Side-slipping

I thought I'd scribble a few thoughts on this most useful of techniques.

What is it?
Side-slipping is flying the aircraft "sideways" putting it into a very high drag condition for a given airspeed.

What's it for?
To either rapidly reduce speed, or to steepen descent-rate without increasing airspeed, or both. It's especially useful if you're "hot" (too fast) coming into land, as you can bleed off energy very quickly with this technique.

How does one side-slip?
Roll on about 30 degrees bank with ailerons, then feed in sufficient opposite-rudder to prevent yaw (turn), controlling your airspeed with pitch attitude. If you start to yaw (turn) in the normal sense for a banked attitude, then feed in more opposite rudder. If you start to yaw the other way, reduce opposite rudder. With practice you should be able to roll to over 45 degrees and keep the aircraft straight with opposite-rudder, once you've mastered it at 30 degrees. Not all aircraft have sufficient rudder authority to negate the yaw caused by the bank.

What are the dangers?
Side-slipping is what's known as flying "cross-controlled", and if cocked-up badly, this can induce a spin, especially if one allows the speed to diminish too much whilst flying with power-on. This leads to a power-on spin entry, which is the most vicious departure to the spin from controlled flight. If you find either that you are yawing, or rolling, then re-centralise both ailerons and rudder, and re-establish with less bank on. Side-slipping aircraft with rotary engines, such as the Camel, is more difficult, especially if power-changes are involved. Master it first on in-line engine aircraft.

For this reason, when practicing side-slipping, do start at a reasonable altitude, and with practice you'll get to the point where you can employ a little side-slip just before the flaring for landing, to bleed-off any surplus speed. Another benefit of being able to sideslip, is if you want to lose a great deal of height quickly, without over-speeding the engine rpm, or shock-cooling the engine.

How to practice?
Start by picking a terrain feature well ahead, then roll and feed in opposite-rudder to keep the aircraft moving in a straight line towards it, remembering to lower the nose to maintain an adequate airspeed. If the terrain feature remains stationary in your view, neither moving left or right (in yaw) or in aspect (in roll), then you're in a stable side-slip. Once you've cracked this, practice side-slipping to an airfield from altitude. My method here is to approach the airfield in my 1 o'clock, then roll left, feeding in right-rudder. In this way I'm lifting the starboard wing, and maintaining a good view of the airfield to my right. All I need to do then is make the turn from base to finals rolling to the right, and relaxing some - but not all - of the right-rudder. Bear in mind that flying cross-controlled near to the ground is a recipe for pranging, so keep movements precise and gentle.

A word of caution to "real pilots". Side-slipping modern aircraft is something that should be taught by a qualified and experienced instructor. Many aircraft: Cessna 150's, 152's (particularly) are not recommended for side-slipping with flaps deployed, because the lateral forces can cause the flaps to jam, or even deploy asymmetrically (very bad!). It is emphatically not something to "teach yourself to do" as if it goes pear-shaped you'll be spinning.  

Good stuff Fidd!!! :)

Wow! Let's get this guy access and transfer this thread to the Training Forum.

I use this often when I'm coming back from a recon mission and have a ton of altitude yet directly over my aerodrome, helps me control my speed in a rapid descent.

What's the difference between "side slip" and "skid"?

Another great use for this is when landing with a hun on your six trying to pilot kill you. Throws off their aim and often causes an over-shoot. I do this very aggressively and it sometimes gets me in trouble at very low altitudes.

No.42_Flatspin wrote:

What's the difference between "side slip" and "skid"?

Skids leave marks.

No.42_Zed wrote:

No.42_Flatspin wrote:

What's the difference between "side slip" and "skid"?

Skids leave marks.

LOL, I couldn't have put it better. There's a very good explanation here:

[You must be registered and logged in to see this link.]

Fidd

In real life I never used a side slip to reduce speed, only to lose altitude.  Of course in real life I never made anything like the approaches I do in game.  

There is also the very minor side slip used in crosswind landings.

To simplify what a skid is, from a top view the aircraft would appear to be doing what a car does when you drift it in a turn.  This can be corrected with the rudder.  When corrected it is called a coordinated turn.  Like a slip it is dangerous when low and slow.  Many pilots have killed themselves when turning final, they see their turn isn't going to line them up with the runway perfectly so they correct with their rudder.  One wing stalls causing the plane to flip over into a dive that they don't have the altitude to recover from.


Edit: To simplify a slip imagine a car on a track with a banked turn, and the car is going too slow so the rear of the car starts to drop off to the inside of the turn.  If the car gets slow enough it will start to slide down.  You put the plane in THAT position except you keep it's flight path in a strait line.

Shnoze_Shmon wrote:

In real life I never used a side slip to reduce speed, only to lose altitude.  Of course in real life I never made anything like the approaches I do in game.  

There is also the very minor side slip used in crosswind landings.

To simplify what a skid is, from a top view the aircraft would appear to be doing what a car does when you drift it in a turn.  This can be corrected with the rudder.  When corrected it is called a coordinated turn.  Like a slip it is dangerous when low and slow.  Many pilots have killed themselves when turning final, they see their turn isn't going to line them up with the runway perfectly so they correct with their rudder.  One wing stalls causing the plane to flip over into a dive that they don't have the altitude to recover from.

Agreed. Side-slip is primarily used to lose height without increasing airspeed, secondarily to lose small amounts of speed quickly (only slight sideslip usually is required) and thirdly to offset wind-drift during a cross-wind landing.

A further consideration for real-life pilots is that on many aircraft, side-slipping can cause the airspeed indicator to tell the most appalling fibs, either grossly under or over-reading, dependant on the degree of slip used, and position of the static-vents on the airframe. Another reason to be have this manoeuvre taught professionally. No such error of the ASI occurs in game.

Side-slipping is a potent flying skill to have, especially if ever you have to drop a light-aircraft into a very small field, BUT, as Shnoze says, it'll really bite you hard if you get it wrong "low and slow" for real.