I had always figured that sport planes in the 68" - 80" wing span category having a wing loading in the high 20's oz./sq. in. was a most desireable attribute for good flying manners.

However, in recent times I have noticed that most of the ARF gas powered sport /aerobatic models offered in this size usually have a wing loading sometimes well in excess of 30 oz.

15 or so years ago it was almost impossible to find a sport/ aerobatic model with a w/loading exceeding the mid 20's.

Could someone please tell me what is the reasoning behind this current trend. Thanks.

because everyone wants 2:1 Thrust/Weight nowadays and then they wonder why wings and tails are blowing off!

It's a trend alright but one due to the dollar rather than any aerodynamic reason. You said the 'A' word that explained it all when you said ARF! There are some so-so planes and some that are in the 'not too bad' group and there is a whole bunch that are absolute dogs.

Please DON"T use BARF wieghts and loadings as desirable criteria because it simply isn't so.

IMO you picked BARF's as a model for design criteria--------there is a difference between a 'model' for criteria such as wing loading -----there is also a 'bad example'----I feel you are confusing the two. Your original numbers are still right------build it yourself and enjoy the right criteria.

No, I'm not very high on BARF's as the best I've flown were ahhh acceptable --------sort of------if you didn't have anything else. But real flyers----haven't flown any (no I haven't flown them all and with any luck at all I won't. They, IMO are for the appliance operators in our hobby. Yes, you can exclude the four grand and up composites-----different deal entirely.

what do u mean??? my barf does great 3d with that big a** motor...

....except for the unexpected snap rolls on final, it's a great flier!

Wing loading is a bit of a puzzle -unless you relate it to wing area.
For a rough idea of good aerobatic loadings
1000sq in =under 25 oz ft loading
1000-1500=25-30 oz ft loading
1500-2000=25-35 oz ft loading.
These are really based on a model which is not flown super slowly -such as a good 3D design.
I did a 800"arf recently for a ---------- which flew fine -till you tried for setting up a sinking or slow flying attitude.
That sucker would fall off so fast you could not believe it.
The loading was 30+oz ft.
My own scratch built stuf is way under the numbers noted above -but in arfs -those are good numbers.

I have never owned or flown an ARF model, and if I knew no better I would certaintly presume that all such major manufacturer in that business would use proper design criteria.

Unfortunately, many of the less informed members of our hobby who read the monthly hobby magazines, look to maufacturers there for some guidance, and are at times overwhelmed by the numerous beautiful advertisements of models and the glowing reports of their flying performance.

Much too often a would be hobbyist is lost to our sport because of a very bad experience with a costly model that due to faulty design criteria was unable to perform as advertised.

Please don't get me wrong, as in IMHO there are very reputable companies around who produce kits and now ARF models of excellent quality and great flying qualities, some of which many of us cut our flying teeth on, and for whose existence we are thankful.

We all know that there has to be a business side to our hobby for it to continue surviving, but why we can't we have a more level playing field, that gives better value for money and not just seeking the capture of the almighty dollar.

Dick,

Thanks for your explanation has certaintly put a different light on this issue for me. I had always pondered on how those large aerobatic models with their very high w/l numbers performed so well. Now I have a much better understanding of it all.

Is it an added bonus that this came from someone that I share the same surname with ?? I don't think so....but thats what the 'h' in karolh stands for.

ARF, scratch built or kit-

BUILT LIGHT, FLIES RIGHT!

I think that user-friendly wing loading is largely a function of the airplane's size. I would hate to fly a 24" model with a 20 ounce wing loading, but some 11 foot wingspan, 64 ounce wing loading UAVs we built for the military were *****cats. Taking this to a ridiculous extreme, a full-scale radio-controlled Boeing 747 would be very easy to fly, since it would appear to be glacially slow, giving the ground-based pilot lots of time to think, despite a wing loading of over 100 pounds per square foot. For the same apparent relative speed, it would appear that wing loading could vary as the square of model size. If you double the size, the model will take the same time to fly its own length, while flying at double the stall airspeed with four times the reference wing loading. An interesting subject.

Your replies have assisted me greatly in having a much better insight and understanding of the mystery of wing loading, and how is should be applied to the various category of our R/C models. Thanks to you all.

the wing loading is/has always been an opinion thing -very subjective.
On our very light models -being in the 4-7 ounce all up flying weight -used for 3D flying-the difference in loading really becomes eerie. (under 5 oz sq ft)
We can -as can other flyers - spot the difference in 1/2 ounce on a 6.5 ounce to a 7 ounce model!
On our 15 lb 1430 sq in YAK the burn off of one pound of fuel is almost undetectable. (26 oz sq ft)
In both cases the models have 2-1 (or better) thrust to weight.
For some modelers who like scale military subjects - the wing loadings -for me -are simply excessive.
Typically due to construction techniques not conducive to best loadings.

Another reference that is not dependent on the plane's size is the Cubic wing loading.
For instance, the wing loading of a full scale Cessna 152 is about 510g/sq.dm
(167-oz/sq.ft), a model aircraft with such a wing loading would hardly be able to fly.
However, the full scale Cessna has a cubic loading of about 13 oz/cu.ft, which
is similar to a typical scale model.