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Old Sep 07, 2012, 12:49 PM
Riley Winglow
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Belt, Montana
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The intent of Vortex Generators is not to slow down airflow, it is to generate vortices....... A sheet of small vortices across the top of a wing. This is supposed to help keep the airflow attached to the wing at higher angles of attack.
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Old Sep 07, 2012, 12:51 PM
Flyr John in Floyd VA
United States, VA, Floyd
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VG's

Can't remember the exact source, but one said they should be angled 18 degrees from the airflow. FWIW

John
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Old Sep 07, 2012, 12:51 PM
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Originally Posted by Gordks View Post
Does anyone know why in some graphics the VGs are shown in line with the airflow, but in most they are at a considerable angle?
Some more information here:

http://www.flyfbi.com/Black_Max_Air_...anual-Rev1.pdf
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Old Sep 07, 2012, 01:13 PM
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Originally Posted by GLM View Post
Like I don't have enough projects...

But all this is very interesting! I started thinking of how to make these for our beloved Cub.

Let talk size...

I took the size of a full scale Cub (35.3 feet) divided by 7.7 and got 55" our FC wingspan.

Very cursory research yields 10 percent of wing chord back from the leading edge of the wing for placement. The FC wing has a chord of 9" - 10% of that is .9" This dimension puts the VG line just ahead of the undulations in the FC wing - very convenient...

The size of the full scale VG's appears to be roughly 1" x 3/8" to 1/2" for effective area from Prof100's picture. Good work BTW!

Scaling down is the right thing to do but my short stumpies cramp up when I think about handling that many small little pieces let alone gluing them precisely on my beautiful wing.

Without getting into Reynolds number scaling...

I'm going to scale them to 1/4" long to 1/8" high at 5 degrees off line of travel 1/2" apart and make a mold of that - or at least that's what I'll shoot for.

Any input at this stage would be welcome.

I'll do a drawing of what I propose later today.

Everything I've read (at this point very little) suggests easier flight characteristics all around and greater take off weights. For me this means handling of bigger motors gets easier.

Too much power - nonsense!

VSTOL Baby VSTOL

Gary
Gary,

Don't forget air molecules don't get smaller with our RC planes. Therefore, scalling down to appropriate size to match the RC scale size may not work well at all.

You could always use the TLR method.

Bill
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Old Sep 07, 2012, 01:50 PM
GLM
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Originally Posted by Prof100 View Post
Gary,

Don't forget air molecules don't get smaller with our RC planes. Therefore, scalling down to appropriate size to match the RC scale size may not work well at all.

You could always use the TLR method.

Bill
I haven't - the calculated scale was .064 of a square inch or something so 1/4"x 1/8" is huge scale wise but easier to work with.

TLR?

This is what I have so far.
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Old Sep 07, 2012, 01:58 PM
JOHN 3:16
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Originally Posted by GLM View Post
TLR?

That
Looks
Right
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Old Sep 07, 2012, 04:43 PM
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I think they just used a thin wire running parallel and near to the leading edge, held off the surface with spacers in the old Free Flight days and on gliders, seemed to work well and is an easier method to try out rather than gluing a load of bits to your wing.
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Old Sep 07, 2012, 04:46 PM
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Originally Posted by Turner2 View Post
Thanks! Good reading. Well, this is looking like so much fun I may just be doing this myself soon. Anything slower and more controlled than a standard FunCub is going to be very hard to believe.

Gord
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Old Sep 07, 2012, 05:06 PM
GLM
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The mold needs some work - needs to be a little more robust...

I was able to make a couple of parts before the glue let go of a few fins.

As far as TLR goes - what do you guys think?

Might need to be a bit bigger?

When the design settles I'll produce these.

Cheers!

Gary
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Old Sep 07, 2012, 06:43 PM
Good Better Best quest.
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I have often wanted to try this pattern wich is a combination wing cap made from ABS sheet, would be simple for you to try,easy to attach for trials with double sided tape.
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Old Sep 07, 2012, 07:06 PM
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Originally Posted by GLM View Post
The mold needs some work - needs to be a little more robust...

I was able to make a couple of parts before the glue let go of a few fins.

As far as TLR goes - what do you guys think?

Might need to be a bit bigger?

When the design settles I'll produce these.

Cheers!

Gary
Gary,

I say it passes the TLR test although I would make them a bit more pointy on the front. That said, if those are molded in plastic right now I would glue them on your plane and test fly it to see how they help with slow flight. You could be done with the design. I like the strip which probably needs a self adhesive tape like carpet tape or equivalent.

Well done Gary.

Bill
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Last edited by Prof100; Sep 07, 2012 at 07:36 PM.
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Old Sep 07, 2012, 07:11 PM
GLM
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Thanks Bill,

I'll tape or canopy glue them on this weekend and give it a go. I can make them a little more pointy on the next rev. - I need a bigger base so it's more easily cut out from the rough stock.

Carpet tape - good idea!

Thanks

Gary
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Old Sep 07, 2012, 07:18 PM
build, fly, crash...repeat
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United States, WA, Redmond
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Originally Posted by GLM View Post
Hi Beamen,

The optional motor mount for the Floor/Stiffener kit gives you a firewall to install a cross mount on - this is different than the stock mount. In this install the bell or can of the motor is in front of the firewall not behind.

Check out my website for pictures of the installation.

Thanks for the interest!

Cheers!

Gary
Any recommended cross mounts that work with the Morgan motor mount? The HK cross doesn't appear to work. Also, any pictures of motors mounted using the Morgan setup?

Thanks
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Old Sep 07, 2012, 11:21 PM
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okay, this conversation just went beyond my comprehension. But man it's interesting
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Old Sep 07, 2012, 11:34 PM
GLM
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Originally Posted by marksp View Post
Any recommended cross mounts that work with the Morgan motor mount? The HK cross doesn't appear to work. Also, any pictures of motors mounted using the Morgan setup?

Thanks
Mark,

Here is a drawing of a Eflight Power 10/15/25 cross mount in green - it fits my motor mount just barely but will fit. Do you have some dimensions for the HK Mount?

I'm working on an additional firewall to attach to the optional motor mount for the larger cross mounts however some foam will have to be removed to accommodate it - it's the larger outside one.

Is it that you don't have enough room for the cross mount?

Gary
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