REFLECTOR: Velocity 20B update

[John Dibble]

Al Gietzen wrote:

>
>      I’m no expert either, but it’s more complicated when you add
>      a ‘fowler flap’ elevator to the airfoil.  The issue seems to
>      be the canard stalling before you can get full down
>      elevators. The incidence was initially set exactly to the
>      gauges (presuming they are correct).  I then reduced the
>      canard incidence by about 1 degree (roughly 3/16” front to
>      back on a 12” wide canard).  It helped, but not a lot.  The
>      advice from the factory was not to decrease incidence
>      further because of risk of reducing the differential between
>      canard and wing too much.
>
>      I agree that reducing the differential too much poses the
>      huge risk of a deep stall.  However sometimes individual
>      planes don't fit with factory standards.  My W&B calcs
>      indicate when I fly solo, I am aft of the aft cg limit.
>      However I have done a stall test and determined that my
>      canard will stall, so I am satisfied with that and decided
>      not to add ballast to the nose.  I think actual stall data
>      should carry more weight than calculated values.  Still, if
>      you are going to push the envelope, you have to be very
>      careful.  If the vg's work that is obviously a safer
>      approach.
>
>
>      I think that is very interesting.  Unless I misunderstand,
>      the sole function of the sparrow strainer is to increase the
>      stick force in pitch at higher speeds to reduce the
>      ‘apparent’ pitch sensitivity.  It makes you push harder
>      against the spring in one direction, and the airfoil load in
>      the other.
>
>      That's my understanding as well.  Based on my experience, I
>      conclude that the trim spring alone provides adequate pitch
>      stability.  I believe others have flown without the strainer
>      without stability problems.
>
>      John
>
>
>
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