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 !

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 !

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

Model

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

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
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 !

The LS6 in the worshop

This is winter, the LS6 is now grounded and is waiting in the worshop to be fully checked.

The first task was to build a proper bench for handling the fuselage :



Now the car has a friend in the garage !

Slope flying with the LS6 at "La Montagne Noire"

Some nice souvenir of two flights from LFMG

Old timer flying

I had the opportunity to fly some old timer sailplane from APPARAT group. this was a big time for me, as I have mainly flown fiber ships !

First was french Breguet 905 "Fauvette". This is a V-tail, 15m wooden sailplane. Very light to handle, the V-tail mixer is at first surprising, but once used to it you hardly notice it !



Then I had the chance to fly the Slingsby T-21 with Julien. This is a british side-by-side twin seater. Aerotowing is a big story, as you fly far too quickly for this old lady ! Once free, flying at 60kph it is much more bearable to have the head out !



Nice souvenir !

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