Mailing List lml@lancaironline.net Message #65749
From: Jack Morgan <jmorgan1023@comcast.net>
Sender: <marv@lancaironline.net>
Subject: LML stall technique
Date: Fri, 07 Jun 2013 08:11:13 -0400
To: <lml@lancaironline.net>
Hi Peter,

I appreciate the dialog on this critical and controversial subject.

The point I am trying to make is that in all emergencies, including the ones you note below, allowing the airspeed to decay into the high sink part of the IV envelope will result in a fatal crash unless you have enough altitude to get the nose down and the speed back up. Whatever the stall speed you end up with you will have such a high sink rate near that speed that ground contact, even if still wings level, is likely fatal to those in the airplane.

If you review the IV fatal accidents you will find that almost all occurred with either complete loss of control or high sink rates while in control. If you have 100 knots or so you can arrest the descent rate before ground contact, improving survivability.

The high sink in the IV is very different than production GA aircraft due to the high wing loading. GA aircraft really don't have a significant high sink area in their envelope so us GA types spend a lot of time worrying about stall characteristics. This sink characteristic is common in airliners, etc. and they don't spend any time discussing stall characteristics since it is not an allowable operating part of the envelope and much training drills it into the pilots to not go there. Recall the airbus that went into the ocean with full power and full aft stick to appreciate this high sink region.

I think us IV drivers will be safer if we become convinced that below 100 knots or so is not allowed and that the thinking that there is some safety margin to be gained by operating the airplane below that speed in emergencies is taken off the table.

Jack Morgan

On Jun 7, 2013, at 6:02 AM, Lancair Mailing List wrote:

From: PETER WILLIAMS <peterpawaviation@hotmail.com>
Subject: RE: [LML] Stall technique
Date: June 6, 2013 4:44:16 PM EDT


JACK

My hope is to never need the reduce stall speed or the safe limits that an AOA shows. 
   but 
      say at 300 altitude with a sudden engine stoppage
   when i need it.  i will really need it
    or
 at 90 knots in landing configuration. a child runs onto the runway
   when i need it.  i will really need it

    it is a little like looking in the cowling for a birds nest; i went 19 years before i saw one that could have started a fire.
were those years of looking wasted?
      no
that day i needed it.  i really needed it

to me it is not for the normal situation, it for the unexpected. for the unwanted situation. for the emergency i did not ask for.
(for the moment when my ability to maintain 100 knots is impaired)

peter
    




Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster