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C of G calculation

Anything to do with gliders & gliding.
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Nigel Argall
Posts: 141
Joined: 20 Mar 2015, 18:26
Location: Cornwall

C of G calculation

Post by Nigel Argall »

Forgive me, this must have been asked many times before but can anyone direct me to a centre of gravity calculator? I know there are some dodgy ones online. I have a couple of model aerodynamics books but both are unavailable. Thank you!

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Cliff Evans
Posts: 203
Joined: 29 Dec 2019, 15:13
Location: Bristol
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Re: C of G calculation

Post by Cliff Evans »


Nigel Argall
Posts: 141
Joined: 20 Mar 2015, 18:26
Location: Cornwall

Re: C of G calculation

Post by Nigel Argall »

Thanks Cliff - that looks a lot easier than the tape measure/pencil/paper/calculator stuff I have used before!

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ian davis
Posts: 118
Joined: 18 Mar 2015, 12:33
Location: Bishopstoke UK

Re: C of G calculation

Post by ian davis »

Hi Nigel

I used the calc that Cliff references for many years believing it to be fall proof. The results seemed OK over many models.

I discovered https://www.ecalc.ch/cgcal and the differing results between the two calcs was alarming.

There is a problem with the definitions for the neutral point in the Calc that Cliff suggests. I would recommend using ecalc. I've tried and tested it over a large number of gliders with absolute success.

You could always try both and decide for yourself.


Ian ;)

John Vella
Posts: 234
Joined: 20 Mar 2017, 22:09
Location: UK

Re: C of G calculation

Post by John Vella »

Hi Nigel, in practical terms if you find the MAC of your wing and find a point at 28 to 30 % chord at that position and take the perpendicular line from it to the fuselage you will have a safe C of G to start with. Regards John.

Jilles
Posts: 196
Joined: 22 Mar 2015, 10:27
Location: Australia
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Re: C of G calculation

Post by Jilles »

the rcplanes calculator I use now for a couple of years and it works for me on scale and other models. For the maiden flight you do not have to worry if the COG will be o.k.or not. You can always make changes later but in my case there are hardly any. for the static margin I use a 10% setting on scale gliders.

john greenfield
Posts: 551
Joined: 18 Mar 2015, 07:52
Contact:

Re: C of G calculation

Post by john greenfield »

I give another vote for ecalc

https://www.ecalc.ch/cgcal

I have used it for many models and have always found it reliable even with multi panel wings and canards.

AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)

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RobbieB
Posts: 572
Joined: 07 Mar 2015, 22:22
Location: North West

Re: C of G calculation

Post by RobbieB »

The CG calc page seems to have been moved to: https://www.ecalc.ch/cgcalc.php

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