Clay Walters

I see continuous reference to "scale" airplanes yet I've made a diligent search online to find a list of the various classifications and their definitions. I obviously haven't applied the proper search term...

Does one exist?

Thanks in advance,

Clay

Acs_guitars

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Look at RCKen and Minnflyer's new site.... the definitions may not be as detailed as you are looking for, but they are correct. Here: [link=http://www.gettingairborne.com/index.html]Getting Airborne[/link]
A true scale airplane is very detailed and has the same dimensional proportions as it's full scale counterpart. Scale modelling takes a lot of care and is best done by a pefectionist who has the patience to do all the fine detail work. Alot of warbirds can be lumped into this category as well.

Missileman

Scale means the model is a miniature copy of a real airplane like a Piper Cub or P-51 Mustang ect...

ByLoudDesign

I think there is a sort of situation where there is a "SCALE" A/C, which in my minds eye means exactly as stated above. If it is 1:10 every dimension and detail is divided by 10. I also think there is what would be called "TRUE SCALE" or "MASTER SCALE" that is a model or plans that provide for every nut, bolt, rivet, zerk and panel line, these are started with the same detail of size and shape and taken to the third dimension of extream detailing.
Charlie

opjose

And to muddy the water a bit... there is Scale, and there is ARF ( * B-Arf? * ) scale.

Most ARF planes need many compromises to fly and/or be afordable, so usually the depart from resembling the original planes.

True scale planes are a work of art... almost difficult to discern from the real thing.

Montague

There are tons of "classifications" and most of them are more in the eye of the beholder than anything. Getting overly wrapped up in those kinds of definitions will drive you nuts.

"scale" usually means that the model's appearance is based on a "full scale" piloted (usually) aircraft. How accurate the representation is varies a LOT, and the word "scale" does not imply how much it does or doesn't at all. (in other words, I disagree with some of the posts above). "scale" is more in the eye of the beholder, and what is and isn't "scale enough" for their tastes.

"sport" usually means a model that is NOT based on a larger aircraft. Most trainers and planes like the 4-star would fall into this category.

There are dozens more that you might see:
warbird - a scale model of a military aircraft, almost always a particular individual aircraft.
giant scale - any model (scale or sport) with a wingspan over 80" (for monoplanes, 60something for biplanes, if I recall)
pattern - a model designed to fly the AMA or FAI acrobatic precision routines "patterns".
IMAC or scale acrobat - models that are designed for IMAC acrobatic routines (kinda like, but different from pattern). They are very approximately scale models of piloted aircraft with totally non-scale color schemes.
3D - models designed for a particular style of acrobatics that are mostly performend at slow speed and high angle of attack.
profile - a model that looks like the body was run over by a steam roller

And lots more, and combinations of the above in some cases.

Clay Walters

I'm glad to know its clear as mud.

Began to wonder where 1/8A started and ended and 1/2A started & ended because I thought 1/2A stopped at .05 and that .051 started the A class. And then you see 1/4th scale cub, or a 30%Extra and I wondered "30% Extra?...What class would that be in?" sort of thing. Reckon I always thought of "scale" as being true to the original aircraft plans, only scaled down for modeling purposes but dimesionally and proportionally, and wing loading accurate; Not just "made to look like" the real thing.

Thanks the replies!

Clay

carrellh

I've never taken the time to learn the "A" classifications. All of that was before my interest in the hobby started.

The modern stuff I'm aware of is grouped by engine size, or by its size relationship to a full size piloted plane.

The engine size classifications I'm most familiar with are .20, .40, .60, 1.20; and that refers to cubic inch displacement of the recommended two stroke glow engine.

To muddy this up even more, the recommended engines for a "40" size plane actually range from .40 to .55 cubic inch. Most of the popular two cycle engines in this range are very close to the same physical size and usually fit the same engine mount without modification. Weight varies some among the many brands and models available in this engine class.



A 1/4 scale cub could also be called a 25% Cub. Its size is theoretically 25 percent of the full size piloted airplane.
A 30% Extra is theoretically that percentage of the size of the full size piloted plane.

I write "theoretically" because most models that are small versions of an actual production plane have been redesigned some so they will fly well as models. The wing size may be perfectly 'scale' but the tail feathers are bigger than they should be; or some other variation.

dalolyn

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lets not forget that the airfoil on a scale airplane is modified from its full scale counterpart.

Montague

Right, it's actualy very rare for there to be a model that is exactly 100% accurate to scale in outline and airfoil. Scaled down airfoils don't work very well, and many piloted aircraft have tails and other control surfaces that are small and can cause problems in a model. Now, flying a highly accurate scale model can be a real challange, and that's half the fun of that kind of flying.

And no scale model is going to have "scale weight" or scaled down wingloading. Those kinds of things don't scale right, and a 1/4 scale model that actually weighed 1/4 the full scale would never get off the ground. (and, you could argue, that since weight is a function of volume and density, and volume scales as the cube, that a 1/4 scale model should actually weigh 1/64 the full scale, but I digress. And the models don't do that either).

Also, it's very very rare for a scale RC model to have a the same power-to-weight of the piloted prototype. Most RC models have much more power than the origional, and without that excess power, most RC pilots would have a heck of a time flying the model at all.

Clay Walters

Well, if models are used for testing and design in the development of a new aircraft, I presume that will be the closest scale model of the final full-size aircraft.

But, none of that was the reason for this thread. I truthfully just wondered if there was a "rule book" somewhere of all the various classifications so I could just educate myself. The question popped in my mind initially when I found folks speaking of over size .050 in the 1/2A section and whenever I saw that an airplane over 80" wingspan (single wing) was IMAA legal. I realized I was ignorant of the various classes and began to take notice as I perused the various kits and ARFs now available. I knew some of this was more of a knowledge via familiarity for a lot of flyer but I thought that by chance there might just actually be a published concise listing that bulletpointed all of the items used to qualify an aircraft (or disqualify) to a class or group.

Right now it almost appears there's really only an "open" class unless a particular field has its own adopted rules the participants mutually observe. Surely that's not the case?

Regards,

Clay

Montague

That's pretty much it. There are specific rules for specific purposes (IMAA you already mentioned. IMAC has rules about how much you can change the outline of an Extra to be legal. I personally compete a lot in RC Combat, where we have lots of rules about classes of competition. FAI pattern limits the wingspan to 2meters and has a weight limit (I forget the limit though). AMA scale competition has the AMA's over all weight limit (55lbs), but the rest is judged, so if you're really far out of scale, you can still enter, you just get docked points and won't win the competition.

For just flying around, sport flying, having fun, no real rules or anything. It's just terms people use to try to communicate. Like "1/2A" for a sport flier is going to mean anything close to an .049. I personaly would call an .061 an "1/2A" engine, even if some Free Flight rules don't. (The AMA RC Combat rules DO call .061 "1/2A", but I digress).

When you talk electrics, you see "speed 400" a lot, which is a description of a rough size of model that can be flown on a particular size of eletric motor. That motor size just happened to be a common industrial size, and cheap, but now there are lots of motors that call themselves "400" or some other number, and it's mostly made up or in a sort-of reference to that old motor size.

When shopping for models on hobby shop websites, "scale" is going to mean what I said above, it looks kinda like a piloted model. "Sport" is everything else in most cases (Like Tower's website, which is this way, more or less). You'll might "gliders" seperate, and "gliders" might or might not include gliders with motors in the nose, and might or might not include hotliners and plane like the Electrostreak (which looks kinda like a glider, but doesn't fly like one).

As for models testing full-scale stuff, it depends on what the model is testing. But the guys building hte full scale know that the model won't fly like the full scale does exactly. Mr. Reynolds took care of that. (models in a wind tunnel work better, because they can control the Reynolds Number in ways to make the model act more like a full scale). And there are lots of things that can be tested by a model even when the over all flight performance isn't the same.

(I'm not even going to bring up "Scale airspeed"....)

TexasAirBoss

My Feedback: (22)

I build "scale" models. I love them. I build "fun scale" , or "semi scale" or "stand off " scale models and a few "scale" models. Back, years ago, when scale was king, there were several classes. Just as there are various skill levels when competeing in pattern contest today , there were various skill levels for competing in scale contest, at least at the Nats, which were the highest level of competition at the time. So, some of the verbage is left over from an old era, some of the language is advertising lingo, and some of it just comes from speaking a living language.

Clay Walters

Thanks for the thoughtful (& thorough) replies gents. Reckon I'll become more accustomed to the lingo the more I'm around it. No use looking for something that ain't there!



Clay