slips in a 182???

My guess is that a 40 degree flap glide ratio at 80mph is between 2:1 and 3:1.
CFIIIG/ASEL.
I don't think it would be nearly that bad. I can't remember what airspeed and descent rate we used to see with full flaps in the 182, but if it was a 2:1 glide ratio, and you were doing 60 knots, you'd need a descent rate of around 3000 fpm. Don't think so.
 
I don't think it would be nearly that bad. I can't remember what airspeed and descent rate we used to see with full flaps in the 182, but if it was a 2:1 glide ratio, and you were doing 60 knots, you'd need a descent rate of around 3000 fpm. Don't think so.

That is a pretty good thought...
Like I said I was just guessing...
2:1= 30 degree glide so the trig says 80mph (7040ft/min)= 3520ft/min
3:1= 18.5 degree glide = 2233ft/min
4:1= 14 degree glide = 1703ft/min
5:1 = 11.5 degree glide = 1379ft/min

1970 manual shows a clean glide of about 10:1
10:1 = 5.7 degree glide = 699ft/min

looking at those number I am thinking in the ball park of 3:1 is probably what it likely does, still just pretty much guessing.

Who has easy access to a 182 to try it an tell what the power off (idle) descent rate is at 80mph with full flaps?
If I get a chance soon a will try to remember to try it.

Brian
CFIIG/ASEL
 
I was looking for an excuse to go Wednesday afternoon and now you’ve provided it.

Of course I get the end of day add on meeting. Maybe this weekend. I no longer use 40 or 30 degree flap settings but can confirm that it drops like a rock.
 
At one point someone mentioned that slips weren't recommended in the long body Mooneys. Turns out to be a thing, at low speeds you can wash out the elevators and get a pitch down motion, at least I think that's what it was.
 
That is a pretty good thought...
Like I said I was just guessing...
2:1= 30 degree glide so the trig says 80mph (7040ft/min)= 3520ft/min
3:1= 18.5 degree glide = 2233ft/min
4:1= 14 degree glide = 1703ft/min
5:1 = 11.5 degree glide = 1379ft/min

1970 manual shows a clean glide of about 10:1
10:1 = 5.7 degree glide = 699ft/min

looking at those number I am thinking in the ball park of 3:1 is probably what it likely does, still just pretty much guessing.

Who has easy access to a 182 to try it an tell what the power off (idle) descent rate is at 80mph with full flaps?
If I get a chance soon a will try to remember to try it.

Brian
CFIIG/ASEL

I've got a 73 182P with sportsman wing and VGs. My VSI only goes to +- 2,000 but its easy to peg it with 40* flaps. But, I'm much slower than 80mph more like 60ish or less. I only use 40* flaps when practicing / doing short field landings, so slower the better.
 
That is a pretty good thought...
Like I said I was just guessing...
2:1= 30 degree glide so the trig says 80mph (7040ft/min)= 3520ft/min
3:1= 18.5 degree glide = 2233ft/min
4:1= 14 degree glide = 1703ft/min
5:1 = 11.5 degree glide = 1379ft/min

1970 manual shows a clean glide of about 10:1
10:1 = 5.7 degree glide = 699ft/min

looking at those number I am thinking in the ball park of 3:1 is probably what it likely does, still just pretty much guessing.

Who has easy access to a 182 to try it an tell what the power off (idle) descent rate is at 80mph with full flaps?
If I get a chance soon a will try to remember to try it.

Brian
CFIIG/ASEL

Interesting data point, had a friend test this today for me in his 182. Q model I think. Full Flaps power idle he reports 1250fpm. So about 5.6:1 glide ratio for him with full flaps.
I still want to do some testing myself.

Brian
 
I can see how slips with flaps would be useful, so that the wearers wouldn't have to pull them all the way up in the john on a cold day.
 
Interesting data point, had a friend test this today for me in his 182. Q model I think. Full Flaps power idle he reports 1250fpm. So about 5.6:1 glide ratio for him with full flaps.
I still want to do some testing myself.

Brian
That's more like it.
 
That's more like it.
I fly a 182S, if you need a steeper decent than 40º and idle then a go around is probably a good idea.
If it is an engine out situation and a Walmart parking lot, I will not be worrying about skin (aircraft) wrinkling.

Eugene
 
‘72 182 with 40 Deg flaps. Full slips no issues. Drops like a rock. Teaches the CFI not to say “think you can make it” when you really f*#k up and are way to high (and should have just gone around).
My 120 taught me well.
 
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 (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.

The larger dorsal fin introduced on the newer models apparently eliminated the issue.

These images illustrate the upwash from the upturned aileron encountering the horizontal stabilizer. In the first image the airplane is in coordinated flight; in the second it is in a slip to the left. In both images the airplane is tracking (in still air) toward the mountain peak in the distance.

Flap slip.jpg


There is a separate, unrelated 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 is entirely benign and common with other high-wing airplanes. My Sport Cub did the same thing.

So although the 172L’s larger dorsal 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 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 for these older models have been revised since then, and in fact the TCDS no longer carries the prohibition against slips with flaps. The POHs for the current C-172S and C-182T contain the same language, indicating that it's no biggie:

Steep slips with flap settings greater than 20° can cause a slight tendency for the elevator to oscillate under certain combinations of airspeed, sideslip angle, and center of gravity loadings.
But a lot of us old-timers read the scary language in the old manuals back then and that's what we remember. And for decades CFIs just regurgitated the old wives' tales and never bothered to find out what it was really all about.
 
Last edited:
Beware the "oscillations of doom":hairraise:

Actually, I assume it's the same as for the 172. You can get a bit of an oscillation if you through in too much slip for the particular flap/airspeed combination you have. If you reduce the slip a bit, they go away. I've never heard of anybody having any real problems with it. It's been discussed ad nauseum on the red board, probably a few times here too.

You'll notice it says "avoid" not "prohibited." I think the lawyers got a bit excited on that one.

If you're nervous about it, go to altitude and slip away and see what you think. That's what I did, and I couldn't get it to do anything nasty.

Chris

Only the 172 with 40 degree flaps, and even then it's a nop unless you aren't aware of the issue.
 
I operate my 182L out of a short grass strip. Been doing slips with flaps 30 for twenty years. Like was said, rarely a slight oscillation sets up, but it is easily quelled.
 
Back
Top