Side Slip

[Morph]

There is also confusion regarding forward and side slips and it is understandable. What we are talking about here is in fact a forward slip. Let me explain

A forward slip is used when on finals in line with the runway and you find that you are too high. In otherwords you are set up for a straight in approach, wings level. Your airspeed is right, flaps set. You now need to loose height quickly without gaining airspeed and deviating from the path. Throttle is reduced, kick in right or left rudder (I prefer right all the way in as I am sitting on the left and I want a view of the runway out of my left window. My rudder all the way in usually gives me about a 30 - 40deg turn to the right). Use opposite aileron and a bit of forward pressure to maintain alignment with the runway (I see it as my hand is aiming at where I want to land, so if you drift right, more left aileron and vice verse). So the aircraft will continue flying in a straight path, but the nose will be pointing either right or left. The side of the plane acts as a brake to prevent over-speed. You will also use the forward pressure on the stick to maintain airspeed so there should not be any reason for an up elevator situation to develop. Then once you have lost the required altitude, neutralise everything, and proceed with the normal landing. Your airspeed should remain fairly constant. People incorrectly call these side slips because you turn the plane side ways.

A side slip is different. Here you are flying lined up with the runway and there is a crosswind that blows you off the right hand side for example. So to get back on track you drop the left wing first, starting a left turn to get you back to the centre line(in the other one you introduce rudder first to rotate the plane) and simultaneously introduce enough opposite rudder to just straighten the plane out so that it's nose now maintains runway heading. Throttle is used here as in a normal landing to control to rate of decent. In this case the plane's longitudinal axis will thus stay lined up with the runway but you will have a wing dipping into the direction of wind. Here more or less aileron will move you left and right, and the rudder will keep the aircraft 's nose pointing down the centre line. Here you fliy her all the way in, touching the one wheel first, then the other. You don't neutralize before touchdown.

Slips are easy and safe to do. Practise them at altitude, using a road as an imaginary runway. You will be surprised how quickly you loose altitude in the forward slip.

[RV4ker (RIP)]

Awesome post Morph.

I have been playing with the forward slips and I have seen 3000ft a min at 80mph.... Gets you attention fast... Am also amaised at how late you can actually kick out without getting into a tangle. I suggest as morph has you go play at alt then work your way slowly. I prefer to do without flaps, simply beacuse my max flap speed is 100mph and if I get it wrong (which I often do) I may maak droog.

[Morph]

Here is the recipe for a snap roll:

Starting from a speed slightly above the stall, apply a sudden yaw with the rudder, apply opposite aileron, and pull back on the yoke. SNAP! — One wing stalls and the plane rolls over inverted

This setup is very different to those preceeding a slip
a. You are close to the stall ( in a normal approach you should be at least Stall X 1.3)
b. You intentionally bang in the foot
c. followed by opposite aileron
d. Followed by yanking back on the stick.

So it is an deliberate extreme movement and one that is very dangerous and I advise you stay away from it unless you are in an aerobatic aircraft, with an instructor or you have the ratings and training yourself.

I suppose the closest we could come to this is during takeoff. Here we are at full throttle, above the stall, rudder compensating for the rotational effect of the engine, wings level. Suddenly, engine cuts, we hit stall, nose drops, rudder still applied, the wing drops towards rudder, panic, full opposite aileron, and sudden pulling back to prevent nose dropping., Bang you are inverted, with nowhere to go.

[justin.schoeman]

This is a great article on slips, skids (and the occasional snap roll):

http://www.av8n.com/how/htm/snaps.html

[Morph]

In short, a slip is a high rudder, low wing scenario, i.e. low left wing, rudder right facing high wing

A skid, is a low rudder, low wing, i.e. low left wing, rudder facing left. This typically happens turning onto final and using more rudder than necessary you speed up the turn.

Now if you loose concentration and stall the plane will roll towards the rudder deflection. So in the first instance it will roll towards the level and you will have time to react and recover. In the second it will roll steeper into the turn, leaving you no time to correct it, if you are close to the ground.

This is one of the biggest single killers of students during their training, turning into finals. Slow, flaps on, using more left rudder because you have drifted to the right of the runway. The left rudder tries to increase the bank angle, the pilot uses right pressure on the ailerons to try and hold this bank off, the stall speed is higher because of the bank angle. So if your stall is 50mph, your approach should normally be 50 X 1.3 = 65mph. In a 30 deg bank your stall is now 50 X 1.15 = 57.5mph leaving you with only 7.5mph to play with. A momentary lapse in concentration and speed bleeds off and you are in trouble. To be safer I only slow to the correct approach speed once turned into finals and lined up.

So I typically fly downwind at 1.5 Stall (75mph), Base at 1.4 x Stall(70 mph), and slow to 1.3 X stall over the fence (65mph)

[andrepieterse]

Important to keep speed constant during the forward slip when trying to lose height as the nose tends to pitch up during this excercise. Remember the ASI is also less accurate (under reads) during slip, so use a little more nose down attitude than normal. To control airspeed is by nose attitude relative to the horison and cross checking ASI inbetween (not fixating on ASI).

Regarding skidding when turning from base to final. I agree with Mogas. Ball in the middle. You don't have to keep your eyes on the ball all the time. Just don't let the nose direction slip out. e.g If you are turning left, as you apply left aileron, anticipate the use of left rudder to prevent the nose going right. Not too much, just the right amount. Most pilots get this right with practice.

Good website to check out is www.airbum.com. Good articles on slips, crosswind landings, and co-ordinating turns.

I have found that some pilots start flying with aircraft which require minimal use of rudder (e.g. Cessnas) or even no rudder (trikes). When transitioning to for example light sport types their feet are "lazy" and it takes some extra effort and practice to anticipate the correct use of rudder during turns and slips.

If unsure get instructor to show you how and then practice.

Regards

André

[RV4ker (RIP)]

Thought Mogas would enjoy this one...
http://www.youtube.com/watch?v=Af0Ky4Xomew&NR=1

[RV4ker (RIP)]

Check the RYDAAR on this one.
http://www.youtube.com/watch?v=lWxxKbCxlNc&NR=1

[RV4ker (RIP)]

Doesn't always go according to plan
http://www.youtube.com/watch?v=omChsodS ... re=related