finding CG with out wings

[sundown57]

messing around with a plane of my own design and ran into a dilemma. the top of the fuse is fairly flat for about 3 or 4 inches, so I can move the wings forward or back quite a bit. so that got me wondering about CG. Is the plane likely to fly no matter where I place the wing as long as I get the balance 1/3 back or do I need to somehow figure a balance point of the fuse before mounting the wing?

 

[JasonK]

this article goes into were the GC vs AC vs NP should end up and how to calculate them, at least for a normal plane shape:
https://www.flitetest.com/articles/easy-aircraft-design

 

[Merv]

...Is the plane likely to fly no matter where I place the wing as long as I get the balance 1/3 back...

Yes, the plane will likely fly if the CG (balance point) is about 25% of the wing cord.

With any new plane, I always due a trial banance test to see if I'm close to getting the CG where it needs to be. Tape things in place and see where the plane is going to balance. Then move things around until you are happy. After everything is installed, do another balance test to finalize the location of the battery.

 

[Hai-Lee]

messing around with a plane of my own design and ran into a dilemma. the top of the fuse is fairly flat for about 3 or 4 inches, so I can move the wings forward or back quite a bit. so that got me wondering about CG. Is the plane likely to fly no matter where I place the wing as long as I get the balance 1/3 back or do I need to somehow figure a balance point of the fuse before mounting the wing?

The required balance point is a function of the wing and its centre of pressure.
On a conventional design the CG point is around 25% of the mean wing cord whereas on a flying wing this figure is around 10% and canards it can be actually forward of the wing altogether.

Once you determine the wings required balance point then find the centre of mass of the fuselage and put the 2 points directly over each other!

The plane will fly, (not sure how well as that is a matter of the design and the control inputs)!

Have fun!

 

[sundown57]

thank you all I did read the link and understood little of it. but I was able to just put the fuse together with motor, battery, and so on and find the balance point of that. then found where the wing balanced and just put the 2 together. Thanks all