Side-slipping

[FNG]

Air law has been somewhat prominent in recent discussions here and, of course, it's an important subject, but may we talk about some aspect of aircraft handling that has not been done over recently? I suggest that we overshoot away from landings, but what about something like side-slipping? How many people are or are not taught how to do it? How many people regard it as part of their everyday skill set? If possible, can we avoid concentrating exclusively on the wisdom or unwisdom of slipping in C172s with the flaps down, although by all means go on about that if it gets your cookies. What else? Lowering flaps in the final turn? Fireproof shreddies? Cup holders?

[shortstripper]

Learnt forward and side slipping when flying gliders ... second nature now.

C172 ... I've slipped it OK with full flap but like you I don't really want to go there as the subject has been done to death!

SS

[DRJAD]

It was only when I expressly asked for some extra crosswind landing instruction, post PPL, that I was taught anything about side-slipping and some uses for it.

Since having that training, I'm convinced that confidence has improved more rapidly since it gives and extra technique for use in various circumstances. I.e. a backup on occasion.

In the light of this, I'd have thought s/s should form part of the PPL syllabus.

[FlyingForFun]

Ooh, side-slipping - Fun! Depending on the aircraft, of course.

I got my PPL on a PA28, and my instructor taught me to side-slip. Have never had any problems, and it can be a very useful technique.

Then I switched to a PA18, and one of my instructors taught my to side-slip properly (doesn't count unless you are using full rudder.... and preferably whilst turning in the opposite direction to that in which you've applied the rudder). Had a go at doing the same in a PA28 once, and it wasn't quite so comfortable as the PA18.

Then had a chance to fly a couple of aircraft like the Great Lakes, Pitts S2B and Tiger Moth where knowing how to side-slip is not just useful (and fun) but pretty much essential.

My Europa is not a nice aircraft to side-slip - it likes to pick up speed, and will very quickly go above Vfe with the flaps down unless you keep an eye on it. I try to practice regularly, but it's not something to do close to the ground unless you're in practice.

And finally there's the C172 - the ones I fly warn against side-slipping with full flaps in the POH, so I've never tried it.

The moral of the story? From my limited experience, it seems to depend very much on the type of aircraft you fly. Some can't do it, some can but only if you're careful or only up to a certain point. Others are brilliant at side-slipping. Definitely something that you should get someone to show you if you fly a suitable aircraft, though, IMHO.

FFF
------------

[Genghis the Engineer]

I've never sideslipped a 172 either.


But it strikes me that there are two possible reasons for such a prohibition. One is that it creates a handling problem, most likely longitudinal or directional instability (I saw both on a prototype once when sideslipping with full flaps, quite exciting). The other is that there is a combined rudder / aileron / flap (probably the last two) stress case which is considered hazardous to the airframe and therefore was prohibited.

Now if shortstripper has found no handling problem in sideslipping a 172....

G

[tacpot]

I was taught to do it properly during taildragger difference training on an aircraft without flaps, so again it was pretty much essential. Until then it had not really been taught very well, i.e. I hadn't learned to do it. :)

[TonyR]

I fly a Rallye 100 into 320 M of grass, over trees from one end. In zero wind I "MUST" side-slip to get down in order to leave a reasonable margin to stop.

It goes back to the thread on "real pilots", For some reason young instructors in the main don't teach side-slipping, many new PPLs don't know about it nor when to use it.

If you must come in "high" over trees etc, or you "end up" too high on approach, you want to loose as much height as possible while travelling the least forward distance.

Therefore if you are still high while flying at minimum approach speed then you must "make" the aircraft fly less efficiently to increase the rate of "sink", side-slipping is the safest way to do this.

The C172 with 40 degree flaps should not be sideslipped with "full" flap. This is not because the aircraft will fall apart, but because the vertical fin could stall due to the disturbed airflow over the fin and rudder at a slow speed. As you already may have input full aileron, the aircraft could roll unexpectedly and perhaps through 90 degrees before you are able to recover. (not something you would want to happen close to the ground).

To side-slip without full flap in a 172 with 40 degree flap, will not give you any advantage over just using full flap and keep the speed at min approach speed.

Go out and learn to fly cross controls, find a good old "cub" pilot to go with you.

Tony

[RodgerF]

Quote:

In the light of this, I'd have thought s/s should form part of the PPL syllabus.

It is. Part of Exercise 8.

R

[TonyR]

PPL syllabus, by Tony R

20 hours in a can, 172 or PA28
5 hours in a Glider
5 hours in a Cub
2 hours Aeros ( Cap10 or something similar)
5 hours instrument (at least one ILS to 500 feet FOR REAL)
2 Hours in something fast and complex
1 flight in a multi engine
1 or more parachute jump to finish

After which you can go and learn to find your way around.

Tony

[WestWind1950]

I was always told that you NEVER side-slip with flaps down... especially not full flaps. I can't find anything about it in all the flying books I own, but it seems sensible to me.

Westy

P.S. side-slipping a PA18 is sooo much fun!! :p

[Flyin'Dutch']

was always told that you NEVER side-slip with flaps down... especially not full flaps

Why would that be then?

FD

[foxmoth]

I was always told that you NEVER side-slip with flaps down
Depends totaly on the aircraft - read the POH

[TonyR]

Most aircraft are Ok to slip with full flap. and in most aircraft if you don't use full flap your side-slip will make little difference to your approach, so why bother.

[High Wing Drifter]

Re the flaps and as per my ATPL course: When side-slipping, if flaps are deployed then the mean lift point moves in board towards the root. This reduces the stabilsing leverage and makes the aircraft unstable. Propeller wash has a similar effect. Apparently, low-wing aircraft are also generally unstable in the side-slip. High wing and swept wing aircraft are the most stable. If you draw a picture it is instantly possible to see the AoA differences and imagine how the airflows overthe fuselage and onto the wings. Intersting stuff.

However, I don't have the courage to try side-slipping for real without being taught. Where can I go in the Surrey/Hampshire area to learn how to do these kind of things?

[Send Clowns]

I would suggest taking any type of light single you fly, take it high, preferably with an instructor or experienced safety pilot, and glide down, slipping it even as far as full rudder deflection in each direction. Note to avoid spinning and killing yourself - KEEP THE SPEED UP, and treat the ASI with caution (it may under-read).

Tried this recently with a high-hour "student" (was retraining from lots of experience stateside - I learnt there under a very good instructor, why can't they all teach what he taught me? Why is there so much bad training of Europeans out there, when much of the FAA training is quite good?) who really had never been shown the sideslip. Very useful exercise, especially in a Robin 200 (tiny flaps, maximum 20 degrees).

High-wing - if you can get to the other side of Hampshire I'd be delighted to show you.

TonyR

I could show you what can be done by way of angle of descent with sideslip but little flap.

[Final 3 Greens]

I've never asked Mr Cessna why side slipping with full flaps on the 172s I've flown is prohibited, but it certainly is not allowed in the POH.

There is a view amongst some jocks with much more experience than me that the 172 can stall with a very big wing drop and enter into a spin when slipping with full flaps if the airspeed is allowed to decay , but as I say, I've always followed the rules.

Having slipped PA28s extensively, its a great way to lose height rapidly and anyone who hasn't learned it would do well to spend some time with an instructor - the best thing is as soon as you remove the cross controls, the aircraft flies completely normally again, not pitch up or down as experienced when latering the flap settings in some aircraft.

[MikeeB]

That's interesting, as I was taught side slipping at the same place that DJRAD wasn't. It was shown to me in more than one lesson, infact I remember coming in a bit high on a dual circuit once or twice during lessons, so sideways we went :)

I also remember one of the comments which was said in jest, "OOOoooooo flash ba5tard"

The thing that I should practice more is getting out of it without coming off the centre line of the runway, as I tend to find that I always let off either more foot than stick and go all over the place.

Something like that anyway.

[TheSilverFox]

HWD. You know where you can come to in surrey to be tought!

As for the cessna slip with full flap:-

1 )Think about the relative airflow in that condition

2) Think about what will happen to the airflow that passes over (and under) the wing (Into the slip)

3) Think about which control surfaces will be masked by aforementioned wing & flap

4) You have your answer!

Send Clowns. The ASI may Under or Over read depending on the direction of slip (Assuming only one static vent).

As mentioned by a pevious poster. The sideslip is part of the JAA syllabus (as it always was with the CAA syllabus).

[IO540]

May I ask what is the purpose of side slipping, in the context of PPL training?

I know the ald argument about crab v. sideways landings, but apart from that.

[Thirty06]

I'd read about side slipping and already crabbed and attempted wing down landings (they just dont feel natural!)

I was doing an approach and my instructor said (quite rightly) you're obviously too high here, so do something about it.

A bootful of left rudder and a twist of the yoke adjusted the vertical hold nicely (2 reds 2 whites). Controls to centre brought us back onto a normal descent. I think it took my instructor by surprise.

Pity I forgot to do it at Gloucestershire on my QXC as I sailed over the runway at about 500ft with full flap, throttle off and me bashing the dash with a kneepad shouting 'Down Boy !! Land dammit'. After go around I stopped short of the gravel trap (marked satisfactory) .

Must try it on a PA 28 next time I'm looking down at the threshold from on high.

I reckon it's better than just winding on the flap and wishing you had spoilers.

[High Wing Drifter]

Send Clowns,

Thanks! You're in Bournmouth right? I would like to get out and about to meet fellow Pruners anyway so you better be careful as I might take you up on that :ok:

SilverFox,

True, true. Thing is until this thread I never actually considered that one of your chaps could show me this stuff in a 152, with flaps the size of a small Pacific atol it hardly needs it. Thought it was the stuff of Cubs, Austers and Tigers (don't ask why) :) Wonder if the ol' AA5 is any good at this stuff :D

[paulo]

Well welll! Mr Clowns here in the private forum. Well, I bid good day to you sir despite some previous skirmishes elsewhere. :ok:

I've been mucking around with some sideslips, but not in the usual sense. Basically messrs. Cassidy* has advised in his great book that the right way to enter a comp. turn is to rotate longitudanly(?) then put the turn in, i.e. roll (no yaw please) then bank.

Can I just say this is an arse to do in a low powered mount. I can get the Robin over to, maybe, 30 degrees with full opposite boot before it's going to turn whether you like it or not.

Is the 'correct' comp technique assuming Pitts or better or am I doing something wrong? Stik? Anyone?

* Much respect.

[TonyR]

Send Clowns,

You stated you could teach me "what can be done by way of angle of descent with sideslip but little flap".

Also you stated "KEEP THE SPEED UP"

I fly into very short strips every week and the reason I sideslip is to "decend steeply over the shortest distance"

I must fly the aircraft at the minimum approach speed to achieve this, and the minimum speed is achived with full flap on most a/c with few exceptions.

I have 53 aircraft type logged and most fly the same.

HWD, you state "Apparently, low-wing aircraft are also generally unstable in the side-slip"

This is just NOT TRUE

Tony

[High Wing Drifter]

TonyR,

My mistake, I should have written low wing configurations are more unstable rather than low wing aircraft. As aircraft designers, one would assume, have sought to combat that!

According to my notes:

For low wing aircraft, the principle being that the airflow over the fuselage generates an upflow of air over the lee wing (outside wing) increasing the lift of that wing and hence increasing the angle of bank (which is the definition of unstable) rather than decreasing it (the definition of stable).

However, dihedral directly combats this effect by reducing the angle of attack of the lee wing. Swept wings provide a stabilising influence too, to do with amount of wing directly presented to the airflow.

Apologies for my rather anal contribution to this thread but I like these discussions because they add a dimension of realism to my studies.

[TonyR]

Just before anyone gets in the club a/c and goes sideslipping, this should not be practiced on your own at low level, but it is a good way to get to know more about your a/c.

Many of you are already doing it when crosswind landing!

[Monocock]

Your last post was well pointed out there TonyR. With full flaps some of the club a/c do have a tendency to bite. They side slip beautifully.......to a point. Unfortunately that point suddenly appears and at the kind of heights we are talking about on final, there is rarely enough time, height or power to do much about it.

I spent several years flying the 172 and only the 172. I side slipped a lot especially in situations where there was a quick loss of height required late on. An example would be the northerly runway at Popham where the trees can keep you quite high above the threshld especially on a war an dcalm day where you can anticipate plenty of float.

I did once go up to 4000 ft and try out some side slipping with 30 degrees and then 40 degrees of flap. The stall was reasonably predictable with 30 degrees, with 40 degrees it was a killer. The trouble with practicing at this height is that you do not get the visual effect of the onset of the stall and the sudden height loss. Only the VSI tells you what is happening in terms of "falling" and at this point, you are working to get it straight and level again, not glancing at instruments.

I now have a flapless Luscombe and have learned a lot more about side slipping. My view is that the final approach on flapless a/c does tend to be slightly flatter than the approach associated with an a/c with flaps. Speed control is paramount to avoid floating down the runway and tiny side slip inputs are invaluable to maintain the correct speed over the threshold. I feel that too many people see sideslipping as a "quick way to lose unwanted height". They boot rudder and opposite stick, lose 150 feet and then continue a normal approach after they have settled the a/c.

Sideslipping can be used all the way down if required. We all know that descent must be controlled by power and speed by pitch. There comes a point in the descent where your 6th sense tells you that these inputs alone will not bring you neatly over the threshold.

At this point I tend to gently ease in a sideslip (always right rudder and left stick for obvious visibility reasons) and then hold it for a second. The sideslip seems to need a second or two to develop and there is much skill in balancing both inputs to avoid "overyaw" or "wingdrop". If the input is not sufficient, the pressures can be increased gently until the correct descent rate is felt.

I often find the nose can lift involuntarily during the sideslip but the ASI still reads a healthy number. This is where I am always extra cautious, especially when stopping the slip. If the nose isn't lowered when the control inputs are cancelled this can leave the a/c perilously close to the stall especially when it is slightly "wallowing" after the sideslip has been cancelled and it is re-balancing itself.

I do hope this hasn't all seemed like a load of drivel. I wouldn't be writing all this if the sun was shining and I could be flying!

Hoping to get to Popham later if the cloud lifts, the wind is slightly from the North. Time for some side slipping over those trees !:ok:

[englishal]

Side slipping is fun, its great to see how fast you can come down :D Its good fun going out and experimenting with what your aircraft is capable of.

Another important thing to prcatice, which probably isn't practiced enough is slow flight, for example flying a 172 straight and level at 50kts or less. My standard of flying improved dramatically when I did the CPL, before this I would have classed myself as an average pilot, who could fly, but not particularly beautifully. During my training, me and my very good instructor used to do a lot of "exploring the envelope", very slow flight, accellerated stalls, cross controlled stalls, all sorts of stuff. We used to push it, he used to tell me to "go for it, if we spin, we'll recover".

As a PPL I had picked up loads of terrible habits, like looking at the instruments too much during stalling exercises "to keep the ball centered", so a lot of my training involved covering up all of the instruments (except oil guages) and flying by "the seat of the pants". Bloody excellent, it taught me a hell of a lot, especially when flying as slow as possible, with no reference to the ASI, but just "feeling" the aircraft, or stalling while watching the wing tip.

Good fun.
EA:D

[Mike Cross]

I echo Monocock's sentiments. Get used to a Luscombe and your skills will improve. Sideslipping down from the trees on 03 at Popham is a very useful skill and very good with a crosswind as it straightens everything out for you.

So everything suddenly went quiet and the only tenable field is short and awkward with a crosswind and obstacles on the approach. Being confident with this skill could be a lifesaver.

Apart from helping you with sideslipping the Luscombe will also improve your approaches by making you nail the right speed.

Sideslipped a 172 all the way down to the runway last year on my BFR in the US last year after the instructor gave me a PFL with flap failure. It was very well behaved but my right leg muscles were getting tired. I imagine the prohibition in slipping them with full flap is because the turbulent airflow off the trailing barn door is running spanwise and screwing up the effectiveness of that aileron.

Mike

[High Wing Drifter]

TonyR,
Many of you are already doing it when crosswind landing!
Now I'm confused. Please explain.

Mike,
I was taught to do tight S turns to get into a field without flap. I have used this techique when, on a couple of I occasions, I was too after getting a straight in approach (sometimes hard to judge without the preceeding circuit).

[WestWind1950]

I've been checking some of my flight training books about doing forward slips and flaps. Here's what Kerschner's Flight Instructor's Manual says:

The two main reasons you should avoid letting the student put the flap-equipped airplane into a forward slip in the presolo period are: (1) .... .. (2) airplanes with flaps extended may have bad reactions to excessive cross-controlling and an accident could result (or at best he could scare himself on one of his early solo flights). Some planes have placards forbidding deliberate slips with flaps extended. .

He goes on to explain how to do it and, as I also learned, tells that you apply aileron first and then the rudder.

Interesting how the views about it varies.

Glider plane training comes in handy when learning to slip :p

Westy

P.S. I'll continue checking my other books..... ;)

[Monocock]

That is interesting...

I suppose I have always entered the rudder input first to enable me to look ahead better before pushing the stick over.

I shall try your method later on Westy.

If this is the last post you ever read from me, you'll know that it wasn't very successful

:ouch: :ooh:

[shortstripper]

Lots of interesting stuff but some rather off the ball answers!

Send Clowns ... I'm sure your "keep the speed up" bit was simply to try and add a safety margin, but it's really misplaced over-cautiousness. It's actually very difficult to spin from a side or forward slip. Two main reasons, but don't take this a wholly true as there may well be exceptions! ... Most aircraft will tend to run out of rudder authority before you reach stall and will naturally start to turn back into trim. You will by then of course be VERY near stalling so it won't take much to tip the balence but you'd be a fool to miss the signs. Also, unlike skidding manouvers, you are in a pretty safe configuration as the inner wing (relative to airflow) has a better "bite" of the airflow unlike outer wing which would cause that wing to stall first. As the slightest easing of rudder pressure will swing the outer wing back into relative airflow faster than the inner wing it will very quickly take hold again. I'm probably not very good at explaining this, so go up to height and try it. I was taught to completely ignor ASI when slipping but this was basically because a glider has a pot pitot which is VERY inaccurate in the slip. The habit stuck though and I find it's easier to go by attitude and feel. To slip effectively though, you will tend to find you need a slightly higher nose up attitude than when you fly "in flow" to keep the same airspeed. It can seem a bit scary until you get used to it but there's no point in letting the nose drop in a slip because you will loose all that short landing advantage by the ensuing float.

I note of caution ... some homebuilds and I guess some factory types don't have the strongest of sternposts. Slipping is OK at slow speed, but not at all appropriate at too high a speed as stressing will be high!

C172 slipped very well. I was with an instructor at the time and he was under the impression that what he called a myth was to do with elevator blanking. I hadn't read the POH and I guess if I had I may have not been so enthusiastic. However, it slipped beautifully, came down very quickly, which in itself is dodgy as all that downward momentum takes some checking! To be honest with those very powerful barn door flaps, the one aeroplane you really don't need to slip IS a 172 :\

SS

[stiknruda]

IO 540 asked:

May I ask what is the purpose of side slipping, in the context of PPL training?

I guess that in simple terms it is another very potent weapon in one's flying arsenal.

For finessing landings it is absolutely essential - I am not talking about bringing a PA31 with eight friends in the back into 6 000' of billiard table smooth tarmac, where throttle and flaps can effect the same seamless transition from aircraft to ground vehicle.

What I mean is judging your touchdown point very accurately in an aircraft with no flaps or with u/s flaps.

When will this be useful?

Well several scenarios spring to mind;

1 forced flapless landing into a confined space
2 landing into a short strip
3 landing something hot and fast (sports biplanes?)
4 3 pt landing something with very poor forward vision (C195)
5 wishing to land and avoid hay bales and cowpats on a farm strip!

Of the two aircraft that I own, if I was not competent at side-slipping then I'd never get them down!

Paulo - the comp turn is a low K factor, however if you do exactly what Uncle (aka The Master) says in his book you will generally score quite high. Having never flown a Robin I can not really comment on technique but are you sure that you are not being too energetic with your feet?


Stik

[JoshCritchley]

Its been enlightening (as always) reading everyone's responses on side-slipping (good thread FNG).

7 hrs into my tailwheel conversion, apart from being a much poorer tailwheel student than I hoped to be (!), its been interesting to learn how poor my side-slipping skills are. I also find it slightly intimidating to do it on finals when relatively close to the ground.

I'm sure all this will sort itself out with practice, but its certainly proving to be an interesting learning experience!

Stik - who's the Uncle?

[stiknruda]

ChiSau, (cantonese for toilet!)

Uncle is an old nickname of Alan Cassidy, multi times winner of the BAeA Unlimited Championship, after his last victory in 03, it was suggested by the competition director that he be referred to as The Master, an appelation reserved for Neil Williams!

Cassidy's book was mentioned in Paulo's post on p2.

Stik

[bluskis]

IO540

Or even forces flaps down landing into an adeqate length field.
How do you do your engine out landings without the extra tool of side slipping to adjust your touch down point?

[TonyR]

HWD

I was talking about flying using "cross controls" during a crosswind landing, most people do it naturally.

Using s turns can mess up your approach, sideslipping keeps you on a constant visual picture during final.

If PPls were also taught how to fly at minimum drag speed, with power, then most approaches would not need side slipping.

Why do most people fly their final approach 20 knots faster than necessary?

[Evo]

7 hrs into my tailwheel conversion, apart from being a much poorer tailwheel student than I hoped to be (!)


Don't worry, I suspect most of us find that! I did :O

[FNG]

This is all good stuff, and no one has asked if it's legal, which makes it even better. Bit disappointed that we didn't get on to cup holders, but you can't have everything. Mmmmmmmm, side-slipping...yesss. Could be a life-saver, I reckon, if trying to force land, with or without flaps. When I last did a PFL in a Bulldog, I ended up rather too high on final (those who have flown the lead-lined sack of heavy things that this aircraft becomes without power may share my surprise at this), but a bit of side slipping sorted that out.

[Pinga]

If you fly as badly as me then you would be an expert at sidesliping too! You know, too high, too fast! Whooooa get this beast down:uhoh: A good sideslip on shot final makes it even seem like I know what I'm doing.:mad: :ok: :E

[TonyR]

If any of you have never flown in a glider, please go and have a lesson, it will be the best £40 odd you will have ever spent on flying.

[Monocock]

Sorry TonyR, you wouldn't get me in one of those if you paid me £40 a minute.

If I did go in one it would be under the following criteria....

1. It would have to be painted an obvious colour so I could at least be seen by powered pilots travelling at 140 kts.

2. I would make sure the pilot didn't "hang around" the exit areas from busy airspace and near VOR's like they all seem to.

3. I would have the radio OFF so all that 123.45 garbage wouldn't get in the way of someone actually trying to transmit something useful.

Apart from that would love to!! Any offers?!!!!!:}

Sorry, but I think the biggest problem and cause of bad PR in low level airspace is the gliding fraternity.

[TonyR]

I never had a radio in any glider I was in but it is 20 years since I have sat in one, I must go for a flight soon,

There is the Ulster gliding club over here in "not so busy airspace", give me a call and fly over, they welcome GA and have a big 800 x 600 M field to land in any direction.

Tony

[Shaggy Sheep Driver]

Every pilot should try to get sideslipping into their flying 'skills base'. Sideslipping the Chipmunk helps with short strips if you're a tad hot or high and the power's off and full flap's down, but that lovely round-section rear fuselage is not that draggy when presented a bit sideways to the airflow, so the ROD isn't dramatically increased.

But last week I was flying a friend's non-flap Citabria, and finding myseld a tad hot on short final, it was almost a reflex action to push rudder and slip the ship. She slips superbly, loads of added drag from that slab-sided fuselage, and we arrived over the numbers at the right height and speed.

There is a tendency when slipping to allow the nose to drop (as someone else said), which lets the speed build up, and you'll float past the end of the strip. You will need to haul back a tad on the stick when slipping to prevent this - and like evrything else in flying, continued practice makes it second nature.

SSD

[High Wing Drifter]

TonyR,

Ah OK. I must admit that I only crab in a crosswind but will use crossed controls at takeoff to prevent wind-cocking. Doesn't result in sideslip though.

Why do most people fly their final approach 20 knots faster than necessary?
Can't speak for anybody else, but I have only ever flown according to the POH. For the AA5 that is around about the CAA recommended 1.3 x Stall speed. The C152 POH does have about a 5 knot margin over that which does seem a touch excessive. Not sure why, haven't asked. But it maybe due to its profile drag that slows the a/c quickly once you cut the power for flare. Must ask my instructor.

Since writing this half truth I went back to the text. The 1.3 x stall is for Vat across the threshold and not for the approach speed. It appears that POHs diverge here as the AA5 Vat is 10kts more than stall with full flap. Also, it would be induced drag and not profile that would be dominant below Vimd (in theory).

[JoshCritchley]

Thanks Stik - very close.....but not quite


;)

[locksmith]

Did some sideslipping today, The instructor was not too hot at it so we both had a lot of attempts at getting some serious "sink" with very little forward distance.

It felt good to do something different, that will be useful in the future.

Also did some "slow flying"

Ken

[Snakecharmer]

FNG - good idea for a thread!

Interesting to hear peoples' experiences of classic aeroplanes and the 'running out of rudder' tales...

If you really want to sideslip... try the Tiger Moth... beautifully controllable slip... and see what happens when you run out of... aileron!

[IO540]

It seems to me that

"Real" pilots would like the PPL syllabus to include full spins, side slipping, barrel rolls, etc (but surely one can do additional training for aerobatics)

Taildragger pilots would like every PPL to have taildragger training, so they can fully appreciate the fun of flying a taildragger (but surely you can get differences training for that)

Pilots who got into flying to go places (myself) want the PPL syllabus to include much better nav training, GPS, the IMC Rating, as well as wanting instructors that actually fly IFR for real, as well as being able to rent planes that aren't falling to bits, etc (no likely solution to this one; you have to do the IMCR / IR and then buy a decent plane)

ATCOs, judging from their regular moaning here and everywhere else anyone is likely to read it, would like people to (somehow) know where they are when they are flying. I suppose they want better nav training (but how much more certain of position can Mr Average Pilot get when all he's been taught is a stopwatch and a piece of string?). Nothing will change on this front until dead reckoning is abandoned or supplemented with something better.

None of these groups are going to get what they want, because the 45hr-min PPL syllabus is far too short to teach someone all this stuff, and any changes have to be internationally agreed. In 45hrs, you can learn to just about takeoff, fly level, and land, safely. It's no good complicating things beyond that. And one has to keep the 121.5 people in their jobs - if everybody got a GPS and used it correctly, they would be completely redundant :O

[WestWind1950]

because the 45hr-min PPL syllabus is far too short to teach someone all this stuff,
but that's just a MINIMUM.... no one says you can't, or should, do more. It's up to the instructors and schools to advise doing more... the minimum of 45 ist quite enough... anymore will just scare potential students from getting into flying to begin with. Once they get the flying bug, they often don't care how many more hours they need until getting that piece of paper....

my opinion..

Westy

[Skylark4]

Monocock,
You really should go to a Gliding club for a chip removal session.
Colour:- Most modern,(glass), gliders are white, so are an awful lot of modern light aircraft for the same reason. Gliders are usually either turning in a thermal, in which case they are easily seen due to the sun glinting off the wings,(assuming you are spending more time looking out than admiring your GPSDMEVORHDI), or they are flying 'on track' in which case their speeds are similar to most powered aircraft and the glider pilot has probably seen you anyway.
Exit areas:- Gliders do not generally enter controlled airspace so they will tend to be 'crushed against the fence' so to speak. If you are cleared to operate in airways, stay in there where it's nice and safe and cozy and leave the open airspace to those of us with eyes. Glider pilots don't know about VOR and wouldn't know where to find one to cluster around it in the first place. I suspect you are seeing gliders when you start doing a proper lookout, i.e. when you leave controlled airspace or approach a VOR and think "dodgy area, this, I'd better have a look out of the window."
Radio:- Most gliders are on Radio but they are on 130.4 or 130.1 or a few other dedicated glider frequencies. They have never heard of 123.4. Unfortunately, they also do not generally carry lists of frequencies and tend to get busy low down which is why they may land at your airfield without making any radio calls. In most cases it would be illegal for them to do so as they do not have radio licenses and are only allowed to use the gliding frequencies.
PR:- 99.95% of the general public have never seen a glider in the air. Non air-minded people do not look above head height unless a noise causes them to look.

I cannot remember the last Glider/Power mid-air and I will just about guarantee that the power aircraft concerned would have been a glider tug.

Mike W

[FNG]

Leaving aeros and spinning aside, the point of side slipping is indicated above, and it's surely something that every pilot needs to be famliar with. The point of recommending some tailwheel flying is that it may educate pilots out of attempting to land too fast, and reduce the number of bent nosewheels and props. My landings in nosewheel aircraft have improved greatly since I took up tailwheel flying, to the point that I don't recall mucking up a nosewheel landing since then. My tailwheel landings remain very variable in quality, but it's fun trying to get better.

[rustle]

Skylark4

I cannot remember the last Glider/Power mid-air and I will just about guarantee that the power aircraft concerned would have been a glider tug.

Mike W

Power/Glider collision see here: (1996) http://www.dft.gov.uk/stellent/groups/dft_avsafety/documents/page/dft_avsafety_502371.hcsp

Powered aircraft, an AA5, wasn't a tug. :rolleyes:

[Skylark4]

Rustle,
Quite happy to be corrected. What a sad story. From the reading of that, he would have been O.K. if he had pushed or pulled the stick rather than turned. The tip of his left wing hit the tip of the gliders right wing with the AA5 in a right turn. He was still unlucky in that the damage appeared to be minor but his mass ballance weight got jammed.
I don't know if that was the result of a search or if you remembered it. If that is the most recent one there is, it was ten years ago.( I am not trying to start a contest, it's just that I feel that this is an overrated risk)

Mike W

[Justiciar]

My tailwheel landings remain very variable in quality, but it's fun trying to get better

Thank g*d for that. I thought it was just me:{ :O

[IO540]

FNG

"the point of side slipping is indicated above, and it's surely something that every pilot needs to be famliar with. "

Do you really mean EVERY pilot? With gear down and max flaps, I can descend at about 2000fpm and if that isn't enough then I should have started the descent a few miles further back. It doesn't do the engine that good to do this, either. It's also a good way of making rear passengers sick.

"The point of recommending some tailwheel flying is that it may educate pilots out of attempting to land too fast"

Why not just teach them to fly the correct airspeed? If you can't teach a PPL to fly a specific airspeed (plus or minus say 5kt) on final, then he (or the instructor) doesn't have a hope.

Something vastly more important than side slipping is teaching people how to trim correctly. I know many people aren't taught this properly. I was shown how the trim wheel is used to cancel the yoke pressure, but was never told that the trim setting in effect determines the airspeed. Yet lack of this understanding is at the root of speed control problems.

Changing the student to a very different aircraft just to fix speed problems is very wasteful. Currency ON TYPE is so important. And if it is a PPL holder, the chances are that he isn't doing enough hours to stay current anyway.

Those that do lots of hours can of course play around and no doubt they will benefit, just as a car driver benefits from driving different vehicles. But these are not viable solutions to what is basically poor teaching, or trying to teach someone who is just wasting their own money.

I have done plenty of c**p landings (none heavy in the damaging sense; just very untidy, bouncing/balooning etc) and in hindsight 95% of them were the result of landing too fast. As for the other 5%, they don't worry me because perfection cannot be attained in this activity, certainly not in variable winds etc.

[Shaggy Sheep Driver]

"The point of recommending some tailwheel flying is that it may educate pilots out of attempting to land too fast"

Why not just teach them to fly the correct airspeed? If you can't teach a PPL to fly a specific airspeed (plus or minus say 5kt) on final, then he (or the instructor) doesn't have a hope.


IO540

Tailwheel aeroplanes teach more than the importance of a correct approach speed. Far more important, IMHO, is that they teach a correctly held-off touchdown. If you fail to hold off enough, or hold off too high, do it too early or too late, you won't get away with it in a tailwheel machine - it is intolerant of sloppy technique. No matter how good your instructor, there is no finer teacher of landings than an aeroplane that demands correct technique. Every time.

In a nosewhweel aeroplane, you'll get away with quite appalling airmanship (within limits) - until the noseleg decides enough is enough. Then there will be another bent firewall, busted prop, bent panels, and shock-loaded engine.

SSD

[englishal]

"The point of recommending some tailwheel flying is that it may educate pilots out of attempting to land too fast"
I think its more important to:

a) Teach pilots to make critical decisions. If you come in too fast and are not going to make it, do something about it early on. I.e. if it doesn't look right, it probably isn't.

b) Teach pilots how to handle the result of their actions. Crossing the threshold at 100kts won't do any damage to the aircraft IF the pilot knows how to react, and there is sufficient runway remaining. If you keep holding it off, and holding it off, you can make a very nice, all be it long, landing.

They'll soon learn from their mistakes:D


(I can vouch for this, 5000' in a 172, and 7000' in a Seminole :O )

EA

[Monocock]

Skylark4

Thanks for the advice. I am sorry I hit such a raw nerve with you. Had I known it was such a sensitive subject I probably would have never made my post so polite and would have really said what I felt.

As mentioned before, my tolerance of the gliding fraternity is quite low these days and this is not just due to a single event.

I have had two incidences of outdoors stock having to be shot after gliders landing on my land. One of them was a calf that had run into a fence and had its head stuck for three hours. The glider pilot was stopped about 50 yards from it and can't possibly not have heard/seen the problems this animal was facing. The wheel marks showed where the tug had arrived and flown off with the glider and left the poor little mite to strangle itself.

Three weeks of temporary stock fencing work destroyed by a lady glider pilot who didn't even apologise after ploughing through it on landing. She was more concerned about her fibreglass scratches.

Countless gliders actually land on my airstrip and then not say thanks when I offer to hold their wing on departure by tug.

Gliders sometimes circle over the approach to my strip at 400 ft waiting to see if they might just get a bit more lift before using it as a bolthole WHILE I AM SITTING WAITING TO DEPART!!!!

This thread is about sideslipping and I think it is an excellent thread. We have both made our points. There are enough Glider V Powered threads in the archives to keep us entertained for hours if we want that kind of thing. I should know, I posted on most of them.
;)

[TonyR]

They must be nicer glider pilots in Ireland, I never had a problem and I fly into a gliding site and sometimes they land with me.

Its a bit like Those at the "Big airport" saying "dam those fu..ing microlighters, and the microlighter talking about the spam cans, the Pfa,ers hate everybody else and no one wants the poor old glider.

We gave up farming a few years ago and planted 30,000 trees, a good way to put the gliders off.

They do know how to sideslip though

Tony

[Flyin'Dutch']

Speed control is paramount when flying.

The fear of people to stall/spin is such that a lot of emphasis is put on not going to slow. This invariably leads to folks going too fast.

The fact that there are more folks going through the fence at the far end rather than landing short is the best proof of this.

And going back to the original thread; when you sideslip it is the attitude which is important to control speed. Anyone who thinks that the ASI gives any valuable information during the slip does not understand how the cookie crumbles.

FD

[Skylark4]

Monocock.
I have tried to send you an e-mail through this site but I suspect something may have gone wrong. Please contact me if you can.

Mike W

[FNG]

IO540, you say,

"With gear down and max flaps, I can descend at about 2000fpm and if that isn't enough then I should have started the descent a few miles further back. It doesn't do the engine that good to do this, either. It's also a good way of making rear passengers sick."

Suppose that your engine should mischievously stop and you find yourself too high to arrive safely in the only suitable field in range ? Go back and start the descent again? I agree, however, that not making your passengers feel even slightly woozy is far more important than not crashing. Why oh why can't they make aeroplanes properly so that they don't have to do that silly tippy uppy thing to go around corners?

It seems a shame to allow your rabid and endlessly reiterated hostility to all forms of aviation tradition to reduce your armoury of flying skills.

[High Wing Drifter]

Suppose that your engine should mischievously stop and you find yourself too high to arrive safely in the only suitable field in range ? Go back and start the descent again?
An alternative to sideslip is just do loads of S turns to increase the distance flown. Doesn't require any skill over and above PPL general handling.

[IO540]

S turns, exactly. Work very well.

As for FNG's comment, I have already said that someone who had done their PPL and has plenty of time/money, can learn additional skills at their leisure. My comments were clearely stated as relative to what can/should reasonably be taught in a basic PPL. As for engine failure... statistically this can happen anytime and there is a procedure for a forced landing, isn't there?

[foxmoth]

S turns are fine at height but do you REALLY want to do this below 200ft or so - if you learn to sideslip properly this can be kept up right to the flare if needed, it is also something that can be easily varied to increase/decrease the glide angle - a MUCH better tool IMHO than S turns.
I am also surprised nobody has mentioned "fishtailing", where you just hold your attitude and kick the rudder from side to side. Again not as good as a sideslip, but good to have all you can in the armoury AND you can do it in a Cessna full flap if needed.:ok:

[Flyin'Dutch']

Fishtailing?

Just using the rudder like that will induce skidding which if done slow enough is a recipe for a spin.

No place for this in anyone's armoury unless they want to spin.

Maybe approach to land is not the place for this.

If you are so high that you can not safely make the runway with the techniques you master and are appropriate for your aeroplane it is probably time to go around and give it another go.

FD

[Mike Cross]

HWD

What causes a wing to stall? Angle of Attack.
Throwing in tight turns at low altitude in order to recover from too much height on the approach to a forced landing is not the answer. It increases your AoA and will require an increase in airspeed if you want to remain safe. If the landing area is tight excess airspeed on touchdown is the last thing you need.

Consider the S turn itself, you are lined up on the approach but too high so you turn away, let's assume you are way too high so you turn 90 degrees. Your landing area is now alongside the aircraft and moving backwards. To regain the approach you now have to turn 180 degrees and backtrack to the approach path then turn 90 degrees back on to the approach. By turning 90 degrees you have given yourself another 270 degrees to turn, during which you are going to lose a lot more height. Yes you could cut the corners but if you do that you are moving yourself closer in to the field. Believe me a sideslip is much easier. You stay pointing at the runway, you can stop it any time you want without leaving yourself with additional turns to do and it doesn't increase your airspeed.

When you do your renewal why not choose an instructor who can teach you the skill? (Maybe not one concentrating on his ATPL)

Mike

[MichaelJP59]

I'm a student PPL so may be missing something crucial in this discussion, but isn't the wing-down crosswind landing method just a side-slip?

And also confused about the Cessna thing mentioned, are people saying you should always use the crab method in a C150/152 flapped crosswind landing?

- Michael

[Flyin'Dutch']

Michael,

You did not miss anything.

I personally prefer the crab and kick-off method as it will work for any aeroplane and any crosswind.

But even with that you will cross control the last bit (which is fine)

Deliberate sideslipping to come in when too high is good fun and can be appropriate, depending on aeroplane and situation.

FD

[MichaelJP59]

Flyin'Dutch', is it correct that the only difference between the wing-down and crab approaches is where in the approach you transition to a side-slip attitude?

Given that, isn't it easier for inexperienced pilots to transition to wing-down further back in the approach so that they can get used to the cross-control feel for longer before touch-down?

- Michael

[foxmoth]

Just using the rudder like that will induce skidding which if done slow enough is a recipe for a spin

Totally correct - and if you fly the aircraft too slowly in a straight line it is the perfect recipe for a stall, which is why you keep your speed where it should be:hmm:

[High Wing Drifter]

Chaps,

Cripes! I really did not mean to say S turns are better. I would not know (as you all know). Just that it is the only technique I was taught for giving myself more time to loose height. It has worked well in PFLs thus far. Obviously one does not throw one's a/c around the countryside, but just some turns back and fro. However, I know full well that a PFL is just that and is only preperation for the real thing. I like to think that I would not be tempted to depart from my training should the event happen for real. Odds are one day I will find out!

BTW, Thanks again to those for their kind offers of assistance. I will be enquiring about some extra training with my School so I am convinced it is a technique worth mastering. No argument there.

:ok: :D

[KCDW]

Hmmm slideslipping and the PA18 - heaven.

Loved it so much, my instructor on the differences training asked me to lay off it for a bit.

Should it be on the PPL? Tricky one, but don't think so.

Personally, I feel 45 hours for the PPL isn't really enough. If we were to add in all the stuff we weren't taught, or was glossed over, it would be more like 75 hours, but that would seriously reduce the intake, so the desirable stuff has to be left out.

That said, the taildragging course, like the IMC rating, opened up new flying horizons for me.

My advice... Do the PPL, get some hours up showing the relatives their houses, then really learn to fly with IMC, taildragging, aeros etc.

KCDW

ps - the other real treat on a PA18 - really steep turns... 60 deg is for nancys!

[englishal]

I thought side slips were on the PPL....at least they were on mine, sideslipping to flapless landings an all that...

EA

[Milt]

Some references in this thread to "forward side slipping"

Whatever can that be?

Not too sure about the danger in lighties but with the bigger ones there can be some that will suffer from rudder over balance. There have been some even get their certification with rudder over balance so bad that at very high sideslip angles the rudder will lock over.

So be wary if the rudder force starts to diminish at high sideslip angles.

[shortstripper]

"Forward slip" and "side slip" not "forward side slip" ... two different things, although the same :\

I've never heard of rudder overbalence during a side or forward slip in a light aircraft ... but I may be wrong?

It's amazing how these sort of threads always come back to what or what should not be taught at PPL level. Or if one kind of skill is relevent to any other kind of flying. Does it really matter? You simply can't teach everything at an early stage (although side slipping would be worth it "oops, I'm at it too"). The point IS that side slipping is a VERY useful skill to know, takes little to learn, isn't that hard to perfect and could ... just could save you or your aeroplane during a forced landing. It's also good fun ... GO ON ... anyone who can't ... learn to do it next time you're up with an instructor :ok: (and if he/she doesn't know how to either at their stage in the game ... change instructor!!!)

SS

[Flyin'Dutch']

Michael,

I like slipping but not to set off a crosswind. I think the crab and kickoff method is better for that for the reasons set out above.

There is (IMO) little to be gained from kicking off high and then doing the wing low approach over a longer trajectory for students as:

1. You miss some of the visual clues which make the kick off easy to teach and understand when you are higher up and

2. Why teach something which you are not going to use later on.

By all means if people want to learn to sideslip do this initially higher up along ground references.

Foxmoth,

You are of course correct. But if you get your aerodynamics books out you will see that slipping is an inherently safe activity whereas skidding is not. A lot of stall spin accidents happen because folks try to rudder the aeroplane around the corner when slow and low rather than flying coordinated.

SS,

As you say the only thing that exists is slipping and whether that is sidewards of forwards depends on where you steer your ship.

Any other nomenclature only confuses the subject so that hangar fliers can make it sound more interesting and difficult than it is.

;)

FD

[FNG]

I would rather slip than S-turn on the final approach for a forced landing. I'd rather not be turning at that point, and certainly not away from my intended landing point.

[Flyin'Dutch']

I would agree with that but one does not necessarily exclude the other.

As with most things in life there is a time and place for everything.

FD

[Send Clowns]

Sorry I have not come before to clarify the points put to me.

Good day to you, Paulo sir, I am not often here and even less so when I am busy as I have been!

High Wing

Yes, I fly from Bournemouth, and have access to PA-28s (140 to 180), C-152/C-172 and Robin HR200 or DR400 to fly. Would be delighted to help a fellow PPRuNer to improve aviation safety, as many here have done so for me.

TonyR

I agree that if the speed is kept high with no flap then it would be pointless to sideslip into your field. However there are two points: (i) you are using sideslip for an unusual purpose - it is mostly used for adjusting a glide approach or for crosswind landings (I never teach it for the latter; "maintain the runway centreline with co-ordinated use of rudder and pedals") and (ii) the reason I emphasise keeping speed up is because this is a public forum where my advice can be misinterpreted, and speed is a safety factor.

While speed should not be allowed to drop and in theory should rise a little due to the tilted lift vector, in reality angles of bank in the slip are not often high, and speed need only be increased fractionally. However for safety this must be practised a fair amount at high altitude first, as a stall in the slip can cause a spin or at least severe wing drop. Depending on the spin characteristics crossed controls can give complimentary pro-spin input.

This happens at a time when the ASI is unreliable. With a lot of practice you can feel your way all the way down to just above the stall, but get the practice in with plenty of height and an instructor if you feel the need.

Shortstripper

I disagree about the likelihood of spin. While I agree not all aircraft will, some may. Notice that in, for example, a slip left-wing-down, the aircraft has right rudder, the right aileron is down, increasing AoA. You are quite right that the slip and dihedral decrease the AoA of the right wing compared with the left, but we still have a higher AoA near the tip, due to the aileron. Therefore the exact balance of the aircraft comes into play. So the right wing may tip stall, or the wings produce even moments at the stall, with (full) right rudder. These are the conditions for the spin, I had a Robin HR200 go incipient when a student put in similar control inputs, although not from the sideslip.

[Flyin'Dutch']

SC,

Flying too slow in a slip will not cause a spin.

FD

[Send Clowns]

Well, as I said, I had a student use those same control inputs in an aircraft, and it flicked incipient. I'll believe the aircraft.

[Flyin'Dutch']

flicked incipient

Wot is that then?

I know of 'flick rolls' and 'incipient spins' but not the 'flicked incipient'

Enlighten us.

FD

[shortstripper]

SC

If you re-read my earlier post I said that a spin is very unlikely but possibly not impossible whilst slipping. I said this as I believe aeroplanes can always do the unexpected! However, in my experience which is based wholly on gliders and light aircraft, it really would be nigh on impossible to induce a spin whilst slipping ... I've tried and failed on several types. You mention your experience in the HR200 and then say that whilst the control imputs were the same you weren't slipping. What were you doing? if these imputs are put in quickly with a sharp up elevator at the same time, you almost have a flick roll entry, albeit with opposite aileron to normal (which could easily be overcome with powerful rudder and engine torque). In a nicely established intentional slip you have a lot of control and plenty of "feel" which makes the whole thing very controlled. Referance to your ASI is irrellevent as you should fly by attitude in a slip and teach your students the same. If you maintain the same attitude as you were flying pre slip, you will have already built in a safety element. To use a slip to it's full potential though, a higher nose up attitude is required and is still IMHO safe.

Why is TonyR's use of slipping to get into a strip unusual? Most farmstrip flyers and others use slipping for this very purpose frequently.

I'm sorry but I really think that mixing the words slipping, banking near the ground and spinning is inappropriate and could encourage a student/PPL to disregard this useful tool as too unsafe. He/she may then get used to using S turns to loose height in a poorly judged approach. These things tend to balloon at times of stress such as engine failures or even PFL's. It doesn't take much then to end up with an over ruddered skidding turn for fear of banking close to the ground. Now that really IS a SPIN senario!!! :uhoh:

SS

[Flyin'Dutch']

SS,

Well said.

Still waiting to be enlightened what an 'incipient flick' might be.

FD

[mark147]

SS,If you maintain the same attitude as you were flying pre slip, you will have already built in a safety element. To use a slip to it's full potential though, a higher nose up attitude is required and is still IMHO safe.Could you explain that a bit more? My naive thoughts are that if you hold the same attitude in the slip (with its higher rate of descent), that would give you a higher angle of attack. Where does the 'built in safety element' come from?

Intuitively, I think I'd find myself lowering the nose to maintain AoA/airspeed, as I would if I reduced the power. What am I misssing?

Mark

[Flyin'Dutch']

In a good slip there is an balance between the turning force generated by the bank of the wing and the opposite rudder force which you apply to keep going straight.

Due to the fact that the relative wind blows against the fuselage you increase the drag. To overcome this you can either increase the speed or the angle of attack.

When you increase the speed there will come a point where the force the banked wings will become greater than the opposite rudder can compensate for and the aircraft will 'run out of the slip'

When you increase the angle of attack by pulling on the stick the force of the banked wing will reduce and the rudder (if continued to be applied full) will 'win' and the aircraft will start to yaw towards the direction of the applied rudder.

FD

[Send Clowns]

Shortstripper

We were at the point of the stall, no sudden elevator inputs although the rudder was put in quite sharply. There was some power, but in fact it autorotated in the opposite sense to the usual wing drop, although it was with the torque of the prop. Was a stall, wing dropped a lot due to some elevator and the student went rather overboard on the rudder to prevent it.

[Flyin'Dutch']

SC,

Can I comment that for an instructor you use very sloppy terminology.

The movement around the three axis of an aeroplane are: yaw, pitch and roll.

Autorotating is what you do in a helicopter when the engine stops.

Remember the set up for a spin?

When you are doing some slow flying and want to demonstrate a spin you will come up to the stall and when you are there slow down the inboard wing by giving a bootful of into spin rudder and at the same time increase the AOA on that inboard wing by giving opposite aileron.

What happens?

You spin.

Now compare that to the slip.

Which wing will stall first? The same wing as in the pro-spin scenario or the other one?

Think of the falling leaf manoeuvre and you will get the answer.

FD

[foxmoth]

Autorotating is what you do in a helicopter when the engine stops.

I was taught in the services and there the term "autorotation" was used in relation to spin entry, also if you use the Trevor Thom books you will find HE uses the same term (Book1 page 188).

Interesting that you should talk about the falling leaf after your comments about fishtailing at low speeds. If you should do this (fishtail at too low a speed) the falling leaf is what you will end up with in most aircraft as you are going to opposite rudder by the time the aircraft has started autorotating (yes that term again) in the first direction - this is not of course the idea in the fishtail and as stated I would normally prefer to sideslip, but is good to have ALL manouvers in your armoury.:=

[John Farley]

Flying’Dutch’

May I respectfully suggest that you search out a basic aerodynamic text book and read up on the state of autorotation which is essential for any aircraft to spin. This may lead you to reconsider some of your comments.

Sorry Foxmoth - you beat me to it while I was away typing with one finger!

[Flyin'Dutch']

F,

I was not taught in the services and would obviously not dare to question Thom's so if that is what they call the simultaneous movement around the three axis on spin entry so be it.

Fact is though that if you go too slow in a slip you will NOT spin.

If you go too slow the high wing will stall first and if you whilst this is happening reverse the inputs (as in rudder and aileron) you will end up in a sideslip opposite to the one you started with.

You can repeat this infinitum (obviously height permitting)

FD

[shortstripper]

Phew! I'm glad FD stepped in there as I'm hopeless at explaining aerodynamics :(

Mark

I didn't really phrase that bit you quoted very well for the reason stated above. I meant that by keeping the same attitude you are giving yourself plenty of margin over the raised attitude slip not over the in-balence flight you are transitioning from. However, it will not be as efficient as a slip held at the correct attitude (which is slightly raised) . In practice it simply means that if you don't raise the nose slightly you will find your speed is same or slightly higher than it was when you straighten up but you will have travelled further for the height you've lost. In a well excecuted slip you will have to lower the nose slightly as you straighten up but you will have lost a lot more height for a given distance. Don't forget that you are not actually flying that close to the stall in the first place, you are at approach speed which is approx 1.3X stall so you have that margin too. If you get much slower it will be difficult to maintain the slip anyway, so the are plenty of clues apart from your ability to fly by attitude. I use the term attitude over AoA simply because I'm looking at it more from a pilotage point of view. AoA is very difficult to think about scientifically as you fly, whereas your training should have shown you that your airspeed is fairly easy to maintain by visual referance to either the horizon or aiming point and is safe enough under normal circumstances.

SC

Surely if you are at the point of stall you would expect an aircraft to possibly do odd things? It doesn't take much of an over imput of anything to diverge from S and L flight. It's a bit misleading to compare this to a properly flown intentional slip. I can see that as an instructor you might want to play it safe with what you say on here but I just think that you are over stating the danger bit. Sure, to begin with you'd want to practice at height, but once you are proficient and used to the slip characteristics of the aircraft you are flying it is essentially a very safe and controlled manouver.

SS

[Flyin'Dutch']

JF,

Did not see your post and happy to stand corrected on the autorotation issue as I posted above. If you want me the reconsider the comments vis-a-vis 'sloppy terminology' then I would be happy to do so.

Maybe you can contribute to the slipping debate on how you see the issues that are raised.

FD

[foxmoth]

FD

And if you DON'T reverse the inputs?

[Flyin'Dutch']

And if you DON'T reverse the inputs?
Never tried.

FD

PS Thinking about it you would then go into a spin, and if you look at it from that perspective happy to concede that SC's experience was an 'autorotation' However this sequence of events is not what was advertised as 'If you slip too slowly you will suddenly end up in a spin'

[shortstripper]

Oh ******! :\

At least I never said you couldn't spin ... just that it's unlikely :p

Good thread innit? LOL

SS

[High Wing Drifter]

FD,

If you go too slow the high wing will stall first and if you whilst this is happening reverse the inputs (as in rudder and aileron) you will end up in a sideslip opposite to the one you started with.
The ATPL text I am reading agrees with you so long as there is sufficient dihedral in a low wing configuration or when the a/c has a high wing configuration...which I assume most light a/c are one of.

[John Farley]

Standby for Broadcast

(I am sorry but that is a military expression used at the start of a Tannoy broadcast to everybody on a station)

With a conventionally designed aeroplane left rudder will make it roll left.

To enter a steady heading sideslip with this left rudder applied you will have to use the ailerons to the right until the nose stops moving left round the horizon and the aircraft stops rolling left.

This means putting down the left aileron and the right one up.

This aileron action markedly increases the angle of attack of the left wing tip.

This aileron action also reduces the angle of attack of the right tip.

Please be very careful before believing that under these conditions the right wing will always stall first on all aircraft

On many aircraft if you fly slower and slower with left rudder applied you will finish up with autorotation to the left.

If you autorotate left you will spin left.

End of Broadcast

(sorry that is a military expression used when completing a Tannoy broadcast to everybody on the station)

I do hope that is all clear…….

[Flyin'Dutch']

J,

So if I read that back you say that the wing where the AOA at the tip is reduced due to the aileron being moved upwards will stall first. In this scenario the lower wing.

That is not my experience nor the way I understand the aerodynamics to work.

It is my understanding that on a conventional designed aircraft (with dihydral) due to the increased angle of attack (as a result of the relative wind over the wing and the downward aileron on this side) the high wing will stall first.

FD

[foxmoth]

"Dutch"
I think you have read JFs post wrong, in his example he has LEFT rudder and right aileron, ie. you would have the right wing down in a sideslip and you would roll LEFT ie towards the UPPER wing.
(correct me if i am wrong please John) as you say yourself.
Possibly oversimplifying it - rudder Left- spin left, rudder right - spin right. Not ALWAYS true, but for our purposes I would suggest true enough. (And ALWAYS CHECK the spin direction if unsure for recovery - assuming you have the height:sad: )

[Flyin'Dutch']

F,

he has LEFT rudder and right aileron, ie. you would have the right wing down in a sideslip and you would roll LEFT ie towards the UPPER wing.

So keep the full rudder in left and pick the lower right wing up with the aileron?

That is indeed not how I read JF's post.

Is that how it was meant to read?

FD

[foxmoth]

I don't know how you sideslip but I always seem to end up with TOP rudder so left rudder means right wing down - but maybe you do it differently:\
Johns post actually saysuse the ailerons to the right until the nose stops moving left round the horizon and the aircraft stops rolling left.
If you try this I think you will find the nose does not stop moving left UNTIL you have some right wing down (think about this-if you keep wings level and left rudder you will still turn left. If you are still banked left with left rudder then the nose will swing towards the ground)

[Flyin'Dutch']

Agree with that.

Left rudder means right wing down if you want to slip.

But tell me what in your experience will happen if you manage to slow down so much that you stall in that situation. Which wing will drop? The right (lower wing) or the left (higher wing)

FD

[foxmoth]

Left (top) wing - which I believe is what JF said:ok:

[Flyin'Dutch']

Nope,

He wrote:

This means putting down the left aileron and the right one up.

This aileron action markedly increases the angle of attack of the left wing tip.

This aileron action also reduces the angle of attack of the right tip.

Please be very careful before believing that under these conditions the right wing will always stall first on all aircraft

FD

[foxmoth]

John could you sort please:hmm:

[Skylark4]

A year or two back, I was curious to see the effect of flying too slow in a sideslip so I tried it in the Skylark. She certainly did not do anything dramatic (she's a real Lady, mind), there was no 'flick into a spin' or anything like that. As I remember, it was just like approaching the stall but with more buffet and general airframe shaking. I think she tended to run out of control to the point where it was difficult to keep the slip on.
I suggest you all go out and try it, at a suitable height, of course.

I don't know if it has been mentioned earlier but sideslips don't work all that well if the speed is too high. Normal approach speed is about it. Any higher and you just won't get the sideways attitude.

Mike W

[TonyR]

I don't know where this is all going, perhaps there are too many of us telling each other how much we all know.

I would like to go back to "why does the average PPL in a light aircraft need to side slip"

I was taught sideslipping as a 17 year old SPPL in various aircraft as a way of loosing height in the least forward distance.

I still use side slipping for the same reason today (30 years later)

Example: PA28 (any model)

You are down wind at a height of 1000 ft, you expect to turn base and fly a 2 1/2 mile final, decending at about 500 fpm at 70 knots,

ATC request you "to keep it tight" and you turn on final at just under 1 mile, but are still at 800 feet, even with with full flap you are not sinking fast enough. If you put the nose down you will speed up and never get in.

This is where it is useful to side slip, to loose the excess height and still land at or near the start of the runway.

Done properly at the correct speed (ie.normal approach speed or slightly less) you will not damage the a/c nor will you spin or loose control in any other way.

Tony R

[Sliding member]

I was shown sideslipping in a '152 at my last check ride, pretty impressive too, did it with full flap, went down like a brick, intresting noises too at 85kt! What used to worry me a bit is the side loads on the tail, but I'm sure they're well accounted for. I'll have to try it a bit more next I fly (don't know when:( )

[shortstripper]

SM

What used to worry me a bit is the side loads on the tail, but I'm sure they're well accounted for.

Not really. Slipping is not supposed to be a high speed manouver and it does indeed put some strain on the tailplane and sternpost. Besides which, what is the point of slipping at higher speeds? ... OK, I guess if you're in combat there might be a need :uhoh:

JF

Thanks for that answer of yours! ... trust a test pilot to make it sound so complicated ;) I reckon I'd better shut up now as my brain is getting sore with all this thought on what to me is a dark science ... aerodynamics :\

SS

[WestWind1950]

here again a quote from one of my many training books (I left out non essential sentences):

The Slip
The purpose of the "forward slip" is to dissipate altitude without causing airspeed to increase, e.g., airplanes without flaps. In planning the slip, take into cosideration wind direction. Slip into the wind.

Establish normal glide.

Establish slightly less than normal glide speed

Use of elevator: Control speed should be slightly less than normal glide speed.

Use of aileron: Principal control to maintain desired bank. Remember steepness of bank affects angle of descent.

Use of rudder: rudder is used in opposite direction of slip. Another use of the rudder is to keep the airplane from turning and to control the rate of turn.

Maintain original flight path

Note:
check manufacturer's recommendation for use of wing flaps extended during slips

recovery: allow enough altitude for safe recovery. Raise the low wing and release rudder pressure simultaneously to keep the airplane aligned with the runway. Assume normal glide before touchdown. Riase low wing with ailerons. Reduce rudder pressure.


That all coincides with the way I learned it.....

Westy

edited for spelling :ugh:

[TonyR]

It is not a good idea to sideslip too fast in any aicraft, 85 knots is too fast in a 152. You could damage the aircraft

Anyway there is no point in slipping fast it defeats the purpose.

The purpose of the "forward slip" is to dissipae altitude without causing airspeed to increase,

Tony

[Sliding member]

Thats what I thought, I must add that the instructor was showing a way of loosing as much height as possible in the event of the a/c being on fire preparing for a forced landing. I'd prefer to stick to slower speeds for slipping though.

[Send Clowns]

Ah, I think we have the source, of misunderstanding, Mr Shortstripper. I was intending to convey the possibility of a spin in sideslip if the speed reduced and reached the (slightly increased) stall speed. I think you were reading it as an entry into spin as per the spinning exercise - at a high stall speed caused by pulling full elevator. In a sideslip if you keep the speed at normal approacjh speed or above, then you will keep flying. The danger is in an unreliable ASI and in allowing distraction and a low initial speed to bring the aircraft to the stall, hence my warning (remember I am telling people, not demonstrating this with me to keep a student out of trouble) to keep speed up. Wouldn't want to tempt any of our friends here into lethal situations :{