Date   

Re: Sparrow strainer stall conundrum

Jay Scheevel
 

Problem is, Ben. It is always needed. The elevator will always want to push up (causing the plane to dive), so something needs to keep it in place. If it is not for the sparrow strainer, then you will have to constantly pull back on the stick, just to stay level.

 

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Ben Wilson
Sent: Wednesday, February 23, 2022 2:54 PM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 

Jay - Keep going!
This is great fun.
With yarn video and your flow analysis it's clear there is a problem.
What about an articulating tab, up only when it's needed?
Ben Wilson


Re: Sparrow strainer stall conundrum

Michael Dunning
 

Anthony, I believe what you are talking about is an elevator slot, similar to a slotted flap? Jay's proposed elevator design is plain-flap style, unlike the R1145MS which does make use of an elevator slot for improved performance (see animation about halfway down this page).
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Re: Sparrow strainer stall conundrum

Ben Wilson
 

Jay - Keep going!
This is great fun.
With yarn video and your flow analysis it's clear there is a problem.
What about an articulating tab, up only when it's needed?
Ben Wilson


Re: Sparrow strainer stall conundrum

Jay Scheevel
 

I think you are misunderstanding a concept. The airfoil only changes the direction of the flow, it does not occlude the flow. It doesn’t matter how closely you “tuck in behind” another body. The relative wind (streamlines) you encounter is that of the flow behind the body. The exception to this rule is when the body in front is stalled and creating a bubble of turbulence behind. This does not happen when the stall conditions have not been exceeded.

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Anthony P
Sent: Wednesday, February 23, 2022 1:32 PM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 

Ok, thank you.

Very hard to believe that an airfoil in free stream would behave similarly to the same airfoil tucked closely behind another body.
I'm obviously missing something.  I'll go back and re-read your posts on the development of your elevator profile.


--
Q2 N86KL


Re: Sparrow strainer stall conundrum

Anthony P
 

Ok, thank you.

Very hard to believe that an airfoil in free stream would behave similarly to the same airfoil tucked closely behind another body.
I'm obviously missing something.  I'll go back and re-read your posts on the development of your elevator profile.


--
Q2 N86KL


Re: Sparrow strainer stall conundrum

Jay Scheevel
 

There I virtually no aerodynamic impact of the transition from the fixed elevator slot core to the elevator, so if that is what you mean, then no there is no effect.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Anthony P
Sent: Wednesday, February 23, 2022 12:45 PM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 



"Elevator Slot" = "pocket"

(pic taken from http://samhoskins.blogspot.com/search?updated-max=2014-06-18T04:55:00-07:00&max-results=20&start=27&by-date=false)




--
Q2 N86KL


Re: Sparrow strainer stall conundrum

Anthony P
 


Re: Sparrow strainer stall conundrum

Jay Scheevel
 

Not sure what you mean by “pocket”??

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Anthony P
Sent: Wednesday, February 23, 2022 11:17 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 

Jay, this is all very interesting.

Do your (model) numbers for the above profile include the effect of the pocket that the elevator partially occupies and the gaps to the trailing edges of the pocket?

I can't wait for you or someone else to try this.  Sparrow strainers are a P.I.A.
No lift, or net lift at the elevator pivot point would be great.

I'm willing to partially fund the investigation.


--
Q2 N86KL


Sparrow Strainer

Bruce Crain
 

Here is about the best pic I could find without going out to the airport (sore throat). If I get a chance I will go to the airport for a side view so it can bet better evaluated. This is my set up that requires vortex generators on the bottom of the strainers. Due to the fact that without vortex generaters they stall out when I push over to kill lift on the elevator. That puts the generators up and behind the elevator at a high negative upside down angle of attack. Before vortex generators I would have to stall the aircraft to get the strainer to reattach the relative air under them. Now they slightly stall when I push forward before completing an aileron roll for just a second. Then immediately reattach when the stick is pulled back to normal flight.
Clear as mud?


Re: Sparrow strainer stall conundrum

Anthony P
 

Jay, this is all very interesting.

Do your (model) numbers for the above profile include the effect of the pocket that the elevator partially occupies and the gaps to the trailing edges of the pocket?

I can't wait for you or someone else to try this.  Sparrow strainers are a P.I.A.
No lift, or net lift at the elevator pivot point would be great.

I'm willing to partially fund the investigation.


--
Q2 N86KL


Re: Sparrow strainer stall conundrum

Jay Scheevel
 

Hi Brian,

 

So here is the non-engineering answer:

 

The solution was developed a long time ago. John Roncz solved most problems for the Long EZ canard by introducing the new airfoil (Roncz MS1145). The quickie GU shortcomings were solved with the installation of the VG’s and the GU did not require the sparrow strainer anyway (this VG solution was not discovered until after QAC had gone entirely to selling the LS1).

 

Most people who built with the LS1 did not question the use of the sparrow strainers because they work as intended, are called for in the plans, albeit the additional drag issue was never discussed by QAC.

 

What we are talking about here is optimizing the solution, either by improving the sparrow strainer design or by eliminating the need for them with a modified elevator design.

 

Below is my working model for a redesigned elevator solution, where the sparrow strainer is likely not needed.  This is not a tested design, so PLEASE DON’T USE THIS.

 

Cheers,

Jay

 

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Brian Larick
Sent: Wednesday, February 23, 2022 9:17 AM
To: main@q-list.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 

My non engineer question.  Is there an efficient solution with a change to the shape of the elevator?  Would seem that if there was that it would have been developed a long time ago.

Brian



On Feb 23, 2022, at 10:48, Jay Scheevel <jay@...> wrote:



Thanks Michael,

 

I did read this after David pointed me in that direction. The problem with this approach is that the net moment arm is smaller because it is closer to the trailing edge, and the problem that the sparrow strainer is trying to solve is much larger than trying to balance trim spring loads. The basis of the problem is the shape of the elevator, which causes it to have a lot of upward deflection in the absence of the sparrow strainer. The issue that Burt was addressing was more of a tweak for builders that did not get everything perfectly set up while building.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Michael Dunning
Sent: Wednesday, February 23, 2022 8:12 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 

Jay, that RAF CP 59 that Dave listed makes some interesting points. Burt recommended fixed tabs riveted on (and 10" long, to boot) to unload the elevator trim springs; different idea but something to think about.

Note that the attached pdf is one I found before he posted his repository link. Might be poor quality.


--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Re: Sparrow strainer stall conundrum

Frankenbird Vern
 

 We think so..but remember that aerodynamics since 1980 has itself changed quite a bit, Brian.  Aerodynamics is still an evolving study. Actually Manufacturing and Structures Design is also. Internal Powerplant design is also improving.  AeroGeeks have learned a great deal since the days of Disco due to new tools like micro cameras that can be attached to birds.  

 No one knew back then how Peregrin Falcons could descend in an attack tuck at such incredible speeds. Impressive for a bird that is actually light weight compared to others like them. We understand more now. Still learning too.   

 So the answer is..probably.   

Vern   


From: main@Q-List.groups.io <main@Q-List.groups.io> on behalf of Brian Larick <blarick@...>
Sent: Wednesday, February 23, 2022 10:17 AM
To: main@q-list.groups.io <main@q-list.groups.io>
Subject: Re: [Q-List] Sparrow strainer stall conundrum
 
My non engineer question.  Is there an efficient solution with a change to the shape of the elevator?  Would seem that if there was that it would have been developed a long time ago.

Brian

On Feb 23, 2022, at 10:48, Jay Scheevel <jay@...> wrote:



Thanks Michael,

 

I did read this after David pointed me in that direction. The problem with this approach is that the net moment arm is smaller because it is closer to the trailing edge, and the problem that the sparrow strainer is trying to solve is much larger than trying to balance trim spring loads. The basis of the problem is the shape of the elevator, which causes it to have a lot of upward deflection in the absence of the sparrow strainer. The issue that Burt was addressing was more of a tweak for builders that did not get everything perfectly set up while building.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Michael Dunning
Sent: Wednesday, February 23, 2022 8:12 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 

Jay, that RAF CP 59 that Dave listed makes some interesting points. Burt recommended fixed tabs riveted on (and 10" long, to boot) to unload the elevator trim springs; different idea but something to think about.

Note that the attached pdf is one I found before he posted his repository link. Might be poor quality.


--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Re: Sparrow strainer stall conundrum

Brian Larick
 

My non engineer question.  Is there an efficient solution with a change to the shape of the elevator?  Would seem that if there was that it would have been developed a long time ago.

Brian

On Feb 23, 2022, at 10:48, Jay Scheevel <jay@...> wrote:



Thanks Michael,

 

I did read this after David pointed me in that direction. The problem with this approach is that the net moment arm is smaller because it is closer to the trailing edge, and the problem that the sparrow strainer is trying to solve is much larger than trying to balance trim spring loads. The basis of the problem is the shape of the elevator, which causes it to have a lot of upward deflection in the absence of the sparrow strainer. The issue that Burt was addressing was more of a tweak for builders that did not get everything perfectly set up while building.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Michael Dunning
Sent: Wednesday, February 23, 2022 8:12 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 

Jay, that RAF CP 59 that Dave listed makes some interesting points. Burt recommended fixed tabs riveted on (and 10" long, to boot) to unload the elevator trim springs; different idea but something to think about.

Note that the attached pdf is one I found before he posted his repository link. Might be poor quality.


--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Re: Sparrow strainer stall conundrum

Jay Scheevel
 

Thanks Michael,

 

I did read this after David pointed me in that direction. The problem with this approach is that the net moment arm is smaller because it is closer to the trailing edge, and the problem that the sparrow strainer is trying to solve is much larger than trying to balance trim spring loads. The basis of the problem is the shape of the elevator, which causes it to have a lot of upward deflection in the absence of the sparrow strainer. The issue that Burt was addressing was more of a tweak for builders that did not get everything perfectly set up while building.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Michael Dunning
Sent: Wednesday, February 23, 2022 8:12 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall conundrum

 

Jay, that RAF CP 59 that Dave listed makes some interesting points. Burt recommended fixed tabs riveted on (and 10" long, to boot) to unload the elevator trim springs; different idea but something to think about.

Note that the attached pdf is one I found before he posted his repository link. Might be poor quality.


--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Re: Sparrow strainer stall conundrum

Michael Dunning
 

Jay, that RAF CP 59 that Dave listed makes some interesting points. Burt recommended fixed tabs riveted on (and 10" long, to boot) to unload the elevator trim springs; different idea but something to think about.

Note that the attached pdf is one I found before he posted his repository link. Might be poor quality.


--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Re: Tri q 200 project for sale

Steve S
 

Sent them to your phone 


On Wed, Feb 23, 2022 at 8:33 AM, Steve S via groups.io
<chopndrag@...> wrote:





On Wed, Feb 23, 2022 at 8:25 AM, pablo barrozo
<pablobarrozo09@...> wrote:
More pics will be great. You can send them to 352 9425449.  Thx.

On Wed, Feb 23, 2022, 8:22 AM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Not sure 4000 it's ready to have the wings on tons of parts there I couldn't load all the pictures 


On Wed, Feb 23, 2022 at 7:48 AM, pablo barrozo
Am local. What you looking to get out of it?
Thanks.
Paul. 

On Tue, Feb 22, 2022, 9:20 PM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Don't have time to Finish this project.  Taking reasonable offers located in Zephyrhills Florida 


Re: Tri q 200 project for sale

Steve S
 






On Wed, Feb 23, 2022 at 8:25 AM, pablo barrozo
<pablobarrozo09@...> wrote:
More pics will be great. You can send them to 352 9425449.  Thx.

On Wed, Feb 23, 2022, 8:22 AM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Not sure 4000 it's ready to have the wings on tons of parts there I couldn't load all the pictures 


On Wed, Feb 23, 2022 at 7:48 AM, pablo barrozo
Am local. What you looking to get out of it?
Thanks.
Paul. 

On Tue, Feb 22, 2022, 9:20 PM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Don't have time to Finish this project.  Taking reasonable offers located in Zephyrhills Florida 


Re: Tri q 200 project for sale

Steve S
 






On Wed, Feb 23, 2022 at 8:25 AM, pablo barrozo
<pablobarrozo09@...> wrote:
More pics will be great. You can send them to 352 9425449.  Thx.

On Wed, Feb 23, 2022, 8:22 AM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Not sure 4000 it's ready to have the wings on tons of parts there I couldn't load all the pictures 


On Wed, Feb 23, 2022 at 7:48 AM, pablo barrozo
Am local. What you looking to get out of it?
Thanks.
Paul. 

On Tue, Feb 22, 2022, 9:20 PM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Don't have time to Finish this project.  Taking reasonable offers located in Zephyrhills Florida 


Re: Tri q 200 project for sale

pablo barrozo
 

More pics will be great. You can send them to 352 9425449.  Thx.


On Wed, Feb 23, 2022, 8:22 AM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Not sure 4000 it's ready to have the wings on tons of parts there I couldn't load all the pictures 


On Wed, Feb 23, 2022 at 7:48 AM, pablo barrozo
Am local. What you looking to get out of it?
Thanks.
Paul. 

On Tue, Feb 22, 2022, 9:20 PM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Don't have time to Finish this project.  Taking reasonable offers located in Zephyrhills Florida 


Re: Tri q 200 project for sale

Steve S
 

Not sure 4000 it's ready to have the wings on tons of parts there I couldn't load all the pictures 


On Wed, Feb 23, 2022 at 7:48 AM, pablo barrozo
<pablobarrozo09@...> wrote:
Am local. What you looking to get out of it?
Thanks.
Paul. 

On Tue, Feb 22, 2022, 9:20 PM Steve S via groups.io <chopndrag=yahoo.com@groups.io> wrote:
Don't have time to Finish this project.  Taking reasonable offers located in Zephyrhills Florida 

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