In groundschool they say "never slip a 172 with flaps!" Reasons being loss of rudder I think... Never got a definitive answer.
Then when out flying, my instructor goes ahead and does it so I tell him I though you aren't supposed to and he says its fine, no reason not to. One of the clubs planes has a placard saying no slips with flaps, others don't. Some instructors say its bad, some don't. None of them know why. Any ideas?
Slipping 172 with full flaps
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RadicalRadial
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Re: Slipping 172 with full flaps
Some models have a POH that says something like "slips with full flaps not recommended". I don't think it says "prohibited."
You can get a vibration through the control column; nothing too awful in my experience.
You can get a vibration through the control column; nothing too awful in my experience.
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Colonel Sanders
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Re: Slipping 172 with full flaps
I googled "Cessna 172 slips with flaps" and
got 978,000 results
It is not a prohibition. The placard says
AVOID SLIPS WITH FLAPS
and it is not a safety or controllability issue.
It is theoretically possible, during a slip with
flaps, to get an oscillation in the control yoke
due to the airflow over the elevator. It is
not a safety or controllability issue.
The issue is pilots getting upset when it happens,
and doing something stupid or dangerous.
Read the POH. Or the 978,000 posts on the
internet about it!
As usual, if you want to know what the problem
is with slips with flaps in a 172, look in the mirror.
PS Your instructors are incompetent. When they
discover the internet and this thing called "google"
their knowledge might improve. I hope.
got 978,000 results
It is not a prohibition. The placard says
AVOID SLIPS WITH FLAPS
and it is not a safety or controllability issue.
It is theoretically possible, during a slip with
flaps, to get an oscillation in the control yoke
due to the airflow over the elevator. It is
not a safety or controllability issue.
The issue is pilots getting upset when it happens,
and doing something stupid or dangerous.
Read the POH. Or the 978,000 posts on the
internet about it!
As usual, if you want to know what the problem
is with slips with flaps in a 172, look in the mirror.
PS Your instructors are incompetent. When they
discover the internet and this thing called "google"
their knowledge might improve. I hope.
Last edited by Colonel Sanders on Sun Feb 10, 2013 4:17 pm, edited 1 time in total.
Re: Slipping 172 with full flaps
I think the placard says "Avoid slips with flaps extended"
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Instructor_Mike
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Re: Slipping 172 with full flaps
Yep not recommended (at least in the models I fly). Slips are more effective (as much as you can slip in a 172photofly wrote:Some models have a POH that says something like "slips with full flaps not recommended". I don't think it says "prohibited."
You can get a vibration through the control column; nothing too awful in my experience.
) with the flaps up as well. Try a few crosswind landings with and without flap, you'll notice the difference in the feel.-
Shiny Side Up
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Re: Slipping 172 with full flaps
Notably Cessna likes to placard everything that is a prohibition or safety issue with their charming "MAY RESULT IN INJURY OR DEATH" the flap indication conspiciously not being placarded with this.Colonel Sanders wrote: It is not a prohibition. The placard says
AVOID SLIPS WITH FLAPS
and it is not a safety or controllability issue.
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Colonel Sanders
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Re: Slipping 172 with full flaps
I scanned in this excerpt from a 1975 C172M POH:
I don't see a "prohibition" here.
I don't see a "prohibition" here.
Re: Slipping 172 with full flaps
I got this from here. The Cessna 172 Club.
http://www.cessna172club.com/forum/ubbt ... mber=67547
It seems like an interesting site for the Cessna 172 crowd. The article the origional poster (Mr. Jeff Jacobs) posted on 11/Feb/12 refers to an article that is a bit dated (1991), but still valid.
------------------------------------------------
... It’s not a myth, but it’s not a big deal, either.
Here’s what Bill Thompson, former Manager of Flight Test & Aerodynamics at Cessna, had to say about the issue of slipping with full flaps in the 172 (Cessna — Wings for The World, by William D. Thompson, Maverick Press, 1991, p. 41):
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 deg. 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 crosswind 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 counteract it if it occurs close to the ground.
You'll notice that beginning with the 1972 model year ('73 for European-built models) 172s have a larger dorsal fin. This apparently eliminated the "pitch-down" problem.
However, there is also an unrelated, more benign phenomenon that Thompson described in newer models in full-flap slips: “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 really isn't a problem and it's not limited to Cessnas -- my Sport Cub does it, as well, and it doesn't keep me from slipping with full flaps in either airplane.
So although the 172L’s larger dorsal apparently solved the pitch-down issue, they kept the cautionary note in the POH because of the latter phenomenon.
Unfortunately Cessna contributed to the “end of the world” fear of slips with flaps, by not explaining the pitch-down phenomenon in the manuals; and in fact, many earlier C-172 manuals expressly said that slips with full flap were prohibited. I rummaged through my collection of old Cessna owners manuals:
1958 C-172: “prohibited”
1959 C-175: “prohibited”
1966 C-172F: “prohibited”
1972 C-172L (first year of the big dorsal): “should be avoided”
The manuals and TCDS for these older models have been revised since then, and there is now no legal prohibition against slips with flaps -- but that’s what a lot of us old-timers read back then and remember.
_________________________
Jeff Jacobs
CC11-100 / C-172N-180
KVUO / Vancouver, WA
Cut and pasted by TTJJ without permission for training purposes. I hope he doesn't mind.
http://www.cessna172club.com/forum/ubbt ... mber=67547
It seems like an interesting site for the Cessna 172 crowd. The article the origional poster (Mr. Jeff Jacobs) posted on 11/Feb/12 refers to an article that is a bit dated (1991), but still valid.
------------------------------------------------
... It’s not a myth, but it’s not a big deal, either.
Here’s what Bill Thompson, former Manager of Flight Test & Aerodynamics at Cessna, had to say about the issue of slipping with full flaps in the 172 (Cessna — Wings for The World, by William D. Thompson, Maverick Press, 1991, p. 41):
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 deg. 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 crosswind 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 counteract it if it occurs close to the ground.
You'll notice that beginning with the 1972 model year ('73 for European-built models) 172s have a larger dorsal fin. This apparently eliminated the "pitch-down" problem.
However, there is also an unrelated, more benign phenomenon that Thompson described in newer models in full-flap slips: “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 really isn't a problem and it's not limited to Cessnas -- my Sport Cub does it, as well, and it doesn't keep me from slipping with full flaps in either airplane.
So although the 172L’s larger dorsal apparently solved the pitch-down issue, they kept the cautionary note in the POH because of the latter phenomenon.
Unfortunately Cessna contributed to the “end of the world” fear of slips with flaps, by not explaining the pitch-down phenomenon in the manuals; and in fact, many earlier C-172 manuals expressly said that slips with full flap were prohibited. I rummaged through my collection of old Cessna owners manuals:
1958 C-172: “prohibited”
1959 C-175: “prohibited”
1966 C-172F: “prohibited”
1972 C-172L (first year of the big dorsal): “should be avoided”
The manuals and TCDS for these older models have been revised since then, and there is now no legal prohibition against slips with flaps -- but that’s what a lot of us old-timers read back then and remember.
_________________________
Jeff Jacobs
CC11-100 / C-172N-180
KVUO / Vancouver, WA
Cut and pasted by TTJJ without permission for training purposes. I hope he doesn't mind.
Re: Slipping 172 with full flaps
Directly out of the C-170B POH.
" (3) The flaps on the 170 allow
steep, well controlled approaches
making slips unnecessary.
Slips with full flaps are
to be avoided because if the
slip is extreme enough at a
relatively high airspeed, the
airflow is disrupted over the
tail surface resulting in a
sudden and steep, downward
pitch of the nose. "
The C 170B, has the same wing and flaps, as the early C-172, up to 1972
One person on the 170 forum, claims he tried it from 5,000 ft and very quickly lost 1,200 feet before
he was able to recover. He said it pitched full down very rapidly.
( I would not want to experience that situation close to the ground, when approaching to land )
" (3) The flaps on the 170 allow
steep, well controlled approaches
making slips unnecessary.
Slips with full flaps are
to be avoided because if the
slip is extreme enough at a
relatively high airspeed, the
airflow is disrupted over the
tail surface resulting in a
sudden and steep, downward
pitch of the nose. "
The C 170B, has the same wing and flaps, as the early C-172, up to 1972
One person on the 170 forum, claims he tried it from 5,000 ft and very quickly lost 1,200 feet before
he was able to recover. He said it pitched full down very rapidly.
( I would not want to experience that situation close to the ground, when approaching to land )
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iflyforpie
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Re: Slipping 172 with full flaps
However, the C-170 has a completely different tail than the 172... including the mounting of the horizontal stabilizer in a completely different position.
Re: Slipping 172 with full flaps
Yes the 170 has a completely different tail. ( round vrs square, and larger control surfaces.)
The C-170 and C-170A have a differant wing and flap , but the wing and flaps on the C-170B is the same the wing and
flaps as the early C-172
But does not the C-172 have the same warnings ? ...... ( don't slip it with full flaps )
Most slip applications are to loose altitude, rapidly ( when too high on final )
The C-170 and C-170A have a differant wing and flap , but the wing and flaps on the C-170B is the same the wing and
flaps as the early C-172
But does not the C-172 have the same warnings ? ...... ( don't slip it with full flaps )
Most slip applications are to loose altitude, rapidly ( when too high on final )
Re: Slipping 172 with full flaps
I only have a few hundred hours on a 172, and that almost 30 years ago, so perhaps my memory is fading, but as I recall if you put power to idle and dump full flaps, and slow down the things almost drop like a rock..About 65 kts or thereabout IIRC...Which brings me to the question of who cares if it can slip or not with flaps? What kind of strips are you folks going into that requires descent profiles any steeper than you can obtain in the above configuration..
This sounds to much like some poeple have nothing better to do than once again enhance the training experience instead of learning the basics.. If you want to learn to slip, leave the flaps alone.
Because something is not prohibited, and just to be avoided, is not an invitation to try it out...particularily if there is a student on board. It is no wonder that the poor old ppl students are taking 80 hours to get their license..
The op was confused...That should be a loud and clear message to his instructors...
This sounds to much like some poeple have nothing better to do than once again enhance the training experience instead of learning the basics.. If you want to learn to slip, leave the flaps alone.
Because something is not prohibited, and just to be avoided, is not an invitation to try it out...particularily if there is a student on board. It is no wonder that the poor old ppl students are taking 80 hours to get their license..
The op was confused...That should be a loud and clear message to his instructors...
Re: Slipping 172 with full flaps
Had an instructor a few years back who said after a long enough debate on this, he picked up the phone, called cessna and asked them about it.
Their response was "it is not recommended for passenger comfort." So it is nothing to do with controllability of the aircraft, it just sounds different which can scare some passengers sitting in the back beside the flaps. (As well as the high descent rates)
Their response was "it is not recommended for passenger comfort." So it is nothing to do with controllability of the aircraft, it just sounds different which can scare some passengers sitting in the back beside the flaps. (As well as the high descent rates)
Re: Slipping 172 with full flaps
Meh. Full flap slips in a 172 is part of flying and learning all about the limits of the flight envelope of the particular aircraft. If it's not unsafe, and you can do it with regular flight controls then have at it. All part of flying with confidence, verve and flair.
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Slappy the Squirrel
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Re: Slipping 172 with full flaps
I also always taught my students that while it was not recommended, you certainly could do it in a pinch (ie. Screwed up a forced approach or spot landing and you have no other options). I would usually get them to do at least one just so they could feel what it felt like, and so that they could see how much you would have to pitch forward in a full flap forward slip.
But I definately remember the associated control yoke oscillation, I could see how that might spook some unknowing new pilot.
But I definately remember the associated control yoke oscillation, I could see how that might spook some unknowing new pilot.
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Steve Pomroy
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Re: Slipping 172 with full flaps
+1. And you almost quoted the FIG:photofly wrote:Meh. Full flap slips in a 172 is part of flying and learning all about the limits of the flight envelope of the particular aircraft. If it's not unsafe, and you can do it with regular flight controls then have at it. All part of flying with confidence, verve and flair.
So if the aircraft can do it safely (it can, except perhaps the above noted models with the term "prohibited" in the POH), and it's useful (it is), students should see it and try it. The pitch oscillation isn't a big deal, but I wouldn't want a low time PPL seeing it for the first time without an instructor -- especially in an emergency (e.g. - forced approach) where it might actually be needed.Flight Instructor Guide wrote:Teach your students to have mastery over the aircraft; to fly with verve and spirit to the limit of the aircraft's flight envelope
Cheers,
Steve
http://www.flightwriter.com
http://www.skywriters.aero
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RadicalRadial
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Re: Slipping 172 with full flaps
Ok thanks for the informative replies. My flying club has most models of 172 and I have two of the models POHs. Those don't have the flaps issue.
I'm a little confused with some of your responses saying to read the POH and look it up on google... Yea I can easily wait until later in the week when I'm at the flying club to look it up on the POH I don't own, and yes I can search it up on google. But I want to hear difinitive answers directly from a known reliable source, in this case being fellow pilots.
Ok I've vented my pet peeve, and I thank you for the answers. The reason I asked is because I have heard that it can cause a total tail stall, it can cause loss of rudder control or it can cause a bit of buffeting and it seems to be the latter. Now I know.
I'm a little confused with some of your responses saying to read the POH and look it up on google... Yea I can easily wait until later in the week when I'm at the flying club to look it up on the POH I don't own, and yes I can search it up on google. But I want to hear difinitive answers directly from a known reliable source, in this case being fellow pilots.
I see this website as a resource for information on aviation that can answer any questions I might have. I want to get my answers from here, not from random google websites. I see no reason for anybody to tell me to go look somewhere else for my answer when this website is here to answer questions and share ideas on aviation. Why don't some of you try exercising the idea that no question is a stupid question, especially for new pilots.Colonel Sanders wrote:
Read the POH. Or the 978,000 posts on the
internet about it!
PS Your instructors are incompetent. When they
discover the internet and this thing called "google"
their knowledge might improve. I hope.
Ok I've vented my pet peeve, and I thank you for the answers. The reason I asked is because I have heard that it can cause a total tail stall, it can cause loss of rudder control or it can cause a bit of buffeting and it seems to be the latter. Now I know.
Re: Slipping 172 with full flaps
As it was pointed out to me, some ( I haven't flown C 172s in many years ) but I am told some have only 30 degrees of flaps,
and older ones have 40 degrees . This may explain some of the differant results, in this issue ??
and older ones have 40 degrees . This may explain some of the differant results, in this issue ??
Re: Slipping 172 with full flaps
Thanks to TTJJ for correctly referring to Thompson's remarks about this, he's the fellow who knows.
As mentioned, this is neither trivial, or critical. I have done this during testing, and you can get quite a ride out of it, but the plane remains flyable, if flown through. Remember that as a certified aircraft, it (all 172 models) has demonstrated compliance with the handling requirements, and it is certain that had the test pilot not found that the aircraft could not be safely flown in the configuration, it would not have been approved. This was more an "It's okay, and passes, but is not perfect, and you should know anyway" situation. If "prohibited" were to be the appropriate wording for a placard for this characteristic, certification would not have been permitted.
As mentioned, this is neither trivial, or critical. I have done this during testing, and you can get quite a ride out of it, but the plane remains flyable, if flown through. Remember that as a certified aircraft, it (all 172 models) has demonstrated compliance with the handling requirements, and it is certain that had the test pilot not found that the aircraft could not be safely flown in the configuration, it would not have been approved. This was more an "It's okay, and passes, but is not perfect, and you should know anyway" situation. If "prohibited" were to be the appropriate wording for a placard for this characteristic, certification would not have been permitted.
Would be a very wild exaggeration of a present, but manageable characteristic. Control in yaw is not affected, only in pitch.it can cause a total tail stall, it can cause loss of rudder control
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Class 1 Instructor
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Re: Slipping 172 with full flaps
The private aircraft forum on PPRUNE.ORG is, in general, much more accommodating to newer pilots and their questions.......RadicalRadial wrote:Ok thanks for the informative replies. My flying club has most models of 172 and I have two of the models POHs. Those don't have the flaps issue.
I'm a little confused with some of your responses saying to read the POH and look it up on google... Yea I can easily wait until later in the week when I'm at the flying club to look it up on the POH I don't own, and yes I can search it up on google. But I want to hear difinitive answers directly from a known reliable source, in this case being fellow pilots.I see this website as a resource for information on aviation that can answer any questions I might have. I want to get my answers from here, not from random google websites. I see no reason for anybody to tell me to go look somewhere else for my answer when this website is here to answer questions and share ideas on aviation. Why don't some of you try exercising the idea that no question is a stupid question, especially for new pilots.Colonel Sanders wrote:
Read the POH. Or the 978,000 posts on the
internet about it!
PS Your instructors are incompetent. When they
discover the internet and this thing called "google"
their knowledge might improve. I hope.
Ok I've vented my pet peeve, and I thank you for the answers. The reason I asked is because I have heard that it can cause a total tail stall, it can cause loss of rudder control or it can cause a bit of buffeting and it seems to be the latter. Now I know.
Re: Slipping 172 with full flaps
FWIW I "avoided a slip with full flaps" on my PPL flight test per the placard and was dinged. The rather gruff examiner noted that it says "avoid" and also told me the story about the vibrating yoke. I made the field on my engine failure, but he called overshoot higher than I had ever overshot in my training.
I had been sideslipping throughout my training with full flaps and my instructor and he never mentioned anything.
There's something insightful amongst this anecdotal mess... I'm just not sure what.
I had been sideslipping throughout my training with full flaps and my instructor and he never mentioned anything.
There's something insightful amongst this anecdotal mess... I'm just not sure what.
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RadicalRadial
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Re: Slipping 172 with full flaps
I'm sorry, but nowhere does the forum section say "flight training, for advanced pilots only"Class 1 Instructor wrote:The private aircraft forum on PPRUNE.ORG is, in general, much more accommodating to newer pilots and their questions.......
I am using this website what it was meant for. I realize that you could be trying to be helpful but I have found the information from the people on this website much more abundant than pprune.
If a pilot has a question about anything to do with aviation, there should be no reason not to ask it on an aviation forum. Especially if there is a section specifically for the type of question asked.
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Colonel Sanders
- Top Poster
- Posts: 7512
- Joined: Sun Jun 14, 2009 5:17 pm
- Location: Over Macho Grande
Re: Slipping 172 with full flaps
What I learned is that the C172 is a wild bucking broncoThere's something insightful
of an airplane that no one understands how it was certified
because of it's extremely challenging and hazardous
handling characteristics. A real fire-breathing dragon!
Re: Slipping 172 with full flaps
Radical... Your question got answered and is now in the process of being beat to death...by multiple "reputable" internet sources on THIS forum, so stop worrying. Suggesting you use all the tools at hand to research an issue is good advice, especially on the net...especially in net related aviation inquiries! This is the nicest most well mannered thread on the training forum AND you got a good answer out of it! AvCanada bonus! Toughen up
That said...My instructor yelled at me once (post PPL) for slipping with full flaps in a 172M, he got very jumpy when I pitched down to keep the airspeed up. I really didn't see what the big deal was as I had done this many times on solo flights before so I felt more then comfortable doing it (and find it fun).
I have personally never felt the oscillation but I have had one of my passengers note seeing the flaps shaking about which freaked him out a bit for a second. From what I understand it takes a very specific set of variables to make it oscillate... Try the slip with your instructor (unless placarded otherwise), get comfortable with the nose down attitude, be prepared for some shaking and then add it to your bag of tricks...it's a non event. Circuits can get repetitive after a while doing your CPL/night rating/currency flights etc... might as well spice things up and make things "sporty" with some steep approaches. Change up your circuits, try different things and challenge yourself. My .02 (CPL student)
Jub
That said...My instructor yelled at me once (post PPL) for slipping with full flaps in a 172M, he got very jumpy when I pitched down to keep the airspeed up. I really didn't see what the big deal was as I had done this many times on solo flights before so I felt more then comfortable doing it (and find it fun).
I have personally never felt the oscillation but I have had one of my passengers note seeing the flaps shaking about which freaked him out a bit for a second. From what I understand it takes a very specific set of variables to make it oscillate... Try the slip with your instructor (unless placarded otherwise), get comfortable with the nose down attitude, be prepared for some shaking and then add it to your bag of tricks...it's a non event. Circuits can get repetitive after a while doing your CPL/night rating/currency flights etc... might as well spice things up and make things "sporty" with some steep approaches. Change up your circuits, try different things and challenge yourself. My .02 (CPL student)
Jub
Re: Slipping 172 with full flaps
Because this is exactly the reason (the bold part) that I dont think it necessary to teach enhanced flying to PPL students..."it is fun".....so lets subject our pax to the the experience..That said...My instructor yelled at me once (post PPL) for slipping with full flaps in a 172M, he got very jumpy when I pitched down to keep the airspeed up. I really didn't see what the big deal was as I had done this many times on solo flights before so I felt more then comfortable doing it (and find it fun).
Where are you flying into that you cannot get in with a full flap approach without slipping? The problem with teaching some young idiots the outside of the envelope is they are not smart enough to realize it is the outside of the envelope..
And worse, want to show off to their poor trusting pax....good job!
