What is a "Forward Skip"?

"kontiki" wrote in message
...
In theory of course. In the case of the 172 with 40 degrees of flaps they
contribute more drag than lift.

In practice too. The relative amounts of drag and lift are irrelevant to
the fact that using the flaps lowers the stall speed, and that doing so does
not make it any easier "to end up real slow in a slip".

Your assertion that "With full flaps its easy to end up real slow in a slip
and approach a stall" is just plain nonsense, and certainly has nothing to
do with the *warning* (not prohibition) against slipping while flaps are
extended (even if there were something to your claim about flaps making it
easier to stall).

Pete

whatever.

Peter Duniho wrote:

"kontiki" wrote in message
...

In theory of course. In the case of the 172 with 40 degrees of flaps they
contribute more drag than lift.


In practice too. The relative amounts of drag and lift are irrelevant to
the fact that using the flaps lowers the stall speed, and that doing so does
not make it any easier "to end up real slow in a slip".

Your assertion that "With full flaps its easy to end up real slow in a slip
and approach a stall" is just plain nonsense, and certainly has nothing to
do with the *warning* (not prohibition) against slipping while flaps are
extended (even if there were something to your claim about flaps making it
easier to stall).

Pete

"AnthonyQ" wrote

I was told many years ago that a full rudder slip in a C172
(especially the older models with 40deg flaps), it is possible to
induce a tail stall....not good close to the ground....

From the book "Cessna, Wings for the World" by William Thompson,
Manager-Flight Test and Aerodynamics for the Cessna Aircraft
Company where he also served as an Engineering Test Pilot and
other positions for a total of 28 years.

"With the advent of the large slotted flaps in the C-170, C-180, and C-
172 we encountered a nose down pitch in forward slips with the wing flaps
deflected. In some cases it was severe enough to lift the pilot against
his seat belt if he was slow in checking the motion. For this reason a
caution note was placed in most of the owner's manuals under "Landings"
reading "Slips should be avoided with flap settings greater than 30° due
to a downward pitch encountered under certain combinations of airspeed,
side-slip angle, and center of gravity loadings". Since wing-low drift
correction in cross-wind landings is normally performed with a minimum
flap setting (for better rudder control) this limitation did not apply to
that maneuver. The cause of the pitching motion is the transition of a
strong wing downwash over the tail in straight flight to a lessened
downwash angle over part of the horizontal tail caused by the influence
of a relative "upwash increment" from the upturned aileron in slipping
flight. Although not stated in the owner's manuals, we privately
encouraged flight instructors to explore these effects at high altitude,
and to pass on the information to their students. This phenomenon was
elusive and sometimes hard to duplicate, but it was thought that a pilot
should be aware of its existence and know how to counter-act it if it
occurs close to the ground.
When the larger dorsal fin was adopted in the 1972 C-172L, this side-slip
pitch phenomenon was eliminated, but the cautionary placard was retained.
In the higher-powered C-172P and C-R172 the placard was applicable to a
mild pitch "pumping" motion resulting from flap outboard-end vortex
impingement on the horizontal tail at some combinations of side-slip
angle, power, and airspeed."

This is probably as close to the real story as we will get.

Bob Moore
ATP CFI
PanAm (retired)

"kontiki" wrote in message

Spinning requires a stall.

Thanks Amelia. A properly trained pilot can recover from a stall during a
slip on final unless they're really close to the ground. (That might happen
on a real forced approach trying to put it down on an impossibly short
rea. - Cue new thread.) A recovery from a spin on final is
near-impossible. OK?

le moo


Happy Dog wrote:

"kontiki" wrote in message

With full flaps its easy to end up real slow in a slip and approach a
stall.


It's easy without flaps too. Stalling isn't the real danger though, it's
spinning. With proper elevator input though, there's no danger of
either. And, this has nothing to do with Cessna's warning.

moo



wrote:


In the context it is used, and for my level of flying experience, yes
they
are interchangeable. I do not know more about the danger of this than
Cessna, so I would prefer to trust what they say. You level of
experience
is certainly different that mine, so your decision may be different than
mine.

That is not say that in the event of emergency I would not perform a
slip
to land with full flaps if the need dictated.


Peter R. wrote:


) wrote:



Cessna 172M

"Avoid slips with full flap extension"

Are the words "avoid" and "prohibited" interchangeable?

"kontiki" wrote in message

But any properly trained low time student can recover from a stall
without spinning.

Stefan

I would not necessarily go so far as to say that. Working on my CFI
I had to undergo spin training... actually recovering from spins
multiple times. That training is not nromally a part of student
pilot training.

Yeah. Drag that. It is in Canada. Requirement on CPL test.

Remember that a spin requires a stall of one wing... the other
can be flying quite normally. Students are typically tought stalls
under coordinated conditions.

Have you stalled in a slip? It's no harder to recover than any other power
off stall. Which wing drops?

Moo

PS Try not to top post.



Stefan wrote:

kontiki wrote:

It's easy without flaps too. Stalling isn't the real danger though,

it's spinning.

Spinning requires a stall.

"kontiki" wrote in message news:t%hDd.

Peter Duniho wrote:.

Well of course. Proper control inputs 100% of the time would eliminate at
least 50% of the accidents.
The point is that flaps don't change the control inputs required to
avoid a stall in a slip. If anything, they make a stall less likely,
since they lower the stall speed.

In theory of course. In the case of the 172 with 40 degrees of flaps they
contribute more drag than lift.

In reality.

moo

Top posting idiot. If you have no interest in actually discussing aviation,
go elsewhere. Or, at least, thank the other poster for correcting your
misinformation for the benefit of others who might be learning. (Hopefully
more successfully than you.)

moo

"kontiki" wrote in message
...
whatever.

Peter Duniho wrote:

"kontiki" wrote in message
...

In theory of course. In the case of the 172 with 40 degrees of flaps they
contribute more drag than lift.


In practice too. The relative amounts of drag and lift are irrelevant to
the fact that using the flaps lowers the stall speed, and that doing so
does not make it any easier "to end up real slow in a slip".

Your assertion that "With full flaps its easy to end up real slow in a
slip and approach a stall" is just plain nonsense, and certainly has
nothing to do with the *warning* (not prohibition) against slipping
while flaps are extended (even if there were something to your claim
about flaps making it easier to stall).

Pete

"Bob Moore" wrote in

"AnthonyQ" wrote

I was told many years ago that a full rudder slip in a C172
(especially the older models with 40deg flaps), it is possible to
induce a tail stall....not good close to the ground....

From the book "Cessna, Wings for the World" by William Thompson,
Manager-Flight Test and Aerodynamics for the Cessna Aircraft
Company where he also served as an Engineering Test Pilot and
other positions for a total of 28 years.

Thanks for that. I note, though, that it doesn't mention a tail stall
anywhere.

moo

"With the advent of the large slotted flaps in the C-170, C-180, and C-
172 we encountered a nose down pitch in forward slips with the wing flaps
deflected. In some cases it was severe enough to lift the pilot against
his seat belt if he was slow in checking the motion. For this reason a
caution note was placed in most of the owner's manuals under "Landings"
reading "Slips should be avoided with flap settings greater than 30° due
to a downward pitch encountered under certain combinations of airspeed,
side-slip angle, and center of gravity loadings". Since wing-low drift
correction in cross-wind landings is normally performed with a minimum
flap setting (for better rudder control) this limitation did not apply to
that maneuver. The cause of the pitching motion is the transition of a
strong wing downwash over the tail in straight flight to a lessened
downwash angle over part of the horizontal tail caused by the influence
of a relative "upwash increment" from the upturned aileron in slipping
flight. Although not stated in the owner's manuals, we privately
encouraged flight instructors to explore these effects at high altitude,
and to pass on the information to their students. This phenomenon was
elusive and sometimes hard to duplicate, but it was thought that a pilot
should be aware of its existence and know how to counter-act it if it
occurs close to the ground.
When the larger dorsal fin was adopted in the 1972 C-172L, this side-slip
pitch phenomenon was eliminated, but the cautionary placard was retained.
In the higher-powered C-172P and C-R172 the placard was applicable to a
mild pitch "pumping" motion resulting from flap outboard-end vortex
impingement on the horizontal tail at some combinations of side-slip
angle, power, and airspeed."

This is probably as close to the real story as we will get.

Bob Moore
ATP CFI
PanAm (retired)

This the best explanation I have seen yet..

I have tried it, 1974 172 m, 40 deg., all the rudder we had,
.....

Pitched for 55 knts...no prob.

Reversed the slip..solid , no prob..

2 people on board, 2/3 tanks...

Beware, it comes down like a parachute!..Could come in handy
sometime.

Straight decent resumed instantly upon relaxing the slip
input.

YMMV.....

Dave



On Thu, 06 Jan 2005 22:11:07 GMT, Bob Moore
wrote:

"AnthonyQ" wrote

I was told many years ago that a full rudder slip in a C172
(especially the older models with 40deg flaps), it is possible to
induce a tail stall....not good close to the ground....

From the book "Cessna, Wings for the World" by William Thompson,
Manager-Flight Test and Aerodynamics for the Cessna Aircraft
Company where he also served as an Engineering Test Pilot and
other positions for a total of 28 years.

"With the advent of the large slotted flaps in the C-170, C-180, and C-
172 we encountered a nose down pitch in forward slips with the wing flaps
deflected. In some cases it was severe enough to lift the pilot against
his seat belt if he was slow in checking the motion. For this reason a
caution note was placed in most of the owner's manuals under "Landings"
reading "Slips should be avoided with flap settings greater than 30° due
to a downward pitch encountered under certain combinations of airspeed,
side-slip angle, and center of gravity loadings". Since wing-low drift
correction in cross-wind landings is normally performed with a minimum
flap setting (for better rudder control) this limitation did not apply to
that maneuver. The cause of the pitching motion is the transition of a
strong wing downwash over the tail in straight flight to a lessened
downwash angle over part of the horizontal tail caused by the influence
of a relative "upwash increment" from the upturned aileron in slipping
flight. Although not stated in the owner's manuals, we privately
encouraged flight instructors to explore these effects at high altitude,
and to pass on the information to their students. This phenomenon was
elusive and sometimes hard to duplicate, but it was thought that a pilot
should be aware of its existence and know how to counter-act it if it
occurs close to the ground.
When the larger dorsal fin was adopted in the 1972 C-172L, this side-slip
pitch phenomenon was eliminated, but the cautionary placard was retained.
In the higher-powered C-172P and C-R172 the placard was applicable to a
mild pitch "pumping" motion resulting from flap outboard-end vortex
impingement on the horizontal tail at some combinations of side-slip
angle, power, and airspeed."

This is probably as close to the real story as we will get.

Bob Moore
ATP CFI
PanAm (retired)

It is required student training in Canada.

Lotsa spins...

Dave

On Thu, 06 Jan 2005 21:05:17 GMT, kontiki
wrote:

That training is not nromally a part of student
pilot training.

Snip

But any properly trained low time student can recover from a stall
without spinning.

Stefan