Originally Posted by 172_driver
(Post 11139132)
How about this one - slow below best glide speed to steepen the approach angle!?
Never taught it to my students. But tried it a few times on my own and worked like magic. Discuss. |
Posters on this thread seem to me to be about 50/50 split between knowledgeable, helpful folk and Walts/trolls. Folk with a bit of experience can tell the difference, but I do worry about any body else reading it.
ATB |
Originally Posted by sagan
(Post 11139883)
Later on figured out he stalled the fin. It was nasty.
. You are low and slow, kick the rudder to get a strut out of the photo, the fin stalls and the rudder locks out. On the 7 the only way out of this was a full stall. |
the fin stalls and the rudder locks out During testing of a modified Cessna Grand Caravan last winter, the authority required that I demonstrate a stall to the break from a 75% power climbing 30 degree bank turn in each direction, with full rudder applied in each case. (Yes, this is about a spin entry). The airplane handled it just fine, no rudder lock, benign recovery attitudes. I find a sideslip to be a very useful tool for descent control, and have done it in many types with no difficulty nor alarm, though no, I would avoid it in a DC-3! |
Originally Posted by Pilot DAR
(Post 11140081)
... I have slipped 172's with flaps extended, and experienced the burble in pitch which is warned as an "avoid".
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The position out the wing (the wing station) of the outboard end of the flap corresponds poorly with the outboard end of the horizontal stabilizer. In a slip, the wake off the outboard end of the flap can impinge on the H stab, and blanket part of it, and perhaps induce some elevator motion, which will create unexpected momentary pitch control forces, and some pitching. It's more surprising than a real problem, but it is a thing. It varies with models of the 172, some are worse than others, but it was the cause of the "avoid slips" placard common to most 172's. It's also a thing with C 170B's. It's worthy of understanding, and an imperfection with the design, but it did pass certification, and is manageable. C 150/152 don't suffer, as their flaps don't reach as far out the wing. 18x don't seem bothered by it (I've tried all of them!).
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Originally Posted by Heston
(Post 11139926)
Posters on this thread seem to me to be about 50/50 split between knowledgeable, helpful folk and Walts/trolls. Folk with a bit of experience can tell the difference, but I do worry about any body else reading it.
ATB Well back in this thread, I mentioned the potential importance of using a slip(yes it is a forward slip) when appropriate.. I was well aware that there are occasional rare cases of aircraft types that one wants to avoid using this procedure(such as the C170B with ‘barn door’ flaps), a type I used to fly. That is why I stated in that post “if safe to do so in aircraft type”, which in my opinion would be most of the light single engine propeller types(and the 767-200 for those who know the story). You may have to dig around to find out how a particular type behaves. A type club can be very useful as that is where I learned about C170B handling characteristics in a slip, which can be deadly due to stalling the horizontal stab. |
Originally Posted by Pilot DAR
(Post 11140101)
The position out the wing (the wing station) of the outboard end of the flap corresponds poorly with the outboard end of the horizontal stabilizer. In a slip, the wake off the outboard end of the flap can impinge on the H stab, and blanket part of it, and perhaps induce some elevator motion, which will create unexpected momentary pitch control forces, and some pitching. It's more surprising than a real problem, but it is a thing. It varies with models of the 172, some are worse than others, but it was the cause of the "avoid slips" placard common to most 172's. It's also a thing with C 170B's. It's worthy of understanding, and an imperfection with the design, but it did pass certification, and is manageable. C 150/152 don't suffer, as their flaps don't reach as far out the wing. 18x don't seem bothered by it (I've tried all of them!).
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I seem to remember that a C152 would go down like a lift with full flap, IAS about 5 KT above full flap stall speed, idle power, and side-slipped as hard as possible. Total control was retained throughout. I have no idea what the rate or angle of descent was, but it seemed very steep indeed, especially with a good headwind.
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Originally Posted by sagan
(Post 11139883)
Just a quick note re side slipping Cessna's with full flap.
Had an instructor demonstrate a fairly vigorous side slip in a 150. This was over 35 years ago and was to show me how to 'fix up' a stuffed practice forced landing into some paddock. Lost control at around 200ft, flick rolled and ended up near enough inverted. After he recovered and during the awkward flight of shame back home I asked what happened... 'No idea' was the reply.... Later on figured out he stalled the fin. It was nasty. . https://cimg0.ibsrv.net/gimg/pprune....cbc98325ba.png |
From the handling, I see side and forward slip as just names. I got my PPL on an aircraft without flaps or airbrakes. Most of my flying has been on an aircraft with airbrakes, not flaps. I can stop a slip without taking my hand off the throttle, so I seldom used the airbrakes. Only recently did I encounter the term "forward slip".
The distinction is like that between "Stop:sign-braking" and "Red-light-braking" which I don't think driving instructor has ever taught. :) |
Originally Posted by Rozy1
(Post 11140254)
I’m thinking the instructor showed you a forward slip.
https://cimg0.ibsrv.net/gimg/pprune....cbc98325ba.png |
Yes, there is a difference! Can you not see the picture?
Hint- look at the ground path and the angle between said ground path and the leading edge of the wing. |
Sitting at 10 knots above the stall on the approach? Your operating outside the normal envelope of the aircrafts operation, it’s called Loss of Control
( I)
Originally Posted by henra
(Post 11138864)
And this is why many here -after acknowledging the good judgement- suggested that a carefully executed sideslip, after having made sure that sufficient energy is available to reach the runway even if the engine completely quits, would have been the icing on the cake.
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Had an instructor demonstrate a fairly vigorous side slip in a 150. This was over 35 years ago and was to show me how to 'fix up' a stuffed practice forced landing into some paddock. Lost control at around 200ft, flick rolled and ended up near enough inverted. After he recovered and during the awkward flight of shame back home I asked what happened... 'No idea' was the reply.... Later on figured out he stalled the fin. It was nasty. One author has said in a typical Cessna 152/172/182, depending on the amount of slip, the airspeed can easily be off by 20%, which means the energy is off by 40%. This is enough to cause real trouble. Location of the static source induces errors. |
Originally Posted by Maoraigh1
(Post 11140278)
From the handling, I see side and forward slip as just names. I got my PPL on an aircraft without flaps or airbrakes. Most of my flying has been on an aircraft with airbrakes, not flaps. I can stop a slip without taking my hand off the throttle, so I seldom used the airbrakes. Only recently did I encounter the term "forward slip".
The distinction is like that between "Stop:sign-braking" and "Red-light-braking" which I don't think driving instructor has ever taught. :) Yes they are names, but there is a difference. I think most people, even pilots, intuitively think of the slip as a side slip because the side of the airplane is headed towards the runway, not the spinner/longitudinal axis. Just my guess as to why so many get it backwards. A lot in aviation is taught incorrectly. Like two molecules leaving the leading edge, then because of a rendezvous they have set up at the trailing edge, the one on the top of the wing goes faster. I have heard lift described thusly from more pilots than I care to admit. |
A miss is as good as a mile.
Any landing you can walk away from is a good landing. Any landing that you can fly away from is a great landing. Nobody panicked even if they didn’t nail the landing. Once you become a glider, your options are limited, and although all private pilots train for engine out emergencies, it’s hard to get over the instinct that altitude is good. Once upon a time, a man spun in and landed his single engine plane inverted in a field, with his family onboard, near where I lived because he thought that it was better to press on regardless at the edge of an approaching hurricane rather than sit it out and await better weather the following day. The plane looked pretty good, aside from being upside down and somewhat crunched. No survivors. |
Forward slip vs side slip versus crab landing…
If you land with your landing gear at an angle to the runway, you risk the sideways force collapsing them under the plane. Always best to land with the plane aligned with the runway. I have landed with strong steady crosswinds in a forward slip on approach according to the above diagram, which I was told was a crab landing, then switched to a side slip in order to keep the landing wheels aligned directly with the runway, albeit with plenty of rudder which meant that the upwind wheel touched down first, and the other main touching down second when speed/lift dropped sufficiently. I have also done S turns on approach if I wanted to burn off speed/time/landing distance, but only when there was another plane ahead of me on the runway/approach. Yes, this pair could have done S turns/weave back and forth to burn off speed/distance, but they may not have had the time/leisure to think it through and it may not have reduced their altitude fast enough. |
Also, in terms of “slips” when you are not trying to land…
If you want to go from point A to point B in a crosswind, you will be pointing into the wind in order to maintain heading to your destination, so you will be flying “sideways” relative” to the ground. It reduces your net speed over the ground, which increases your fuel consumption for a given flight, but otherwise crosswinds are only a major problem when you try to land. Hat, coat, door… |
Wind correction angle is not a slip.
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