Hey Gang, a question on how to balance my HOB Decathlon. Its a 2lb .10 sized electric conversion. I've got a build thread SLOWWWLY being completed here;

http://www.rcuniverse.com/forum/m_77...tm.htm#7705600

I was instructed to use a screw eye at the CG point and lift the plane with thread tied to the screw eye. Aside from the hole in the wing sheeting this seems to be a pretty fool proof method. The airplane gets laterally balanced too. At any rate my question is this; What attitude should the airplane be in when its balanced? Wings level is pretty obvious, but what about pitch? Should the top of the fuselage be parallel to the ground? The bottom? The pictures I've included are at home without nose weight (we added an ounce at the field).

Thanks for any input!

You can use the line where the red meets the white on the side of the fuse as a reference. Balance it so that line is even or SLIGHTLY nose-down.

Thanks!

Yeah.. start out slightly nose down.. even a bit more than slightly. You can recover a nose heavy plane but you will never recover a tail heavy plane. So, start out nose heavy and then work it out a bit at a time until you get it to where you want it.

CGr.

I wouldn't go too much more than "Slightly" - This is a Decathlon, It's just as likely to do weird things if it's balanced wrong either way.

If the Cg is being targeted at a specific point and it usually is with that point expressed as a given distance to the rear of the leading edge of the wing next to the fuselage then please note: The airplane will not be balanced at that point if it is not level but slightly nose down instead it will be balanced at an unknown point forward of the targeted point. The differance can be substancial with oh say ten degrees nose down and how do you measure that and you can only say you don,t best balance level.

That is the reason for the caution above go easy on the 'slightly.'

John

What is better?
To balance with a full tank of fuel or an empty tank?
I balance mine at the sides of the fuse and also at the wing tips then make sure I have a straight line between the 2 points.
When I removed the nose wheel I moved the battery toward the front and I have 7* nose down.
Vegas/

Whirley Bird,
The plane should be balanced with the tank empty. If not, you'll wind up with a plane that is tail heavy when the tank is empty.

Ken

What Ken said is correct

Yes with any conventional configured model aircraft when CG is specified it is always with an empty tank. And as indicated above if you balance with a full tank you will be in most cases (there are always exception such as a tank centered on the CG) excessively nose heavy. If this works for you then fine but realize its not the orginal target CG.

If you think about it its no different than full scale one always starts out with an actual calculated empty weight CG from actually weighing the three wheels and this is required Wt. & balance data for each airplane then you start with this to caculate the actual flight CG for each flight. Which of course must be within specified limits.

So if you think about with our models we balance the airplane at the specified limits and our opportunity to screw things up is far more limited all we really add is fuel and in most cases it will make the actual flight CG a bit forward and safely not rearward. This is another good reason not to balance much nose down, You see that 7 degrees you use means you are balanced further foreard than you think. Seven degrees nosedown would make it difficult to keep the airplane from sliding off the balance rods.

John