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Wing Tip washout popularity

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Wing Tip washout popularity

Old 07-27-2008, 08:40 AM
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CoosBayLumber
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Default Wing Tip washout popularity

I have a few older models, and instructions there indicate to carefully build the wing dead flat. No tip washout angle is desired.


When about did the popularity of Wing Tip washout angle come in to vogue? Know of any examples? for most of the eliptical tipped models were built somewhat flat.




Wm.
Old 07-27-2008, 11:53 AM
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iron eagel
 
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Default RE: Wing Tip washout popularity

I just got back into RC a few years ago after a long lay off from it, and at that time discovered washout as a popular thing in RC planes.
My Guess is that it came about after the studies NASA did in the 70's and 80's about airplane stalls and there development of the drooped wingtip.
I recall it is mentioned in Andy Lennon's book about model aircraft design which was published in the 90's also.
I would be interested when this was applied to models myself.
Old 07-27-2008, 12:21 PM
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Default RE: Wing Tip washout popularity

Deliberate warping of the wing surfaces (wash in and wash out) has been around almost as long as model aircraft. Wing section changes to do the same thing has been around at least since reliable R/C, and probably before on competition F/F. The idea is not new.
Evan.
Old 07-27-2008, 12:26 PM
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Default RE: Wing Tip washout popularity

I highly favor washout in trainers and scale airplanes that have a tendency to tip stall. I do not use any in my aerobats.

God Bless,

Jay
Old 07-27-2008, 05:30 PM
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iron eagel
 
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Default RE: Wing Tip washout popularity

Just learned some thing new, my early days I just built kits as per the instructions, and just really got into learning aerodynamics when I got back into the hobby a few years back.
Old 08-02-2008, 07:34 PM
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Default RE: Wing Tip washout popularity

Evan....


If you read the instructions that came along with the early era model, many-many cite to build flat.

Nothing to do with modern man-carrying full sized aircraft. Nowdays it cites to add in some washout when building the model.

Wondering when that transistion as to thinking came about.

Wm.
Old 08-02-2008, 09:21 PM
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Default RE: Wing Tip washout popularity

Wm, probably when the high power/weight (FAI) type F/F came along, I know that many of the old A1 and A2 class gliders stipulated warps, and tilted tailplanes and the like, as did the rubber classes, so from the late '40s onwards at least, it would have been uncommon to find one that did not have intentional warps.
Evan.
Old 08-02-2008, 09:29 PM
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Default RE: Wing Tip washout popularity

Sorry Wm, didn't read it right. I guess the 'add some washout' instruction on modern takes of old models came about when installing controllable rudders and elevators arrived, the beginning of the modern vintage movement, if you like. (Modern vintage??). Some of the old dears can fly so slowly that an unwary pilot could get into the position of hauling lots of rudder and elevator to 'make the strip' and inadvertently get the inboard wing to stall. A bit untidy, hence the usual exhortation to add a couple of degrees of washout.
Evan.
Old 08-03-2008, 08:56 AM
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da Rock
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Default RE: Wing Tip washout popularity

Keep in mind that the planform of the wing has a great deal to do with the need for and the effectiveness of washout.
Old 08-03-2008, 10:52 AM
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Default RE: Wing Tip washout popularity

Evan....


Not to doubt your word, but last nite I had dug out old A-1 and A-2 plans here from the 1950's and 1960's and not one word on them or the article as to adding any washout. Most of my magazines of that era are American Modeler, and Model Airplane News.


Not that it could not have been done. But certainly was not spoken about during that era. Wonder if it was not discussed in some magazine that I do not have?


Wm.
Old 08-03-2008, 12:52 PM
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Default RE: Wing Tip washout popularity

The Sig Kavalier and Kougar both have washout. They will do some basic outside manuevers, but they fly great and excell at low speed and landing. I have found memories of both...

turbo
Old 08-03-2008, 11:57 PM
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Default RE: Wing Tip washout popularity

Possibly Wm, most of my education was the 'Aeromodeller' when I was but a wee nipper. The old hand downs I got as a kid had a sort of 3 view and a discussion done by the proud builder where he explained his trimming process, and how he introduced the warps to keep the thing flying...
Evan.
Old 08-09-2008, 10:10 AM
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Default RE: Wing Tip washout popularity

There are other reasons besides tip-stall-resistance that can favor washout. If you're designing a wing for minimum induced drag, you want to design toward an elliptical lift distribution. You can do this by making the planform geometry elliptic (like a Spitfire), or you can make a rectangular planform behave ellipticly by twisting it (you can only make it truly elliptic at one angle of attack). This has two advantages... the wing sections at the tip have more chord and therefore more Reynolds number (this can be good for both drag and stall resistance)... the other plus is that rectangular (or linearly tapered) planforms are easier to build.
Old 08-09-2008, 02:44 PM
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Default RE: Wing Tip washout popularity

There was lots of washout used in old models. However it was always mentioned far later in the instructions during trimming. Or in many cases it was just "common knowledge" of the time passed on from one club member to the next. The first need was to build the wing flat for structural accuracy and then the washout was added when "de-warping" the wings after covering.

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