Date: Tue, 2 Nov 1999 14:56:40 -0500
From: Lynda Frantz <LFrantz@compuserve.com>
Subject: Approach Speeds for L-360
Sender: Lynda Frantz <LFrantz@compuserve.com>
To: "INTERNET:lancair.list@olsusa.com" <lancair.list@olsusa.com>
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Message text written by INTERNET:lancair.list@olsusa.com
>He believes that my approaches should be slower. 1.3 times stall or about
80 mph for calm days. He also suggested adding 1/2 the crosswind 
component, plus all of the gust speed up to a maximum of 33 mph. In all of
 my past training (from Lancair also) I have been told to stay at 120 mph.
 How do the rest of you approach?
In my experience, flying approaches at 1.3 times the stalling speed
 is OK provided the stalling speed is known. In the absence of having an AOA,
1.4 Vs is typically recommended because the exact staling speed is unknown!
 The problem is that stalling speed varies with weight, bank angle CG and
turbulence.  To be conservative most light aircraft operators recommend
using about 1.4 Vs or higher for approaches.The jet operators typically
use variable speeds based mostly on GW with 1/2 the cross wind component
and all the gust as additives which result in approach speeds between about
1.25 and 1.4 Vs.  Generally the heavy operators use AOA either directly or
indirectly to compute the approach speeds.  Glassy water landings in
amphibious aircraft are flown as slow as 1.15Vs. The best soltion
regardless is to install an AOA instrument because AOA is self
compensating.
Flying the best approach AOA on my Lancair 360 results in an airspeed
between 76 and 86 knots depending mostly upon the landing gross weight.I
would not recommend flying my L-360 with approach speeds below about 85
knots straight and level using IAS alone.  I understand that Lancair check
pilots recommend at least 85 knots for approach depending upon who the
check pilot is with some recommending 100 knots.
If you fly a fixed approach IAS, the margin above stall will vary from one
approach to another depending mostly upon GW.Also the energy required to
flare will not be consistant with the amount of excess kinetic energy 
going into the flare.  Neither of the above situations is conductive for
good landings and short rollouts.  For more information see
www.angleofattack.com
Jim Frantz  

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