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Old Jan 15, 2007, 05:27 PM
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Define Scale?


How "true to scale" is that latest 1/3 scale glass slipper you just paid your hard earned mega-bucks for?

How "true to scale" are the 1/4 to 1/3 scale sailplanes from the most reputable manufacturers?

I've read before that one 1/3 scale ASH-26 for example was "more scale" than another and both come from reputable manufacturers. (One has a narrower fuselage than the other.)

What is an acceptable compromise?

Is it okay if the fuselage cross sections are a little off? Maybe a little narrower or wider, longer or shorter?

What about the Wing... obviously, at our reynolds numbers the airfoil should be a suitable model airfoil. But what about the horizontal and vertical stab and the control surfaces to include the ailerons and flaps? Is it acceptable for them to be a little larger than scale?

Regards,
TommyT
Last edited by tommyt; Jan 15, 2007 at 07:21 PM.
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Old Jan 15, 2007, 05:53 PM
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It all depends on what you are doing with the airframe....are you building it to fly and have fun with it....or are you building it for competition? Here in the states there are no "official" scale sailplane competitions beside the AMA Nats that I know of and then they only do "stand off scale" I believe. Most manufactures do "tweak" their airframes to make them more "friendly".......the only way to get a "true" to scale airframe is to "roll you own".....and then even then it can be tough to do if you don't have factory drawings to go off of.
Old Jan 15, 2007, 06:28 PM
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Mr Reynolds and his Numbers change with scale so 1:1 cannot equate with 1:4
Dave.
Old Jan 15, 2007, 06:51 PM
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"ish"...works for me

But I only see it at 50 ft out and blazing across the slope.....

Horses for course I suppose
Old Jan 15, 2007, 07:25 PM
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IMO if you can't visually detect the deviation that's more than good enough for me. If you need a ruler/tape to show it's out, it's probably not worth worrying about...
Old Jan 15, 2007, 09:12 PM
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All of the original TMRC designs are near perfect scale, except for any errors such as those SZD16 points out which are due only to following factory three views, blueprints, or other documentation that has been published in error.

For example, the book Sailplanes by Schweizer by Simons and Schweizer points out in the text that the 1-26E airframe was all aluminum except only for the movable surfaces. The drawing by Martin Simons shows the fixed horizontal stabilizer as fabric covered too however. Which is correct? Both authors are experts in the field and their own book has contradictions.... plus a misprint in that it begins this paragraph with "the 1-23" which was clearly meant to be the 1-26 since that is the subject of the paragraph.

I've drawn all of our E model 1-26s with sheeted stab to simulate a sheet-metal-skinned structure, this is however incorrect. Visit Jim Phoenix's web pages here http://www.jimphoenix.com/jimphoenix...empennage.html and you will see serial number 686's empenage, an E model with it's riveted aluminum framework with fabric covering, just as Martin has drawn it.

Tom
Last edited by mmartin55; Jan 15, 2007 at 09:17 PM.
Old Jan 15, 2007, 09:22 PM
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Everyone has their own definition of what scale is. Unless of course you enter a scale contest and then the rules of the contest will define "what" scale is for that contest. For me I like a plane to be recognizable as a model of it's full scale counterpart. I really don't care if it's perfectly scale and I will change whatever I need to in order to make a plane fly well. If that means adding flaps to a plane that did not have em, so be it if it means a bigger wing or tail then I will do that too (Unless of course I am going to build a plane for the scale masters). I enjoy building and flying and it it does not fly well, to me ther is no point in building it. Unless it's a contest build and fly what you like!
Old Jan 16, 2007, 09:21 AM
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Quote:
Originally Posted by TFLG
Everyone has their own definition of what scale is. Unless of course you enter a scale contest and then the rules of the contest will define "what" scale is for that contest. For me I like a plane to be recognizable as a model of it's full scale counterpart. I really don't care if it's perfectly scale and I will change whatever I need to in order to make a plane fly well.
Is this pretty much every ones opinion?

Regards,
Tom
Old Jan 16, 2007, 09:34 AM
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Quote:
Originally Posted by tommyt
Is this pretty much every ones opinion?

Regards,
Tom

You know what they say about opinions

There are at a minimum 3 definitions for "scale"

(1) Webster's, 2 a : to arrange in a graduated series b (1) : to measure by or as if by a scale (2) : to measure or estimate the sound content of (as logs) c : to pattern, make, regulate, set, or estimate according to some rate or standard : ADJUST <a production schedule scaled to actual need> -- often used with back, down, or up <scale down imports>
intransitive verb


(2) A Contest's definition, AMA's for example can be found here. http://www.modelaircraft.org/comp/07...book/Scale.pdf

(3) Your own definition. My definition is mine and I don't know if anyone else agrees with it or not. However, I've designed and sold several thousand (sorta scale) PSS kits over the years I suppose at least a few modelers like my definition .

Cheers
TFLG
Last edited by TFLG; Jan 16, 2007 at 10:38 AM.
Old Jan 16, 2007, 10:27 AM
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Unless you are competing in the Scale masters....scale is what you want it to be. If it looks good to your eye and the price works for you.......go with the flow man!!
Old Jan 16, 2007, 10:58 AM
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It's that damn small white thing that sits on the floor and tells me I have to DIET!!!!
Old Jan 16, 2007, 01:14 PM
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Quote:
Originally Posted by tommyt
What about the Wing... obviously, at our reynolds numbers the airfoil should be a suitable model airfoil.
I found out that my 20+ year-old Multiplex ASW 20 sports the airfoil of the original ASW 20 wingroot which looks kind of strange compared to the typical model airfoils...
The wing geometry, aspect ratio etc. are very near to scale as well. Don't know about the fuse though.

I maidened it on Saturday and was not at all impressed with its performance, but maybe that was just my incompetent piloting... I will test it again on a better day and have an experienced pilot fly it.

It is obviuos that it would be possible to build a very good performing ASW 20 with scale wing geometry and a modern airfoil. Maybe I'll do a new set of wings if these really dont work out...

Philipp
Old Jan 16, 2007, 01:27 PM
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Opinions vastly differ. In my past experience, basically here's how it works. The smaller the scale plane, the less scale it is. Bigger tailplane, larger wing tips,....etc. Larger planes like 1/3 scale and up, more closely resemble the full size . Now each mfg has their idea of scale. Some believe that a general scale looking plane, but modified to have better handling (no nasty tip stalls, gentler pitch authority and all), will generate more customer base. Others stick to strictly scale and believe if you can't handle it, you shouldn't be flying it!! Again, given two similar models of the same size (e.g. ASW-24 at 1:3.75 scale) from different mfg will look some what different. One is more scale than other. I've noticed most people don't care if a plane it's slightly out of scale. Then again some people want exact scale and end up flying it with no pilots in the cockpit...How scale is that??? It's all up to what YOU want.
Old Jan 16, 2007, 04:46 PM
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I failed linkage geometry
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Quote:
Originally Posted by timmig
It's that damn small white thing that sits on the floor and tells me I have to DIET!!!!
lol. me too
Old Jan 17, 2007, 03:00 AM
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If you scratch build your own (definition = start by drawing your own plans), then you will always try your absolute best to make it true scale, all apart from the airfoil for reasons discussed. It prays on my mind if I subsequently find something is incorrect, especially if someone else has pointed it out.

If you buy off the shelf you may have already got excuses for errors but you will never have the same pride as you get when rolling your own. You will quickly become intollerant of discrepancies


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