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Author Topic: Flap area on unequal wings?  (Read 452 times)

Offline Larry Wong

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Flap area on unequal wings?
« on: February 02, 2020, 12:01:45 PM »
Should the flap on the inboard wing be more or less in area ?or same?
Larry

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Offline Motorman

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Re: Flap area on unequal wings?
« Reply #1 on: February 02, 2020, 01:11:57 PM »
Less.
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Offline Brett Buck

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Re: Flap area on unequal wings?
« Reply #2 on: February 02, 2020, 01:13:32 PM »
Should the flap on the inboard wing be more or less in area ?or same?

  What do you mean by "unequal wings" - I wuill presume you mean standard asymmetry (inboard wing longer). Flap areas should be the same inboard and out, or, maybe slightly larger outside flap. Errors in the sizes are made up by tabs.

   Brett

Offline Larry Wong

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Re: Flap area on unequal wings?
« Reply #3 on: February 02, 2020, 01:49:32 PM »
Thanks Brett. Just wondering I noticed that David was using tab on inboard wing and others did it on outboard
Larry

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Offline Brett Buck

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Re: Flap area on unequal wings?
« Reply #4 on: February 02, 2020, 02:07:55 PM »
Thanks Brett. Just wondering I noticed that David was using tab on inboard wing and others did it on outboard

   It depends what it needs when you get done. It's a bit guesswork what you actually need. He may have overdone it on the large outboard flap, if so, put a tab on the inboard.

    Brett

Offline Howard Rush

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Re: Flap area on unequal wings?
« Reply #5 on: February 02, 2020, 02:52:56 PM »
There's no aerodynamic theoretical significance to equal flap area between wings, nor is there a formula to tell you what flap shapes or sizes to use.  It's done by experiment.  You are fortunate to have Brett, David, and Ted in your neighborhood.  They are masters at the subtleties of flap area distribution effects and can show you what to tweak.  Some tweaking methods are uglier than others.  My guess is that you are looking for a prettier way to make flaps than the designer of the airplane you fly uses. 
The Jive Combat Team
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Offline Shorts,David

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Re: Flap area on unequal wings?
« Reply #6 on: February 02, 2020, 03:20:27 PM »
Hi Larry. I just did flaps last night on my Junar. Granted it's a 30 year old design already, but it TQed for the fai team (I think). Anyhow, outboard flap is shorter yet wider, so approximately equal with the inboard. Not sure how it all plays out. Definitely tweaking down the road I assume.

Offline Brett Buck

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Re: Flap area on unequal wings?
« Reply #7 on: February 02, 2020, 04:36:26 PM »
Hi Larry. I just did flaps last night on my Junar. Granted it's a 30 year old design already, but it TQed for the fai team (I think). Anyhow, outboard flap is shorter yet wider, so approximately equal with the inboard.

   That's the general approach, you guess and then adjust afterwards.
   
    Brett

Offline Mike Scholtes

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Re: Flap area on unequal wings?
« Reply #8 on: February 02, 2020, 11:24:46 PM »
This thread got started because I admitted to Larry that I put the flaps on the wrong wing panels of my symmetrical-panel Oriental Plus. I had mislaid the plans and figured the narrower flap should go on the outer panel, due to slightly greater speed and need to avoid rolling on flap deflection. David looked at it at one of our trim sessions at Davis and said, "That doesn't look right." I contacted the designer, Dee Rice, who confirmed that, yep, narrower flap on inner panel. Flaps are equal length but one is narrower chordwise. Now I have a tab on the (wrongly) narrow outer flap and cut 1.5" off tip end of inner panel flap. Live and learn. It is somewhat comforting to learn there is no real way to figure it out in advance as a matter of design. Flaps were glued to hinges so no easy way to swap panels.

Offline Howard Rush

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Re: Flap area on unequal wings?
« Reply #9 on: February 03, 2020, 02:14:38 AM »
I do stuff like that all the time.
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Online Dennis Nunes

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Re: Flap area on unequal wings?
« Reply #10 on: February 03, 2020, 04:06:00 AM »
I do stuff like that all the time.

Howard, isn't that one of Murphy's Laws? That is, "if there are two ways to do something you will always select the wrong way"!   n~ n~

I hate that Murphy guy.   HB~> HB~>


Dennis
If at first you don't succeed ---- let someone else try it!  ;)

Offline john e. holliday

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Re: Flap area on unequal wings?
« Reply #11 on: February 03, 2020, 09:13:03 AM »
But, once in a while he gets it right. D>K
John E. "DOC" Holliday
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Offline Ken Culbertson

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Re: Flap area on unequal wings?
« Reply #12 on: February 03, 2020, 06:59:04 PM »
I used to have the smaller one outboard until someone on this forum a few years back was talking about tabs to help support tip weight.  Humm….
Now, (when I actually have a plane to fly) I always start out with the outboard flap about 2 sq" larger than the inboard by making the chord about 1/8" larger.  Being a big fan of line tension, it lets me carry just a tad more tip weight and not screw up tight corners.  Seems to work.   Still Brett has it right.  Take a sophisticated wild a** guess then fix it.  Every plane seems to be different.

Ken
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If it is not broke, don't fix it.
USAF 1968-1974 TAC


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