is out of rig, everybody spins it doing accelerated stalls,
but your student didn't."



"Kyle Boatright" > wrote in message
. ..
|
My thought is that we're splitting hairs in this thread. If the airplane is
in coordinated flight and stalls straight ahead (no wing drop), a spin can't
happen. But on most aircraft, one wing will drop first even if the ball is
centered. This wing drop creates a yaw, opening up the possibility for a
spin.

Jose wrote:
>> A "normal" turn is accomplished by splitting the lift vector, NOT by
>> holding in yaw. Yaw should only be present in the turn dynamic during
>> the entry into the turn and exit from the turn.
>
> Ok, then what exactly is "yaw"? My understanding is that it is a change
> of direction of the longitudinal axis of the aircraft in the plane that
> is roughly coplanar with the wings.

Yaw, as we define the term in flight test as it relates to directional
stability is defined as moments about the VERTICAL axis, not the
longitudinal axis. These moments also relate to Yaw Angle, Yaw Rate, and
Sideslip Angle.


--
Dudley Henriques

Dudley Henriques schrieb:

> When someone asks what causes a spin, ... the correct answer is
> that stall and yaw rate must be present to produce a spin
....
> If you then ask a student to explain the aerodynamics in play as a spin
> develops, it's THEN you want the auto rotational aerodynamics.

Different approach. You, as a military pilot (as I think to have
understood), believe in the behavioristic approach. Me, as a scientist
(and amateur pilot) follow the cognitive approach. Your approach yields
pilots who exactly know what to do in this or that situation, but
probably without really understanding the deeper reasons. My approach
tries to understand the underlying physics and to deduct the needed
pilot action from there. Not nessecairy for a pilot, but it's my style,
I think it's interesting and it's the prerequisite if you want to go on
your own feet beyond the tought stuff.

Now if only that fog around here would go away so I could go and rent
that Cap 10 and do some spins...

clarification edit inserted
"Jim Macklin" > wrote in message
...
| In my experience, a stall break while straight and level or in a 60 degree
| bank if perfectly coordinated will drop the nose straight down.
[edit--relative to the pilot, not the horizon]
| The kicker is that 98% of the pilots have lazy feet and don't really keep
| the aircraft coordinated. If power is ON, the aircraft will need more
| rudder to control yaw and that amount of rudder will increase as speed is
| decreased approaching the stall. Some airplanes may not have enough
rudder
| to stay coordinated to the stall, most pilots will not use the rudder that
| is available.
| Some airplanes will not spin, even wit yaw supplied by maximum rudder
input
| at the stall in a pro-spin direction. The Beech Skipper [BE77] requires
| that the stall be entered, just before the stall, full pro-spin rudder is
| applied to induce a roll. At a 90 degree bank angle, sudden and full
| aileron in the opposite direction as the rudder is necessary to stall the
| wing crisply at the outer half. That will cause the airplane to roll
| rapidly and enter a spin. If not timed or done correctly, the aircraft
will
| enter a spiral.
|
| In the accidental spin, the pilot is likely to do exactly the same thing,
| just not with thought and skill. The plane is stalled while yawing
| [uncoordinated] and when the break happens, the poorly trained and
| non-current pilot's reaction will often be to try to pick-up the wing that
| is falling and the nose with aileron and up elevator. The natural
reaction,
| which training and experience correct, is to "fight" the falling nose, the
| falling wing, with normal control input.
|
| IF the aircraft is coordinated perfectly, the difference in lift vector is
| due slightly to the radial airspeed difference between the L&R wings, but
| more my the dihedral built in the airplane. The problem is that flight is
| very dynamic, control forces are changing, humans have reaction times, and
| the control authority created by the aerodynamic surfaces rapidly falls
with
| a small decrease in airspeed [lift equation] and the other forces, such as
| P-factor and engine torque involve inertia and mass.
|
|
|
| "Todd W. Deckard" > wrote in message
| ...
||
|| "Dudley Henriques" > wrote in message
|| ...
|| > There is only one thing you have to know about spins. To enter one you
|| > need 2 things to be present; stall and a yaw rate.
||
|| So to corner your answer to my question: you cannot? spin from
| coordinated
|| flight.
|| The airplane must be yawed during the stall break (thus the inclinometer
|| ball slips or skids
|| to one side).
||
|| My question is not to seek out practical advice in spins, or recoveries.
| It
|| is to explore two
|| academic debates: Can a certificated airplane depart if the ball is
|| precisely in the middle
|| and is there something telling in the emphasis from the foreign sources
|| cited that exposes a
|| gap in our US training practices and material.
||
|| Thank you for your response.
||
|| I'll be making a new years resolution to try it out in the neighboorhood
|| Decathalon (with an appropriate
|| chaperone) but as it is cold and snowy I thought I would put it to the
|| uunet.
||
|| Best regards,
|| Todd
||
||
|
|

>> Ok, then what exactly is "yaw"? My understanding is that it is a change of direction of the longitudinal axis of the aircraft in the plane that is roughly coplanar with the wings.
>
> Yaw, as we define the term in flight test as it relates to directional stability is defined as moments about the VERTICAL axis, not the longitudinal axis.

Yes, that is pretty much what I said. Change in direction =of= the longitudinal axis, =in= the plane (of the wings), [(therefore) =about= the vertical axis.] I am however using "vertical" and "horizontal" as referenced to the aircraft, not the earth, thus when the aircraft pitches up, the yaw axis (as I understand it defined) would change.

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

I don't know of any autopilot that could be programmed to fly an aerobatic
maneuver based on predicted actions. Yet an autopilot can be designed to
observe and respond to the observed dynamic actions of the airplane.



"Stefan" > wrote in message
...
| Dudley Henriques schrieb:
|
| > When someone asks what causes a spin, ... the correct answer is
| > that stall and yaw rate must be present to produce a spin
| ...
| > If you then ask a student to explain the aerodynamics in play as a spin
| > develops, it's THEN you want the auto rotational aerodynamics.
|
| Different approach. You, as a military pilot (as I think to have
| understood), believe in the behavioristic approach. Me, as a scientist
| (and amateur pilot) follow the cognitive approach. Your approach yields
| pilots who exactly know what to do in this or that situation, but
| probably without really understanding the deeper reasons. My approach
| tries to understand the underlying physics and to deduct the needed
| pilot action from there. Not nessecairy for a pilot, but it's my style,
| I think it's interesting and it's the prerequisite if you want to go on
| your own feet beyond the tought stuff.
|
| Now if only that fog around here would go away so I could go and rent
| that Cap 10 and do some spins...

Dudley Henriques schrieb:

> Yaw should only be present in the turn dynamic during
> the entry into the turn and exit from the turn. Once stabilized in the
> turn, there should be no yaw present.

I don't agree. A coordinated turn is *always* a turn around all three
axes. (The only exception is a turn with a 90 degrees bank.) You can
easily demonstrate this by "hand-flying" a toy airplane.

Jim Macklin schrieb:

> I don't know of any autopilot that could be programmed to fly an aerobatic
> maneuver based on predicted actions. Yet an autopilot can be designed to
> observe and respond to the observed dynamic actions of the airplane.

I don't know of any autopilot that could be programmed to perform
rolling circles, either. But where's the relevance?

Recently, Bertie the Bunyip > posted:
>
> BTW, stalls in a climbing turn are pretty much standard standard stuff
> even for Private pilots.
>
Standard, and _required_ for the practical. I had to do both climbing and
descending turning stalls for my checkride. Possibly because I chose to do
my checkride in the middle of winter with an 18 kt. breeze and the
examiner didn't want to die... ;-)

Neil

Flight is an art based on a science.



"Stefan" > wrote in message
...
| Jim Macklin schrieb:
|
| > I don't know of any autopilot that could be programmed to fly an
aerobatic
| > maneuver based on predicted actions. Yet an autopilot can be designed
to
| > observe and respond to the observed dynamic actions of the airplane.
|
| I don't know of any autopilot that could be programmed to perform
| rolling circles, either. But where's the relevance?

Stefan wrote:

> Different approach. You, as a military pilot (as I think to have
> understood), believe in the behavioristic approach. Me, as a scientist
> (and amateur pilot) follow the cognitive approach. Your approach yields
> pilots who exactly know what to do in this or that situation, but
> probably without really understanding the deeper reasons.

Well...I could say that your comment above is a deep personal insult
(which it is BTW :-) but in this case I will respect the fact that you
simply don't know anything at all about me since you have assumed I am a
military pilot which as half the world knows couldn't be further from
the truth.
I am in fact simply a civilian pilot who has flown military airplanes.
It's as simple as that really....oh yes...there is one more
thing....I've spent about 50 odd years directly involved with the flight
training community as both a CFI and an adviser and consultant at levels
ranging from primary training to teaching people to fly the highest
performance airplanes in the world.

If you surmise that the people I have taught to spin airplanes "probably
don't understand the deeper reasons" involved that YOU as a scientist
can provide, or that the pilots I have trained don't know thoroughly the
complete aerodynamics involved with spins, I fear you are in for a deep
disappointment :-))

We just present these things when it is correct to present them and not
when another explanation is the right explanation :-)

--
Dudley Henriques

Stefan wrote:
> Dudley Henriques schrieb:
>
>> Yaw should only be present in the turn dynamic during the entry into
>> the turn and exit from the turn. Once stabilized in the turn, there
>> should be no yaw present.
>
> I don't agree. A coordinated turn is *always* a turn around all three
> axes. (The only exception is a turn with a 90 degrees bank.) You can
> easily demonstrate this by "hand-flying" a toy airplane.


Axis isn't really used in this way. You will notice if you move your toy
airplane that the axis system remains in place and moves with the
aircraft centered on the aircraft's cg.

To define turn using axis reference is not the best way to explain turn
since once established in a stable turn there should be no movement on
the airplane's axis system. The axis system references the lines
crossing through the aircraft's Cg and are used to define movement and
moment on each axis. The axis system moves in place with the aircraft
and never deviates from it's center point through the cg.
There is movement on the longitudinal axis in roll as the airplane is
rolled into and out of the turn, and movement as well on the lateral
axis in pitch as angle of attack is increased to compensate for the
split in the lift vector. There is movement on the Vertical axis as
rudder is used to compensate for adverse yaw both during and exiting the
turn, but once established in a coordinated turn, (I'm using medium
banked turn here for easy reference as under bank and over bank in
shallow and steep turns cause in turn axis changes complicating the
situation a bit) all movement on the aircraft's axis should be stable.

The proper way to define turn as relates to change in direction is to
define the change in the velocity vector as relates to heading change
not as a change on or around the axis of the aircraft.


--
Dudley Henriques

Recently, Todd W. Deckard > posted:

> That is to say "stall reocover while turning and climbing is not
> mandatory"
>
Any item in the PTS is "required", and can be part of the test. Perhaps
you should re-read item #5 under both power-on and power-off stalls so as
not to be surprised during your check ride.

Neil

> To define turn using axis reference is not the best way to explain turn since once established in a stable turn there should be no movement on the airplane's axis system.

I am not sure I'm getting this.

We'll ignore translation (straight line motion).

The axis system is (as I have been using it) fixed to the aircraft, and the axis system moves whenever the aircraft rotates (around any point). It has nothing to do with the actual earth's horizon.

Then, as I understand it, rotation of the aircraft involves a rotation around one or more of the axes. Yaw involves rotation (=of= the longitudinal axis, and thus the airplane) =about= the (airplane) vertical axis, =in= the plane (roughly described by the wing tips and tail) of the (airplane) horizontal axes.

In a turn, slipping, skidding, or coordinated, the nose of the airplane (dragging the longitudinal axis with it) is changing its direction. The airplane is changing heading. If this happens at a constant rate (say, 3 degrees per second), I would say the aircraft is yawing at a steady angular velocity, and undergoing no acceleration in yaw. To =enter= or =leave= this state would require an =acceleration= of yaw in one direction or another.

Where do our understandings and vocabulary diverge?

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

Jose wrote:
>> To define turn using axis reference is not the best way to explain
>> turn since once established in a stable turn there should be no
>> movement on the airplane's axis system.
>
> I am not sure I'm getting this.
>
> We'll ignore translation (straight line motion).
>
> The axis system is (as I have been using it) fixed to the aircraft, and
> the axis system moves whenever the aircraft rotates (around any point).
> It has nothing to do with the actual earth's horizon.
> Then, as I understand it, rotation of the aircraft involves a rotation
> around one or more of the axes. Yaw involves rotation (=of= the
> longitudinal axis, and thus the airplane) =about= the (airplane)
> vertical axis, =in= the plane (roughly described by the wing tips and
> tail) of the (airplane) horizontal axes.
>
> In a turn, slipping, skidding, or coordinated, the nose of the airplane
> (dragging the longitudinal axis with it) is changing its direction. The
> airplane is changing heading. If this happens at a constant rate (say,
> 3 degrees per second), I would say the aircraft is yawing at a steady
> angular velocity, and undergoing no acceleration in yaw. To =enter= or
> =leave= this state would require an =acceleration= of yaw in one
> direction or another.
>
> Where do our understandings and vocabulary diverge?
>
> Jose
Jose;
Do some research on the aircraft axis system and what each axis
represents, then research forces in turns. It should become clearer then.
Thank you


--
Dudley Henriques

Todd W. Deckard wrote:
> Can you depart and spin from coordinated flight? Specifically a coordinated
> climbing turn?

During training and several BFR's I have done stalling turns with a CFI
present. I have never spun.

Your Mileage May Vary.

On Dec 27, 10:07 am, Dudley Henriques > wrote:
> Todd W. Deckard wrote:
> > But the links that Dan_Thomas sent me indicated that the airplane would not
> > stall "straight ahead" if you were in a climbing turn. The outside wing
> > has a higher AoA
> > which diverges even further as it initially drops.
>
> Dan isn't wrong.
> Climbing turn stalls are a bit complicated to nail down to a strict
> behavioral pattern as each airplane and indeed each stall entered in a
> specific airplane will probably be exhibiting slightly different stall
> behavior due to varying control inputs by the pilot. The result of this
> is that climbing turn stalls can produce different results depending on
> what the pilot is doing with the airplane up to and at the instant of
> the stall break.
> Basically, if you are (as we say) coordinated, the top wing will stall
> first and the airplane will roll off in that direction. The reason for
> this is that as the stall is approached both wings start losing lift
> causing the airplane to mush into a slip. The highest wing gets
> interference from the fuselage and usually quits first. If you watch the
> ball as this happens, as you get near to stall, you'll probably notice
> that if you can't hold it centered, and a slip develops, that high wing
> will usually be the one to go first.
> This doesn't always happen however :-)) and if you skid the airplane,
> the bottom wing can break first.
> The bottom line is that in most climbing turn stalls, you will get a
> roll off as the stall breaks, but remember, this is a ROLL OFF, not a
> yaw rate!! Just reduce the angle of attack and use aileron to raise the
> lowering wing and no pro spin forces are present.
>
> --
> Dudley Henriques

But we've had full-blown spins develop from the climbing-turn
stall. If the pilot isn't expecting it, it will roll off the high side
and start yawing in that direction, and if full power is still on it
can get violent. It'll spin readily, as this re-quoted excerpt states:

"Full power stalls in a balanced climbing turn tend to result in the
outer
wing stalling first, because of the higher aoa of the outer wing, with
a
fairly fast wing and nose drop (particularly so if the propeller
torque
effect is such that it reinforces the roll away from the original
direction
of turn and the aircraft is a high wing configuration) and likely to
result
in a stall/spin situation that any pilot lacking spin recovery
experience
may find difficult to deal with."

By "balanced" I presume these Aussies mean "coordinated." And if
the stall is fully developed the aileron won't help and might
aggravate things.
Of course if the pilot gets the nose down quick, and uses rudder
rather than aileron, it will recover OK. But he has to understand
immediately what's happening.

Dan

wrote:
> On Dec 27, 10:07 am, Dudley Henriques > wrote:
>> Todd W. Deckard wrote:
>>> But the links that Dan_Thomas sent me indicated that the airplane would not
>>> stall "straight ahead" if you were in a climbing turn. The outside wing
>>> has a higher AoA
>>> which diverges even further as it initially drops.
>> Dan isn't wrong.
>> Climbing turn stalls are a bit complicated to nail down to a strict
>> behavioral pattern as each airplane and indeed each stall entered in a
>> specific airplane will probably be exhibiting slightly different stall
>> behavior due to varying control inputs by the pilot. The result of this
>> is that climbing turn stalls can produce different results depending on
>> what the pilot is doing with the airplane up to and at the instant of
>> the stall break.
>> Basically, if you are (as we say) coordinated, the top wing will stall
>> first and the airplane will roll off in that direction. The reason for
>> this is that as the stall is approached both wings start losing lift
>> causing the airplane to mush into a slip. The highest wing gets
>> interference from the fuselage and usually quits first. If you watch the
>> ball as this happens, as you get near to stall, you'll probably notice
>> that if you can't hold it centered, and a slip develops, that high wing
>> will usually be the one to go first.
>> This doesn't always happen however :-)) and if you skid the airplane,
>> the bottom wing can break first.
>> The bottom line is that in most climbing turn stalls, you will get a
>> roll off as the stall breaks, but remember, this is a ROLL OFF, not a
>> yaw rate!! Just reduce the angle of attack and use aileron to raise the
>> lowering wing and no pro spin forces are present.
>>
>> --
>> Dudley Henriques
>
> But we've had full-blown spins develop from the climbing-turn
> stall. If the pilot isn't expecting it, it will roll off the high side
> and start yawing in that direction, and if full power is still on it
> can get violent. It'll spin readily, as this re-quoted excerpt states:
>
> "Full power stalls in a balanced climbing turn tend to result in the
> outer
> wing stalling first, because of the higher aoa of the outer wing, with
> a
> fairly fast wing and nose drop (particularly so if the propeller
> torque
> effect is such that it reinforces the roll away from the original
> direction
> of turn and the aircraft is a high wing configuration) and likely to
> result
> in a stall/spin situation that any pilot lacking spin recovery
> experience
> may find difficult to deal with."
>
> By "balanced" I presume these Aussies mean "coordinated." And if
> the stall is fully developed the aileron won't help and might
> aggravate things.
> Of course if the pilot gets the nose down quick, and uses rudder
> rather than aileron, it will recover OK. But he has to understand
> immediately what's happening.
>
> Dan

It's nothing unusual for an airplane to spin out of a climbing turn
stall.....IF yaw isn't corrected as the stall breaks. It depends in a
large part on how ham handed the pilot is as the stall is approached.
The break can be clean nose down, usually high wing first, and can even
be low wing first. In ALL scenarios, yaw must be eliminated from the
equation as the stall breaks to prevent spin. If the angle of attack is
recovered normally as the stall breaks, even if roll off is present, by
coordinated use of flight controls raising the wing and the yaw is
eliminated, a normal recovery will be accomplished.
If the pilot applies incorrect control responses and doesn't eliminate
the yaw, the combination of stall and a yaw rate can easily spin the
airplane.
These power on climbing turn stalls can be done all day long by pilots
using proper recovery technique as the stall breakes with absolutely no
spin issue in the recovery equation.


--
Dudley Henriques

For my conclusion I am fixed in the stall + yaw = spin (where I was to start
with).

I appreciate the references to the Transport Canada material as the tendency
for the airplane to
"go over the top" when snapping over from a climbing turn was a very needed
reminder and
I intend to experiment with it aggressively next year with the appropriate
equipment and circumstances.

At Mr. Henriques suggestion I solicited an explaination from Rich Stowell:

He is the evangelist for the P-A-R-E recovery acronymn.

Power (to idle)
Ailerons (to neutral)
Rudder (against the spin)
Elevator (briskly forward to break the stall).

I must say he drafted a very thoughtful response to me in a direct email.

The only conclusion I can offer to this essay is to point to his web site,
and his book(s):

http://www.richstowell.com/

He articulately explained that the inclinometer is not a precise indication
of coordinated flight and that
some form of yaw is a necessary ingredient to the spin.

With this I'll sign off, thanks for the responses.

Todd Deckard