From my perspectiv= e, the key phrase is spin resistance.

Having= researched the NASA material and having also seen the Lancair videos of act= ual flight testing, rightly or wrongly, I installed the wing cuffs to the Le= gacy on the basis that they seemed to offer the opportunity to make it harde= r to get into trouble, but accepting that if pushed too far into a spin, the= n the aircraft may or may not be recoverable. So, if one accepts the = view of many which is that "as was", the aircraft was not spin recoverable, = there would only appear to be upside from installing the cuffs. The flaw is,= of course, that if indeed the Legacy is spin recoverable without wing cuffs= , then the addition of the wing cuffs may preclude spin recovery= !

Unless someone goes to the trouble of spin testin= g the Legacy, or any other type fitted with cuffs, one will never know wheth= er spin recoveries are possible under what flight and loading circumstances = and, of course, with or without wing cuffs.

Meanwhi= le, per my prior post on this, all I can say is that the albeit very limited= flight testing (straight and level, and continuous 30deg AoB turns) in my L= egacy fitted with the cuffs shows that there is plenty of warning of the imp= ending stall – stall strips give the first "gentle" warning", followed= by the more severe intermittent "shuddering" as the centre section drops in= and out of the stall (whilst the outboard sections are still flying).

I'm happy to talk to anyone if they are interested to ta= lk about this more…. numbers below, but please note time is UTC + 8!!<= /div>

Regards,

John

John N G Smith
Tel / fax:    +61-8-9385-8891
Mobile:      +61-409-372-975
Email:         john@jjts.net.au
=

From= : <marv@lancair.net>
= Reply-To: Lancair Mailing List <lml@lancaironline.net>
Date: Tuesday, 8 January 2013 2:25 AM
To: <lml>
Subject: [LML] Re: Stalls & Spins

<= /div>

Posted for "= Peter Field" <pfield.avn@gmail.com<= /a>>:

Dear Lancair Drivers:

I've been following the discussion= on stalls and spins and I want to add
some additional factual information purely for your personal consumption and
reflection. &= nbsp;Attached are excerpts from 10 different 1980-90 NASA flight
test final reports on a series of GA airplanes in which NASA evaluated the
u= se of cuffs on leading edges to improve the behavior of the test airplane
approaching the stall.  For various reasons the cuff= s improved lateral
control entering the stall, but had the adverse effect of destabilizing the
aircraft once a fully developed spin was ac= hieved.  Essentially, stall
behavior was improved at the sacrifice of spin recovery.  Cuffs on wing
leading edges are = an add on design fix, the more elegant solution is
"washout," where the wing is twisted so the outer portions of the wing
always operate at a l= ower angle of attack.

To my knowledge, Lancair has never subjected any of their aircraft to a
fully developed spin matrix comple= te with appropriate instrumentation and a
spin recovery chute.  There is no FAA requirement for them to do so - it's
= an Experimental Category airplane.  Early on they may have lightly touched
on such testing; but I have never seen any documentatio= n on a fully
completed spin matrix, which would involve at least 160 spins at various
cg's and lateral loadings.  In my opinion, i= t would be highly risky to fool
around much beyond the stall in any Lancair - there is no documentation that
indicates any of these airplan= es can always be recovered from a one turn
incipient phase spin or any fully developed spin.  Being good at spin
recovery isn't so m= uch a matter of how skillful a pilot you are, it's a
matter of how many spins you've experienced in airplanes known to be
recoverable. &nb= sp;Being familiar with the stall characteristics of your own
airplane should be a matter of personal preference.

B= est regards,

Pete Field (LNC2)

USNTPS graduate & spin recovery instructor

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