Saturday, December 29, 2007

Wing inertia

For handling quality studies, mass distribution & inertia the saiplane are part of the eigen modes solutions.
It is nevertheless very difficult to access such data among existing sailplanes.

Here is a simple spreadsheet tool that evaluate inertia of a wing on main axes (Ixx, Izz, Iyy) .

Some simplifying hypothesis are made (wing seen as a beam, simplified mass distribution, etc), in order to be able to evaluate realistic values of inertia.

Inputs :
  • estimation of the spar & "skin" mass
  • geometry elements
  • water quantity
Simplifying hypothesis are made about how to spread/share thoses mass along span & chord. The effects of filling tanks is also evaluated, once again with some hypothesis.

Outputs :
  • Inertia/ inertia radius, at elements CG
  • Inertia/ inertia radius, at wing CG
  • Inertia/ inertia radius, at a reference point
Similar modeling will be needed for fuselage.

If you happen to have data on sailplane inertia, just tell me !

Thursday, December 20, 2007

2007 cross country flight with AD

This is winter, right time for reviewing the outcome of 2007 flying season.

Approx 50h logged in the LS6: this year was a quite disappointing season, partly due to weather situation this summer.
Here is a general view of cross country flights performed with AD.

Best performance was 360km. I am still not a big champion, nevertheless I do like those rides a lot !

Sunday, December 16, 2007

LS6a command system

I am "opening" the LS6 for checking purpose. This is the first time I work on a flapped sailplane, so I watch carefully how it is done !

Before removing the seat, everything is carefully faired :

Once removing the seat, here is a general view of all the cranks and tubing from the stick, AB & flaps levers.

Then a detail over stick area, with the big green trimm wheel.

Finally the mixer, that commands the flapperons

Wednesday, December 5, 2007


As I wrote, a lot of things have started for me with models.

Here is my last model, fresh out of the molds...

Eloïse (so is she named) is in good health, as is her mother !

Proudly, Matthieu

Saturday, December 1, 2007

Mesured sink polar of LS6

Here is the scan of original LS6 sink polar, as measured by DLR back in 1986 :

The reading of this polar has confirmed to me the way to fly (without water):
Do not use flap -5 before 150kph !

Then, up to 150 kph you are virtually flying a LS8...

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

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 !