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#11
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I can do both, trailer or outside. I am more security oriented. I don't
want to put the ship into aerobatics but still want to feel safe in rough air. |
#12
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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. |
#13
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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 -- |
#14
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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 |
#15
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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 |
#16
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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 |
#17
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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 |
#18
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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 |
#19
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Wallace Berry writes: 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. Which raises an important point: with modern Dacron covering systems, and a good trailer or hangar, it's possible, and tempting, to leave the fabric on for 20 or 30 years. But they should be recovered much more often than that, to allow you to inspect the structure and fix all the popped glue joints. For example, 20 years is probably too long, see http://www.tux.org/~milgram/k8.html. 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 |
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