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spins from coordinated flight



 
 
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  #1  
Old December 27th 07, 02:42 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Todd W. Deckard
external usenet poster
 
Posts: 65
Default spins from coordinated flight

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/u...ml#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/...p?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/ge...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


  #2  
Old December 27th 07, 03:25 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Dudley Henriques[_2_]
external usenet poster
 
Posts: 2,546
Default spins from coordinated flight

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/u...ml#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/...p?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/ge...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
  #3  
Old December 27th 07, 03:45 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Stefan
external usenet poster
 
Posts: 578
Default spins from coordinated flight

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.
  #4  
Old December 27th 07, 03:56 PM posted to rec.aviation.piloting, rec.aviation.aerobatics
Bertie the Bunyip
external usenet poster
 
Posts: 316
Default spins from coordinated flight

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
  #5  
Old December 27th 07, 04:20 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Dudley Henriques[_2_]
external usenet poster
 
Posts: 2,546
Default spins from coordinated flight

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
  #6  
Old December 27th 07, 04:56 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Todd W. Deckard
external usenet poster
 
Posts: 65
Default spins from coordinated flight

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.



  #7  
Old December 27th 07, 05:04 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Todd W. Deckard
external usenet poster
 
Posts: 65
Default spins from coordinated flight


"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


  #8  
Old December 27th 07, 05:13 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Jose
external usenet poster
 
Posts: 897
Default spins from coordinated flight

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.
  #9  
Old December 27th 07, 05:15 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Dudley Henriques[_2_]
external usenet poster
 
Posts: 2,546
Default spins from coordinated flight

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
  #10  
Old December 27th 07, 05:21 PM posted to rec.aviation.piloting,rec.aviation.aerobatics
Kyle Boatright
external usenet poster
 
Posts: 578
Default spins from coordinated flight


"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


 




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