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Design => Stunt design => Topic started by: Dennis Toth on September 16, 2014, 08:44:43 AM

Title: Flap taper or straight constant cord - impact?
Post by: Dennis Toth 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
Title: Re: Flap taper or straight constant cord - impact?
Post by: Howard Rush 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. 
Title: Re: Flap taper or straight constant cord - impact?
Post by: Avaiojet 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.

Title: Re: Flap taper or straight constant cord - impact?
Post by: Howard Rush 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.
Title: Re: Flap taper or straight constant cord - impact?
Post by: Chris Wilson 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). "
Title: Re: Flap taper or straight constant cord - impact?
Post by: Avaiojet 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?
Title: Re: Flap taper or straight constant cord - impact?
Post by: Avaiojet 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~
Title: Re: Flap taper or straight constant cord - impact?
Post by: Chris Wilson 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!
Title: Re: Flap taper or straight constant cord - impact?
Post by: Howard Rush on September 16, 2014, 09:23:37 PM
That's a degenerate case, and I'm a degenerate.  It all fits together.
Title: Re: Flap taper or straight constant cord - impact?
Post by: Tim Wescott 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!