Gliders > Combat

PSS-JET T1000

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IceWind:
Ok, it's done and it was maddened.

It's not perfect, but at least it fly.
I was using 20gr lead plus 2 AA batteries and even moving it a bit further to the back it was dropping the nose.
In the manual (that now i can read, it was only available in German before)  they say to balance it at 110mm from the LE backwards. And indeed making it balance on that point it has a bit too much weight in the front.

Brian:
Hi Ice,
Using your photo ,which has your near wing half pretty much in plan view, I calculate the CG at 140mm-145mm.

Brian

IceWind:
Hi Brian,

Out of curiosity what values did you used to calculate the CG point?
As i also obtain a different value from the one said on the manual.

Brian:
Hi Ice,
I normally fly F3A.
CG has an element of personal preference.
I always end up at 32% of Mean Average Cord (MAC).
For slope slightly forward helps penetration, so go for 30% MAC.
That figure I gave is a guestemate from photo.
That wing is tapered so MAC is half way out a wing panel.
Measure 30% from LE at half span each wing panel and join the two points through the centre to get the point at the root.

Brian

Fred:
Hi there,

Might help everyone, but here is how to find the Center of Gravity using the geometric method...
You can find loads of excel spreadsheets on the internet to find your CG aswell !  :D

First job, is to find the MAC, then you position the CG at whatever % you want (I usually go between 25 to 33% depending of the profile, machine type and so on...) on the MAC.
Draw a line from that point to the root (perpendicular to the root), and that is your CG line.
Basically, you can do the CG of your plane anywhere on this line.



Fred

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