Here is a question I have been pondering..what effect does wing loading have on a models aerobatic ability? What are the typical wingloading on some of the 35-40% aircrafts?

The lower the wing loading, the better they fly--to an extent. If the plane is made too light it will drift around in the wind like a kite. A good cubic wing loading is around 8

28 oz per foot is very light in this size plane 31-32 are perfectly acceptable {the 87 inch ohio extra 300 came in at 32.5 and flies great}. Along with what volare said too light a wing load also makes it difficult to tumble the plane, and slows the roll rate.

One additional point. Higher wing loading are acceptable on larger planes. A 35oz/sqft wing loading on a 40% plane is better than a 35oz/sqft wing loading on a 25% plane

The higher wing loading on larger planes is partially due to the displaced wing area, ie a wing with a NACA 0011 airfoil, 48" WS, 12" root & 8" tip will displace 366 cubic inches of air while flying. For arguements sake, lets say this plane weighs 5 lbs, so the wing loading would be 24 oz. a sq. ft.

If you increase the wing by 2x, (to a 96"ws, with a 24" root & 16" tip) the area doesn't double (remeber wings are 3 dimensional) but increases by 2^3, or to 2,930 cubic inches. Let's say this plane weighs 27 lbs. The wing loading would go up to ~32.5 oz. a sqft., however, if we were to look at the weight per cu. inch of air displaced by the wing, we would see that the larger wing is actually carrying substaintailly less. The 48" WS would have to carry .2186 oz. per displaced cubic inch of wing area, while the 96" WS would only have to carry .1474 oz. per cubic inch. The small wing is actually carrying almost 50% more weight per cubic inch of displaced air! It's an over simplification, and I'm not qualified to totally explain it, but hopefully you get the point. Bottom line is, everything else being equal, bigger flies better.

Rick

Thanks for the response guys..my 35% Giles has a wingloading around 39oz/sq ft. Just wanted to know if this was acceptable. Plane weighs in right around 27lbs dry. The 50% Cap I'm building has a wing loading in the 42-43oz/sq ft range, depending on the final weight. A couple guys I talked to who have this plane describe it as a real floater. Any additional input would be appreciated.

A 14.0 lb plane having a wing of 1010 sq in will have a wing loading of
(14X16)/(1010/144) = 32 oz per sq. ft., right?

These are the stats for my H9 edge 540 with the BME 44 gasser on it. Haven't flown it yet, but will do so this weekend.

Lets say the edge came in at 16lbs, the wing loading would increase to 36.5oz/sq ft. How would this effect the way it flies?
Does anyone have any ideas on this?

It would not fly as well and would stall at a faster speed.

I have a Giles ARF with a YS140 and another one with a Brison 2.4 gas engine. The planes weigh 14 and 17 lbs gross weight. I will let others do the math, but both planes land the same and other than pulling power, flies the same. The glow flies straighter because it was assembled straighter. Other than that, I can not tell any difference in performance.

I will agree that if you are doing 3D maneuvers, an extreemly light wing loading is desirable. What I don't understand is the wing loading difference in normal fight if your power to weight ratio is high enough to handle the extra weight.

Please help me understand the technicals!
Thanks

The biggest problem with "HIGH" {and as Geistware said this is a relative term} loading is the increase in stall speed. Along with obviously increasing the landing speed, it will slow the rate that the aircraft will transition from level to vertical, instead of a sharp pull up it will sort of mush through the transition. Roll, yaw and the rate of pitch change will not be affected only the path the plane takes through the pitch will suffer. This deviation from the flight path may be so small it can't be seen unless the planes are flying side by side. Geistware, if you really want to see the differance find someone with equal talent to yours and go have a dog fight with the two planes you'll see the change. Also lighter is better but too light a wing loading is bad for 3-D because of its reluctiance to enter a tumble

My new 1200 sq in model - powered by 40cc ZDZre, will have wing loading of just under 21 oz /sq ft.
This was an exercise done to see what real advantages could be had, in a 2mx2m aerobatic (FAI legal) setup.
Should have it up and flying next week.
BTW- typical models this size/weight are powered by 1.4 glo engines. (23cc)
I have built a bunch of those.

You guys make some interesting points-- how will the power to weight ratio effect the planes performance with a higher wing loading. If my planes has a power to weight ratio of say 2:1 will it still be able to perform maneuvers as well as a plane with a lighter wing loading? Has anyone reduced the weight of their planes and noticed a big difference in the way it handles?

Dear Mr Giant
Will power to weight changes affect a model with higer wing loading?
Of course.
Unless you are considering only diving maneuvers.
Power to Weight and Wing Loading are two , entirely different things.
The whole reason for power, is to control angle of attack , whilst maneuvering.
with a very light model- the angle of attack required is always less for any given maneuver .
Why? It fights gravity much more easily.
With lots of power - you use speed (thrust,ability to maintain speed)to keep the proper angle of attack.
If you lighten a given model- two things happen:
1- the wing loading drops
2- the power to weight improves
Here is where things get kinda strange-
You can't change one-without affecting the other.
Bottom line -On powered models -ligher improves everything.
Have I tried it ?
Yep.

OUTCAST,
While I have not dog fought, what I have done is had my friend and I swap planes and fly the IMAC Basic and Sportsman pattern. He has a laser with "no" wing loading

What we have found is that I have adjusted my plane so that the mush that you call is natural looking. He has found that his responses are a lot quicker than mine and he needs more expo and less deflection to do the same maneuvers that I do. I really thought it was interesting!

Guistware, Its my personal opinion that people are spending WAY too much time worrying about things like this. If a 70 inch plane at 28 oz per foot flies great, at 32 oz per foot it will still fly great and probably at 35. It may not make as square a corner or bleed speed as fast on the down line but, there are probably 75 members in the club that I fly with and if four could tell the difference I'd be surprised. Playing with them is fun, talking about them is fun, but as you have seen for your self, its not worth loosing sleep over.

I will guarantee you that at 35 oz to the ft- a 70 " span model - at 4500 ft elevation will easily be seen as toooooo heavy.
You are correct tho - many modelers simply can't tell the difference.
They are not stupid - just have not flown enough different setups to see the advantages.

Dick, you make a good point. Last year, I flew a 1/3 scale Staudacher that was set up for competition and found that was GOOD! In the local contest, I placed first after my 4th flight. I wish we had more than 4 rounds, I would have done a lot better. I know the value of the proper setup and the proper setup can make a heavy plane more forgiving!

I have spent the last few weeks flying a model with 1280 squares and under 20 oz ft wing loading -
and extremely high power loading.
(11 lbs and ZDZ40 on a tuned can)
Theory is one thing - actual results show that the model flies heavy winds better than heavy models --the power is the reason-and the low weight allows full power to instantly go in directions wanted -
This setup is completely different than the "typical" high powered pattern/IMAC setup.
I am convinced that this type of setup excells -in any wind condition.
As for tumbling - the model tumbles wildly - including wing tip over tip -sideways.
Snap recoveries - in any attitude - the best ever.
The "waterfall is a rapid multiple flip.
Bottom line - you simply can't - for all practical purposes - get the model too light.
Too flimsy - yes - too underpowered (easiest)
too little control authority - yes again.
You have to try this type setup to see the results -
It is a whole different ball game.

Dick, I have no doubt that your report is accurate and the plane flies great, I've read enough of your posts to respect your opinion.
In this example though we don't have a base line for comparison since this is a one of a kind plane and may fly like it does through configuration and design. My suggestion is to ballast the plane with 10 onces on the CG and report the difference in handling. We know the vertical and stall speed will suffer, but I would like you opinion on the changes in response and aerobatics other than high alfa.

good point - that is why I dropped the airframe weight to below 20 oz ft - rather than just a little lighter than the 25 oz ft which is considered light -
I wanted to se if a big reduction helped - and it does. and the weight is the only real difference - I used same moment arms, same airfoils etc- just a whole lot lighter.

Dick, you've got me interested in your plane. Which plane is this?
Thanks.

I made a "mule "-actually a couple of em -to see if the weight reduction was really needed/desirable -so now I am working up a purty design -the prototypes are basic aerobatic setups with 3D capability -

I wish we would all start using cubic or volumetric loading as some have suggested. It would be much simpler to say a model, regardless of size, has a volumetric wing loading of .18 oz/cid. Yes, smaller wings are less effective because of Reynolds number etc. It would also reveal why big airplanes fly more realistically. In most cases, they have much lower volumetric loading AND they fly at higher Reynold number.

Yes volume numbers are more "accurate".
The oz /ft are quick and dirty -but if one throws in the area- it all makes sense.
Frankly -I have found that 90% of all the airfoil stuff for model aerobats is just whimsy- in fact -I have tried same exact wing area and weight -with different airfoils - thick thinner 14%-11% etc- and if one really did not have one to compare against the other - it would be hard -if not impossible to know which wing was on the plane.
The full scale aircraft "engineers" will argue this -but most don't have any practical experience in models of the size we use in the weights we deal with and in the performance envelope we fly in.
Not to say that the text book larnin is not necessary!- it does work for a lot of stuff - mostly in full scale applications.