ASG-29/ASW-27 wing refinish

The page he is refering to can be found he

http://www.dg-flugzeugbau.de/sicherheitscockpit-e.html

Hope this helps,

Markus

Eric Greenwell wrote:
Gary Evans wrote:

While other manufactures have been content with building
what looks strong enough DG has actually participated
in crash testing.

This is not correct. Gerhard Waibel won an OSTIV prize for his work in
cockpit safety about 20 years ago. Gerhard's ideas, and the ASW 24
cockpit (the first of the really crashworthy cockpits) was based on
extensive testing by a group at MIT, and others. In the years since
then, Schleicher continues to monitor the performance of their designs
by examining their gliders that are involved in crashes, either when
they are brought to their shop for repair, or using pictures sent to
them by the mechanics repairing the glider elsewhere. An advantage of
this approach is it shows what happens in an actual crash.

As a result of this testing they
offer the consummate safety cockpit as an option on
the 800 series and as standard on the 1000.

I have been impressed with DG's improvements in safety over the years,
but their single seaters cockpits still do not match what Schleicher has
done. This page on the DG website shows that this view is shared by
others (go to the "Safety Cockpit" row):

http://www.dgflugzeugbau.de/ash-dg-ventus-e.html

These differences are not surprising. The low sides and open nose of the
DG single seater cockpit pose a difficult engineering problem for the
designer, compared to the greater enclosure of the Schleicher cockpits.

I'm not suggesting that the DG cockpit is unsafe or inadequate, but only
that it does not match what Schleicher has done. A prospective owner
should consider the value of that protection along with the other
features of the gliders he is considering; for example, the lower sides
of the DG cockpit (particularly if the NOAH option is selected) should
make baling out easier than from a Schleicher cockpit.


If you counting on higher frame rails for protection
you may also want to read this.
http://www.dg-flugzeugbau.de/index-e.html

I was unable to find this reference, but I would like to read it.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

At 16:12 11 November 2006, Eric Greenwell wrote:
Gary Evans wrote:

While other manufactures have been content with building
what looks strong enough DG has actually participated
in crash testing.

This is not correct. Gerhard Waibel won an OSTIV prize
for his work in
cockpit safety about 20 years ago.

20 years ago, wasn't Chicago still a swamp? A lot has
happened in the past 20 years. The crash tests I referenced
that DG participated in were done in 1994. This is
the correct link.

http://www.dg-flugzeugbau.de/sicherheitscockpit-e.html

Gerhard's ideas, and the ASW 24
cockpit (the first of the really crashworthy cockpits)
was based on
extensive testing by a group at MIT,

DG claims that the DG100 from the late 70's was the
first to use a double wall construction that is commonly
referred to as a safety cockpit. Was the 24 done before
or after that advancement?

and others. In the years since
then, Schleicher continues to monitor the performance
of their designs
by examining their gliders that are involved in crashes,
either when
they are brought to their shop for repair, or using
pictures sent to
them by the mechanics repairing the glider elsewhere.
An advantage of
this approach is it shows what happens in an actual
crash.

I suppose looking at the damage after the fact is worth
doing if that’s all you have but actual crash testing
will reveal more information as explained in the previously
referenced test. The car manufactures don't use crash
testing just because if costs a lot of money. They
gave up just looking at a crashed car a long time ago.
It is however expensive but what is safety worth?


As a result of this testing they
offer the consummate safety cockpit as an option on
the 800 series and as standard on the 1000.

I have been impressed with DG's improvements in safety
over the years,
but their single seaters cockpits still do not match
what Schleicher has
done.

That could be termed a matter of opinion unless there
is factual data available to prove that advantage.
If so post it up.

This page on the DG website shows that this view is
shared by
others (go to the 'Safety Cockpit' row):

What your referring to is the old original safety cockpit.
As I stated before the term safety cockpit refers to
the double wall construction but DG has gone way beyond
that as a result of the crash test data. What they
now offer is termed a Consummate safety cockpit, which
is described in the article.


http://www.dgflugzeugbau.de/ash-dg-ventus-e.html

These differences are not surprising. The low sides
and open nose of the
DG single seater cockpit pose a difficult engineering
problem for the
designer, compared to the greater enclosure of the
Schleicher cockpits.

I'm not suggesting that the DG cockpit is unsafe or
inadequate, but only
that it does not match what Schleicher has done. A
prospective owner
should consider the value of that protection along
with the other
features of the gliders he is considering; for example,
the lower sides
of the DG cockpit (particularly if the NOAH option
is selected) should
make baling out easier than from a Schleicher cockpit.

I almost forgot NOAH another big safety step forward.
Wonder who developed that? It wasn't DG was it? I think
DG may have made the design available to other manufactures
so it may be possible for the older guys to actually
be able to get out of the high 26 side rails in an
emergency. Maybe not though as some seem to believe
that whatever Schleicher has done is good enough and
anything more is, to steal anothers line, unnecessary
like the Lexis auto park option.



If you counting on higher frame rails for protection
you may also want to read this.
http://www.dg-flugzeugbau.de/index-e.html

I was unable to find this reference, but I would like
to read it.

Here it is.

http://www.dg-flugzeugbau.de/cockpit-e.html

The point is that in a crash there is a G force beyond
which survival is unlikely due to the lack of a crush
zone. When the cockpit has been strengthened to the
point it will not deform and kill the occupant below
that force then design improvements are best turned
to what else can be done to prevent fatalities(like
the better visibility brought by DG style canopies
and the NOAH system) rather than just adding more strength
to the cockpit. DG's new Consummate safety cockpit,
which another poster advised is now standard equipment
on the 800/808 and 1000, was designed to prevent the
temporary cockpit deformation that occured during crash
testing. If DG had only been following Schleicher's
method of looking at damage after the fact this safety
advantage would never have occurred.


--
Eric Greenwell - Washington State, USA
Change 'netto' to 'net' to email me directly

'Transponders in Sailplanes' on the Soaring Safety
Foundation website
www.soaringsafety.org/prevention/articles.html

'A Guide to Self-launching Sailplane Operation' at
www.motorglider.org

Gary Evans wrote:
At 16:12 11 November 2006, Eric Greenwell wrote:
Gary Evans wrote:

While other manufactures have been content with building
what looks strong enough DG has actually participated
in crash testing.
This is not correct. Gerhard Waibel won an OSTIV prize
for his work in
cockpit safety about 20 years ago.

20 years ago, wasn't Chicago still a swamp? A lot has
happened in the past 20 years.

That was to support my claim Schleicher lead the way to a significant
improvement in cockpit crash protection. Of course, Schleicher's work
did not stop with the prize or the 24.

snip

DG claims that the DG100 from the late 70's was the
first to use a double wall construction that is commonly
referred to as a safety cockpit. Was the 24 done before
or after that advancement?

The 24 first appeared 1988. It uses a very strong, straight, and stiff
cockpit sill to maintain the integrity of the cockpit near the pilot and
to absorb the loads from the fuselage and wings. The cockpit itself is
single wall construction of at least three materials (some carbon, but
primarily fiberglass and synthetic fabrics, including some hybrid
fabrics) selected and fabricated to crush progressively to absorb energy
in a controlled fashion. As I recall Waibel's explanation, the strong
sill and mixed materials made it easier to achieve the desired crash
protection than a double-walled cockpit.

For pictures and more explanation, unfortunately only in German, go to
the Schleicher website:

http://tinyurl.com/y3pk9m
http://tinyurl.com/tufw6

Google language tools did an almost adequate job of translating.

snip


This page on the DG website shows that this view is
shared by
others (go to the 'Safety Cockpit' row):

What your referring to is the old original safety cockpit.
As I stated before the term safety cockpit refers to
the double wall construction but DG has gone way beyond
that as a result of the crash test data.

The table I referenced at

http://www.dgflugzeugbau.de/ash-dg-ventus-e.html

is labeled "ASH26E / DG-808C / Ventus 2cM - The Differences", so I
believe it refers to current production.

What they
now offer is termed a Consummate safety cockpit, which
is described in the article.

http://www.dgflugzeugbau.de/ash-dg-ventus-e.html

Included in this article is a reference to another article
(http://www.dgflugzeugbau.de/sicherheitscockpit-e.html), which includes
this remark:

"The cockpit sides [of the other gliders] are higher than the DG
sailplanes. The large canopy is one of our "Trade Marks" and leads to,
we must admit, slightly less strength than the higher cockpits."

And from another article: "The more enclosed cockpit of the same
construction can certainly absorb a higher impact energy than one with a
large canopy."

So, I conclude the table I referred to accurately reflects DG's opinion.

snip

If you counting on higher frame rails for protection
you may also want to read this.
http://www.dg-flugzeugbau.de/index-e.html
I was unable to find this reference, but I would like
to read it.

Here it is.

http://www.dg-flugzeugbau.de/cockpit-e.html

The point is that in a crash there is a G force beyond
which survival is unlikely due to the lack of a crush
zone.

Quoting from the article you reference:

"The more enclosed cockpit of the same construction can certainly absorb
a higher impact energy than one with a large canopy."

That's all I'm trying to point out.

Prospective owners have to determine for themselves what particular
features of each glider are important to them and their situation. My
determination was, for me, a crash was more likely than a mid-air
collision where G forces pinned me in the cockpit, and that the extra
visibility afforded by the DG cockpit would not significantly reduce my
chances of a mid-air collision. So, for this safety aspect of the
glider, I prefer Schleicher's solution.

If the particular safety aspects of a glider are important to a
prospective owner, I urge you to talk directly to the designers (DG,
Schleicher, Schempp-Hirth, etc). I have found them to generally be
candid in person, pleased to speak to a pilot that is interested in
safety, and eager to describe how they chose their particular solution
to a difficult problem. A good place to meet them is at the SSA
conventions, but I also recommend getting on a plane and visiting the
factory. Flights are available in the $500 range, a cheap price for a
pilot contemplating a new glider.

Or, you could start with a phone call!

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

If the particular safety aspects of a glider are important to a
prospective owner, I urge you to talk directly to the designers (DG,
Schleicher, Schempp-Hirth, etc). I have found them to generally be
candid in person, pleased to speak to a pilot that is interested in
safety, and eager to describe how they chose their particular solution
to a difficult problem. A good place to meet them is at the SSA
conventions, but I also recommend getting on a plane and visiting the
factory. Flights are available in the $500 range, a cheap price for a
pilot contemplating a new glider.

Or, you could start with a phone call!

Eric,

I, too, had a great experience corresponding directly with the
factory...and with Gerhard Waibel himself when I was seeking
information about a new ASW 24 15 years ago. I would also encourage
anyone who has a question to do the same.

For example, I had a number of questions about the canopy wire
deflector bar that was then mandatory in Holland (and which I ordered
and still use): how did it affect visibility, would it stop a telephone
or powerline strike, was it a potential hazard to the pilot's head in a
crash, etc.? Herr Waibel answered each question in a fax and mailed me
a drawing of the bar with the suggestion to sit in a '24 after taping
up the canopy with black tape to simulate the bar positions to check
visibility. I cannot conceive of an American manufacturer being as
candid and straightforward and refreshingly free of "caution: flying
may be hazardous to your health" warnings. Similarly, anyone reading
the DG site must also be amazed at their candor on the subject of
safety.

FWIW, I "voted with my wallet" and paid a price premium for my '24 over
the other brands even though they were all said to have equivalent
performance simply because of the enhanced safety I thought the '24
offered at the time. That it's turned out to be a wonderful glider that
is still fully competitive is a bonus.

Chip Bearden
ASW 24 "JB"