REFLECTOR: Adjustable Canard

Sun Feb 5 09:42:16 CST 2006

Andy,
What are you hoping to accomplish by adopting an adjustable canard as
compared to the existing canard/elevator/pitch trim design?
If you are doing this as an engineering exercise - just to have fun - then
great!  I'm going to guess this modification will add well over 100-hours of
building time.  It will involve designing a new method of mounting the
canard and a prototype mechanism to adjust the incidense of the canard
during flight .  These "unknowns" add an element of risk with regards to
flight safety.  Designing a fairing that is both functional and looks nice
will be a real challenge as well.
I love Mooney aircraft - but because a design feature works well on a Moony
does not necessarily mean it will work well on other aircraft.  And when I
think about how an 180-hp _fixed gear_ Velocity SE cruises about 10-knots
faster than a 200-hp M20E http://www.mooneypilots.com/mapalog/m20e.html ...
I would say from my cost-time-safety vs benefit points of view, the proposed
changes are not worth the effort.  One person's opinion.
Best regards,
Scott Baker

----- Original Message -----
From: "Andrew Ellzey" <ajlz72756 at yahoo.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Saturday, February 04, 2006 6:10 PM
Subject: Re: REFLECTOR: Adjustable Canard

> All this talk of having trim problems, I am seriously considering making
my
> canard adjustable. I stated this about a week ago to see what kind of
> reaction it would get, but now I am truly going to pursue the
possibilities
> of making it happen .Someone made the comment that this would be a
dangerous
> option to consider and I disagree. With careful consideration to the pivot
> point hinges and placement of a single or double jack screws to distribute
> the load, and a good position indicator to know what your angle of attack
> was at all times, I believe you would have a valuable addition to an
already
> sound design. I owned, restored and flew a 1964 M20E for 12 years with the
> standard Mooney adjustable tail, and always laughed when I looked at the
> elevator trim system on a Piper 180, (not a lot different to the current
> design of our Velocities) and thought of how much drag that huge trim tab
> must have produced. The tail of a Mooney pivots on two hinges with 5/16
> bolts for the hinge pins and the jack screw is only a 1/2 inch acme thread
> screw. Mooney also had a safety strap that would limit the distance that
the
> tail could move if the jack screw were ever to break or strip. The whole
> trim system was manually operated with the trim wheel mounted on the floor
> next to the pilot seat. The trim indication system was built like a lawn
> mower throttle cable moving a pointer on a small indicator which was
marked
> for take off and landing trim settings, nothing about the system needed
any
> electrical power.    I know that it would take some additional work to
> design a seal system for the dog house, but again well worth the effort.
>
> Andy Ellzey
> XLRG
>
> ----- Original Message -----
> From: "Ron Brown" <romott at adelphia.net>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Saturday, February 04, 2006 7:54 AM
> Subject: REFLECTOR: Sparrow Strainer
>
>
> > More trim "info" from something I saved from Mike Pollack a while back:
> >
> > "The sparrow strainer has negative lift by design.  As the airspeed
> > increases, the sparrow strainer tries to pull the aft side of the
elevator
> > down causing the nose of the airplane to rise which slows the airspeed.
It
> > works in relation with the fixed trim system to give a wider trim range
> > airspeed without retrimming manually.  It also seems to keep the canard
> > more stable in level flight. I have flown with and without one and
prefer
> > the sparrow strainer."
> >
> > And to add fair and balanced coverage, here is what Steve Korney had to
> > say:
> >
> > "My sparrow strainer works as a trim tab...The faster I go, the more it
> > pushes the elevator up, keeping the nose down...My sparrow strainer has
a
> > positive incidents of about 15 degrees...That is, the cord line angles
up
> > from the trailing edge to the leading edge...Are we all confused...???"
> >
> > Yep,
> > Ronnie
> >
> >
> > ----- Original Message -----
> > From: "Pat Shea" <xl340hp at yahoo.com>
> > To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> > Sent: Wednesday, February 01, 2006 2:51 PM
> > Subject: Re: REFLECTOR: Elevator Trim Spring
> >
> >
> >> Steve,
> >>
> >> Actually, if the sparrow strainer is installed as the
> >> factory prescribes, it makes the trim situation WORSE
> >> at cruise. It has a negative angle of attack relative
> >> to the elevator and is an upside down airfoil. Both of
> >> this work to pull the trailing edge of the elevator
> >> down at high cruise. Since the Trialing edge of the
> >> elevator is above the in-trail position at high
> >> cruise, the sparrow strainer is working against you
> >> the faster you go. Of course all this would be very
> >> undesirable without a pitch trim system - the good
> >> news is we have one.
> >>
> >> The purpose of the sparrow strainer it to pre-load the
> >> pitch trim spring more (by making it work harder) at
> >> higher speeds. This helps stabilize the plane by
> >> increasing the pilot force required to move the
> >> elevator at these speeds. This increased pre-loading
> >> also increases the amount of external force
> >> (turbulence) requires to induce a pitch change.
> >>
> >> I know you changed you sparrow to be an aerodynamic
> >> trim, but that is a completely different arrangement.
> >>
> >> Pat
> >>
> >> --- steve korney <s_korney at hotmail.com> wrote:
> >>
> >>>
> >>> Guys.....
> >>>
> >>> The sparrow strainer takes care of the trim in
> >>> cruise and top speed...  If
> >>> it's set right...
> >>>
> >>>
> >>> Best... Steve
> >>
> >>
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