Akaflieg Karlsruhe AK-X

On the SB13, the pitch oscillation was discovered to couple to the bending mode of the wing. The spar was therefore build with hogh modulus fibres (a first in aviation) in order to push the bending frequency out.

The pitch oscillation could be mostly suppressed by moving the cg aft.

Which then resulted in a very nasty stall behaviour due to span-wise flow on the swept wing. Boundary fences did help on that.

All in all, tricky optimisations. Plus a complicated lay-up plan for the swept-back spar in order to get the torsional load into the wing skin.

On Sat, 09 Dec 2017 13:13:31 -0800, Tango Whisky wrote:

On the SB13, the pitch oscillation was discovered to couple to the
bending mode of the wing. The spar was therefore build with hogh modulus
fibres (a first in aviation) in order to push the bending frequency out.

Fair enough. I've subsequently found similar comments about the Horten
S.IV and the DH.106.

All in all, tricky optimisations. Plus a complicated lay-up plan for the
swept-back spar in order to get the torsional load into the wing skin.

From what I've read this seems to be a major problem with all swept
tailless designs.


--
Martin | martin at
Gregorie | gregorie
| dot org