Re: Tuft test video


Mike Dwyer
 

For people with flying airplanes, installing a new elevator is impractical.  I wonder how many Q's are actually being built these days.  1 a year?

Jay, your cowl flap is huge.  Is that controlled automatically or manually?  I actually don't have any cowl flap but generally only fly between 60F and 95F.  Still it would be nice to open it for takeoff and climb and close it for cruise.

Fly Safe,  
Mike Dwyer

Q200 Website: http://goo.gl/V8IrJF


On Sun, Feb 20, 2022 at 2:59 PM David J. Gall <David@...> wrote:

Jay,

 

I concur: Eliminate the sparrow strainers (they’re a hack anyway) and, instead, design an elevator that has a small amount of reflex on its trailing edge. That is exactly what John Roncz did on his Long-EZ canard replacement airfoil in the 1980s that is now the standard airfoil for those planes. The elevator “floating angle” should give the needed elevator deflection to make the canard give just the right amount of lift for a slow cruise speed, around 1.3 to 1.4 times stall speed. Rutan spells out this requirement in his Canard Pusher issue … 59(?) … where he discusses all the design requirements for pitch trim stability of canard airplanes. This “fix” could also be applied to the GU canard….

I can’t wait to see your results!

 

 

David J. Gall

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Jay Scheevel
Sent: Sunday, February 20, 2022 11:36 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Tuft test video

 

Good point Mike. That was Charlie’s suggestion also, based on his experience from his dragonfly.   I have a redesigned elevator on the drawing board that I have discussed before on this forum that is neutral in trail, so would not require the strainer. Sometime when I get the motivation, I will build a new set of elevators using this design and flight test them.

 

The LS-1 airfoil was never designed to have an articulated control surface.  I think the use on the Q200 was a bit of a hack, so required the sparrow strainer to correct the unintended consequences. The LS-1 is still the primary airfoil used on wind turbines, since it is very resistant to degraded performance caused by surface contamination, but those blades are one piece, so it is the perfect choice.

 

Cheers,

Jay

 

From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Mike Dwyer
Sent: Sunday, February 20, 2022 12:28 PM
To: main@q-list.groups.io
Subject: Re: [Q-List] Tuft test video

 

Great video Jay.  Agreed, looks like a drag point to me also.  Strainer looks to be in turbulent air.  Maybe a smaller strainer mounted in the air below would be better?

Fly Safe,

Mike Dwyer

 

Q200 Website: http://goo.gl/V8IrJF

 

 

On Sat, Feb 19, 2022 at 7:37 PM Jay Scheevel <jay@...> wrote:

Hi Guys,

 

I put the camera back on today and added some yarn tufts to the side of he fuselage, the canard root strake, the elevator and the sparrow strainer.  The video goes from runup through take off, then a pass at 1000 AGL along the runway and normal cruise with a couple of slow climbs. The tufts seem to lay down nicely with my contours on the strakes, which makes me happy, but the tufts on the sparrow strainer show that it is perpetually stalled. This is shown by the tufts from the top of the strainer wrapping around to the bottom of the strainer and occurs  at any airspeed above 80 mph. Alhtough the sparrow strainer works nicely to push down against the up-pushing of the undercamber on the elevator, this is a huge drag point on the airplane, and I am sure it limits the high speed performance significantly. There has to be a better way to do this …….

 

https://youtu.be/N-Gnd_CSywA

 

Cheers,

Jay

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