Slipping Cessnas with full flaps.....

E_Dawg · May 6th, 2003, 12:52

OK I realize this has been discussed; however today I found something that makes sense and pretty much seals the deal for me.

"Slips with flaps are either prohibited or not recommended in the POHs. The slip problem arises from the possibility of extended flaps under certain conditions such as in slips or wind shear blocking or interfering with the airflow over the horizontal tail surfaces. I have had such an occurrence in a C-150. The tail surfaces stall and the nose pitches straight down before the stall warner has a chance to yelp. Cessna merely admits that there may be control oscillations."

He does also mention that this only happened once in 9000hrs of flying. Prior to coming across this I was never opposed to slipping with full flaps; however I'm going to rethink that now!

http://www.whittsflying.com/Pagec2C-...m#anchor917446

ready2fly · May 6th, 2003, 12:59

HEEEEEY - my instructor demonstrated a slip with 20% flaps in a 150 a while back!!

YIKES! Our approach is over water.... shallow water. Shallow enough for what's left of the plane after hitting the water to be TOTALLY smashed against the bottom, and deep enough to completly submerge you in what's left of the plane should you somehow survive.

... so much for THAT maneuver.

pscraig · May 6th, 2003, 14:07

I've flown a few 172s that have some vicious pitch oscillations in turbulence when slipping with full flaps. Don't know how truly dangerous it was, but at 400AGL on final, not the kind of experience I am after.

EatSleepFly · May 6th, 2003, 16:54

Guess it depends on the year. I've slipped 172's plenty of times. Creates a little buffeting, but nothing too adverse.

sbav8r · May 6th, 2003, 17:44

[ QUOTE ]
HEEEEEY - my instructor demonstrated a slip with 20% flaps in a 150 a while back!!

YIKES! Our approach is over water.... shallow water. Shallow enough for what's left of the plane after hitting the water to be TOTALLY smashed against the bottom, and deep enough to completly submerge you in what's left of the plane should you somehow survive.

[/ QUOTE ]

And if you do get out then all the blood in the water would attract a feeding frenzy of sharks.

E_Dawg · May 6th, 2003, 21:30

[ QUOTE ]
I've slipped 172's plenty of times.

[/ QUOTE ]

Me too.... but it only takes once.

I dunno; I was a big fan of slipping with flaps until I read it; just thought I'd put it up. It's the first concrete reason I've found to avoid slips, and it's a good one.

E_Dawg · May 6th, 2003, 21:32

[ QUOTE ]
And if you do get out then all the blood in the water would attract a feeding frenzy of sharks.

[/ QUOTE ]

And those sharkes would attract jellyfish which would sting you sensless.

sbav8r · May 6th, 2003, 22:09

Then the waves would pound your bloddy beaten body against the coral before spitting you onto the 180 deg. sand.

E_Dawg · May 6th, 2003, 22:59

which would then burn you to a fine ash residue which would be swept up, ironically, by your wake left by the slipstream....

All because you wanted to slip a Cessna. Now to me, that just dosen't.....

Baronman · May 7th, 2003, 06:41

Some Cessna POHs specifically make note of trying to avoid slips with flaps extended. Others make no mention of it. I frequently slip a 1978 C152 with up to 20 degrees extended.

Also keep in mind guys that a forward slip is not just a maneuver to loose huge amounts of altitude. That is to say that not every forward slip is full rudder deflection with 15 degrees of bank.

I doubt Cessna (or any other manufacturer) could certify an aircraft that demonstrated such consistent and violent reaction to a forward slip with some degree of flaps extended.
Just my $.02

Scorpio11982 · May 8th, 2003, 03:40

Belive it or not I'v actually done it with 30 degree flap extention( Back when i was training for PPL)

We generally landed with 30 degree of flaps; 95% of the time during my PPL training... When high he tells me to Slip.

Nothing in our 1980 C-152 POH against it...

If it's a very windy day .. Would it be okay to Do the slip with flaps extended and full Power???

ready2fly · May 8th, 2003, 08:18

SCOOOOOORRRRP!! You back, man?

E_Dawg · May 8th, 2003, 13:11

[ QUOTE ]
Belive it or not I'v actually done it with 30 degree flap extention( Back when i was training for PPL)

We generally landed with 30 degree of flaps; 95% of the time during my PPL training... When high he tells me to Slip.

Nothing in our 1980 C-152 POH against it...

If it's a very windy day .. Would it be okay to Do the slip with flaps extended and full Power???

[/ QUOTE ]

Yeah I've slipped it plenty of times with 30* in there too (with no problems I might add).

And if it's windy I wouldn't use 30*, more like 20 at the most. However even with 30* I wouldn't hesitate to correct for the wind despite the supposed problems.

All I'm saying is that I'm going to think twice before I slip it for the hell of it, and I'm more likely to go around if I'm high than try to slip it.

Scorpio11982 · May 9th, 2003, 11:19

Hey R2F, how is it going. I'm not back yet(

)but in just 3 months we will be relieved and sent home. The "Tempo" is "Lower" now so We have more time to do other things.
This is an Addictive website you know

( My name is Scorpio11982, and I'm a Jetcaholic

)

Hey Skyguy, You are right about the go-around thing.

I said something wrong in my last post. I said my CFI
"Always" told me to Slip whenever i was to high... He did not always tell me to do that. I have performed Slips quite a few time with him, mostly during windy days.

P.s It Really sucks not flying for 3 months.. I feel like a fourlogh..

stultus · May 9th, 2003, 17:17

[ QUOTE ]
All I'm saying is that I'm going to think twice before I slip it for the hell of it, and I'm more likely to go around if I'm high than try to slip it.

[/ QUOTE ]

I've slipped a 150 with flaps a handful of times too...and now I think I'll be a little more cautious. Actually, I have been pretty cautious already--normally if it's not windy and I slip--I usually recover from the slip with time to put some flaps down before crossing the numbers. Is there anything wrong with that method? What about pitching the nose down and retracting the flaps before you enter a slip if you're too high? I've never tried it that way.

NJA_Capt · May 17th, 2003, 09:45

Unless I have overlooked something in the above posts. Some important considerations have been left out.

It is true that some single Cessnas are prohibited from slips with full flaps. However, some are not. We own a 1951 C170A which is approved for slips with all 50 degrees of flaps.

Early model C150/172s had 40 degrees of flap travel. I have long forgotten the changeover date, but somewhere in the 1970s Cessna changed from 40 degrees to 30 degree max flap travel. This was in response to the "problem" with tail stalls in the slip. Perhaps the man with the aggressive stall from slipping was doing so in a 40 degree flap airplane.

Used to love 40 degree flaps....you could make a heck of a short field landing

As always...read YOUR POH.

NJA_Capt · May 17th, 2003, 10:12

[ QUOTE ]
I usually recover from the slip with time to put some flaps down before crossing the numbers.

[/ QUOTE ]
I'm not sure why you would want to do this. It is an unnecessary configuration change VERY low to the ground. It requires moving the flaps and retrimming the elevator, when all that is necessary is easing out of the slip and flare.

[ QUOTE ]
What about pitching the nose down and retracting the flaps before you enter a slip if you're too high? I've never tried it that way.

[/ QUOTE ]
Easier to just go around. Again, this is an unnecessary configuration change. My preference is if you are going to slip, leave the flaps up. If you're using full flaps, don't slip.

The beauty of a slip is not needing to retrim much in a go around. Ever try a go around in a Cessna with full flaps and full trim? I do not recommend this for entertainment!

MidlifeFlyer · May 18th, 2003, 07:31

[ QUOTE ]
It is true that some single Cessnas are prohibited from slips with full flaps.

[/ QUOTE ] I'm new here and missed the discussion. So far, I haven't come across a Cessna single in which slips with full flaps was prohibited. Recommended against, yes, but prohibited, no.

NJA_Capt · May 18th, 2003, 11:13

[ QUOTE ]
So far, I haven't come across a Cessna single in which slips with full flaps was prohibited. Recommended against, yes, but prohibited, no.

[/ QUOTE ]

The first POH I just ran across is for a 1964 C172 with 40 deg of flaps, page 2-9, quote:

"LANDING
Normal landings are made power-off with any flap setting. Slips are prohibited (emphasis added) in full flap approaches because of downward pitch encountered under certain combinations of airspeed and sideslip angle."

Remember, it also is only recommended that you not poke your finger in your eye.

JDMcFly · May 18th, 2003, 12:36

Why risk it, really?

MidlifeFlyer · May 18th, 2003, 16:14

[ QUOTE ]
Normal landings are made power-off with any flap setting. Slips are prohibited (emphasis added) in full flap approaches because of downward pitch encountered under certain combinations of airspeed and sideslip angle."

[/ QUOTE ]Thanks, I never saw one before.

[/ QUOTE ]Remember, it also is only recommended that you not poke your finger in your eye.

[/ QUOTE ]Although there's a difference. Poking you finger in your eye is dangerous. Slipping a 172 with a no-slip-with-flaps recommendation isn't. Do it all the time, especially in crosswinds.

stultus · June 1st, 2003, 15:51

[ QUOTE ]

I'm not sure why you would want to do this. It is an unnecessary configuration change VERY low to the ground. It requires moving the flaps and retrimming the elevator, when all that is necessary is easing out of the slip and flare.

The beauty of a slip is not needing to retrim much in a go around. Ever try a go around in a Cessna with full flaps and full trim? I do not recommend this for entertainment!

[/ QUOTE ]

I'm not sure why I'd want to do it either...I'm pretty low time and haven't done tons of slips to land. I've asked a couple of instructors about it and they've said you can recover from the slip whenever you want before the flair and didn't see any problem with putting in flaps once you're out of the slip.

Why use full trim when landing? I usually don't readjust the trim after downwind (should I be?) A little forward pressure isn't something that bothers me. It also seems to me like another thing to worry about in a go around--though I don't know that i'd be that entertaining.

say_speed · June 8th, 2003, 13:14

remember, the elevators create negative lift; the lift vector is downwards, therefore an elevator stall is characterized by a tail drop.

Fly Safe

E_Dawg · June 8th, 2003, 17:06

It would be a nose drop because you no longer have the negaive lift of the elevator 'holding' the nose up.

That's also why you shouldn't use any more flaps than absouletely necessary on an iced up high wing... the airflow from the flaps can disrupt the tail surface flow and cause a tail stall; in which case the only way to recover is by pulling BACK on the yoke... totally counter intuitive from what you would normally do to recover from a stall.

say_speed · June 8th, 2003, 23:39

[ QUOTE ]
It would be a nose drop because you no longer have the negaive lift of the elevator 'holding' the nose up.

You are absolutely right, the center of lift being aft of the center of weight, the elevators creating negative lift, the nose will drop if the elevator is stalled...
Brain fart I guess, thank you for correcting me.

May 6th, 2003, 12:52	#1
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,171	Slipping Cessnas with full flaps..... OK I realize this has been discussed; however today I found something that makes sense and pretty much seals the deal for me. "Slips with flaps are either prohibited or not recommended in the POHs. The slip problem arises from the possibility of extended flaps under certain conditions such as in slips or wind shear blocking or interfering with the airflow over the horizontal tail surfaces. I have had such an occurrence in a C-150. The tail surfaces stall and the nose pitches straight down before the stall warner has a chance to yelp. Cessna merely admits that there may be control oscillations." He does also mention that this only happened once in 9000hrs of flying. Prior to coming across this I was never opposed to slipping with full flaps; however I'm going to rethink that now! http://www.whittsflying.com/Pagec2C-...m#anchor917446

May 6th, 2003, 12:59	#2
ready2fly Old Skool Join Date: Nov 2001 Location: DFW Posts: 7,143	Re: Slipping Cessnas with full flaps..... HEEEEEY - my instructor demonstrated a slip with 20% flaps in a 150 a while back!! YIKES! Our approach is over water.... shallow water. Shallow enough for what's left of the plane after hitting the water to be TOTALLY smashed against the bottom, and deep enough to completly submerge you in what's left of the plane should you somehow survive. ... so much for THAT maneuver.

May 6th, 2003, 14:07	#3
pscraig Senior Member Join Date: Jul 2001 Location: Houston, TX Posts: 1,021	Re: Slipping Cessnas with full flaps..... I've flown a few 172s that have some vicious pitch oscillations in turbulence when slipping with full flaps. Don't know how truly dangerous it was, but at 400AGL on final, not the kind of experience I am after.

May 6th, 2003, 16:54	#4
EatSleepFly Old Skool Join Date: Dec 2002 Location: ?? Posts: 4,600	Re: Slipping Cessnas with full flaps..... Guess it depends on the year. I've slipped 172's plenty of times. Creates a little buffeting, but nothing too adverse.

May 6th, 2003, 17:44	#5
sbav8r Junior Member Join Date: Feb 2003 Location: Santa Barbara, CA Posts: 195	Re: Slipping Cessnas with full flaps..... [ QUOTE ] HEEEEEY - my instructor demonstrated a slip with 20% flaps in a 150 a while back!! YIKES! Our approach is over water.... shallow water. Shallow enough for what's left of the plane after hitting the water to be TOTALLY smashed against the bottom, and deep enough to completly submerge you in what's left of the plane should you somehow survive. [/ QUOTE ] And if you do get out then all the blood in the water would attract a feeding frenzy of sharks.

May 6th, 2003, 21:30	#6
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,171	Re: Slipping Cessnas with full flaps..... [ QUOTE ] I've slipped 172's plenty of times. [/ QUOTE ] Me too.... but it only takes once. I dunno; I was a big fan of slipping with flaps until I read it; just thought I'd put it up. It's the first concrete reason I've found to avoid slips, and it's a good one.

May 6th, 2003, 21:32	#7
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,171	Re: Slipping Cessnas with full flaps..... [ QUOTE ] And if you do get out then all the blood in the water would attract a feeding frenzy of sharks. [/ QUOTE ] And those sharkes would attract jellyfish which would sting you sensless.

May 6th, 2003, 22:09	#8
sbav8r Junior Member Join Date: Feb 2003 Location: Santa Barbara, CA Posts: 195	Re: Slipping Cessnas with full flaps..... Then the waves would pound your bloddy beaten body against the coral before spitting you onto the 180 deg. sand.

May 6th, 2003, 22:59	#9
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,171	Re: Slipping Cessnas with full flaps..... which would then burn you to a fine ash residue which would be swept up, ironically, by your wake left by the slipstream.... All because you wanted to slip a Cessna. Now to me, that just dosen't.....

May 7th, 2003, 06:41	#10
Baronman Senior Member Join Date: Dec 2001 Location: NEWARK Posts: 1,049	Re: Slipping Cessnas with full flaps..... Some Cessna POHs specifically make note of trying to avoid slips with flaps extended. Others make no mention of it. I frequently slip a 1978 C152 with up to 20 degrees extended. Also keep in mind guys that a forward slip is not just a maneuver to loose huge amounts of altitude. That is to say that not every forward slip is full rudder deflection with 15 degrees of bank. I doubt Cessna (or any other manufacturer) could certify an aircraft that demonstrated such consistent and violent reaction to a forward slip with some degree of flaps extended. Just my $.02

May 8th, 2003, 03:40	#11
Scorpio11982 Junior Member Join Date: Dec 2001 Location: NYC Posts: 186	Re: Slipping Cessnas with full flaps..... Belive it or not I'v actually done it with 30 degree flap extention( Back when i was training for PPL) We generally landed with 30 degree of flaps; 95% of the time during my PPL training... When high he tells me to Slip. Nothing in our 1980 C-152 POH against it... If it's a very windy day .. Would it be okay to Do the slip with flaps extended and full Power???

May 8th, 2003, 08:18	#12
ready2fly Old Skool Join Date: Nov 2001 Location: DFW Posts: 7,143	Re: Slipping Cessnas with full flaps..... SCOOOOOORRRRP!! You back, man?

May 8th, 2003, 13:11	#13
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,171	Re: Slipping Cessnas with full flaps..... [ QUOTE ] Belive it or not I'v actually done it with 30 degree flap extention( Back when i was training for PPL) We generally landed with 30 degree of flaps; 95% of the time during my PPL training... When high he tells me to Slip. Nothing in our 1980 C-152 POH against it... If it's a very windy day .. Would it be okay to Do the slip with flaps extended and full Power??? [/ QUOTE ] Yeah I've slipped it plenty of times with 30* in there too (with no problems I might add). And if it's windy I wouldn't use 30, more like 20 at the most. However even with 30 I wouldn't hesitate to correct for the wind despite the supposed problems. All I'm saying is that I'm going to think twice before I slip it for the hell of it, and I'm more likely to go around if I'm high than try to slip it.

May 9th, 2003, 11:19	#14
Scorpio11982 Junior Member Join Date: Dec 2001 Location: NYC Posts: 186	Re: Slipping Cessnas with full flaps..... Hey R2F, how is it going. I'm not back yet( )but in just 3 months we will be relieved and sent home. The "Tempo" is "Lower" now so We have more time to do other things. This is an Addictive website you know ( My name is Scorpio11982, and I'm a Jetcaholic ) Hey Skyguy, You are right about the go-around thing. I said something wrong in my last post. I said my CFI "Always" told me to Slip whenever i was to high... He did not always tell me to do that. I have performed Slips quite a few time with him, mostly during windy days. P.s It Really sucks not flying for 3 months.. I feel like a fourlogh..

May 9th, 2003, 17:17	#15
stultus Senior Member Join Date: May 2003 Posts: 523	Re: Slipping Cessnas with full flaps..... [ QUOTE ] All I'm saying is that I'm going to think twice before I slip it for the hell of it, and I'm more likely to go around if I'm high than try to slip it. [/ QUOTE ] I've slipped a 150 with flaps a handful of times too...and now I think I'll be a little more cautious. Actually, I have been pretty cautious already--normally if it's not windy and I slip--I usually recover from the slip with time to put some flaps down before crossing the numbers. Is there anything wrong with that method? What about pitching the nose down and retracting the flaps before you enter a slip if you're too high? I've never tried it that way.

May 17th, 2003, 09:45	#16
NJA_Capt Senior Member Join Date: Jan 2003 Location: Low Earth Orbit Posts: 1,355	Re: Slipping Cessnas with full flaps..... Unless I have overlooked something in the above posts. Some important considerations have been left out. It is true that some single Cessnas are prohibited from slips with full flaps. However, some are not. We own a 1951 C170A which is approved for slips with all 50 degrees of flaps. Early model C150/172s had 40 degrees of flap travel. I have long forgotten the changeover date, but somewhere in the 1970s Cessna changed from 40 degrees to 30 degree max flap travel. This was in response to the "problem" with tail stalls in the slip. Perhaps the man with the aggressive stall from slipping was doing so in a 40 degree flap airplane. Used to love 40 degree flaps....you could make a heck of a short field landing As always...read YOUR POH.

May 17th, 2003, 10:12	#17
NJA_Capt Senior Member Join Date: Jan 2003 Location: Low Earth Orbit Posts: 1,355	Re: Slipping Cessnas with full flaps..... [ QUOTE ] I usually recover from the slip with time to put some flaps down before crossing the numbers. [/ QUOTE ] I'm not sure why you would want to do this. It is an unnecessary configuration change VERY low to the ground. It requires moving the flaps and retrimming the elevator, when all that is necessary is easing out of the slip and flare. [ QUOTE ] What about pitching the nose down and retracting the flaps before you enter a slip if you're too high? I've never tried it that way. [/ QUOTE ] Easier to just go around. Again, this is an unnecessary configuration change. My preference is if you are going to slip, leave the flaps up. If you're using full flaps, don't slip. The beauty of a slip is not needing to retrim much in a go around. Ever try a go around in a Cessna with full flaps and full trim? I do not recommend this for entertainment!

May 18th, 2003, 07:31	#18
MidlifeFlyer Old Skool Join Date: May 2003 Location: Denver Colorado Posts: 2,977	Re: Slipping Cessnas with full flaps..... [ QUOTE ] It is true that some single Cessnas are prohibited from slips with full flaps. [/ QUOTE ] I'm new here and missed the discussion. So far, I haven't come across a Cessna single in which slips with full flaps was prohibited. Recommended against, yes, but prohibited, no.

May 18th, 2003, 11:13	#19
NJA_Capt Senior Member Join Date: Jan 2003 Location: Low Earth Orbit Posts: 1,355	Re: Slipping Cessnas with full flaps..... [ QUOTE ] So far, I haven't come across a Cessna single in which slips with full flaps was prohibited. Recommended against, yes, but prohibited, no. [/ QUOTE ] The first POH I just ran across is for a 1964 C172 with 40 deg of flaps, page 2-9, quote: "LANDING Normal landings are made power-off with any flap setting. Slips are prohibited (emphasis added) in full flap approaches because of downward pitch encountered under certain combinations of airspeed and sideslip angle." Remember, it also is only recommended that you not poke your finger in your eye.

May 18th, 2003, 12:36	#20
JDMcFly Old Skool Join Date: Apr 2003 Location: New York Posts: 1,664	Re: Slipping Cessnas with full flaps..... Why risk it, really?

May 18th, 2003, 16:14	#21
MidlifeFlyer Old Skool Join Date: May 2003 Location: Denver Colorado Posts: 2,977	Re: Slipping Cessnas with full flaps..... [ QUOTE ] Normal landings are made power-off with any flap setting. Slips are prohibited (emphasis added) in full flap approaches because of downward pitch encountered under certain combinations of airspeed and sideslip angle." [/ QUOTE ]Thanks, I never saw one before. [/ QUOTE ]Remember, it also is only recommended that you not poke your finger in your eye. [/ QUOTE ]Although there's a difference. Poking you finger in your eye is dangerous. Slipping a 172 with a no-slip-with-flaps recommendation isn't. Do it all the time, especially in crosswinds.

June 1st, 2003, 15:51	#22
stultus Senior Member Join Date: May 2003 Posts: 523	Re: Slipping Cessnas with full flaps..... [ QUOTE ] I'm not sure why you would want to do this. It is an unnecessary configuration change VERY low to the ground. It requires moving the flaps and retrimming the elevator, when all that is necessary is easing out of the slip and flare. The beauty of a slip is not needing to retrim much in a go around. Ever try a go around in a Cessna with full flaps and full trim? I do not recommend this for entertainment! [/ QUOTE ] I'm not sure why I'd want to do it either...I'm pretty low time and haven't done tons of slips to land. I've asked a couple of instructors about it and they've said you can recover from the slip whenever you want before the flair and didn't see any problem with putting in flaps once you're out of the slip. Why use full trim when landing? I usually don't readjust the trim after downwind (should I be?) A little forward pressure isn't something that bothers me. It also seems to me like another thing to worry about in a go around--though I don't know that i'd be that entertaining.

June 8th, 2003, 13:14	#23
say_speed Junior Member Join Date: Jun 2003 Location: Cali Posts: 194	Re: Slipping Cessnas with full flaps..... remember, the elevators create negative lift; the lift vector is downwards, therefore an elevator stall is characterized by a tail drop. Fly Safe

June 8th, 2003, 17:06	#24
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,171	Re: Slipping Cessnas with full flaps..... It would be a nose drop because you no longer have the negaive lift of the elevator 'holding' the nose up. That's also why you shouldn't use any more flaps than absouletely necessary on an iced up high wing... the airflow from the flaps can disrupt the tail surface flow and cause a tail stall; in which case the only way to recover is by pulling BACK on the yoke... totally counter intuitive from what you would normally do to recover from a stall.

June 8th, 2003, 23:39	#25
say_speed Junior Member Join Date: Jun 2003 Location: Cali Posts: 194	Re: Slipping Cessnas with full flaps..... [ QUOTE ] It would be a nose drop because you no longer have the negaive lift of the elevator 'holding' the nose up. You are absolutely right, the center of lift being aft of the center of weight, the elevators creating negative lift, the nose will drop if the elevator is stalled... Brain fart I guess, thank you for correcting me.

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