REFLECTOR: sparrow strainer QUESTION???

Laurence Coen lwcoen at hotmail.com
Wed Oct 19 12:19:16 CDT 2011


Kerry,

I had a similar problem with the sparrow strainer where I had to apply forward stick when flying solo.  I fixed the problem by reducing the negative angle of attack of the sparrow strainer.  With your present set-up you apparently have neutral or perhaps negative pitch stability.  An FAA requirement for certification of light aircraft is that they exhibit positive stability in all three axis. The purpose of the sparrow strainer is to increase pith stability but you can have too much of a good thing.

Larry Coen
N136LC


From: Kerry Woods 
Sent: Wednesday, October 19, 2011 10:56 AM
To: Velocity Aircraft Owners and Builders list 
Subject: Re: REFLECTOR: sparrow strainer QUESTION???


I'm flying without my SS right now but do not really like it very much. If you have a bump pitch the nose down it goes down and will not correct it's self at all just keeps going faster until I pull on the stick. With it on I had to apply a lot of forward stick beyond the trim spring just to cruise straight and level. My thought is to cut it in half, instead of the 6'' long make it only 3'' long. Any thoughts on that.
Kerry 
  ----- Original Message ----- 
  From: Scott Derrick 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Wednesday, October 19, 2011 10:45 AM
  Subject: Re: REFLECTOR: sparrow strainer QUESTION???


  I think you would get the same effect of no SS but more drag!

  -------- Original Message --------
  Subject: Re: REFLECTOR: sparrow strainer QUESTION???
  From: Douglas Holub <douglas.holub at gmail.com>
  To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
  Date: 10/19/2011 09:23 AM

    I wonder if I mounted two sparrow strainers on the elevator, one right side up and one upside down, if I would get the best of both worlds: improved pitch stability and less trimming.

    Doug Holub
    Standard FG
      ----- Original Message ----- 
      From: Alex Balic 
      To: 'Velocity Aircraft Owners and Builders list' 
      Sent: Wednesday, October 19, 2011 10:50 AM
      Subject: Re: REFLECTOR: sparrow strainer QUESTION???


      The elevator is statically balanced by the counterweights to help prevent flutter- it is not aerodynamically balanced-  look  at the airfoil section not even close to being symmetrical - it is held in the required position by the trim spring, the strainer was added to reduce the amount of trimming on the elevator due to speed differences- since at higher speeds the elevator loads up more, and at higher speeds, the strainer produces more force. 


      From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of aminetech at bluefrog.com
      Sent: Tuesday, October 18, 2011 4:05 PM
      To: Velocity Aircraft Owners and Builders list
      Subject: Re: REFLECTOR: sparrow strainer QUESTION???


      As I understand it, the elevator is extremely balanced which makes it unstable and the strainer was added to create a force for stability.  The bottom line is that you need a spring to hold the elevator in one spot for stability.


      John

      --- velocity_pilot at verizon.net wrote:

      From: "Alex Balic" <velocity_pilot at verizon.net>
      To: "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>
      Subject: Re: REFLECTOR: sparrow strainer QUESTION???
      Date: Tue, 18 Oct 2011 14:41:49 -0500

      I don't think that the sparrow strainer has anywhere near enough force to act as the main trim system, even if you could make it electrically adjustable- plus the problems that Doug mentioned. 

      Remember, the "elevator" on a canard is really a flap, and it takes a lot of load- not like a standard elevator that is more or less aerodynamically balanced during normal flight. 

        

      From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Douglas Holub
      Sent: Tuesday, October 18, 2011 2:06 PM
      To: Velocity Aircraft Owners and Builders list
      Subject: Re: REFLECTOR: sparrow strainer QUESTION??? 

        

      A couple cons would be more drag and a mechanical assembly out in the weather instead of in the cabin. 

      ----- Original Message ----- 

      From: Jeff Howell 

      To: reflector at tvbf.org 

      Sent: Tuesday, October 18, 2011 2:07 PM 

      Subject: REFLECTOR: sparrow strainer QUESTION??? 

        

      Question???
       
                    A fellow Velocity builder and I were talking.... We got to discussing the sparrow strainer trim tab on the elevator. Our question to everyone out there is... Could you use the sparrow strainer in conjunction with some sort of actuator as an elevator trim and remove the stock Velocity glass spring and elevator trim actuator??? what would be the pros and cons of having the sparrow strainer as your adjustable trim tab??? Thanx Jeff 


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