REFLECTOR: elevator cuff

Al Gietzen ALVentures at cox.net
Fri Jun 8 20:09:57 CDT 2007


Subject: Re: REFLECTOR: elevator cuff was Brake authority

 

Al,

The way I understand it, the elevator cuffs were one of three things done to
address the deep stall problem.  Your current main wing was redesigned and
the canard was shortened.  The cuffs are no longer needed.  They were a
modification for existing Velocities at that time.  I received cuffs with my
kit but never installed them.  Their purpose is to increase the stall speed
of the elevator which would explain your high stall speed.

 

Larry Coen

 

Hum-m-m; well, my canard was not shortened - it came from Wingco with 8"
greater span than stated in the manual, and with the cuffs already in place
on the elevators.  At the time I was installing the elevators, there was
still some controversy about the cuffs/no cuffs, so I compromised by
removing about 40% of its width, thinking I'd decide about the rest after
flying.

 

As I did canard stalls today, I found there really wasn't any pitch-bucking.
Holding level flight and reducing power just resulted in increased
deflection until about 70 KIAS, below which it just wouldn't hold altitude,
and the sink rate would increase. Sometimes just the mildest of pitch break
and recovery.  So I would conclude that the cuffs are not helping anything -
and if they are increasing stall speed, then the next step is to remove them
completely.  All this is with the CG about the middle off first-flight box
and total weight about 2000#

 

I have already reduced the incidence of the canard about a degree (two stick
thicknesses under the leading edge of the incidence gauge), and that solved
the top end issue of full forward stick when getting over about 180 -190
KIAS.  It also reduced the canard stall speed, but it seems to still be a
bit high.

 

Al

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