Power On and Power Off Stalls


“Do you remember what a Stall is?” asked Tim as we began the usual ground briefing before flying. It was Saturday September 17, 2011, a cloudy day, slightly cooler than what we’ve been used to, about 65 F. “It’s when the relative wind hits the wing at the Angle of Attack and there’s no more lift”, I replied. “Yes, but when does the actual stall occur?”, “It occurs when the critical Angle of Attack is exceeded”. “That’s correct”, said my instructor. He further went on to explain that a Stall can occur at any speed, and that there were two types of Stalls, the Power-on and the Power-off Stalls. “To be more precise, the Angle of Attack is created when the relative wind hits (in the wing) the Cord Line”, said Tim. The Cord Line is an imaginary line that begins from the front of the wing (also known as the leading edge) and the end of the wing. The front and end being referred to is the width of the wing, and not the length. “It’ll be easier to understand once we’re flying, and it’ll be easier for me to demonstrate it too”, said Tim. As we were leaving to go out to the plane, Tim asked if I wanted to go to St. Paul as there was a store out there where I could buy a good pair of headsets. Of all the days I’ve been coming to my flying lessons, today was the day I deliberately decided to leave my wallet at home since I knew I wouldn’t need it, never have when I attended classes. “I left my wallet at home Tim, maybe we can go tomorrow if they’re open?” I said. He said yes that would be fine and we boarded the plane.

Having reached an altitude of 3500 ft, Tim took control of the plane and said that he would first show me how to do the Power-off Stall. First he did 90 degree turns to the left and to the right to make sure that there were no other planes flying nearby. He then proceeded to reduce the RPM to 1500 and reduced by pulling the throttle out and keeping the mixture rich. Before the speed reduced to about 65 mph he pulled the lever that engaged the flaps to its first stage. A few seconds later he pulled it again to the second stage and then a few seconds later he pulled it to the final and third stage. This considerably slowed the plane down. The plane’s nose moved up each time the flap lever was pulled and he had to push on the yoke to keep the nose down. As this was happening he maintained the altitude and the wings level. Now the plane was much slower than before and the Stall Alarm went off as we had reached the Angle of Attack. Now we were in Stall mode and Tim quickly pushed the throttle in and the plane immediately began to rapidly rise. Tim then gradually returned the flap lever i.e. through the stages, 3, 2 and 1. The Angle of Attack was reduced and the alarm went off and we were out of Stall mode. It all happened very quickly and Tim said, “Okay you try it now, I’ll hand over the control of the plane to you”. I was a little nervous because I was wondering if I had gotten all the steps down correctly. “Don’t worry I’ll be right there with you”, said Tim. So, I first reduced the RPM to 1500 by pulling the throttle back and ensured that the mixture was rich. Then as we rapidly began losing speed I pulled the flap lever through its stages 1, 2 and 3 with intervals of a few seconds in between the stages, before we reached 65 mph. Again I noticed that each time I pulled the flap lever, the nose of the plane went up and I had to push on the yoke to keep the nose from moving up. Now the plane was very slow and the Angle of Attack was exceeded and Stall Alarm went off indicating that we were in stall mode. I quickly pushed the throttle back in and to increase the power. The Stall alarm went off but, as I was doing this, I allowed the plane to lose some altitude and the wings were not level. So Tim told me to increase the rudder pressure to the right as the plane was banking right, and the ball was out of its place. As the plane continued rising due to increased power I disengaged the flaps through 3, 2 and 1, and we were completely out of the Stall.

Next we were going to do the Power-on Stall. This was much easier as all we had to do was reduce the Angle of Attack. Again we reduced speed by pushing in the throttle to 1500 mph and the slowly pitching the plane. This time however no flaps are engaged, and as the plane continues to pitch the Stall alarm goes off as we reach the critical Angle of Attack. To get out of this Stall mode, you simply push the yoke in to push the nose down i.e. reduce pitch and the Angle of Attack is reduced and you’re out of Stall mode as the Stall alarm goes off. Again it was my turn to do the same or at least attempt to. I was a little confident in doing the Power-on Stall because it didn’t require as many steps and it was much quicker. Tim passed on the controls of the plane to me and I reduced the RPMs to 1500 by pushing the throttle in and pitching the plane at the same time as we reached a speed of 65 mph. The Stall alarm went off and I pushed the throttle in all the way to increase power and pushing the yoke in to reduce pitch. Now because we reduced the pitch, we reduced the critical Angle of Attack and the Stall alarm goes off and we’re out of Stall mode.

“Do you want to do try and do more of each?” asked Tim. I thought what we did today was enough. It was a little much and I asked Tim if we would do these again and he said yes as it was required by the FAA and that I would be tested on this during the exam. “Don’t worry you’re not the first person to not want to do it again so soon after their first attempt. Many students are the same”. I was a little relieved having found out that I wasn’t the only one.

Next, although it wasn’t part of today’s class we once again practiced emergency landing procedures, even though we didn’t actually make a landing in an open space or a nearby field. After this, we headed back to Crystal airport and this time Tim took control of the aircraft just as we were about to land, up until then he guided me to the runway as we approached Crystal airport. Once we landed we went through the after landing check list and went into the airport building. Here I completed my flight log book and Tim signed it, we shook hands and I said “See you at 8.30 am tomorrow Tim!” to which Tim nodded and said “Sure!”

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