REFLECTOR: sparrow strainer QUESTION???

[Glenn Babcock]

Canard aircraft create lift from both the main wing and the canard. This makes them stable in pitch.  Trim for a given pitch, let go of the stick and it will stay there, even as the speed changes. This means that if you trim for a few degrees pitch down, the plane will accelerate quickly and not attempt to pull up on its own. 

On aircraft with tails, the tail creates downforce, which makes them stable in airspeed. Trim for an airspeed and it will hold it. If you trim for an airspeed then pull the power back, the nose will drop but the airspeed will remain about the same. 

The sparrow strainer is an upside down wing shape. As airspeed increases, it generates downforce, moving the trailing edge of the elevator down. This increases pitch, causing a canard aircraft to act more like an aircraft with a tail. 

I have never installed my sparrow strainer and I'm ok with it like that. Some people prefer to have it. It's safe either way, just as long as you know what to expect. It's a personal choice. 

The trim spring is just that, a trim device. The sparrow strainer is also a type of trim device. In theory you could combine them, but I agree with the opinion that it adds complexity with little or no benefit. 

Regards,

Glenn
N697RG
Elite RG, flying 


On Oct 18, 2011, at 7:03 PM, "Douglas Holub" <douglas.holub at gmail.com> wrote:

> I thought there were many planes flying without the sparrow strainer. I flew mine for awhile without it. I added it to improve pitch stability. Without the strainer, when I let go of the stick to evaluate pitch stability, the initial descents were so fast it was scary. 
>  
> Doug Holub
> Standard FG
> ----- Original Message -----
> From: aminetech at bluefrog.com
> To: Velocity Aircraft Owners and Builders list
> Sent: Tuesday, October 18, 2011 5:05 PM
> 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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