Crashing a '12

[Mark Grubb]

The 12 has a composite Glass - Balsa - Glass Fuselage
that is probably at least 0.75 inches thick. It is
a very, very sturdy structure.

The 12 would probably be airworthy with either the
glass alone or the wood alone. Laminated together,
it is a tank.

[Eric Greenwell]

Mark Grubb wrote:
> The 12 has a composite Glass - Balsa - Glass Fuselage
> that is probably at least 0.75 inches thick. It is
> a very, very sturdy structure.
>
> The 12 would probably be airworthy with either the
> glass alone or the wood alone. Laminated together,
> it is a tank.

The designer of the ASW 12 also designed the ASW 24, for which he was
awarded an OSTIV prize for his contribution to safety. I'm tempted to
believe he learned a lot between the 12 and the 24. Some features, like
the very stiff cockpit rails, glass, Kevlar, and carbon construction,
and a "soft" nose, are not present in the 12.

It would be interesting to hear his opinion (and those of other
knowledgeable people) on the relative merits of the two fuselage
constructions.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[[email protected]]

I have had a couple of very heavy landings/groundloops in my LAK 12
('12). Comments after the first one, which involved a tree and resulted
in lots of paperwork, is that no German glider would have survived with
no damage. Thank goodness for Eastern Block over-engineering.
Clinton Birch
LAK 12

[Eric Greenwell]

wrote:
> I have had a couple of very heavy landings/groundloops in my LAK 12
> ('12). Comments after the first one, which involved a tree and resulted
> in lots of paperwork, is that no German glider would have survived with
> no damage. Thank goodness for Eastern Block over-engineering.

I think you were misled by the "12" in the subject line, because the '12
Mark and I were referring to is the ASW 12. It's quite unlike the LAK
12, which is basically an ASW 17.

As far as "over-engineering" goes, I've looked at the LAK 12, and I
didn't see anything special about the design of the cockpit, which
seemed to share all the design features and problems of gliders designed
in the 70's. The cockpit design is the part of the glider that interests
this pilot the most when it comes to crashing.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Clint]

> I think you were misled by the "12" in the subject line, because the '12
> Mark and I were referring to is the ASW 12. It's quite unlike the LAK
> 12, which is basically an ASW 17.
>
> As far as "over-engineering" goes, I've looked at the LAK 12, and I
> didn't see anything special about the design of the cockpit, which
> seemed to share all the design features and problems of gliders designed
> in the 70's. The cockpit design is the part of the glider that interests
> this pilot the most when it comes to crashing.

I did understand you were referring to the ASW 12. Beautiful glider
but I have never had the chance to see one. I used the string to refer
to the LAK 12 because it is also incredibly strong - I should have
added a :-) when I referred to the LAK 12 as a '12.

I apologise if my understanding of the term "over-engineering" is
different from that associated with the term elsewhere in the world. I
used it to express the common disbelief in the engineers'
calculations. It is the exact opposite of "beautifully-engineered"
which would be used to express amazement at the fine calculations used
to manufacture a piece with no excess or waste (Lennie would
appreciate "beautiful-engineering" but despise "over-engineering" :-)
). The use of extra material just in case the engineers' calcs are
incorrect is "over-engineer" e.g. using a piece 2" thick when the
engineer says 1" is more than adequate. The LAK appears to have been
constructed with that principle in mind and the result is an
incredible tough aeroplane - like most things built by the old Eastern
Block countries. You should see the suspension system on the LAK T4
trailers - could have come off a T62 tank!

The LAK 12 manual does say the glider has a crashworthy cockpit but I
agree that there isn't the beautiful design found in modern AS gliders
with their strengthened cockpit structures. I think it is considered
crashworthy because it is so thick.

It is a common mistake to say the LAK 12 is basically an ASW 17. The
two have similar profiles and wingspans but the wing profile is closer
to the Nimbus 2 (Wortman FX67) than ASW 17 (modified Wortmann FX62).
The details are actually more Jantar 1 than anything German. The LAK
12 has a single piece wing, which is very different from the Nimbus 2
or ASW 17, which have 2 piece wings. What is similar is the docile
handling and performance - although at higher speeds the ASW 17 should
run away from the LAK. The LAK 12 was designed at a time that the ASW
17 and Nimbus 2 were already being replaced by the ASW 22 and Nimbus 3
respectively. It was designed as a training glider for the Russians
(future airforce pilots and government sponsored clubs), rather than a
competition machine.

Off the topic - the weather bureau are predicting 4m/s thermals and 17
000ft cloud base. A bit of a poor day as earlier in the week they were
saying 6m/s and 20 000ft. Looks like the old LAK will have to stretch
its legs tomorrow. Eat-your-heart-out all those in the Northern
Hemisphere!

Clinton Birch
LAK 12

[Bert Willing]

"Crashworthy" nowadays refers to the pilot's ability to survive a crash -
not the aircraft structure comeingout of a crash undamged. A sturdy,
tank-like design very often means not crashworthy _at all_.

--
Bert Willing

ASW20 "TW"


"Clint" > a écrit dans le message de news:
...
>> I think you were misled by the "12" in the subject line, because the '12
>> Mark and I were referring to is the ASW 12. It's quite unlike the LAK
>> 12, which is basically an ASW 17.
>>
>> As far as "over-engineering" goes, I've looked at the LAK 12, and I
>> didn't see anything special about the design of the cockpit, which
>> seemed to share all the design features and problems of gliders designed
>> in the 70's. The cockpit design is the part of the glider that interests
>> this pilot the most when it comes to crashing.
>
> I did understand you were referring to the ASW 12. Beautiful glider
> but I have never had the chance to see one. I used the string to refer
> to the LAK 12 because it is also incredibly strong - I should have
> added a :-) when I referred to the LAK 12 as a '12.
>
> I apologise if my understanding of the term "over-engineering" is
> different from that associated with the term elsewhere in the world. I
> used it to express the common disbelief in the engineers'
> calculations. It is the exact opposite of "beautifully-engineered"
> which would be used to express amazement at the fine calculations used
> to manufacture a piece with no excess or waste (Lennie would
> appreciate "beautiful-engineering" but despise "over-engineering" :-)
> ). The use of extra material just in case the engineers' calcs are
> incorrect is "over-engineer" e.g. using a piece 2" thick when the
> engineer says 1" is more than adequate. The LAK appears to have been
> constructed with that principle in mind and the result is an
> incredible tough aeroplane - like most things built by the old Eastern
> Block countries. You should see the suspension system on the LAK T4
> trailers - could have come off a T62 tank!
>
> The LAK 12 manual does say the glider has a crashworthy cockpit but I
> agree that there isn't the beautiful design found in modern AS gliders
> with their strengthened cockpit structures. I think it is considered
> crashworthy because it is so thick.
>
> It is a common mistake to say the LAK 12 is basically an ASW 17. The
> two have similar profiles and wingspans but the wing profile is closer
> to the Nimbus 2 (Wortman FX67) than ASW 17 (modified Wortmann FX62).
> The details are actually more Jantar 1 than anything German. The LAK
> 12 has a single piece wing, which is very different from the Nimbus 2
> or ASW 17, which have 2 piece wings. What is similar is the docile
> handling and performance - although at higher speeds the ASW 17 should
> run away from the LAK. The LAK 12 was designed at a time that the ASW
> 17 and Nimbus 2 were already being replaced by the ASW 22 and Nimbus 3
> respectively. It was designed as a training glider for the Russians
> (future airforce pilots and government sponsored clubs), rather than a
> competition machine.
>
> Off the topic - the weather bureau are predicting 4m/s thermals and 17
> 000ft cloud base. A bit of a poor day as earlier in the week they were
> saying 6m/s and 20 000ft. Looks like the old LAK will have to stretch
> its legs tomorrow. Eat-your-heart-out all those in the Northern
> Hemisphere!
>
> Clinton Birch
> LAK 12

[Mike Hessington]

Clint,

You are confused.

I have visited the LAK factory. As a result of this
visit I can't agree with you views on 'over engineering'
of LAKs.

The LAK 17/19 is under engineered. The spars appear
flimsy and the cockpit has no real protection at all.
In fact, one of them broke up at low level during
a test flight and just about killed the pilot.

If I had to crash a glider I would want to be sitting
in an ASW27 or 28.

The Germans calculate, design and test in order to
get things right. Over engineering is fine if you
are building tanks, not gliders.

Mike
X01



At 07:42 04 November 2004, wrote:
>I have had a couple of very heavy landings/groundloops
>in my LAK 12
>('12). Comments after the first one, which involved
>a tree and resulted
>in lots of paperwork, is that no German glider would
>have survived with
>no damage. Thank goodness for Eastern Block over-engineering.
>Clinton Birch
>LAK 12
>
>

[Ian Cant]

As I sadly recall, over-engineering means adding unnecessary
complexity; adding unnecessary material is over-building.

Ian



At 11:36 05 November 2004, Mike Hessington wrote:
>Clint,
>
>You are confused.
>
>I have visited the LAK factory. As a result of this
>visit I can't agree with you views on 'over engineering'
>of LAKs.
>
>The LAK 17/19 is under engineered. The spars appear
>flimsy and the cockpit has no real protection at all.
> In fact, one of them broke up at low level during
>a test flight and just about killed the pilot.
>
>If I had to crash a glider I would want to be sitting
>in an ASW27 or 28.
>
>The Germans calculate, design and test in order to
>get things right. Over engineering is fine if you
>are building tanks, not gliders.
>
>Mike
>X01
>
>
>
>At 07:42 04 November 2004, wrote:
>>I have had a couple of very heavy landings/groundloops
>>in my LAK 12
>>('12). Comments after the first one, which involved
>>a tree and resulted
>>in lots of paperwork, is that no German glider would
>>have survived with
>>no damage. Thank goodness for Eastern Block over-engineering.
>>Clinton Birch
>>LAK 12
>>
>>
>
>
>
>

[Marc Ramsey]

Mike Hessington wrote:
> You are confused.
>
> I have visited the LAK factory. As a result of this
> visit I can't agree with you views on 'over engineering'
> of LAKs.

No, he's not confused. You are. The LAK-12 is an over-engineered tank.
I've seen a LAK-12 make it through a botched takeoff with a few
scratches, that would have reduced many other gliders to a pile of
debris. With all that over-engineering, the one-piece wing of the
LAK-12 weighs only a few pounds more than the inner panel of the similar
ASW-17 wing.

> The LAK 17/19 is under engineered. The spars appear
> flimsy and the cockpit has no real protection at all.
> In fact, one of them broke up at low level during
> a test flight and just about killed the pilot.

The LAK-17/19 are entirely new designs that have nothing much to do with
the 12. The the spar looks flimsy because it is made of pultruded
carbon rods. It is as strong or stronger than wings made using
traditional composite spar techniques. The 17/19 cockpit area has
several layers of Kevlar. It is not a "safety" cockpit like the newer
Schleicher and DG designs, but it is certainly safer than many older
German designs.

I believe the LAK-16 that crashed had a traditional spar...

> If I had to crash a glider I would want to be sitting
> in an ASW27 or 28.

I agree, I wish I could afford one.

> The Germans calculate, design and test in order to
> get things right. Over engineering is fine if you
> are building tanks, not gliders.

The LAK-17/19 have several innovative design/safety features that the
Germans haven't managed to pick up on with all of their fine
engineering. I have some real issues with the factory about their
post-sale support, but I think the basic structural design of the
LAK-17A we own is as good as the DG-303, Ventus B, ASW-20B, and Duo
Discus (which was among those needing spar repair, BTW) I've also owned.
I've flown my LAK-17A in some of the strongest conditions in the
world, and it hasn't broken up on me yet...

Marc

[Raphael Warshaw]

Does anyone have more information on the "low level breakup" of a LAK-17/19
referred to in the Mike Hessington post?

Ray Warshaw
1LK

> At 11:36 05 November 2004, Mike Hessington wrote:
>>Clint,
>>
>>You are confused.
>>
>>I have visited the LAK factory. As a result of this
>>visit I can't agree with you views on 'over engineering'
>>of LAKs.
>>
>>The LAK 17/19 is under engineered. The spars appear
>>flimsy and the cockpit has no real protection at all.
>> In fact, one of them broke up at low level during
>>a test flight and just about killed the pilot.
>>

[Marc Ramsey]

Raphael Warshaw wrote:
> Does anyone have more information on the "low level breakup" of a LAK-17/19
> referred to in the Mike Hessington post?

I believe he is talking about the LAK-16 prototype, from which the
LAK-17/19 fuselage and tail are derived, but the wing was a different
design. I've heard that LAK-17As after serial 6 (like ours) have a
beefed-up spar, not because there was an issue with strength, but
because the early wings flexed so much (like an early ASW-20) that some
pilots found it disconcerting...

Marc

[Robertmudd1u]

>I believe he is talking about the LAK-16 >prototype, from which the LAK-17/19
>fuselage and tail are derived, but the wing >was a different design.

The LAK 16 ia primary glider used for training children. It had no influence on
the LAK-17/19.

I've heard that LAK-17As after serial 6 (like ours) have a
>beefed-up spar, not because there was an issue with strength, but
>because the early wings flexed so much (like an early ASW-20) that some
>pilots found it disconcerting...

The first several LAK-17s were made with carbon roving in the traditional manor
used at the time, early '90s. As a result of the favorable testing of the
carbon rod in the Genesis 2 Sportine Aviacija decided to use the rods in the
new version of the LAK-17/19.

The crash referred to was of one of the first LAK-17s made in the early 90s.
There was a manufacturing defect that occurred while making the spar. The wing
failed during a low altitude, high speed pass at the end of some flight
testing. I have seen the pictures of the crash site, if the cockpit was not
tough the pilot would not have survived. It hit so hard parts had to be dug out
of the ground. The pilot, Vytautas Sabeckis, lived, but today walks with a
limp, however he still flies and did the flight testing on the Genesis 2 and of
course on the new version of the LAK-17/19. He still manages to be the top
glider pilot in Lithuania.

The LAK-17 takes advantage of some things I did with the Genesis cockpit and
new research findings on crashing that were not available when the LAK-17 was
originally designed , however they are constrained by existing molds for the
exterior shape. Sportine Aviacija's chief designer, Klemas Juocas, is very
good, I think he is right up there with the best in the industry.

Robert Mudd

[Marc Ramsey]

Robertmudd1u wrote:
> The first several LAK-17s were made with carbon roving in the traditional manor
> used at the time, early '90s. As a result of the favorable testing of the
> carbon rod in the Genesis 2 Sportine Aviacija decided to use the rods in the
> new version of the LAK-17/19.

You've actually been to the factory, I haven't, but, it is my
understanding that all production LAK-17A models (not the early '90s
LAK-17, which I mistakenly called the "LAK-16") have carbon rod spars.
The LAK-17A was advertised as having ~120 lb wings, and early serial
numbers do have wings in that weight range. When we received ours and
discovered that the wings were ~140 lbs, we complained, and were told
that the spars were beefed up to reduce flexing.

Marc

[Robertmudd1u]

>You've actually been to the factory, I haven't, but, it is my
>understanding that all production LAK-17A models (not the early '90s
>LAK-17, which I mistakenly called the "LAK-16") have carbon rod spars.
>The LAK-17A was advertised as having ~120 lb wings, and early serial
>numbers do have wings in that weight range. When we received ours and
>discovered that the wings were ~140 lbs, we complained, and were told
>that the spars were beefed up to reduce flexing.


Marc,

I worked at S.A. from Jan. '96 to July. '99. All very interesting, and I have
made some life long friends. I go back for visits every other year.

The first of the "new" LAK-17 wings were indeed rather flexible. Making them
stiffer happened after I left. They must have added more than just additional
carbon rod to gain 20 lbs. per wing. The weight of all the carbon rods for one
wing is rather small. As a benchmark the Genesis 2 wings averaged 131 lbs. And
they have a lot more wing area than the LAK-17, but they are also thicker which
helps a lot in keeping the weight down.

I flew a LAK-17 at the Pociunai aerodrome in '99 and found it to be a very nice
glider to fly. My lasting memory was of the great power of the rudder.

Robert Mudd

[Raphael Warshaw]

Robert:

Thanks for the history. Having personally "tested" the integrety of the
LAK-17 wing (and fuselage) in a nasty ground-loop accident, my impression is
that it's incredibly strong. Vytautas' name being on the papers as having
performed the test flight for my ship would seem to be a reasonable vote of
confidence given the experience you relate.

Ray Warshaw
1LK


"Robertmudd1u" > wrote in message
...
> >You've actually been to the factory, I haven't, but, it is my
>>understanding that all production LAK-17A models (not the early '90s
>>LAK-17, which I mistakenly called the "LAK-16") have carbon rod spars.
>>The LAK-17A was advertised as having ~120 lb wings, and early serial
>>numbers do have wings in that weight range. When we received ours and
>>discovered that the wings were ~140 lbs, we complained, and were told
>>that the spars were beefed up to reduce flexing.
>
>
> Marc,
>
> I worked at S.A. from Jan. '96 to July. '99. All very interesting, and I
> have
> made some life long friends. I go back for visits every other year.
>
> The first of the "new" LAK-17 wings were indeed rather flexible. Making
> them
> stiffer happened after I left. They must have added more than just
> additional
> carbon rod to gain 20 lbs. per wing. The weight of all the carbon rods for
> one
> wing is rather small. As a benchmark the Genesis 2 wings averaged 131 lbs.
> And
> they have a lot more wing area than the LAK-17, but they are also thicker
> which
> helps a lot in keeping the weight down.
>
> I flew a LAK-17 at the Pociunai aerodrome in '99 and found it to be a very
> nice
> glider to fly. My lasting memory was of the great power of the rudder.
>
> Robert Mudd
>
>
>