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Old Mar 29, 2011, 12:55 AM
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Ward

Will that effect both axis? when I do a taper both are off 8 mms
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Old Mar 29, 2011, 03:19 AM
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Quote:
Originally Posted by Ward Hagaman View Post
Roger, have you checked your Z offset very carefully? If you are a little off with that much taper, you would end up way off size. For example, for a right wing, if you are too far to the right it will cut small, if you are too far left you would cut big. You have to imagine where the wire or bow pivots from when you set up the marks on your table.
Also carefully checks the position of the foam block on the table.

Gilles
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Old Mar 29, 2011, 08:19 AM
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Originally Posted by gm.cnc View Post
Also carefully checks the position of the foam block on the table.

Gilles
I am just using 50mm wide test blocks 20mm from each tower and 20mm from the wire. and thats my offset

Roger
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Old Mar 29, 2011, 08:38 AM
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Roger, it sure sounds like the Z axis offset isn't matching the placement of your foam block(s). Could you could post a pic of your setup?
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Old Mar 29, 2011, 08:46 AM
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Originally Posted by Ward Hagaman View Post
Roger, it sure sounds like the Z axis offset isn't matching the placement of your foam block(s). Could you could post a pic of your setup?
what do you mean by the Z axis offset.
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Old Mar 29, 2011, 09:00 AM
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Sorry, I should have called it "root axis offset". That is how far the block is from the pivot point of your wire. If you are cutting a 2:1 taper, then if you are off in that measurement, then you will be under or over by that same amount.
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Old Mar 31, 2011, 11:17 AM
the anthropocebo effect
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Percentage camber?

...
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Old Mar 31, 2011, 12:32 PM
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Gilles,

I've never noticed this before, and it may be just something strange with this airfoil I've been playing with, but the percentage camber that GMFC shows is very different than XFOIL/XFLR5/Profili shows. They all say it is 4.81% (same base program, so agreement is not surprising). GMFC says it is 3.789%.

When I calculate the percentage camber by hand, I get 4.81% too. I do notice that the chord line of this airfoil does not go through the actual farthest forward point, so maybe the real camber is lower?

Any ideas?

Thanks,

Kevin
I will have a look. Maybe there is a problem with the starting or end point.

Gilles
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Old Apr 02, 2011, 03:24 PM
Michael K.
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Camber changes?

Why does the camber change when I input a different thickness at the tip than at the root? Try set to the tip thickness back to the same as the root and the camber back to zero...well its really messed up now.
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Old Apr 02, 2011, 03:48 PM
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Why does the camber change when I input a different thickness at the tip than at the root? Try set to the tip thickness back to the same as the root and the camber back to zero...well its really messed up now.
Hi,

This is a rectangle, not a real profile. That's the reason why thickness/camber does not work.

Gilles
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Old Apr 02, 2011, 07:31 PM
Michael K.
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Originally Posted by gm.cnc View Post
Hi,

This is a rectangle, not a real profile. That's the reason why thickness/camber does not work.

Gilles
OK, I was just surprised when the camber changed on its own when I changed the thickness. When I try the same with a real profile there are no surprises.
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Old Apr 03, 2011, 05:56 PM
the anthropocebo effect
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Old Apr 04, 2011, 04:33 PM
Michael K.
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Foam Cut

I guess that the Foam Cut utility is for blocking the foam to a usable size; raise the wire and cut down like a guillotine. Why does the program turn on the heat before raising the wire?
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Old Apr 04, 2011, 04:38 PM
Just fly it!
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Originally Posted by vol-haut View Post
Why does the program turn on the heat before raising the wire?
...to make sure that the wire is hot before cutting. If the wire hasn't fully heated then it will drag through the foam.
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Old Apr 04, 2011, 07:30 PM
Michael K.
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Originally Posted by wyowindworks View Post
...to make sure that the wire is hot before cutting. If the wire hasn't fully heated then it will drag through the foam.
When I click the Raise button the wire heats up for 10 seconds, goes up at full speed, wire heat is off again until I click the Cut button then heats for 10 seconds and then goes down at the cut speed. It really doesn't make sense for the wire to heat when it raises nless it does this so you have a chance to wipe the wire clean.
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