Eta crashed

From: "303pilot" brentUNDERSCOREsullivanATbmcDOTcom
Date: 10/2/2003 10:05 AM Pacific Daylight Time
Message-id:
...
FWIW, I'm with Stephan, if I see "crash" I assume that someone was at the
controls when the integration of the aircraft components became suboptimal
for future use...

Open your mind and you will find the true meaning...

Okay, we can call any sort of "event" we choose. According to articles I=
have read, the things cost more the $1 million US to build. Will the ma=
nufacturer be able to absorb this sort of hit?

Stewart,
There is no such thing as "the manufacturer" for the ETA. Instead, a group
of wealthy people financed the design and the building of the prototypes.
Several different companys contributed by building parts of the plane. The
web site www.eta-aircraft.de is run by the design bureau.

Markus



Stewart Kissel schrieb in Nachricht ...
Okay, we can call any sort of "event" we choose. According to articles I=
have read, the things cost more the $1 million US to build. Will the ma=
nufacturer be able to absorb this sort of hit?

Never assume the glider is stronger than the placarded
limits. As quite rightly stated earlier, exceed them
and you become a test pilot - especially so on excess
speed where there is little margin.

A friend of mine broke the boom on a SF34 (best thing
to do to the beast, some might say;-) recovering from
an intentional spin. He's a Chief Flying Instructor
and engineer so one presumes he knows what he's doing
but even he was caught out. These things are not unbreakable
in flight.

The loads on spin recovery can be quite unpredictable,
especially if the recovery pull-up is done with some
twisting moment still present on the tail - hence we
are trained to stop the spin, unstall the wings, recover,
not one 'pot-stirring', stress-inducing manoeuvre.

Rob

At 09:12 03 October 2003, Stefan wrote:
Bill Daniels wrote:

I think gliders are just as strong as the manufacturer
says, but no
stronger

Most Gliders are built in JAR country and are certified
by JAR rules.
For the utility category, JAR requires an allowed load
of 5.3g at Vne
and 4.0g at Vm. JAR further requires that the break
load be no lower
than 1.5 times the allowed load.

Since every extra strengh comes at a price in weight
and money, the
break load of most gliders acually *is* 1.5 times the
allowed load. This
is when the glider is new. Take some turbulence, and
the safety cusion
is rather small.

As for the Eta, this may turn out to be an intriguing
case. At 31 meters it
is certainly pushing the limits.

Actually this is the whole idea of the Eta project:
pushing the limits.
Remember that the first prototype was too heavy and
extra work was
required to bring the take off mass down to 850 kg!
(The 850 kg limit is
again required by JAR as well as by contest rules.)

Stefan

The loads on spin recovery can be quite unpredictable,
especially if the recovery pull-up is done with some
twisting moment still present on the tail - hence we
are trained to stop the spin, unstall the wings, recover,
not one 'pot-stirring', stress-inducing manoeuvre.


This is an interesting point - I guess lots of pilots employ a mushy
some/loads/a bit of rudder (very slightly ahead of ) stick-forward.
Quickly followed by pull back.

We do this because it works and no one has explained exactly WHY
there are mysterious pauses in the official spin recovery.

--

Jonathan

Robert John wrote:

Never assume the glider is stronger than the placarded
limits.

Don't get me wrong: I didn't say because there's a safety cushion of 50%
you should go for it. Don't! I said theres a safety cushion of *only* 50%
to catch the unpredictable. Besides, as you pointed out, the placarded
load limits are for "straight" load only. Add some twisting forces, and bang!

Stefan

Which Eta was it?

At 20:12 05 October 2003, Pat Russell wrote:
Er...
Perhaps I should have asked how much of the weakening
of the
fuselage was due to the weight reduction.



The weight reduction was mainly in the wings, by using
a foam which absorbed less epoxy.

The web site says as much as 35kg per wing could be
saved with the new method. The rest (30kg) obviously
comes from a lighter fuselage.At 20:54 05 October 2003, Alex Chappell wrote:The weight reduction was mainly in the wings, by usinga foam which absorbed less epoxy.