Flying Lesson # 23 – Side Slipping

July 7, 2012

Advanced manoeuvres are always fun. Stalls and steep turns were definitely a highlight and now side slipping a plane is right up there as well.

Side slipping, for our purpose among others, is used to lose altitude quickly (up to 1300 feet/min as I discovered) whilst not gaining excess airspeed that would usually result from a rapid descent using attitude only. Side slipping is a cross-control manoeuvre which simply means the pilot is inputting for a roll in one direction using aileron, and accompanying this with rudder inputs to produce yaw in the opposite direction – thus, left roll and right rudder, or right roll and left rudder. This causes an increase to the aircraft’s relative frontal area changing the aerodynamic characteristics and increases drag.

Types of slip vary in degree from inadvertently flying cross-controlled in the cruise i.e. one wing slightly low and compensating with opposite rudder, to a fully-fledged cross-controlled turn where the aircraft is steeply banked in a descending turn with full opposite rudder applied. A cross-controlled straight sideslip is a manoeuvres designed to lose height over a short distance, dumping the potential energy of height by converting it to drag turbulence rather than kinetic energy. This is was the focus of our lesson!

We started by heading out to the training area in JOO. The sights out there are becoming a lot more familiar now. Steve started by demonstrated side slipping to the right and then left. Initially, the slip has a shuddering/buffeting-type feeling and you can definitely feel that you are descending rather rapidly. It’s a strange feeling though as one wing is banked heavily, yet you are still travelling in the same direction. For these reasons, it’s reserved as a last option to ditch height; not a manoeuvres to be used with the Queen aboard!

When I gave side slipping a try, as I was not properly coordinated, when I banked the wing, the plane immediately commenced a sharp turn (as you would expect). Then once my rudder work kicked in, the back end of the plane swung around rapidly and somewhere during the pushing and turning I became caught in a pendulum-type motion swinging back and forth trying to find the sweet spot. Clearly this isn’t an ideal way to slip an aircraft, so Steve quickly stopped me and showed me the process again. On my second attempt, I slowly eased the bank whilst applying opposite rudder and continued until my foot was flat to the floor. It was then just a matter of adjusting aileron pressure to maintain the correct track and, with the nose lowered, I successfully completed a slip!

For some reason, I struggled a little with slips to the right. I just couldn’t co-ordinate them correctly. After half a dozen attempts, it finally fell in to place.

On our return to Archerfield, Steve pointed out that the purpose of side slipping is a last ditch effort to lose altitude in a landing without gaining airspeed. So why not practise it in a real life situation? On our approach, he had me remain a little higher than usual and then initiate some side slipping and hold it down to around 300 feet. It worked! I entered the slip (to the right) smoothly and held the centre line of the runway perfectly. Approaching a descent rate of 1300 feet per minute (500 being the usual rate), I released aileron and rudder pressure smoothly at around 300 feet and landed without a hitch. I walked away from this lesson feeling really good about my abilities. I’m sure with a little more practice, slide slips won’t present an issue during my GFPT.

Next lesson will be back with Robert and should involve precautionary search and landing.

Can’t wait!

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