Thursday, 24 March 2016

Stalling - This is your Captain speaking




We have a lot of questions through the message board and by email. We always answer these as best we can. A lot of people that ask these questions cannot make it to our course and that is why it is so important to answer their questions properly.


The question below actually came from someone that attended our course but needed to clarify a couple more worries.  Darren's concern was linked to all the talk in the media of 'aircraft stalling.'  This is one of those unfortunate words that means something completely different in aviation than it does when driving your car.


Here is both the question and answer below. Hope that you find it helpful...


Best wishes,
Paul & Richard
Flying Without Fear


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From: Darren C
Sent: Thursday,
To: Paul Tizzard
Subject: Question about inflight stalls


Hello team,



My main concern (amongst many!) still remains about in flight stalls which are as a result of not enough air flowing over the wings / under the plane (I always get confused which it is). This would make the plane begin to descend.


In the fear of flying book it just says that due to modern computer systems this could not happen, however when there has been an incident involving a plane, the news often says a mid air stall could have been caused by the pilots pulling up too suddenly or rising to avoid / get out of a storm.

How accurate is this? I was looking for maybe a more detailed answer as the one in the book whilst re-assuring is brief and does not really give a thorough understanding of why this couldn't happen?

 

Thank you for your continued help, hopefully now i can give my partner the wedding of her dreams in NYC :)

Regards,

Darren
From: Ralph Miles <ralph@
Sent: Sunday,
To: Paul Tizzard
Subject: Re: pilot question



A wing creates lift because the aerofoil shape, (basically flat underneath and curved on top), causes more air to flow under than on top.  The air that does travel the longer route over the top is caused to speed up to reach the back of the wing at the same time as that going underneath.  In  doing so the air over the top loses pressure and also temperature, (this is a basic law of physics).


Because it loses pressure it creates a lower pressure area on top of the wing relative to the pressure of the air going underneath.  The wing therefore has a tendency to move toward the low pressure air, i.e. move upwards.  This force moving the wing upwards is known as lift.

This lift force will increase the faster you go, and also if you raise the front of the wing to increase the angle it presents to the airflow. This angle is known as the "angle of attack".


However there is a limit to which you can increase this angle, that limit is found when the air no longer tries to go over the top and opts to travel the shorter route underneath.  At that point the wing will no longer produce lift and this point is known as the stall.

All aeroplanes have a speed/angle combination which will cause it to stall.  The slower the speed the lower the angle.  You still hear of aeroplanes stalling but generally these are small private aircraft. Not commercial airliners.



All modern airlines have protections built in to their flight controls which limit the amount of upward pitch than can be applied.  They also have angle of attack sensors which ensure the critical angle is not exceeded.  If the critical angle is reached, a downward pitch movement to the controls is input which cannot be overcome by the pilots and also engine thrust is increased automatically in order to increase airspeed.



Avoidance of storms is normally achieved way in advance by identifying them either by sight or on radar and altering course to go around them.  Pilots never pull up or descend to avoid. Climbing or descending in a storm area would not achieve avoidance as storm clouds are a function of their vertical existence.  Also air traffic control level restrictions would do not allow fluctuation in level.

Future course dates
Premium courses £267: Manchester April 10th; Birmingham April 17th. Gatwick TBC
Ground courses £150: Heathrow April 3rd; Leeds May 29th.
Children's Course TBC









1 comment:

  1. Great post. Excellent description and real world example of stalling. I am going to accept my Uncle proposal to come stay at his place while I learn to fly airplanes at http://www.flyhaa.com/airplane/. Heres to not stalling!

    ReplyDelete