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Wednesday, August 29, 2012

Ballasting a F3X sailplane

It is always a problem to know exactly how to ballast a F3X plane given that they are several ballast compartiments with different size/volume, and none of them is exactly at the center of Gravity. I created the following spreasheet to help you how to determine the ballast, and also calculate the CoG variation.

How to use this spreadsheet ?

Enter in the yellow cells:
  • The position of the CoG
  • The position of the different ballast compartiment (measured at the center of the compartiment)
  • The weight of the ballast slugs for each compartiment
  • The empty weight of the plane
As ouput, it will give you:
  • The total ballast weight
  • The flying weight
  • The wing loading
  • It will highlight in red when exceeding the FAI wing loading of 75gr/dm2
  • More importantly, it gives the variation of the CoG.

Feel free to report mistakes, bugs if you find some. Thank you.


  1. This is something I have been dreaming about! Just get the numbers in and you will know what you are at. Simply amazing! I got it in my smartphone now with all the details for each of my gliders. Especially great while one is playing with a new toy.

    Thanks Pierre! Looking forward to meet with you at Rugen come October.

    Michael from Taipei

  2. Salut Pierre.
    A moins que mes yeux soient très fatigués, je pense que tu as oublié la colonne "flying weight"... (somme de la masse à vide et du ballast)

    Sinon cette feuille est top, ça faisait un moment que je voulais en faire une, tu m'as devancé. ;-)

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