My flight started with the usual checks, including the correct radio program and movement on all the surfaces, I asked Charl when he launched to really push out and slightly nose down(did not wish to have a missfire like Peter). The Ventus went off well and accelerated at quite a dive I let it build speed and then eased in some up, there was very little response , I pulled full up and the glider went into a verticle climb, I adjusted the trim(normally 3 clicks would put it into level flight). It stalled ... my brain working overtime to establish the problem, had the nose weight shifted? something broken? she started downwards gaining speed , only full up brought it back into a verticle climb and a second stall.
This was becoming a roler coaster ride and I wanted off, third stall and dive and it went into the hill with a thud.
I asked the guys who went to collect the pieces to bring everything back and already started trying to understand what had happened, this glider had flown 3 times before , two flights of about 45 mins , had been pushed a little (recorded a speed of 189km on the logger)and flew well, so what happened.
The weights were checked ,I sometimes fly a five cell battery pack , the weight is marked as such, but I then substitute a sinker of a similar weight if I fly with a four cell pack. Both correct weights in and judging by how they got bent still attached at impact, so weight had not shifted.
Paul Carnell made a comment" looks like your elevator may have been jammed".
This is what it felt like but I still had full up and full down movement. When I studied the elevator linkage things fell into place. The silicon keeper which holds the clevis in place was possibly binding on the cutout.
Sure enough when I checked it, it was torn , it was ok before the flight , so why had I not picked up this problem, one explaination is that I move the sticks full travel when testing and it was sticking/binding in the midrange and locking on top or underneath the cut out.The long pushrod linkages taking up the stain before pushing past the sticking point. I like this theory and will put down the loss of this plane to a small piece of silicon. (Sorry about the photo quality but you get the picture)
on experience and gut feel. Here below is a test of the wing inner panel in this photo the weight(me ...is 80kg) this panel only has one side of carbon tows and the sheer web , no skins, it bends but did not break , so with both sides and skins it is well........over engineered by a fair margin.
I feel that I could do well to build these gliders lighter, but still strong so I started with Ventus no 4, this is to be based on the HQ/ 3/12 airfoil much used on scale ships as opposed to the slippery Mh 32 and Sd 7037 used previousely . So far I have saved 700 grams on the fuselage 100 grams by going the balsa foam route on the tailplane, this equates to a saving of 300 grams in the nose, and it looks like I will get a saving of 1000gram on the pair of wings by carefull layup and choice of materials.