KA6E and Foka 4 comparable metal ships - Laister Nugget LP15

Let me throw in my five cents: as a student pilot, I helped to rebuild
our club's Ka-6, Ka-8's and Ka-13, which were already pretty old back
then and had racked up some hours in a rough club operation. Apart from
one aft fuselage bulkhead separating from the skin on the Ka-6 due to
constant mishandling (lifting and pushing on the elevator), I have not
seen any structural problems with the glued joints. Very old ships
built with Kasein (a milk protein based glue, similar to 'Elmer's wood
and paper glue') have a problem if allowed to become wet over and over
again. This glue tends to dissolve or be eaten by a fungus. The factory
built ships were glued with a phenolic resin glue (one brand name was -
or still is - 'Aerodux'), and that stuff does seem to hold up very
well.
Personnaly, I would prefer a wooden ship over a metal ship when flying
the wave. The buying decision wood vs. metal has to be based on what
you are planning to do with the ship, i.e. tie down outside or derig /
store in trailer or a dry hangar.

Uli Neumann


F.L. Whiteley wrote:
Alas, resorcinal glues, unlike wood, have a limited service life.
Reportedly this is about 40 years or so. I seem to recall some issues with
a few K-6 aft frames at about 25-30 years. But that may depend on how they
were stored also. Regluing is an option. Each wooden wing recover process
I've had the opportunity to peak into has also involved the re-gluing of
several rib parts and stringers. Perhaps some of those who've restored
vintage gliders might comment further on the life of older glues and modern
glue developments.

Frank Whiteley

01-- Zero One wrote:

Bob, et. Al.,

The question remains... what about the glue joints and other
extra-material aspects of aging wood ships?

Larry
Zero One



" wrote in message
:

Bob Whelan wrote:
Matthieu wrote (w. snips)...


What would be a nice metal equivalent of the KA6E or Foka 4?

I am asking because those ships are 40+ years old now and I am
concerned about the aging wood... Should I be concerned?


Peace of mind would seem to incompatible w. structural concern of any
kind,
regardless of validity. (FWIW, I've never been able to talk myself
into
flying wood ships. Wood I trust...but those glue joints are another
mental matter!)
- - - - - -

SNIP

My experience - if it was done well originally you never have a problem
again. If I compare the loose rivets and other problems on the L13s that
fly at our club to the wood wing Scheibe ships there is no comparison.
Have seen a student land a Bergfalke on the main wheel and one wingtip -
the Scheibe survived a spectacular groundloop with the only damage to the
wing being a hole where the tip wheel pulled out - try that in metal...

--
Bruce Greeff
Std Cirrus #57
I'm no-T at the address above.
-+-
\_________0_________/

On Sat, 4 Jun 2005 12:39:20 UTC, "01-- Zero One"
wrote:

The question remains... what about the glue joints and other
extra-material aspects of aging wood ships?

I think the only glue I'd worry about would be casein, and I doubt if
that has been used much for fifty years. Cascamite (urea-formaldehyde)
and everything since are plastics: they'll out perform and out live
the wood their attached to.

Ian

--

My club has some problems with a Ka-8. It seems the gluing of the spar
and the torsion box has been done with better glue than that of the
ribs. It has been done with another glue type: dark brown for the
former (probably Aerodux), yellow/very light brown for the latter
(Kaurit?). The latter type of glue seems to fail easily nowadays.

However, metal structures are known to fail, too, and often without
warning, by metal fatigue. Normally, sailplanes are made over strong in
critical metal components, just to allow for this phenomenon, but it's
not foolproof.

Let me get this straight, you're complaining that the LP15's cockpit
is too big? That's a complaint I have not heard before about any
glider.

And yet, the Schempp-Hirth people are producing their "a" model
fuselage (Discus a, Ventus a) for that reason, some competition pilots
complaining that by making their cockpits too big (like the Standard
Cirrus), they were wasting possible aerodynamical advantages... These
fuselages are advertised for slim pilots not bigger than 1.75 m.


--
stephanevdv
------------------------------------------------------------------------
Posted via OziPilots Online [ http://www.OziPilotsOnline.com.au ]
- A website for Australian Pilots regardless of when, why, or what they fly -

stephanevdv wrote:
My club has some problems with a Ka-8. It seems the gluing of the spar
and the torsion box has been done with better glue than that of the
ribs. It has been done with another glue type: dark brown for the
former (probably Aerodux), yellow/very light brown for the latter
(Kaurit?). The latter type of glue seems to fail easily nowadays.
There was / is a general AD out for the Ka range of gliders to check all of the
joints (presumably where the lighter glue is) To my knowledge there have been
three failures of Ka wings due to glue joint failure. Two were on overpowered
winch launches, the third one the pilot lost much of his starboard wing behind
the airbrakes in flight, but landed safely. This appears to be a problem
specific to the glue used on these gliders, their storage conditions and their
structure.

Phenolic glues, like the more modern composites have a very long life. All
phenolic resins are black or brown, strong but not terribly flexible. The latest
epoxy resins are enormously strong, and seem to have indefinite life. They glue
buildings together with the stuff these days.

The main indicators of glue problems seem to be if the joints have been subject
to moisture over a long time.


However, metal structures are known to fail, too, and often without
warning, by metal fatigue. Normally, sailplanes are made over strong in
critical metal components, just to allow for this phenomenon, but it's
not foolproof.


Let me get this straight, you're complaining that the LP15's cockpit
is too big? That's a complaint I have not heard before about any
glider.


And yet, the Schempp-Hirth people are producing their "a" model
fuselage (Discus a, Ventus a) for that reason, some competition pilots
complaining that by making their cockpits too big (like the Standard
Cirrus), they were wasting possible aerodynamical advantages... These
fuselages are advertised for slim pilots not bigger than 1.75 m.

And I am eternally grateful to Klaus Holighaus for the armchair in my Std
Cirrus, even if it loses a little on L/D...


--
stephanevdv
------------------------------------------------------------------------
Posted via OziPilots Online [ http://www.OziPilotsOnline.com.au ]
- A website for Australian Pilots regardless of when, why, or what they fly -



--
Bruce Greeff
Std Cirrus #57
I'm no-T at the address above.

In message , Bruce
writes
stephanevdv wrote:
My club has some problems with a Ka-8. It seems the gluing of the spar
and the torsion box has been done with better glue than that of the
ribs. It has been done with another glue type: dark brown for the
former (probably Aerodux), yellow/very light brown for the latter
(Kaurit?). The latter type of glue seems to fail easily nowadays.
The light brown glue is similar to casein. There were some produced
with both but most were one or the other. The dark brown aerodux ones
are later.
There was / is a general AD out for the Ka range of gliders to check
all of the joints (presumably where the lighter glue is) To my
knowledge there have been three failures of Ka wings due to glue joint
failure. Two were on overpowered winch launches, the third one the
pilot lost much of his starboard wing behind the airbrakes in flight,
but landed safely. This appears to be a problem specific to the glue
used on these gliders, their storage conditions and their structure.

The earlier Ka gliders used a glue called Kaulac or Kaurit (Forgive the
spelling as I can't remember the correct one). This was similar to
casein with all of the drawbacks that casein has. If they are stored
damp then they will, after some time fail. At some point in the Ka6
production they switched to Aerodux, or something like it, and the glue
won't fail until a long time after the wood.

Recently in the uk there have been a series of mandatory inspections for
all early Ka (K4, 6, 7, 8 don't know about 13) types. This was
triggered in part by a fatal accident involving a Ka7, some of the
checks preceded this. These checks haven't, as far as I know, thrown up
many problems and the most likely causes of most problems have been
traced to bodged repairs rather than glue/wood deterioration.

I have just repaired/rebuilt a 1952 aircraft (T31) that had several
bodged repairs made from Aerodux but through poor joint prep the joints
were very weak. In older aircraft that have accumulated repairs this is
a more likely source of failure rather than the original construction.

Phenolic glues, like the more modern composites have a very long life.
All phenolic resins are black or brown, strong but not terribly
flexible. The latest epoxy resins are enormously strong, and seem to
have indefinite life. They glue buildings together with the stuff these
days.


The main indicators of glue problems seem to be if the joints have been
subject to moisture over a long time.

Yes, the point of failure has changed over time though. With pre
synthetic glues the most likely failure was the glue itself (glue rot
and so on) whilst today it is more likely to be the wood through damp or
poor glue adhesion through poor joint preparation.

Cheers

Robin

However, metal structures are known to fail, too, and often without
warning, by metal fatigue. Normally, sailplanes are made over strong in
critical metal components, just to allow for this phenomenon, but it's
not foolproof.


Let me get this straight, you're complaining that the LP15's cockpit
is too big? That's a complaint I have not heard before about any
glider.
And yet, the Schempp-Hirth people are producing their "a" model
fuselage (Discus a, Ventus a) for that reason, some competition pilots
complaining that by making their cockpits too big (like the Standard
Cirrus), they were wasting possible aerodynamical advantages... These
fuselages are advertised for slim pilots not bigger than 1.75 m.

And I am eternally grateful to Klaus Holighaus for the armchair in my
Std Cirrus, even if it loses a little on L/D...

--
stephanevdv
------------------------------------------------------------------------
Posted via OziPilots Online [ http://www.OziPilotsOnline.com.au ]
- A website for Australian Pilots regardless of when, why, or what they fly -




--
Robin Birch

Matt,

Hum, "metal equivalent of the KA6E"
In North America, how about:

SGS 1-23 ~10K$
SGS 1-34 ~15K$
SGS 1-36 ~16K$
Let L-33 ~24K$


You can look these gliders up he

http://www.sailplanedirectory.com/ndxtype.htm


- David
ps Please don't take my suggested prices too seriously.


Matthieu wrote:
Dear expert soaring pilots,

What would be a nice metal equivalent of the KA6E or Foka 4?

I am asking because those ships are 40+ years old now and I am
concerned about the aging wood... Should I be concerned?

Is there any relevant metal alternative to those ships? I would also be
interested in any clues in terms of pricing.

I am a 5'6'' and 137 lbs pilot. What I love about those 2 ships (apart
of their outstanding behaviors and performances) are the narrow - low
cockpit and their light weight for soft-weak conditions flying. I am
flying out of Hope British Columbia.

Last Monday I discovered a nice sexy looking plane on Jean airport in
Nevada; metal and good aspect ratio. The only comment I have concerns
the large and high cockpit size. Other than that this ship is very sexy
and seems robust.

It is a Laister Nugget LP15. Do you know any other metal ships
comparable to the Laister Nugget?

Thanks for all information and advises you could give to the private
owner wanabee I am.

Matt

Aluminum suffers from fatigue failure. Some of the Beech D-18 and Bonanza
spars failed from fatigue.

It also suffers from corrosion. I recall an Ercoupe that lost a wingspar
because mouse urine had corroded it.

Glues have been used to make violins for centuries and I have never heard of
one coming apart. But, they are not left outside for 40 years, either. The
stresses caused by the string tension may be as high as that caused by wave
flying.

It is possible to pull the wings off almost any ship.

Colin

Good point on the metal ships, didn't the Nugget have
a problem with corrosion in its fuselage ballast tank?
JJ

At 20:30 06 June 2005, Wallace Berry wrote:
I used to share your concerns about wooden ships. However,
in the 25
years that I've been aviating, I've run into more structural
problems
with metal aircraft than with wood or plastic. Metal
ships seem to get
more abuse, both in flight and from poor storage (tied
out). I've been
inside the wings of a number of wood aircraft and have
yet to see a
problem that would have compromised the aircraft in
flight. The wood in
the wings of our Ka-8, which is at least 45 years old,
looked as if it
were new when we removed the fabric to recover it.


However, as to your question about the Nugget. I've
heard that they are
great ships, but a little heavy for weak conditions.

Someone suggested a Schwiezer 1-23. The 1-23 D through
H15 models are
truly great ships, good for weak conditions. They are
not fun to
assemble however. Also, they tend to develop cracks
in the wing and tail
skins from 'oil canning'.

My advice would be to get yourself a Ka-6 and go have
fun!

--
Take out the airplane for reply