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From: Gary Casey <glcasey@adelphia.net>
Subject: Turn base to final

There was an interesting comment posted the other day that  
essentially said that a turn to final won't result in an accelerated  
stall because the aircraft is descending and therefore has a load  
factor of less than 1 G.  Of course, as long as the aircraft isn't  
accelerating vertically the situation is the same as for level flight  
- the load factor will be greater than 1 G.  But what if one did  
decide to turn the 90-degree turn while keeping the load factor at 1  
G?  Certainly any turn at any bank angle can be made at 1 G as long  
as the aircraft is allowed to accelerate downward.  How much, I  
asked, so I went to my trusty spreadsheet and did some calculations.   
If you turn 90 degrees at a bank angle of 15 degrees (load factor of  
1.0 instead of the normal 1.04) and an airspeed of about 90 knots you  
will exit the turn at a vertical descent rate of 1,000 ft/min MORE  
than when you entered.  Do it at a bank angle of 30 degrees and the  
number is about 2,000 ft/min.  at first it seemed to me that it is  
unlikely that doing this type of thing makes sense, although I  
suppose one could go from a base leg at level flight and use the turn  
to make the transition to descending flight.  A 1,000 to 2,000 ft/min  
descent rate isn't far off for a normal final approach, so maybe it  
would be a reasonable thing to do as normal practice.  Just a thought.

Gary Casey
ES #157