What’s your angle?

There is a very true and famous saying in aviation: “Never let the aircraft take you where your mind has not already been five minutes before“. Now, as true as that is, it does not mean that we can forget what is happening around us in the very moment. Being in touch with the moment can tell us a lot about our aircraft and how we can manipulate the controls to get the desired effect going forward… or backwards if you are flying helicopters but that’s a discussion for another day. In recent times pilots around the world have been heavily criticized for having lost their ‘stick and rudder’ skills. Let’s have a quick revision to what we mean when we talk about stick and rudder.

It boils down to angle of attack and energy management. The aircraft does not know where the ground is, so it is important that we fly the aircraft through the air first and then relative to the ground. Allow me a moment to get technical. What makes airplanes fly? Some would joke and say: “money”, but in reality, we know it is the wings that creates the lift we desire. When we look at the lift formula we can see that there are parts that we can manage in the short term (think five min ahead), and then there are the ones we have instant control over. The instant ones are the ones we want to talk about today: Speed and Angle of Attack.

Flying safely in the moment relates to your management of energy and angle of attack.

  1. If you exceed the critical Angle of Attack, the aircraft’s wings will stall and you experience a sudden loss of lift. If it’s uneven on the wings it could develop into a spin.
  2. If you exceed the aircraft’s design speed limitations you can rip the wings off, not good either.
  3. If you fly faster than Max Maneuvering (Va) for the current weight yet not exceed Red line speed (Vne) and come close to the Critical Angle of Attack you will over-stress the air-frame. This is where G limits come in, the ratio of lift vs aircraft weight and momentum.

Point three above is not that hard to manage because we can feel it in our body. Unless you are flying aerobatics or in a 60dg steep turn (2G’s), that heavy feeling should immediately set off the alarm bells and have you relax the back pressure on the control column and roll wings level to get back to normal and balanced flight. When we are not loading the wings (Pulling G’s) our wings are creating equal (or slightly less in climbing or descending) amount of lift versus our aircraft weight. So it’s a constant trade between airspeed and angle of attack to create the desired amount of lift.

Have a look at some aerobatic flight here by our CFI, Marko Nel.

Let’s sketch two scenarios:

  1. High Airspeed, Low Angle of Attack: Loading the wing in this scenario is not detrimental for control but you could over-stress the aircraft. You will have to pull relatively hard on the control column to achieve this ‘overload’ as there is a lot of airflow pushing the elevator back into the streamline airflow. This is however a high energy state and care needs to be taken as things happen a lot quicker!
  2. Low airspeed, High Angle of Attack: Loading the wing now by pulling on the control column, even a little can mean a risk of stalling the wings. The elevator moves easy in these conditions with less feedback in your hands. There is your telltale, be careful to over pull on the control column during low airspeed operations. Most often pilots lose control during turns and so another telltale is if you require more than half the input of roll control during normal flying conditions, that should be a sign that your airspeed is too low. Wings that are stalled are tricky to control. Restore the energy and laminar airflow by simply releasing the backwards pressure, fly towards the ground, power up and then climb back to your altitude.

One of the most common risks I see that fresh students create for their flights are not recognizing the typical low energy situations. One example: fixing altitude in the downwind from 1000′ back to 1300′. The pilot already flies relatively slowly and now just pitches up to get back to the desired altitude without powering up for that ‘small’ climb, with 10˚ of flaps. The engine noise will drop, the sky becomes more visible, the controls are already quite sloppy and then there is the work-load of down-wind checks. Add all of this together and we’re getting close to scenario two above. Use all your senses and STAY IN THE MOMENT!

Thank you for your time and see you next time,

Written by Alewyn Burger,
SFC Flight Instructor
http://stelfly.co.za/

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