Wingloading - what the hell does it mean?

Wingloading - what the hell does it mean?

Post by Destro » Wed, 13 Oct 1999 04:00:00



So many planes have a figure like '7.5 oz/sq in' next to them yet I'm
not sure what that means about the plane.

Can someone explain what a high and low number represents in the way a
plane would fly and behave?

Example: Is a high wingloading plane easy or hard to fly? Does a high
wingloading plane glide well or drop like a rock? Does a high
wingloading plane take off easily?

 
 
 

Wingloading - what the hell does it mean?

Post by Craig Greenin » Wed, 13 Oct 1999 04:00:00


The more common reference is ounces per square foot, and it is derived by
dividing the weight of the model in ounces by the square feet of wing it
has. Thus a five pound trainer with a 60" span, 8" chord wing would have a
wing loading of 15 ozs./sq.ft.

For most sport models wing loading can be directly compared but as models
get larger and faster things change a little. It is not unusual for scale
fighter types to fly (and fly well) in excess of 45 ozs./sq.ft.

Craig.


Quote:
> Wing loading is the total square inches of the wing ,LengthX width,
divided by
> the total weight of the aircraft.Less than 10 oz psi is very low  20 or
more is
> very high. With a particular airfoil. with low numbers you can fly slower.
Same
> airfoil with heavy loading will have to fly faster to produce enough lift
to
> fly. Also effects the stalling speed. Thus endeth the lesson for the day.


 
 
 

Wingloading - what the hell does it mean?

Post by CDance74 » Thu, 14 Oct 1999 04:00:00


Wing loading is the total square inches of the wing ,LengthX width, divided by
the total weight of the aircraft.Less than 10 oz psi is very low  20 or more is
very high. With a particular airfoil. with low numbers you can fly slower. Same
airfoil with heavy loading will have to fly faster to produce enough lift to
fly. Also effects the stalling speed. Thus endeth the lesson for the day.
 
 
 

Wingloading - what the hell does it mean?

Post by A.T. » Thu, 14 Oct 1999 04:00:00


The lighter the wing loading the more the plane will float like a glider
and require less power to pull it around. A 2M glider weighing <2lb
requires only a .049 as opposed to a 2M Sukhoi SU.29 <12lb
(Carbon/fibreglass composite constr. )requires something like a ST3250
to enable it to perform 3D aerobatics.
see wingloading charts =
http://www.modelflight.com/~lakeside/wing.html
See basic RC airplane parameters =
http://www.uoguelph.ca/~antoon/gremlins/pmdesign.htm
FWIW many models are built overweight and or overpowered and are dogs to
fly but the CG Bucker Jungman with a K&B100 is a delight. Stick a .60 in
an ARF designed for a .40-.46 and the extra weight required to balance
the model etc increases the wing loading and will detract from the
performance/landing  besides straining the airframe beyond design
limits.
check the WW2 warbirds and compare the wingloading data =
http://www.websitepartners.com/flightline/aircraft.html#upick
http://www.websitepartners.com/flightline/graphwl.html
regards
Alan T.
Quote:

> So many planes have a figure like '7.5 oz/sq in' next to them yet I'm
> not sure what that means about the plane.

> Can someone explain what a high and low number represents in the way a
> plane would fly and behave?

> Example: Is a high wingloading plane easy or hard to fly? Does a high
> wingloading plane glide well or drop like a rock? Does a high
> wingloading plane take off easily?

 
 
 

Wingloading - what the hell does it mean?

Post by Touh » Thu, 14 Oct 1999 04:00:00


On Tue, 12 Oct 1999 19:50:06 -0700, "Craig

Quote:

>The more common reference is ounces per square foot, and it is derived by
>dividing the weight of the model in ounces by the square feet of wing it
>has. Thus a five pound trainer with a 60" span, 8" chord wing would have a
>wing loading of 15 ozs./sq.ft.

>For most sport models wing loading can be directly compared but as models
>get larger and faster things change a little. It is not unusual for scale
>fighter types to fly (and fly well) in excess of 45 ozs./sq.ft.

>Craig.

Craig, in your above example I get 24ozs/sq.ft.
Not 15oz/sq.ft.  
Respectfully, Jesse
 
 
 

Wingloading - what the hell does it mean?

Post by Dr1Driv » Thu, 14 Oct 1999 04:00:00


Quote:
>So many planes have a figure like '7.5 oz/sq in'

It's the amount of weight each sq.in. of wing area carries, but we measure it
in oz/sq.ft.  For example, a wing that's 48" x 10" is 480 sq.in. in area.
Divide by 144 to get sq.ft.  That's 3.33 sq.ft.  Let's say this plane weighs 4
pounds.  That's 64 ounces.  Now divide 64 by 3.33.  That's 19.2 oz./sq.ft.
That's a respectible loading for a sport plane.

The lighter the loading is, the quicker the plane will respond, and the easier
it will fly. A typical glider has a loading of around 5, sport planes range
from 12-20, warbirds fly with 25-30, and I've seen giant scale planes upwards
of 50-75.  Larger planes can carry higher loading due to wing volume, which is
another topic.  These numbers are all general and are not "set in stone".

Quote:
>Is a high wingloading plane easy or hard to fly?

It will fly better in high wind, but not as well as a low load plane.  It will
respond slower and will take longer to stop responding or to recover.

 Does a high wingloading plane glide well or drop like a rock?
It might not drop like a rock, but it won't glide as well as a low load plane.
If you get the loading too high on a small plane, it WILL drop like a rock.
For example, I built a Littlest Stick, a 18" span designed originally for .020
and single channel.  I put a .049 and two channels in it.  I didn't use the
***y servos, but Cox (sized between normal servos and the micros.  All my mods
effectively doubled the weight of the plane.  It flew great, but when the
engine quit, you'd better be within 100 feet or so of the runway, cause it was
coming down, NOW!

 Does a high wingloading plane take off easily?
It will require a longer takeoff roll and more speed.

Dr.1 Driver
"There's a Hun in the sun!"

 
 
 

Wingloading - what the hell does it mean?

Post by Jim McIntyr » Thu, 14 Oct 1999 04:00:00




Quote:
> Wing loading is the total square inches of the wing ,LengthX width,

<snip>

Not quite that simple. If the wing is tapered then you have to do
a little more math to determine the actual area of the wing surface.
Control surfaces should be included as they DO contribute to lift. If
the horizontal stab is a lifting surface (as in most old-timers), it's
area should be included as well.

Wing loading is not the only factor contributing to flying
characteristics, airfoil section and drag coefficient contribute as
much. For example, most old-style biplanes have a low wing loading but
do not glide very far due mostly to induced drag of the design and high
lift/drag of the airfoil.

--
Jim McIntyre
Green River (NE of Toronto) Ontario, Canada
http://members.tripod.com/Jim_McIntyre

Sent via Deja.com http://www.deja.com/
Before you buy.

 
 
 

Wingloading - what the hell does it mean?

Post by Craig Greenin » Thu, 14 Oct 1999 04:00:00


You're right, my mistake. I don't have a good excuse so won't waste your
time with a bad one....

Thanks for the correction.

Craig.


Quote:
> On Tue, 12 Oct 1999 19:50:06 -0700, "Craig

> >The more common reference is ounces per square foot, and it is derived by
> >dividing the weight of the model in ounces by the square feet of wing it
> >has. Thus a five pound trainer with a 60" span, 8" chord wing would have
a
> >wing loading of 15 ozs./sq.ft.

> >For most sport models wing loading can be directly compared but as models
> >get larger and faster things change a little. It is not unusual for scale
> >fighter types to fly (and fly well) in excess of 45 ozs./sq.ft.

> >Craig.

> Craig, in your above example I get 24ozs/sq.ft.
> Not 15oz/sq.ft.
> Respectfully, Jesse

 
 
 

Wingloading - what the hell does it mean?

Post by Mike » Thu, 14 Oct 1999 04:00:00


Gee, and all this time I was using dynes per square parsec...  (For those that use
metric,  1 kilopascal  = 20.8854 Lb/ft^2 )

I just saw someone fly their Littlest Stick with an .020 and micro everything.
What a screamer!  And it glides very nicely.  I have one and was going to try an
.010 but I'm going to .020 after seeing that one fly.

Quote:

> >So many planes have a figure like '7.5 oz/sq in'

> It's the amount of weight each sq.in. of wing area carries, but we measure it
> in oz/sq.ft.  For example, a wing that's 48" x 10" is 480 sq.in. in area.
> Divide by 144 to get sq.ft.  That's 3.33 sq.ft.  Let's say this plane weighs 4
> pounds.  That's 64 ounces.  Now divide 64 by 3.33.  That's 19.2 oz./sq.ft.
> That's a respectible loading for a sport plane.

> The lighter the loading is, the quicker the plane will respond, and the easier
> it will fly. A typical glider has a loading of around 5, sport planes range
> from 12-20, warbirds fly with 25-30, and I've seen giant scale planes upwards
> of 50-75.  Larger planes can carry higher loading due to wing volume, which is
> another topic.  These numbers are all general and are not "set in stone".

> >Is a high wingloading plane easy or hard to fly?
> It will fly better in high wind, but not as well as a low load plane.  It will
> respond slower and will take longer to stop responding or to recover.

>  Does a high wingloading plane glide well or drop like a rock?
> It might not drop like a rock, but it won't glide as well as a low load plane.
> If you get the loading too high on a small plane, it WILL drop like a rock.
> For example, I built a Littlest Stick, a 18" span designed originally for .020
> and single channel.  I put a .049 and two channels in it.  I didn't use the
> ***y servos, but Cox (sized between normal servos and the micros.  All my mods
> effectively doubled the weight of the plane.  It flew great, but when the
> engine quit, you'd better be within 100 feet or so of the runway, cause it was
> coming down, NOW!

>  Does a high wingloading plane take off easily?
> It will require a longer takeoff roll and more speed.

> Dr.1 Driver
> "There's a Hun in the sun!"