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Nov 12, 2007, 11:34 PM
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Discussion

Thrust Line Vs Cord Line


:confused I'm working on an f9f-6 couger. What is the relationship between the thrust line, the cord line? Model at this point is designed around the
gws 40. with an 18" span.
Or, is there another trend that covers this topic?

Dave T.
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Nov 13, 2007, 02:05 AM
It wasn't me...
DanSavage's Avatar
Quote:
Originally Posted by cad4u dt
:confused I'm working on an f9f-6 couger. What is the relationship between the thrust line, the cord line? Model at this point is designed around the
gws 40. with an 18" span.
Or, is there another trend that covers this topic?

Dave T.
Hello Dave,

Cool project.

I think if you ask ten different people, you'd get ten different answers. I'll give you what I like to do.

If I were building this model, I'd make the thrust line zero degrees (0), wing chord line plus two degrees (+2) and the stab chord line zero degrees (0).

Dan
Nov 13, 2007, 08:51 AM
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Larry Dudeck's Avatar
I agree with Dan except on one minor clarification. Since I prefer the ubiquitous Clark Y airfoil, I mount the wing with the flat bottom flat on the building board. This automatically sets the chord line at 2 degrees positive. Other airfoils, such as semi or fully symmetric, will require different considerations such as that suggested by Dan.

My 48" ws F9F
Nov 13, 2007, 11:00 AM
It wasn't me...
DanSavage's Avatar
Quote:
Originally Posted by Larry Dudeck
I agree with Dan except on one minor clarification. Since I prefer the ubiquitous Clark Y airfoil, I mount the wing with the flat bottom flat on the building board. This automatically sets the chord line at 2 degrees positive. Other airfoils, such as semi or fully symmetric, will require different considerations such as that suggested by Dan.

My 48" ws F9F
Thanks. I'd forgotten about airfoil selection driving the incidence.

I agree. If I were using a Clark Y or other flat bottomed airfoil, then I would align the bottom of the wing with the thrust line and for the reasons you suggest.

Dan
Nov 13, 2007, 01:48 PM
smug in granny panties
monkamarm2000's Avatar
well there 3 opinions right there and we all seem to agree Dan! lol I too like 1 to 2 on wing but flat thrust line. few degrees on wing makes it more stable and not so floaty. nuetral wings tend to bob up and down cause there nuetral, so they take little flicks up and down as your attempting to just fly level. So you can end up with a plane that seems to need several different trim settings for level flight at different throttle settings.

Barry
Nov 13, 2007, 08:46 PM
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Thanks to all. I curently have the thrust line and chord line At 1deg. 58'
If I get this project going I might have a good design.

Dave T.
Nov 13, 2007, 09:11 PM
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See plans attached. this may help caus I don't know what I'm doing.
Nov 14, 2007, 01:09 AM
It wasn't me...
DanSavage's Avatar
Quote:
Originally Posted by cad4u dt
See plans attached. this may help caus I don't know what I'm doing.
Even so, it's a good start. Keep going.

Dan
Nov 14, 2007, 05:15 AM
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That would be awesome i would love to build one Im crap at scratch building so
Nov 16, 2007, 05:04 PM
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Any updates on the build?
Nov 26, 2007, 09:25 PM
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Up date:
While improveing my plans I printed out the top and side views. Wow! It's going to be a big one, in fact at 18" span it's to big for a gws-40. I created a side view of the
GWI/EDF-50 fan. and placed it in the top and side views, it fits just fine but I don't think the intake is large enough and the exaust is too small. The drawing I coppied didn't have the area of the fan hub to calculate the fan area. Thats where I am, STUCK!
Nov 26, 2007, 09:27 PM
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one more thing, I will be moveing after the new year. Right now I don't where yet, thinking of Oregon USA.
Nov 26, 2007, 10:00 PM
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Are you going to post plans
Nov 28, 2007, 03:54 PM
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Snipe,
I can create a dxf file from autocad, is there a special way to post it or do I just atach the file? I've done a lot of changes but I still have a few items I'm not sure about. Let me know of any other formats I can use.

David T.
Nov 28, 2007, 04:41 PM
Registered User
You just attach it like you would an image etc.

Thanks


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