Sideslip as a manoeuvre

[Exadios]

Its in the syllabus. To be issued a certificate you must demonstrate sideslipping. Aswel as a slipping turn through 90 deg's. If you havn't been taught or are not confident in this manoeuvre grab your instructor and go and learn it. Its could be a lifesaving skill. Highwings generally slip better then lowings and some aircraft shouldn't be slipped under certain circumstances, so read the POH and talk to an instructor. It is not a dangerous manoeuvre, but care should be taken. The controls are crossed but it is in an ANTI-SPIN configuration.Another consideration is the IAS may change during a slip. This is due to a few factors and depends on type, but in aircraft with pitot tubes a long way out on the wing the airflow into the tube has to travel around a corner and experiences less dynamic pressure, so the tendancy is for the IAS to over read. In some jabirus I have seen it read 6-8 kts in error.

Cheers

 

Fly safe

I've had the IAS go negative during side slip.

 

 

[dazza 38]

Dazza,What happens if your not a morning person, is it ok to slip it in the arvo or before lastlight???

 

Alf

Yes Alf, It is good to practise slipping it in , anytime realy, depending on the occasion.

 

 

[djpacro]

...... but care should be taken. The controls are crossed but it is in an ANTI-SPIN configuration...

Totally agree - I use the words "typically spin resistant" myself. I find that many people don't understand the difference in behaviour exhibited by a slip cf a similarly controls crossed skidding turn and the typical aggressive departure to a PSG (or why it is so).

[facthunter]

That's why I emphasised the stability of pitch attitude needed. The "lighter and draggy" planes are a bit of a worry here. In gusty conditions the airspeed can fluctuate fairly rapidly and I don't even like power off approaches in gusty conditions. (unless of course you are carrying a fair bit of extra speed, but then you need extra runway, and you still have to get rid of the extra speed sometime).

 

While the crossed controls and wing down is not at that stage, likely to cause a spin entry, all it needs is a gust and back stick and you are in trouble.

 

The airspeed indication cannot really be relied on as the pitot may be in disturbed air and is at an angle to the airflow. It usually under reads.. Nev

 

 

[motzartmerv]

Exadious. Yes mate, i agree under reading happens in some types aswel. I have had this occur in types where the static port is flush mounted on the fuse, and is one sided, ie, not connected to a second static port on the opposite side. When the fuse is presented at an angle to the airflow the dynamic pressure increases, and so, the static pressure decreases causing the IAS to under read.

 

A good practice is as Nev said, to concentrate mainly on the attitude, as it always is. I expect pilots to be able to complete a slipping turn onto final with the airspeed indicator coverd completely or the glass turned off.

 

Under reading is an issue, but in my mind not as much as over reading. The tendency to fixate on IAS and raise the nose accordingly should be avoided for obvious reasons.

 

 

[sfGnome]

Totally agree - I use the words "typically spin resistant" myself. I find that many people don't understand the difference in behaviour exhibited by a slip cf a similarly controls crossed skidding turn and the typical aggressive departure to a PSG (or why it is so).

Can I just get a clarification? Is it basically correct (and I'm trying to use simple terms here for clarity - for me, even if for no one else :) ) that rolling the plane and then using top rudder to keep it straight (ie a side slip) is 'spin resistant', while not rolling the plane enough and kicking in bottom rudder (ie a skidding turn) is 'spin inducing'??

On a slightly different tack, I sometimes use a slight side slip (after explaining what I am going to do) so that my passenger can see something on the ground on my side of the aircraft. Bearing in mind that this is normally in cruise, is that likely to over stress the frame? I've never seen a prohibition in a POH, but then I guess the POH doesn't say "do not attempt wing walking while dressed in a Superman cape" either...

 

 

[facthunter]

There was a recommended technique, clearing of the "blind spot" behind the aircraft by pressing left rudder and applying right aileron prior to turning . I still do it at times, but I wouldn't consider it a good idea to do it at cruise speed. Higher speeds really do increase airframe loads

 

IF you have the rudder inputted ( ie Ball off centre) and you go near the stall as in a steep turn (dynamic loading) you run the risk of the plane "flicking" (Doing an uncommanded roll). If you are doing a steep turn to the left (say) and you have a bit of "top" rudder as some people think is ok, (WHICH IT ISN'T) and pull the stick back a bit, it will roll rapidly to the right in some circumstances. This is the deadly tightened turn onto final that puts Lancairs into the deck frequently. Each one only does it once because it's inevitably fatal. Wirraways were noted for it too. They have to be mishandled to do it but some are more sensitive to it than others.

 

Some aircraft have a pitch instability where the control loses back pressure and a pitch-up occurrs . If your plane is operated outside the allowable CofG thia can happen..Nev

 

 

[motzartmerv]

Can I just get a clarification? Is it basically correct (and I'm trying to use simple terms here for clarity - for me, even if for no one else :) ) that rolling the plane and then using top rudder to keep it straight (ie a side slip) is 'spin resistant', while not rolling the plane enough and kicking in bottom rudder (ie a skidding turn) is 'spin inducing'??

DJ would probably be best to answer that question. But in a general sence, yes. Having said that, its important to remember how autorotation (spin) begins in the first place.

 

To keep it as simple as possible (and I am certainly no expert on spinning) if you get a condition where the wing is stalling AND yawing, then autorotation could occur. In a properly executed side slip the aircraft is NOT yawing.There is no movement about the normal axis. It does however yaw initially when the pilot applies the rudder. But remember, that even during a slip, any change in the normal axis is still yawing as per straight and level. So corrections you make either way on the rudder whilst in the slip will be inducing yaw. For this reason its a good idea (in some types) to not apply opposite rudder when leveling out from a slip, but rather reduce pressure on the rudder and let the secondary effects of the aileron (wing level input) , and the natural stability of the aeroplane to realign the nose. I find this to be the smoothest way to exit a sideslip.

 

I have a question. In a slip, do the two sperate wings have a different angle of attack as they do in a normal descending turn. Ie, when the wings are banked but the aircraft is not turning.? I think not, but I could be wrong (i have been wrong once before ;))

 

 

[djpacro]

Perhaps a new thread is worthwhile for some of this discussion?

 

Just to partly respond to Andrew's question on angle of attack - in a straight side slip the "new" factor is that our wing is effectively swept with the undesirable characteristics of a swept wing at low speed.

 

I'm on the road for a weekend of flying in NSW (after a week with some instructor trainees doing this sort of stuff) so more later.

 

 

[motzartmerv]

in a straight side slip the "new" factor is that our wing is effectively swept with the undesirable characteristics of a swept wing at low speed..

Aahhh..of course.......I should have thought of that...Thanks Dave...

 

 

[Guest Maj Millard]

One aircraft that you wouldn't think would slip well, but does, is the Slepcev Storch. Even with full flap out (only two positions OFF or 40deg), it loves to slip. Generally all round it is a sweet and nimble aircraft to fly. The only other that even comes close to the Storchs' slow approach capability, would be the Savannah VG..On airspeed accuracy in a sideslip, it would depend on where the pitot is located. The lightwing has it out midway on a wingstrut, but adjusting the airspeed in the slip by raising or lowering the nose, gives pretty accurate airspeed adjustment, or at least close enough to be onspeed at the round out for landing..........................Maj...

 

 

[djpacro]

It's a long drive to NSW but here I am - with just one more brief comment on a steady slip at high angle of attack. Ailerons will be deflected so we have the usual effective change in angle of attack as a result. One side less and the other side more.

 

The words that come to mind then are unpredictable; uncommanded roll .... but, apart from specific types per other posts, no reason not to sideslip ...... (more later).

 

 

[Guest Maj Millard]

It's been a while since I regularly flew Cessna 172s, but I seem to recall it was 'vorbotten' on those with full flap ?

 

 

[facthunter]

I never sideslipped them, (172's) at all. With the flap available it was a bit academic but in a crosswind you are doing it a bit anyhow as you flare.

 

Sideslipping is not a manoeuver that is done well by most pilots that I have observed. It is necessary to have good control or don't do it at all. It is often taught to do it to about 100'. In a really tight situation you would do it to flare height. Nev

 

 

[Guest Maj Millard]

[Sideslipping is not a manoeuver that is done well by most pilots that I have observed. about 100'. Nev

 

I would agree nev, that it is dependant on the particular pilot skill level. And is also very aircraft specific, some doing it very well, some not doing it safely at all.

 

Unfortunatly it is one of those valuable skills that seems to be going by the way side, however an experienced pilot will keep current and slip often. It appears to be in the RAA training sylibus, so somebody has been smart enough to include it as a valuable manouver to be taught at entry level, as it should be.

 

Pat McGrath one of our local CFIs, (now retired) used to teach it agressivly starting at about lesson three. You didn't get a license from Pat if you couldn't slip well when required !...

 

The Lightwing aircraft which Pat used in his training loves to slip, and can be safely slipped all the way to flare height without any drama, airspeed can also be adjusted easily during the slip.

 

The full crossed-up side slip is a very safe and stable manouver, and one that you can easily get out of simply by relaxing the control input that you need to hold for a slip. I've never heard of an aircraft going over on it's back, or spinning out of a sideslip................................................................................................Maj...

 

 

[motzartmerv]

I don't understand how people can be issued a certificate and NOT be able to slip safely and confidently.

 

Its in the syllabus. The only consideration could be specific aircraft types not recommending it.

 

 

[fly_tornado]

Its economics really, 90% of your students aren't going to complete their flying training, so why teach something that endangers the instructor and aircraft.

 

 

[motzartmerv]

I see your point FT, but I disagree. Slipping is not dangerous when done correctly. I also Disagree with the 90% thing. If a certificate is issued, then the Syllabus has to be adhered to. You can't leave critical sequences out and then claim " I didn't think he was going to finish his training, so we left that part out"??

 

Slipping is an absolutely crucial skill in most light types,that must be taught, and taught thoroughly.

 

 

[fly_tornado]

I agree but I can only think of that one reason to omit slipping from the training. Upset training is important, panic @ 100feet is most likely to kill you.

 

 

[motzartmerv]

Perhaps, but flying into the trees at the far and of a paddock WILL.

 

 

[Guest Maj Millard]

quote="fly_tornado, Its economics really, 90% of your students aren't going to complete their flying training, so why teach something that endangers the instructor and aircraft.

 

Tornado, not being an instructor myself I can't comment accuratly on the 90% , but it does sound high to me. The activity of flight training in general is inherantly dangerous, with or without an instructor on board., it's where most aircraft get bent. I do know that one type aircraft commonly used in training, is doing a great job of scaring off a lot of potential students by being hard to land and handle, resulting in runway excursions, and unwanted and totally unwarranted first-solo dramas, together with much longer pre-solo training, than is normally required in other types. Granted training aircraft shouldn't be simply to fly, but then they shouldn't be super-difficult either !.

 

Make it a drama filled, no-fun time for students at this stage, and I'll guarantee you'll scare 90% of them away from aviation, forever .

 

By comparison, take a very user-friendly and easy to master trainer like the Savannah, in which every lesson is fun, full of accomplishment, and gets the student soloing safer and sooner, then you'll turn out lots of capable enthusiastic UL pilots !.....who still have some cash in their pocket.

 

Slipping is not an unsafe manouver at all, and is usually covered as soon as an instructor feels the student is ready, along with power failures, cross-wind landings etc. Some prefer to leave the more 'advanced' manouvers towards the end of student training, which works well also, as the student has a good feel for the training aircraft at that stage.

 

As I have said many times in the past on this subject, and I'll say again. 'Most pilots who oppose side-slipping are the ones who haven't taken the time, or made the effort, to master the skill themselves'.

 

I've never known an aviator, who has mastered side-slipping, to see it as anything other than the valuable, skillfull manouver that it is....................................................Maj...

 

 

[octave]

I had to sideslip before I could get my cert. and I practice it almost every flight. I see it as an essential technique (in the Gazelle at least) in a forced landing situation to avoid overshooting if it becomes clear that I am too high.

 

 

[fly_tornado]

I was watching AOPA video about a new flight training initiative, that's where I got the 90% drop out rate from. I did side slipping during training but not enough to master it. Just shown what it was.

 

 

[eightyknots]

One aircraft that you wouldn't think would slip well, but does, is the Slepcev Storch. Even with full flap out (only two positions OFF or 40deg), it loves to slip. Generally all round it is a sweet and nimble aircraft to fly. The only other that even comes close to the Storchs' slow approach capability, would be the Savannah VG..On airspeed accuracy in a sideslip, it would depend on where the pitot is located. The lightwing has it out midway on a wingstrut, but adjusting the airspeed in the slip by raising or lowering the nose, gives pretty accurate airspeed adjustment, or at least close enough to be onspeed at the round out for landing..........................Maj...

Hi Maj, you singled out the Savannah VG in this post. Would you care to comment on either (or both) the Savannah XL and Savannah S as well?

 

 

[Neil_S]

Hi All,

 

Learnt sideslipping in the Texan as part of the normal syllabus, and then since we bought the Gazelle I use it quite often as a valuable manoeuvre to lose height on final if necessary (or when practising forced landings). Also, the more confident you are with the technique the better your ability to forward slip when doing crosswind landings IMO.

 

Talking of which I like to practise the following, and would recommend it to people for practising crosswind landings without actually doing the landing.

 

On a day with a reasonable wind find a straight road which is as close to 90 degrees from the wind as possible, then start at one end of the road and try to fly along the road with your nose aligned to the road. To do this you need to take out the crab with rudder then lean the plane into wind with aileron, just as you would when doing a crosswind landing. When you get to the end of the road, turn around and do the same in the opposite direction. Repeat until bored . Obviously you would not want to get below 500 feet AGL - I am around 1000 feet when I do it.

 

Cheers

 

Neil