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Author Topic: Flap taper or straight constant cord - impact?  (Read 5998 times)

Online Dennis Toth

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Flap taper or straight constant cord - impact?
« on: September 16, 2014, 08:44:43 AM »
Guys,
I'm working on a new ship and wanted to have a straight trailing edge and flap look (normal sweep to the leading edge) . This would have the flaps as a constant cord. I was wondering if anyone has used constant cord flaps and is there any negative impact on the control stability with the tips having effectively more flap area then the  wing center?

Best,     DennisT

Offline Howard Rush

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Re: Flap taper or straight constant cord - impact?
« Reply #1 on: September 16, 2014, 12:38:00 PM »
I don't think you mean "control stability", but it shouldn't hurt the airplane stability, and it might be beneficial for hinge moment.  You'll have more flap than you need at the tips, particularly the inside tip, and less than you oughta have at the root, but I doubt if that's a big deal.  If I wanted that look, I'd mask a straight line on the flaps and paint the back black. 
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Offline Avaiojet

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Re: Flap taper or straight constant cord - impact?
« Reply #2 on: September 16, 2014, 06:44:06 PM »
Dennis,

I'm putting a model together with a constant cord wing and straight flaps also.

The aircraft I'm modeling doesn't call for flaps.

I was and probably will, have a 1" to 1.25" flap cord when I'm done.

The thinner the width of the flap, probably the more movement necessary? I'm guessing with that.

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Offline Howard Rush

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Re: Flap taper or straight constant cord - impact?
« Reply #3 on: September 16, 2014, 07:32:15 PM »
The thinner the width of the flap, probably the more movement necessary? I'm guessing with that.

I was guessing with that this past weekend, especially after reading the piece on Gurney flaps.  If the flow is separated, maybe you could have a really small chord flap and move it =/-  90 degrees.
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Offline Chris Wilson

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Re: Flap taper or straight constant cord - impact?
« Reply #4 on: September 16, 2014, 07:54:04 PM »
Dennis,

I'm putting a model together with a constant cord wing and straight flaps also.


Charles, Dennis has a tapered wing - as in "(normal sweep to the leading edge). "
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Offline Avaiojet

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Re: Flap taper or straight constant cord - impact?
« Reply #5 on: September 16, 2014, 08:07:18 PM »
Charles, Dennis has a tapered wing - as in "(normal sweep to the leading edge). "


Chris,

Thanks, I see that now.

I wonder if it's his twin boom?
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Offline Avaiojet

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Re: Flap taper or straight constant cord - impact?
« Reply #6 on: September 16, 2014, 08:10:07 PM »
I was guessing with that this past weekend, especially after reading the piece on Gurney flaps.  If the flow is separated, maybe you could have a really small chord flap and move it =/-  90 degrees.

Spoiler flaps.  LL~
Trump Derangement Syndrome. TDS. 
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Amazing how ignorance can get in the way of the learning process.
If you're Trolled, you know you're doing something right.  Alpha Mike Foxtrot. "No one has ever made a difference by being like everyone else."  Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten. "No amount of evidence will ever persuade an idiot."- Mark Twain. I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.   Proverb 11.9  "With his mouth the Godless destroys his neighbor..."  "Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Offline Chris Wilson

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Re: Flap taper or straight constant cord - impact?
« Reply #7 on: September 16, 2014, 09:05:12 PM »
I was guessing with that this past weekend, especially after reading the piece on Gurney flaps.  If the flow is separated, maybe you could have a really small chord flap and move it =/-  90 degrees.
Flap width = 0
Deflection = 90º

Works for me!
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Offline Howard Rush

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Re: Flap taper or straight constant cord - impact?
« Reply #8 on: September 16, 2014, 09:23:37 PM »
That's a degenerate case, and I'm a degenerate.  It all fits together.
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Offline Tim Wescott

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Re: Flap taper or straight constant cord - impact?
« Reply #9 on: September 17, 2014, 11:45:21 AM »
I don't think you mean "control stability", but it shouldn't hurt the airplane stability, and it might be beneficial for hinge moment.  You'll have more flap than you need at the tips, particularly the inside tip, and less than you oughta have at the root, but I doubt if that's a big deal.

Compared to all the Nobler clones, the newest planes often seem to have very little taper in their flaps -- I'm particularly thinking of the Impact, but I've seen the same thing on other planes.  I'm assuming that this was not done for aesthetics alone.

When faced with the whole "I want straight flaps" question, I just made the flaps run out about 3/4 of the way out, matched by a TE.  I know that's supposed to cause problems, but I wasn't a good enough flyer for it to make a difference!
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