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Old Oct 07, 2012, 06:18 PM
TheyreComingToTakeMeAway!
derk's Avatar
USA, ID, Coeur D'Alene
Joined Dec 2003
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how much of an effect do you think a slightly curved airfoil would have on the wings? would the flight speed drop and the inverted suffer? i really like the idea of a really slow flying plane.
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Old Oct 07, 2012, 07:09 PM
Aircraft Designer Guy
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Melrose, MA
Joined Jul 2005
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You could do that, or just add a few degrees of incidence to the main wing. Wing area is the same, so for a given CL, speed is the same. Slight camber would have a slightly higher CLmax than the flat plate, but with the blunt leading edge on both, it's doubtful they differ much in practice. The cambered section will have a steeper lift curve slope, so it will have the same CL at a lower angle of attack, less drag too. That's were adding a few deg incidence on the main wing would make for a slower cruise at normal looking fuselage attitudes. In the end a 10% increase on chord would have a more pronounced effect than these other changes. If you do want to add camber make sure to radius the leading edge, to take full advantage of the mod. Sorry for nerding out there...

-A
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Old Oct 07, 2012, 08:16 PM
Aircraft Designer Guy
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Melrose, MA
Joined Jul 2005
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Part labels for later use
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Old Oct 07, 2012, 09:30 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,430 Posts
Adam,
That looks really super. The yellow and white colors really make it look nice. Yes, I do need to assemble the covered set of pieces I have. I need to get ours in the air for my oldest son. Strangely he has little interest in building. I'll probably build it, and then he'll fly it.

Gordon
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Old Oct 08, 2012, 06:19 PM
road wart
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United States, CT, Stonington
Joined Aug 2003
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Adam,
is this 2mm depron? Sorry if its been posted and I didnt catch it.....Bruce
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Old Oct 08, 2012, 06:42 PM
Aircraft Designer Guy
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Melrose, MA
Joined Jul 2005
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Quote:
Originally Posted by racie34 View Post
Adam,
is this 2mm depron? Sorry if its been posted and I didnt catch it.....Bruce
Sorry, that's an obvious omission on my part. Everything is 3mm. The origional used Depron Aero, the second regular Depron. The new one is about 2.5g heavier.

-A
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Old Oct 08, 2012, 06:43 PM
road wart
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United States, CT, Stonington
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Thankyou Adam
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Old Oct 08, 2012, 07:25 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,430 Posts
Quote:
Originally Posted by MIT KID View Post
You could do that, or just add a few degrees of incidence to the main wing. Wing area is the same, so for a given CL, speed is the same. Slight camber would have a slightly higher CLmax than the flat plate, but with the blunt leading edge on both, it's doubtful they differ much in practice. The cambered section will have a steeper lift curve slope, so it will have the same CL at a lower angle of attack, less drag too. That's were adding a few deg incidence on the main wing would make for a slower cruise at normal looking fuselage attitudes. In the end a 10% increase on chord would have a more pronounced effect than these other changes. If you do want to add camber make sure to radius the leading edge, to take full advantage of the mod. Sorry for nerding out there...

-A
Adam,
I agree with all this. This is one reason on some of my skeleton planes I use 1.1mm Zepron. It's somewhat heavy for its thickness, but stiff. My thought is that I get less of the blunt leading edge than I'd get with 3mm or 2mm Depron. It's a tradeoff. My hope it I get a smoother airflow that might actually work well with the undercamber airfoil. But, who knows for sure.

Gordon
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Old Oct 08, 2012, 07:29 PM
Aircraft Designer Guy
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Melrose, MA
Joined Jul 2005
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Quote:
Originally Posted by Gordon Johnson View Post
Adam,
I agree with all this. This is one reason on some of my skeleton planes I use 1.1mm Zepron. It's somewhat heavy for its thickness, but stiff. My thought is that I get less of the blunt leading edge than I'd get with 3mm or 2mm Depron. It's a tradeoff. My hope it I get a smoother airflow that might actually work well with the undercamber airfoil. But, who knows for sure.

Gordon
Exactly. At this scale much of the performance is gained or lost at the leading edge. No reason you couldn't swap out the 3mm wing with a thinner cambered section. Should still be sufficiently strong.

-A
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Old Oct 08, 2012, 09:42 PM
Registered User
I R Irv's Avatar
United States, IL, Washington
Joined Nov 2008
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Did I miss the CG somewhere, would it be 25% cord?
TODD
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Old Oct 09, 2012, 07:16 AM
Aircraft Designer Guy
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Melrose, MA
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Quote:
Originally Posted by I R Irv View Post
Did I miss the CG somewhere, would it be 25% cord?
TODD
Another good catch, 1/4 to 1/3 chord is fine.

-A
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Old Oct 09, 2012, 12:01 PM
RC Connectors dot com
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United States, CO, Colorado Springs
Joined Jan 2008
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I know you said that the pdf sheet is 12x24", but can I suggest that a scale somewhere would be a nice bonus, next time you produce them...

Thanks,

Glenn
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Old Oct 09, 2012, 12:55 PM
Aircraft Designer Guy
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Melrose, MA
Joined Jul 2005
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Quote:
Originally Posted by glenn2626 View Post
I know you said that the pdf sheet is 12x24", but can I suggest that a scale somewhere would be a nice bonus, next time you produce them...

Thanks,

Glenn
Plans updated with 1 inch scale.

-A
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Old Oct 09, 2012, 08:12 PM
"Free" in Christ!
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United States, CA, SF
Joined Jan 2012
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Pretty plane!

Did you say the AUW somewhere?(sorry if I missed it)

Free
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Old Oct 09, 2012, 08:35 PM
Aircraft Designer Guy
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Melrose, MA
Joined Jul 2005
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Quote:
Originally Posted by Free View Post
Pretty plane!

Did you say the AUW somewhere?(sorry if I missed it)

Free
30-33g depending on which foam and covering you use. This is with a TP 150mAh cell and the electronics out of an e-flite Extra 300.

-A
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