Tuesday, July 9, 2013

STOL Aircraft - I Learned Something New

If you are the curious type like me, opportunities to learn something new are in front of us all the time. Last weekend I was at an airshow at Max Conrad Field and spotted this rather strange looking airplane. What really caught my eye was that the horizontal stabilizer had an airfoil that would appear to be inverted. The function of the stabilizer on an airplane is normally to keep the wing level by some negative pressure applied at the rear of the plane. Some model airplanes normally of the free flight type have an airfoil that is lifting the complete opposite direction but on these airplanes the balance point of the wing is much further rearward.

Sky Jeep STOL Aircraft

To learn more about this airplane I could have researched the name on the side of the plane, "Sky Jeep" but I inquired about the design through an online model airplane group. My Internet friend Gary sent a link to the Zenith Aircraft Company website section about the tail of the aircraft. It turns out this plane is designed for short take offs and landings, STOL is the acronym for Short Take-Off and Landing aircraft.

Inverted Airfoil on Stabilizer Caught my Eye

There is a fair amount of technical description on the website but basically the downward lifting stabilizer applies more pressure on the tail to bring the nose up so the plane can fly at a steep angle, even when taking off. There are also "flaperons" on the wing which are ailerons that have some separation  from the trailing edge of the wing that function as ailerons and as flaps in less disturbed air flow. There are also leading edge slats but I had not noticed this when looking at the airplane, this further helps the airplane fly at a high angle of attack. The entire vertical fin acts as a rudder for more turning power too.

Company Video of Short Take Off and Landing

Bill Kuhl

1 comment:

  1. I noticed in a three view that, relative to the wing, the wheels appear slightly further back on the CH 701 than on some other aircraft. Combined with the slow takeoff speed, that would probably require a relatively high lift coefficent from the tail. Also, it looks like that wing airfoil, with the slats and flaps, would have a large pitching moment, therefore requiring a bit more down force from the tail.