This video was recorded within the left wing of an "Aeros Combat 09 14.2 GT" hang glider with tail and all carbon options. My hook-in weight was 100 kg.
In the first part, the camera was attached to the crossbar close to the crossbar-leading edge junction pointing outwards (towards the wing tip) and showing the inner sprog (flight info: xc.dhv.de/xc/modules/leonardo/....
In the second part, the camera was attached to the sail, again pointing outwards and now showing the outer sprog (flight info: xc.dhv.de/xc/modules/leonardo/....
The sprog settings of my glider (left wing) were:
Inner sprog: 4.5 degrees
Outer sprog: 7.5 degrees
These are quite high (safe) settings. The DHV settings are 3.75 and 5.7 degrees for the inner and outer sprog, respectively.
The aim was to see the tension of the respective sprog cables with full VG at different speeds. A straight and tensioned sprog cable means that the sprog is engaged and exerts a force on the sail pushing it upwards, thus, limiting the minimum twist/washout of the wing. More twist in a flying wing means more safety by higher pitch stability but less glide performance.
There was and still is a great discussion on whether or not the sprogs are engaged in usual flight, see
www.gleitschirmdrachenforum.de... and links and videos cited therein, e.g.,:
vimeo.com/3635942
• Video
• Micro camera on sprog ...
• Sprog footage
Based on these findings I wouldn't have expected the sprogs to be engaged but obviously I was wrong.
The present video shows that, using the above described glider and setup, the sprogs are actually engaged when pulling 100% VG (with 0% VG, sail tension is low and the sail never reaches the sprog limits - at least within the usual flight envelope). With increasing speed, the inner sprog cable seems to become somewhat less tensioned, while the outer sprog cable stays tensioned over the whole speed range.
I'm going to adjust the sprogs to lower but still safe values, i.e., to DHV settings, at the next opportunity and will take another video then.
Have fun! Fly safely!
28 фев 2016
