Re: REFLECTOR: elevator cuffs

["Reeder Graphics, Inc." <design@reedergraphics.com>]

Thanks Greg Otto for your very informative reply.

To Alan:

I have your wings, canard and control surfaces for a standard wing
(Elite RG).
With your knowledge of the performance of these components, do you
believe the Cuffs are necessary or desirable? I expect, and do not
necessarily wish to eliminate, a pitch-buck but, if it is violent or
extreme then it sounds like the cuffs are warrented. I definately do not
want to increase stall speed nor decrease cruise speed. What is the best
comprimise with your fast build wings?

Thanks,
Jack


Alan Shaw wrote:
> 
> Jack and friends,
> 
> Elevator cuffs limit elevator authority at low speeds to prevent deep stall in small
> winged Velocities.  Relative to the main wing the STD V has a bigger canard than the
> LW and XL  V.
> 
> The large wing Velocities are safer without cuffs because this gets the take-off and
> landing speeds down.  These planes have a lot of safety margin at aft CG were they
> fly best and cannot be PIO forced to main wing stall (deep stall).  If a larger
> canard or engine is added to the LW(173) model then the elevator cuffs should be
> added plus then you are a test pilot.
> 
> On the smaller winged Velocities if the whole cuff has to be removed to get
> sufficient rotation or flare then the canard didn't have enough camber or incidence
> to begin with.
> Again, you have become a test pilot.  **The difference in the canard and main wing
> incidence/area/camber is what loads the canard up first preventing main wing
> stall.**    The trueness of the wings, L.E. radius, AC weight/balance and pilot
> weight are also factors.
> 
> A lot of elevator/canard authority can add utility and safety to your Velocity but
> if yours has gone so far that it can be made to buck violently then don't push that
> end of the envelope.  Violent bucking precipitates roll and yaw oscillations as
> well.   No fun.
> When it first starts to buck it is telling you...... push the nose over a little.
> 
> Alan Shaw

-- 


Reeder Graphics, Inc.
http://www.reedergraphics.com