"smjmitchell" wrote in message
u...
Janusz,

Thanks for the information on build time hours. This is very useful
information. I think it illustrates that labour is where we need to work
at
reducing the cost. One many year is approximately 2000 hrs .. actually
more
like 1700-1800 when holidays etc are considered. So 1400 hrs is a lot.

What I am now wondering is what the difference is between the Jantar
Standard and the SZD-55 ... I need to do some research to answer this for
myself because I am not that familiar with the later. 760 to 1400 hrs is a
big difference. However perhaps you have some comments on this. Are the
materials and tooling similar ? Are the tolerances tighter on the later
model ? Perhaps it is a question of the volume being produced ?

Thanks again,

Steve

Carbon layup, complex curves, flaperons, sparless construction(?), and
finishing work on the SZD-55 and certainly the Diana will take longer than
Standard Jantar glass fiber construction. There's still cure time. If the
molds are heated, then there's the cost of doing that involved. Otherwise,
the parts spend more time in the molds. Earlier mold design was subject to
distortion with time, so only so many accurate pulls could be made before
the planform of the wings changed. These things have been overcome, but
there are incremental price increases as a result. The 1000 hours I
originally mentioned was the early Ventus (15m) line from a visit to
Schempp-Hirth in 1981. I'm sure the number was only approximate, or perhaps
the ideal, but it was quoted to me. Gel-coats may be a bit quicker than
polyurethane during the original build. At one time SH delivered gliders
withn minimal finishing since they knew competition pilots would tune the
wings anyway.

Pre-preg can reduce layup time, but it's nearly 2x the cost of wet layup
(even in filament winding processes) according to some sources I've glanced
at. As far as building a Junior in two days, maybe, but I'd still think in
terms of 680 man hours as the substantial difference is fixed gear vs
retract. Two days is a meaningless concept without knowing whether 30-40
people were involved for 8 or 12 hour shifts.

Filament winding is one method that's been shown to work, at least by Rutan.
However, there are limitations to the process that might make it impractical
for most glider production. Even then, the pod took something like 7 hours
to wind and the fuselage was 24 hours of continuous processing. I'm sure if
any of the factories could conceivably create a paradigm shift in glider
production that would create a price advantage, it's would already be in
use. All that's actually happened is to re-locate to cheaper labor markets,
which is not always the best solution.

Frank Whiteley