Crashing a '12

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

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

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

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

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