User Manual

Fritz Building Instruction December 2020
www.pcm.at 12
8. CG AND AILERON
DEFLECTIONS
The CG should be set from 126mm to 128mm.
- CG at 126mm is for slower flights (thermal flights). It is besides the
safer CG, as Fritz sometimes shows a nod (one to multiple times
nose down) at this CG, when you fly too slowly. What you see more
often is yawing during aileron deflection when you are too slow.
- CG at 128mm is for dynamic flights, for instance at good conditions
on a slope. But keep care, at this CG Fritz shows no nod. If you fly
too slowly, he gets uncontrollable. He doesn´t fall from the sky, but he
flies straight ahead. What you still see, is yawing during aileron
deflection, when you are too slow.
Set the CG as accurate as possible. Flying wings needs more
accuracy in setting the CG than normal configurations.
Accurate measurement of the
CG!
Very often the simplest method is the
best.
In the right picture you see a CG tool,
which is as simple as accurate. Here
you lay the model just onto two
sharpened wood sticks to check the
CG.
This tool has no friction or electronic
parts, which could be incorrect. You
could improve this tool by adding
additional sticks in front and behind
the two existing poles to avoid the
model from tilting.
At the right picture you see, that the
CG has to be measured from the
middle of the wing and then get
marked. These marks have to be
transferred to the right and to the left.
While using modern electronic CG
scales, we didn’t have such accurate
results. Furthermore there is the
possibility to make more measure
mistakes when docking the nose to
the zero points, see pictures on the
right.
Keep care, also mechanical CG tools
could have these kind of zero points.
In this way you always have to
correct the dihedral.