Water & McCready setting

In the waiting of proper weather, here is a table that was derived while studying McCready ring value of various sailplane, with various wing loading. It gives you an equivalent additional Mc Cready setting to be representative of polar change due to waterballast.

This is the result of numerical investigation filtered by the "TAR"* method. For sure your marvelous onboard computer knows better...

The objective is to provide simple figures, easy to memorize, per family of glider (Club class/15m/18m/20m/unlimited), to be used with "Standart Mc Cready ring" (like the good old time).


Example : today I fill my LS6 with 80L of water. I should consider increasing by 0.4m/s my McCready setting due this additional wing loading - on top of other setting (80/100*0.5m/s=0.4m/s)

Don't hesitate to use this "enhanced rule of thumb" !

(& keep in mind it is always more efficient to have a McCready setting "a bit too less" than "a bit too much"...)




* "TAR"="That's About Right" method - i.e. there is a certain dose of approximation in all this.

New technical paper

I have issued a new technical paper on my (old) web site. It is concerned with some method to implement automated wing optimization scheme with constraint span.

The paper is available on my publication page.

Cross country sailplane computer

Here is a computer for sailplane cross country flying. It helps at flying in security while taking the full benefit of sailplane performance.

This is "old school" stuff, I have been taught into this by François Ragot, who was in the WGC once in the 50's - 60's. It is a 100% failsafe device !


Two version of the computer are available :
- The initial "big" version, ideal to learn to compute with.
- The panel version, to be placed among others instruments.

A short user book is also provided.

Download the computer.

The panel version is installed in my LS6, I use it in parallel with Cambridge 302/303, as another (failsafe ;-) ) source of information.

If you happen to build this computer, just send me a photo of it : matthieu.scherrer 'at' free.fr

Preparation of technical study of LS6 glider

I am collecting as much technical information as possible about my glider type.
if you have any information, please don't hesitate to contact me
matthieu.scherrer'at'free.fr

The objective is for me to test available tools for aerodynamic computaton and prediction on a precise book case. I base my study on on LS6 measured planform and wing airfoils.

The geometry of LS6 wing have been translated for MIAReX, my tool coupling lifting line theory and Xfoil results.
The final objective is to test how accurate such a tool could be at predicting the speed polar, and have a first hestimate of non linear behavior of the wing for handling quality evaluation.

I have also been preparing the formated file for having the complete saiplane geometry of LS6 available in AVL.
The objective is to be able to study the rigid, linear handling quality of the LS6 glider over its flight domain.


Using those tools, I hope to progress in the understanding and prediction of the aerodynamic of sailplanes, and mine in the first place !

First message

Publishing on the Internet takes time, so that very often I have not the courage to create new pages. On the other hand, with the developpement of blogs, it is now possible to very quickly edit information.

After 10 years with a classical website, I will try with this blog format.

I hope I will then be able to update this blog more often than my web page, and to keep you interested with my sailplane adventures !

My old web site is kept in current state, and is still available at this address