REFLECTOR: Adjustable Canard

Sun Feb 5 13:11:55 CST 2006

Maybe all the talk of not having enough travel to trim your aircraft for 
different loading and speed considerations has been over blown in the last 
few weeks on the reflector, but if it hasn't, I would think that a 
adjustable canard would be a great asset to an already good design. I am not 
contemplating a radical change to the existing canard or trim system other 
than to, as you say now add an expectable hinge and jack screw system. The 
adjustment of the angle of attack of the canard would only need to travel 
probably 1 or 2 degree up or down from the original design to assist in the 
different speed or passenger loading configurations. I agree with your 
assessment of at least another 100 hours added to the build time. But if 
there is a possibility that the trim system isn't adequate for all realms of 
flight, I would rather fix it as I build rather than retrofit it after my 
aircraft is completed. I also believe that being able to trim you aircraft 
with the canard should net you a 5 to 7 knot gain in speed.

Andy

----- Original Message ----- 
From: "Scott Baker" <sbakr at comcast.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Sunday, February 05, 2006 9:42 AM
Subject: Re: REFLECTOR: Adjustable Canard

> 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
>> >>
>> >>
>> >> __________________________________________________
>> >> Do You Yahoo!?
>> >> Tired of spam?  Yahoo! Mail has the best spam protection around
>> >> http://mail.yahoo.com
>> >> _______________________________________________
>> >> To change your email address, visit
>> >> http://www.tvbf.org/mailman/listinfo/reflector
>> >>
>> >> Visit the gallery!  www.tvbf.org/gallery
>> >> user:pw = tvbf:jamaicangoose
>> >> Check new archives: www.tvbf.org/pipermail
>> >> Check old archives: 
>> >> http://www.tvbf.org/archives/velocity/maillist.html
>> >>
>> >
>> > _______________________________________________
>> > To change your email address, visit
>> > http://www.tvbf.org/mailman/listinfo/reflector
>> >
>> > Visit the gallery!  www.tvbf.org/gallery
>> > user:pw = tvbf:jamaicangoose
>> > Check new archives: www.tvbf.org/pipermail
>> > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>
>> _______________________________________________
>> To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery!  www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
> _______________________________________________
> To change your email address, visit 
> http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery!  www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html 