There are certain hallowed halls where the footfalls of PPL are not often heard, so forgive me for entering without knocking, but I have a question for my elders & betters!
I fly a Koliber, its the Polish-built version of the old Rallye, on steroids! It is fitted with full span retractable leading edge slats, which give excellent low-speed handling and STOL performance.
I was asked recently by a student pax what the slats did, to which I replied that they improve lift at low speeds.
But thinking about this later, it occured to me that I didn't really know how they worked mechanically, nor why they worked aerodynamically.
So if explain how I think they work, can someone come to my rescue and tell me how they really work.
At rest, the slats are held out by springs, (I think - its not in the POH).
As the airflow over the wings increases, a combination of the airflow pushing against the front of the slat and reducing pressure in the 'slat gap' (due to increasing airflow) sucking against the LE of the wing and back of the slats, closes them.
As the aircraft slows down, the strength of the springs is able to overcome the force of the airflow and the slats open. Higher pressure air from under the wing flows through the slat gap venturi, accelerates and becomes low pressure air on the top of the wing, thus increasing the lift.
The slats are kept open as the springs are able to overcome the force of the reducing airflow against them and the net 'suck' within the slat gap is also reducing as the airspeed drops.
OK, so thats Kolibears Theory of Slats - can someone now put me straight?
Excuse me now as I tiptoe out & leave you all in peace
