Why do you balance a low wing upside down? I have been told it does not matter, that it can be done either way, however i have read in several manuals that you do this upside down. Just wondering?

If you try to ballence a low wing plane right side up...it will tip over on you wether its balenced or not...sort of like trying to ballence a pencil on your fingertip...

If you set it upside down...the CG will be below the wing and it will hang nice for you...

I think the bottom line is, its just easier...At least thats the way I see it

Collin

Yes it does make a differance. If you try to balance right side up (wheeles down) on a low wing plane it can cause you to balance wrong and end up with your weight all screwed up.

Try this. After balancing the recommended way (wheels up) then flip it over and see how it balances. Depending on the plane you will see that it acts like it is out of balance.

Ryanpilot must have magic wheels, they change wieght with position. Plain fact of physics, if it balances upside down it will also balance at the same chord position right side up. As stated above, just easier as the CG is below the balance point when upside down on a low winged plane.

I asked my instructor/owner of the LHS the very same question. He then asked me, can you fly upside yet? I said you know I can't, he said, then don't worry about it, & just balance it right side up. [&:] Not a very good answer to my question ( I think he was in -----mood) but I've had instructions tell me to do it both ways, that's why I was confused about it to begin with.


Mark

OK. Take a blalanced model when properly balanced upside down and then put it right side up {on a good balancer} and it will appear to not be balanced. I did not say it wasn't. It is so sensitive to any of the tiniest changes that the average person will fight it and end up without the proper balance.

It is a mass and center issue not magic wheels. Which way would you more easily balance the empire state building? On its base or on the tip of the tower? Of course with the mass low ot the base it would balance easier than trying to get the weight right while on the tip of the tower. Same with a low wing plane, you bring the mass below the line at which you are balancing from (the surface of the wing) and it hangs rather than trying to flip over.

Also it does not matter if you fly upside down or not on weather it is easier to balance inverted and that frankly sounds like a lame answer to a serious question. Why, for many years, has it been taught that it is easier, and should be done, to balance a low wing plane inverted?

Also if you read my post correctly you will see that I said "Depending on the plane you will see that it acts like it is out of balance. Not that it actually was out of balance.

After thirty years of balancing other ways I balance everything right side up in a cradle because it is easier. A pendulum points to the CG.

Bill

The point here is this was a beginner question who may not have the knowledge to have, build, or use any type of cradle and pendulum. At best he may have something like the Great Planes C/G Machine, which does instruct the user to balance low wing planes inverted.

I was simply responding to a thread in the beginners section with a beginner in mind. I find sometimes we get carried away in some of these posts especially in the beginner section.

I balance however the manual or plans advise.

Always figured it was due to the pendulum effect of the fuselage just making it easier to balance a low-wing upside down.

Some of us still a rubber-erasered pencil in each hand to lift and balance.

Hi!
I always balance my airplanes right side up...using my fingers! That's all it takes.
But of course you can do what ever you want...doesn't really matter.

Regards!
Jan K
Sweden

Ever try to balance a highwing cabin airplane with fixed gear upside down? Just about impossible to do with any accuracy. For the same reasons thats why most plans suggest for low wing airplanes be balanced upside down. The bottom line there has to be sufficient static stability (center of mass a little below the balance points) or you are not going to be able to get an accurate reading.

Airplane configuration has a lot to do with this, Other factors are dihedral if any and midwing designs. On occassion say with a midwing the plans may suggest either right side up or inverted and that is predicated on whether or not one of the positions may allow a little static stability to makes things easier (read more accurate).

John

Mark,

What kind of an answer was that from an instructor! Wheeeew!

big dan

I use lead weights.

Sorry Jan, I couldn't resist

To get an object to balance with equilibrium, the center of gravity (CG), which is actually a singular point in space, with a vertical, longitudinal and lateral axis, must be below the pivot point. Attempting to get a low wing airplane to balance with equilibrium, in it's upright position, is exactly the same as attempting to get a high wing airplane to balance with equilibrium while in it's inverted position. Being able to balance with equilibrium is best, as it allows the balance point to be adjusted, by adding weights to the aircraft to achieve balance.

This is actually an old post that someone revived.

Since it's original posting, (And since it has been brought back) I have written [link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=601]This Article[/link] about why you should balance Upside down for low-wing planes.