At 06:49 PM 12/14/2016, you wrote:
Poland is also becoming a threat
Indeed. The GP 14 wing weighs 31Kg and broke at over 10g. Anyone know
how they are building that?
I had a chance to have a really good look at a Diana 1 a few years
ago. When they say monocoque they mean it. Just about nothing in the
fuselage besides the carbon shell apart from the main bulkhead and
there isn't much to that. The cockpit appears to have one molded part
that drops in to form the seat. I don't know if the fin and tailplane
have any foam sandwich but they are small enough that just carbon
monocoque skin would probably do as would the same on the outer parts
of wings. The control system with the side stick is also a model of
simplicity. I was impressed by all that and the small size. When I
look at most gliders now I think that I'm looking at altogether too
much glider.
The Russia AC4 eliminated the pins on the end of the spar stubs. They
fit into molded recesses in the opposite root rib. Means the pins
aren't there to concentrate stresses and fatigue or corrode.
Design is the key. Eliminate parts. Anybody can build something
complex. Good design and engineering is making it as simple as
possible. I don't think the bottle neck to glider production is
actually making the wing and fuselage shells or time in the molds.
Putting in dozens of small parts, all of which had to be made in
molds or the metal shop or cut out of plywood and covered in glass
(Schleicher) plus the finishing shop seems to be the problem. Shaping
the glider isn't a problem if the molds are accurate and parts fit
properly and Schempp obviously solved that problem for wings 30 years
ago. I can see why gel coat is used but there are other ways of
protecting molds and using highly toxic two pack paints would also
seem to be overkill given that gliders generally don't sit outside in
all weathers. A good quality single pack acrylic lacquer over a UV
barrier undercoat would be as useful and very much easier to touch up
and saves around 20 + Kg on a glider. The ongoing use of vorgelat (T
35 or not) is a disgrace.
Certification is a problem and I suspect the established
manufacturers love it as it is a steep barrier to entry for new
manufacturers. Witness the drawn out process for the JS 1 to get
certified in Europe. There was a bitter joke going around a while
back that CS22 Amendment 3 read something like "all non German
gliders must perform worse" meaning if it was better it wasn't going
to get certified. Germany Inc. at work.
Now if gliders were produced as kits and the designs were simplified
as suggested above maybe using automated layup and pre pregs would be
economical. At least certification would go away and owners would
have a much better understanding of their gliders. The design however
must be for the highest performance. In the past kit gliders have
failed because they are only OK performance but not for contests. The
world is awash with very cheap used gliders right now which offer 80%
+ the performance of new ones so a kit of that performance is going to fail.
Mike
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
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