G-STRING,

For slipping in Cessnas, the only advice is to read the relevant POH. The POH for some Cessnas - I believe it's only the later C172s, but don't quote me on that - advise against slipping with full flap. There is no such warning in the manuals for any of the aircraft I fly, and I regularly slip them without any problem.

As for the danger of spinning, if you keep the AoA below the critical angle, no there is no danger. Select a slightly lower nose attitude than you would if you weren't slipping. As a rough guide, keep the airspeed similar to what it would be for a normal approach, but bear in mind that the ASI may have errors during a slip, depending on the position of the pitot/static sensors.

FFF
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I imagine that it would not make much different as the stall is related to the lowering of the stagnation point and that is what pushes the switch up. If the stagnation point is 'high' then by definition, the wing has a low AoA. That's the way I see it. Most likely somebody will point out something not considered.
As far as I am aware, most light a/c are designed to stall at the root first. A tip stall can be induced with a power on stall.

I fly a 1959 C172, and the POH does contain a prohibition on slipping with FULL flap (which is 40 degrees in this aircraft). I'm therefore perfectly happy to sideslip with up to 30 degrees of flap, and some people would say that in practice it's fine to slip with 40 degrees as well. You can bet that the prohibition on full-flap slipping already has a healthy degree of conservatism built into it, so there's no need for the oft-quoted nonsense about not slipping with ANY degree of flap.

I agree that there's no substitute for reading the POH of your particular aircraft, and heeding its advice rather than listening to rumours and old wives' tales.

There is nothing wrong or unsafe with a slipping turn as a technique for losing altitude. I.e., if you know that you are high on the base leg, you don't have to wait until you are established on final before feeding in crossed controls.

GS,

Have you done any spins (at alt of course) in the 172 ?

If not, find an instructor who will demonstrate and teach you how to recover from one.

I fly 172's and it is actually fairly difficult to get them to spin intentionally, much less accidentlally.


>Whilst on the subject of slipping turns: I fly a cessna 172, and if high on finals for any reason, often use crossed controls to lose excess height. (Please note that I don't do this in the turn onto finals, but when the wings are level).

Were you not taught slipping turns?

>I find this effective, but again, is there any danger of spinning?

Again, the answer is to go up with an instructor and at altitude, experiment with slipping, slipping turns, even *skidding*.

The goal is to know what the plane will do under different conditons of flight, so that you can avoid being in a situation that you've never seen or experienced.

I.e. don't try someting that you've never practiced !

Mike

Not so. Stall speed goes up when G increases, not bank angle.

Anyway, this question is like asking "When driving a mountain road, how do I avoid going over the edge?"

Answer: "Don't drive over the edge."

Question: "How do I avoid a spin / stall on the final turn?"

Answer: "Don't stall or spin on the final turn."

And how do you avoid stalling or spinning? Watch the airspeed. Let's not make this too complicated.

QDM

QDM - good to see you back Doc!

And how do you avoid stalling or spinning? Watch the airspeed. Let's not make this too complicated

The problem being that it is not that simple! The very fact that the originator of the question was asking about the turn from base to final automatically increases the complexity.

Without going through the math, which I believe was promulgated on page one, what airspeed would you like me to watch?

The harder you pull, the higher the stall speed (some "root" square calc required!). If you learn parrot fashion that a Cub stalls at 37mph, you gash it out to 1.3x3.7 = 48 = 50.

So you know that you can safely approach at 50....... you pull too hard, are a bit slow on the rudder and whooooosh, top wing goes over, nose arcs around and suddenly one is spinning.

To reiterate - I intentionally spin virtually everytime I fly, the only ones that catch me out are the ones I don't expect..... sure recovery is almost immediate but it still makes ones heart beat just a tad faster. I aerobat down to 500' agl but avoid flicky things and stall turns below 1200'.

Some part of me thinks that you'really need to be a numb-nuts of epic proportion not to realise that the aircraft was about to stall (buffet, buffet), hell, ball is out, welcome to Spin City!


But it does happen! So maybe less reliance upon numbers and more on the "feel" would be a jolly good thing?


Stik

How about a simple answer? keep the aircraft so that the view out of the window looks right, feels right and sounds right then it won't stall.

How about that?

That's way too sensible, Sensible :)

SS

How about practising stalling in the finals turn and approach configuration more often so people can learn to understand what it shouldn't look like. And how about making it compulsory for everyone to do a full spin in their PPL course?

Never ever make a tigh turn on finals without airspeed. And never ever stretch finals.

SnR,

Thanks, nice to be back. Never really went away.

Anyway, you're the man who knows about spins, but it does still come back to the fact that if you don't fly too slowly, you won't spin. If you don't let the speed drop on your approach, you won't spin, assuming you're not pulling a load of G to get back through the centreline.

Of course, the time this becomes really hard is when the engine has quit and you're in the process of screwing up the forced landing. At that point, you have to hope that your instinct to crash with the wings level is more developed than that to pull tighter and rudder harder because you're 'almost' in.

As ever, read Stick and Rudder.

QDM (In his PA18 'Pursoot ship')

Not true, in the case of accelerated stalls. As S& R suggests, and the balance of your post implies, if you suddenly pull a lot of G it's a whole new ballgame. :uhoh:

The ASI only tells part of the story ... the accelerometer can be equally important.

:D :D :D

MLS-12D,

Well, yeah. I mean this is all getting silly, isn't it? Don't fly too slowly for the amount of G you're pulling. Best thing, don't pull G on the final turn.

If you don't stall, you can't spin. This is basic airmanship and requires concentration, of course, but so does driving a mountain road or taking a corner on a motorbike. Misjudge it and you die. Misjudge your speed on approach, over-rudder and you die.

You know what to do and just don't screw up, that's all there is to it. That's why we have flying training.

QDM

Fair few people stall and spin 'cause they try to make the picture look right and end up in a big mess!

At times like that you need to fly with your nut, not your balls (instinct)

Good to see you back!

Airspeed and attitude thats it. No more than 20 degrees bank. I sometimes turn a little early when I can be sure I'm not cutting anyone off because we use two parallel strips about 100 yards apart and it is not wise to stray over the centreline.

As a newbie ppl, I frequently apply a little more power on my turn from Base to final just in case, and I always flick my eyes down to the ASI and the ball in the middle of the turn just to check. By adding a little power I arrest my descent while I turn and avoid the temptation to pull the nose up when I start seeing the whites of the golfers eyes.

For a Cessna 172, over here we would have 20 degrees of flap and 70-75 knots on Base at about 1500-1700 rpm. Complete the turn onto final by 500 feet no more than 20 degrees of bank, then 30 degrees flap and 65 knots, gradually bleeding back to 60 knots at the proverbial FAA 50 foot tree on threshold.

Anymore than 60 knots with a 172 (with no headwind) and you will bounce. For a PA28 the only change would be Vref 63 knots.

Hope this helps. I would welcome advice on the subject.

Look up the Whitt's flying page as well.

Sunfish - next time I see you - I'll ask what you will do if you suddenly find you need to turn tighter than that? (eg to avoid overshooting the runway centre-line at MB where there are parallel runways and opposing circuits)

David, with luck I'll catch up tomorrow. Work is getting in the way of flying. I need another go at rolls and suchlike! Give the ears a workout!

I'm not comfortable doing steeper turns at low level although I demonstrated them at 500 feet on my ppl test with no probs.

Normal appproaches i think there is little chance of stall spinning no matter what bank angle is used.

The danger is when you are stressed by bad weather, limited vis. low level circuit with flap down trying to make continous turn to final on high wing aircraft.
Suprising how quickly speed can bleed off with limited external reference.

This is more of a danger for the experienced pilot who has got used to flying by feel.

Students have it drilled into them to watch airspeed.

BigEnd,
I reckon flying by feel is the key to good piloting. The more you can fly by other senses, the less you have to look inside (at the ASI, in this case). I refer to senses because you should see, hear and feel your aircraft.

I find a Dave Clark headset creates a barrier between me and the aircraft when flying an open cockpit biplane. This is detrimental to my flying performance.

We used to have to fly a blind, in the sense of no instruments, circuit before going solo in a glider.

Sssshhhhhhh - I'm off to a surprise birthday party for the person who taught me to fly and also aerobatics. 80 and still flying.