Topics

Sparrow strainer stall

Bruce Crain
 

Jon Finely here is the iPhone pic of the Sparrow Strainer stall. It is a terrible pic due to vibration but as you see (hopefully) the tufts are wrapped around the back of the strainer and pulled forward.

____________________________________________________________
Urologist Tells Men To "Fix" Their ED With This New Trick!
Med Journal
http://thirdpartyoffers.juno.com/TGL3131/5e03e97e9fe8969792ed2st01duc

Rob de Bie
 

Bruce, that's a great photo, many thanks! I always enjoy seeing the results of tufting.

Rob

At 23:58 25 12 2019, you wrote:
Jon Finely here is the iPhone pic of the Sparrow Strainer stall. It is a terrible pic due to vibration but as you see (hopefully) the tufts are wrapped around the back of the strainer and pulled forward.

____________________________________________________________
Urologist Tells Men To "Fix" Their ED With This New Trick!
Med Journal
http://thirdpartyoffers.juno.com/TGL3131/5e03e97e9fe8969792ed2st01duc



Jon Finley
 

Sorry Bruce... I just saw this.

It's hard to see from the photo - are the tufts on the canard also stalled??

Jon

Jon Finley
 
Edited

Come to think of it, didn't the Wadelow canard work by making the air flow backwards on the bottom of the airfoil and then wrap around the nose to flow over the top surface a second time?? :-)

Bruce Crain
 

Hi Jon!
No the canard isn't stalled but it looks like the elevator is stalled.  The tufts are gyrating in circular motion on the elevator right in front of the sparrow strainer and also in the outboard end of the elevator.  It would be interesting to see if every Quickie had the same scenario with respect to the elevator.  I had suspicion-ed that in the past when I flew through the rain.  The dust mixed with the rain and made trails from out board to inboard.
 
We could be loosing lift in this area but how to correct it?  The elevator slot core is pretty tight so I am not sure a seal is possible.  Also, perhaps an air dam on the outboard end of the elevator could be possible.  If lift is re-attached to the top of the elevator would the sparrow strainer need to be augmented to keep it level in flight?  There would be a lot more up lift in the elevator if re attachment were possible.
 
Could we be loosing airspeed!!!  OMGosh!  Somebody fix it!!  Any aerodynamicists in the room?!!
 
Bruce Crain

---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Tue, 17 Mar 2020 13:00:41 -0700

Sorry Bruce... I just saw this.

It's hard to see from the photo - are the tufts on the canard also stalled??

Jon

Bruce Crain
 

wink_smile

---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Tue, 17 Mar 2020 13:19:30 -0700

Come to think of it, didn't the Wadelow canard work by making the airflow backwards on the bottom of the airfoil and then wrap around the nose to flow over the top surface a second time?? :-)

Jay Scheevel
 

Hi Bruce,

 

A few years ago, Reg Clarke sent me some video of his tufted canard in flight. He was trying to resolve some elevator vibration he had over certain airspeed ranges and he did videos to figure that out. Here (https://q-list.groups.io/g/main/files/Reg_Clarke_tufted_canard_snapshots.pdf) is a sequence of snaps that I put together from his video at different airspeeds from cruise to pattern to touchdown.

 

I have posted a dashed red line that represents my interpreted forward limit of the separation bubble on  the canard. The tuft behavior on the sparrow strainer will look familiar to you, but you can also see that the separation climbs up the elevator and canard so there is no clean stall break, it stalls gradually, which is a characteristic of a laminar flow airfoil.

 

John Roncz created a canard for the Long-EZ to replace the GU canard which incorporated a slot core that had no bottom on the slot, so when the elevator was deflected down, some of the airflow went up through the slot and over the top of the elevator to help keep the flow connected to the elevator’s upper surface. I am not sure how effective this was, since I am not an EZ guy.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Bruce Crain
Sent: Wednesday, March 18, 2020 9:02 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall

 

Hi Jon!

No the canard isn't stalled but it looks like the elevator is stalled.  The tufts are gyrating in circular motion on the elevator right in front of the sparrow strainer and also in the outboard end of the elevator.  It would be interesting to see if every Quickie had the same scenario with respect to the elevator.  I had suspicion-ed that in the past when I flew through the rain.  The dust mixed with the rain and made trails from out board to inboard.

 

We could be loosing lift in this area but how to correct it?  The elevator slot core is pretty tight so I am not sure a seal is possible.  Also, perhaps an air dam on the outboard end of the elevator could be possible.  If lift is re-attached to the top of the elevator would the sparrow strainer need to be augmented to keep it level in flight?  There would be a lot more up lift in the elevator if re attachment were possible.

 

Could we be loosing airspeed!!!  OMGosh!  Somebody fix it!!  Any aerodynamicists in the room?!!

 

Bruce Crain


---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Tue, 17 Mar 2020 13:00:41 -0700

Sorry Bruce... I just saw this.

It's hard to see from the photo - are the tufts on the canard also stalled??

Jon

Jon Finley
 

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

Jay Scheevel
 

Hi Jon,

 

I recently heard someone refer to “gender fluid”. I have been checking at the local auto parts store, but have not been able to find any of that.  😉

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Jon Finley
Sent: Wednesday, March 18, 2020 12:41 PM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall

 

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

Bruce Crain
 

Jon, 
I tried the zig zag tape and did get the stall to go away right up the last test where I finally had all of the zig zag cleaned off.  With the zig zag the stall would not happen on the strainer but it created drag and dragged the strainer up and thus the elevator also.  The elevator would ride up a half inch or so and stay and I would reflex the ailerons up to compensate.
 
I am going to test actual vortex generators next.  Trying to make them small enough so that they don't  create drag and pull the elevator up.  So the zig zag did work but with less than great results for the trim I am used to seeing.
 
Before the next tests I am pulling a cylinder to check for a leak around a cylinder base stud or cylinder base o ring perhaps.
 
Bruce Crain


---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 11:41:07 -0700

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

Jay Scheevel
 

Bruce,
which side of the strainer did you put the zigzag tape on? Top or bottom?
Jay


Sent from my Verizon Wireless 4G LTE DROID


Bruce Crain <jcrain2@...> wrote:

Jon, 
I tried the zig zag tape and did get the stall to go away right up the last test where I finally had all of the zig zag cleaned off.  With the zig zag the stall would not happen on the strainer but it created drag and dragged the strainer up and thus the elevator also.  The elevator would ride up a half inch or so and stay and I would reflex the ailerons up to compensate.
 
I am going to test actual vortex generators next.  Trying to make them small enough so that they don't  create drag and pull the elevator up.  So the zig zag did work but with less than great results for the trim I am used to seeing.
 
Before the next tests I am pulling a cylinder to check for a leak around a cylinder base stud or cylinder base o ring perhaps.
 
Bruce Crain


---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 11:41:07 -0700

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

Bruce Crain
 

On the bottom as the stall was happening on the underneath side of the strainer.  The tufts on the aft of the strainers were disappearing underneath the strainers.
Bruce 


---------- Original Message ----------
From: "Jay Scheevel" <jay@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 19:44:54 -0600

Bruce,
which side of the strainer did you put the zigzag tape on? Top or bottom?
Jay
 
 
Sent from my Verizon Wireless 4G LTE DROID



Bruce Crain <jcrain2@...> wrote:

Jon, 
I tried the zig zag tape and did get the stall to go away right up the last test where I finally had all of the zig zag cleaned off.  With the zig zag the stall would not happen on the strainer but it created drag and dragged the strainer up and thus the elevator also.  The elevator would ride up a half inch or so and stay and I would reflex the ailerons up to compensate.
 
I am going to test actual vortex generators next.  Trying to make them small enough so that they don't  create drag and pull the elevator up.  So the zig zag did work but with less than great results for the trim I am used to seeing.
 
Before the next tests I am pulling a cylinder to check for a leak around a cylinder base stud or cylinder base o ring perhaps.
 
Bruce Crain


---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 11:41:07 -0700

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

Bruce Crain
 

I haven't changed the angle of attach on the strainers yet.  They are set for level cruise and I don't want that to go away so Vortex Generators next.  I  hope that the generators will make a bit of extra lift downward to override the push back and upwards they may produce.  I am moving pretty slow on all of this as I am working on the RV as well.
Bruce  
 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

Jay Scheevel
 

Hi Bruce,

 

If the airflow were to not detach from the elevator (in a perfect world), the airflow would follow the black streamlines shown in the computation below. These “ideal” streamlines suggest that the sparrow strainer would actually see a low angle of incidence, even when the canard is at a high attack angle (10 degrees) and the elevator is deflected 10 degrees down. Since my computation method is incapable of modeling the separation bubble and turbulent counterflow around the trailing edge of the elevator, the streamlines in that region of my model are not representative of real life. In the real world, I suspect what you are seeing from your sparrow strainer tufts is not related to the sparrow strainer stalling per se, but instead the sparrow strainer just happens to be caught up in the larger flow field of air flowing up and around the trailing edge of the elevator within the larger separation bubble. In other words, there is reverse airflow over the sparrow strainer because the elevator is stalled, not because the sparrow strainer is stalled. Not much you can do to get the sparrow strainer to fly when the airflow over it is backwards. My 2 cents.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Bruce Crain
Sent: Wednesday, March 18, 2020 9:18 PM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall

 

On the bottom as the stall was happening on the underneath side of the strainer.  The tufts on the aft of the strainers were disappearing underneath the strainers.

Bruce 

---------- Original Message ----------
From: "Jay Scheevel" <jay@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 19:44:54 -0600

Bruce,

which side of the strainer did you put the zigzag tape on? Top or bottom?

Jay

 

 

Sent from my Verizon Wireless 4G LTE DROID



Bruce Crain <jcrain2@...> wrote:

Jon, 

I tried the zig zag tape and did get the stall to go away right up the last test where I finally had all of the zig zag cleaned off.  With the zig zag the stall would not happen on the strainer but it created drag and dragged the strainer up and thus the elevator also.  The elevator would ride up a half inch or so and stay and I would reflex the ailerons up to compensate.

 

I am going to test actual vortex generators next.  Trying to make them small enough so that they don't  create drag and pull the elevator up.  So the zig zag did work but with less than great results for the trim I am used to seeing.

 

Before the next tests I am pulling a cylinder to check for a leak around a cylinder base stud or cylinder base o ring perhaps.

 

Bruce Crain



---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 11:41:07 -0700

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

Jay Scheevel
 

Oops, put the strainer on above instead of below he airfoil. Looks like the same story though…you decide.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Jay Scheevel
Sent: Thursday, March 19, 2020 9:39 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall

 

Hi Bruce,

 

If the airflow were to not detach from the elevator (in a perfect world), the airflow would follow the black streamlines shown in the computation below. These “ideal” streamlines suggest that the sparrow strainer would actually see a low angle of incidence, even when the canard is at a high attack angle (10 degrees) and the elevator is deflected 10 degrees down. Since my computation method is incapable of modeling the separation bubble and turbulent counterflow around the trailing edge of the elevator, the streamlines in that region of my model are not representative of real life. In the real world, I suspect what you are seeing from your sparrow strainer tufts is not related to the sparrow strainer stalling per se, but instead the sparrow strainer just happens to be caught up in the larger flow field of air flowing up and around the trailing edge of the elevator within the larger separation bubble. In other words, there is reverse airflow over the sparrow strainer because the elevator is stalled, not because the sparrow strainer is stalled. Not much you can do to get the sparrow strainer to fly when the airflow over it is backwards. My 2 cents.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Bruce Crain
Sent: Wednesday, March 18, 2020 9:18 PM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall

 

On the bottom as the stall was happening on the underneath side of the strainer.  The tufts on the aft of the strainers were disappearing underneath the strainers.

Bruce 

---------- Original Message ----------
From: "Jay Scheevel" <jay@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 19:44:54 -0600

Bruce,

which side of the strainer did you put the zigzag tape on? Top or bottom?

Jay

 

 

Sent from my Verizon Wireless 4G LTE DROID



Bruce Crain <jcrain2@...> wrote:

Jon, 

I tried the zig zag tape and did get the stall to go away right up the last test where I finally had all of the zig zag cleaned off.  With the zig zag the stall would not happen on the strainer but it created drag and dragged the strainer up and thus the elevator also.  The elevator would ride up a half inch or so and stay and I would reflex the ailerons up to compensate.

 

I am going to test actual vortex generators next.  Trying to make them small enough so that they don't  create drag and pull the elevator up.  So the zig zag did work but with less than great results for the trim I am used to seeing.

 

Before the next tests I am pulling a cylinder to check for a leak around a cylinder base stud or cylinder base o ring perhaps.

 

Bruce Crain



---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 11:41:07 -0700

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

David J. Gall
 

Bruce,

I don’t think the zig-zag tape “created drag” the way you describe it. To me, your description seems like the tape was doing exactly what it was supposed to be doing: keeping the airflow energized and attached. The fact that the now-attached airflow made the elevator “ride up” is exactly what one would expect from an improvement in the air flow over the top of the airfoil; instead of matching the new elevator position with reflexor, you could have accepted the “new normal” and trimmed for it. My bet is that you’ll see similar or identical results with VGs. Was the airplane slower as a result? If so, perhaps that was caused by the nose-high attitude you created when you trimmed the reflexor TE up instead of elevator TE down, and not by “added drag” from the zig-zag tape.

The problem with the sparrow strainer being stalled is that the little beastie is too small and/or too close to the elevator hinge line. This could be fixed in any of several ways, including making it bigger or re-contouring the elevator. 

I wouldn’t count the zig-zag tape as a failure — according to your description, it was eminently successful!

David J. Gall

On Mar 18, 2020, at 6:25 PM, Bruce Crain <jcrain2@...> wrote:


Jon, 
I tried the zig zag tape and did get the stall to go away right up the last test where I finally had all of the zig zag cleaned off.  With the zig zag the stall would not happen on the strainer but it created drag and dragged the strainer up and thus the elevator also.  The elevator would ride up a half inch or so and stay and I would reflex the ailerons up to compensate.
 
I am going to test actual vortex generators next.  Trying to make them small enough so that they don't  create drag and pull the elevator up.  So the zig zag did work but with less than great results for the trim I am used to seeing.
 
Before the next tests I am pulling a cylinder to check for a leak around a cylinder base stud or cylinder base o ring perhaps.
 
Bruce Crain


---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 11:41:07 -0700

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

David J. Gall
 

Dang it! Bruce, I misunderstood where you were putting the zig-zag tape. Disregard my previous post.......

On Mar 19, 2020, at 12:11 PM, David J. Gall <David@...> wrote:


Bruce,

I don’t think the zig-zag tape “created drag” the way you describe it. To me, your description seems like the tape was doing exactly what it was supposed to be doing: keeping the airflow energized and attached. The fact that the now-attached airflow made the elevator “ride up” is exactly what one would expect from an improvement in the air flow over the top of the airfoil; instead of matching the new elevator position with reflexor, you could have accepted the “new normal” and trimmed for it. My bet is that you’ll see similar or identical results with VGs. Was the airplane slower as a result? If so, perhaps that was caused by the nose-high attitude you created when you trimmed the reflexor TE up instead of elevator TE down, and not by “added drag” from the zig-zag tape.

The problem with the sparrow strainer being stalled is that the little beastie is too small and/or too close to the elevator hinge line. This could be fixed in any of several ways, including making it bigger or re-contouring the elevator. 

I wouldn’t count the zig-zag tape as a failure — according to your description, it was eminently successful!

David J. Gall

On Mar 18, 2020, at 6:25 PM, Bruce Crain <jcrain2@...> wrote:


Jon, 
I tried the zig zag tape and did get the stall to go away right up the last test where I finally had all of the zig zag cleaned off.  With the zig zag the stall would not happen on the strainer but it created drag and dragged the strainer up and thus the elevator also.  The elevator would ride up a half inch or so and stay and I would reflex the ailerons up to compensate.
 
I am going to test actual vortex generators next.  Trying to make them small enough so that they don't  create drag and pull the elevator up.  So the zig zag did work but with less than great results for the trim I am used to seeing.
 
Before the next tests I am pulling a cylinder to check for a leak around a cylinder base stud or cylinder base o ring perhaps.
 
Bruce Crain


---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 11:41:07 -0700

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

Bruce Crain
 

Say Jay I
think the tufts on the elevator were moving the same direction in normal cruise (from outboard to inboard) regardless of the sparrow strainer stalling or not stalling.  It could be exacerbating where the air flow goes due to the strainers moving up and being blanked by the elevator perhaps.  I except when I pull the stick and lower the strainer back to cruise pitch or lower it still takes stalling the canard to alleviate the sparrow strainer stall.  Maybe my outboard strainer is the difference between my Q and others but then I believe DFly's have outboard maybe.  Charlie can you back me up on that?  Or maybe no one else has actually pulled up and unloaded their Quickie to the extent that I have.
 
It has bothered me for a few years that the airflow on the elevator move inboard like it does.  To an aerodynamisist it means a big loss in speed doesn't it?  I am sure when the LS1 airfoil came out they had it working well.  Maybe it's just me.
Bruce Crain  

Please note: message attached

From: "Jay Scheevel" <jay@...>
To: <main@Q-List.groups.io>
Subject: Re: [Q-List] Sparrow strainer stall
Date: Thu, 19 Mar 2020 09:39:12 -0600

Bruce Crain
 

Thanks David, 
For a moment I thought it gave me a bit faster airspeed but the I realized that the air was pretty turbulent and I was having a hard time trimming for straight and level.  I do know that someone said "if you trim the elevator up and compensate level cruise trim with the reflexor you get more airspeed.  I cannot confirm that was the case.  And yes the zig zag did work.  Just made the airplane ride nose high for cruise.
 
Bruce


---------- Original Message ----------
From: "David J. Gall" <David@...>
To: main@q-list.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Thu, 19 Mar 2020 12:10:51 -0700

Bruce,
 
I don’t think the zig-zag tape “created drag” the way you describe it. To me, your description seems like the tape was doing exactly what it was supposed to be doing: keeping the airflow energized and attached. The fact that the now-attached airflow made the elevator “ride up” is exactly what one would expect from an improvement in the air flow over the top of the airfoil; instead of matching the new elevator position with reflexor, you could have accepted the “new normal” and trimmed for it. My bet is that you’ll see similar or identical results with VGs. Was the airplane slower as a result? If so, perhaps that was caused by the nose-high attitude you created when you trimmed the reflexor TE up instead of elevator TE down, and not by “added drag” from the zig-zag tape.
 
The problem with the sparrow strainer being stalled is that the little beastie is too small and/or too close to the elevator hinge line. This could be fixed in any of several ways, including making it bigger or re-contouring the elevator. 
 
I wouldn’t count the zig-zag tape as a failure — according to your description, it was eminently successful!
 
David J. Gall

On Mar 18, 2020, at 6:25 PM, Bruce Crain <jcrain2@...> wrote:

Jon, 
I tried the zig zag tape and did get the stall to go away right up the last test where I finally had all of the zig zag cleaned off.  With the zig zag the stall would not happen on the strainer but it created drag and dragged the strainer up and thus the elevator also.  The elevator would ride up a half inch or so and stay and I would reflex the ailerons up to compensate.
 
I am going to test actual vortex generators next.  Trying to make them small enough so that they don't  create drag and pull the elevator up.  So the zig zag did work but with less than great results for the trim I am used to seeing.
 
Before the next tests I am pulling a cylinder to check for a leak around a cylinder base stud or cylinder base o ring perhaps.
 
Bruce Crain


---------- Original Message ----------
From: "Jon Finley" <jd@...>
To: main@Q-List.groups.io
Subject: Re: [Q-List] Sparrow strainer stall
Date: Wed, 18 Mar 2020 11:41:07 -0700

Howdy Jay,

I recently heard a woman admit that there are "degrees of yes" - I was stunned. Of course, I was very familiar with this phenomena but had never heard the other gender actually admit to it. Now you are talking about "degrees of stalled" - please confirm your gender!! 

:-)

Seriously, I know you are correct. I also saw this in my GU canard tuft testing (moving up/forward on the airfoil). 

Bruce; I don't know what to say on your strainers. I struggled to know how to set them (and eventually gave up on them on my GU, since they weren't needed/per-plans (instead, springs take up the load, as I recall)).  I imagine you have already tried reducing their angle of attack - and noted some change in stick force?? 

Jon  

 

One Sky Dog
 

Bruce,

I have sparrow strainers outboard and added one inboard when my incidence was wrong. I do not fully understand when this is happening to your plane. Is this while you are rolling the plane? I have never rolled a plane and Dragonflies are reported to be poor rollers so I have zero experience in that attitude.

I have lost sparrow strainers in flight which would be equivalent to a fully stalled sparrow strainers in no assistance in keeping the elevators down and loaded. Without a sparrow strainer the elevators raise and the nose goes down requiring constant back pressure on the stick.

Please reiterate when this phenomenon occurs I am missing something.

On Mar 19, 2020, at 7:33 PM, Bruce Crain <jcrain2@...> wrote:

I believe DFly's have outboard maybe.  Charlie can you back me up on that?  Or maybe no one else has actually pulled up and unloaded their Quickie to the extent that I have.