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#1
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Earlier, Steve Davis wrote:
You have described a $20K repair on a product which might not be worth $20K right after the repair. I assume that you're replying to my post of 1:39 today - though it doesn't appear so in the Google view of r.a.s. Please let me know if otherwise. Yes, in the right hands that might be a $20K repair - I know a lot of folks who can manage that, and I'm sure they're salivating over the fallout of this situation. But if there's lots of them to do, a relatively modest investment in tooling can easily cut the costs down to around a third of that, possibly less. For example, it's virtually a no-brainer to build a scarf-router to precisely mill out the required chunk of wing spar. And the pre-fabbed skin repair panels are easy, the layup is dirt simple and takes about an hour to do four; with cure cycles you could probably yield 8 per day from a single wing mold set. I remember when the G103 team was here fixing spar spigots. There was a lot of hand-wringing and gnashing of teeth around a repair that requires hacking huge chunks out of the spar stub. But in the end, they just lined them up and churned them out, and when they were done they all fit fine, looked like new, and no problems since. And, yeah, if it was some dogmeat glider only worth $20K last month, this might all be moot. But the fact is that DG300 have typically commanded around twice that, sometimes much more for young and well- equipped examples. My suggestion for the rods was to try a $2K or less repair which would allow current users the peace of mind to continue flying their gliders. My understanding of the DG 300 is that it has a very stiff wing, presumably even with undulations in the spar caps. A for effort, but I think that the modulii mismatch between the Graphlite and the fiberglass is probably too big to make it work practically, even if the DG is reputed to be "stiff." The axiom of such things is that as much as you might prefer it otherwise, stresses are transferred not to the strongest parts but to the stiffest. If you put any Graphlite into the spar, its stiffer modulus will make it try to take on all of the stress, or fail its glue bond trying. So you'd basically have to put in enough Graphlite to take all of the load, and scarf it in shallow enough to yield enough bond area to get all the load out of the fiberglass into it. And when you're done with that, the surgery is likely no less traumatic than if you'd just done a repair-manual scarf. Another thing to consider is that if you execute an innovative repair, you are probably on the hook to validate it with test it to destruction, or at least to the somewhat-draconian EASA standard of 6.3*1.725. Whereas with a textbook repair, you may be justified in only testing to design load or not testing at all. Since Graphlite ships in two and three ft. dia. spools it must be plenty flexible and it is far stronger than the equivalent amount of fiberglass rovings. Yes, that's the way we've been buying Graphlite ribbon (not rod) for the HP-24 and Glidair projects. Its flexibility is relative, though; with a Young's Modulus of about 23 million it is much stiffer than the equivalent profiles of pultruded fiberglass and is in fact 15% to 20% stiffer than the equivalent hand-laid carbon tape or roving. For new glider wing spar designs I think it is certainly the greatest thing since sliced cheese, but it doesn't always play nice with others. My suggestion would be to saw several kerfs of varying lengths and depths through the undulation area extending for some length on either side of the area possibly to the end of the spar stubs. Graphlite rods could be epoxied into the kerfs, like rebar in concrete, and they would take the load from the rovings they butt up against. I suppose fiberglass cloth could be wrapped and epoxied around the spar butt to prevent the rods from popping out, if that could happen, but I think you would have a much stronger than designed spar with a very stiff wing. As I wrote, that might work, but it inflicts trauma on the same order as the textbook repair, involves a pretty big modulus mismatch, and has no track record. I'd like to see it tried, though, it'd be an interesting experiment. I have heard of someone cutting a kerf in wooden spars and putting in the Graphlite rods to improve the strength. Yes, I've heard of that too - I think it was on a Bowlus Baby Albatross. Thanks, and best regards to all Bob K. |
#2
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Yes Bob, I was responding to your earlier post.
Thanks for your reply; there seems to be a lot more going on in the spar than I had realized. I was just guesstimating at the value of a DG 300 now vs. after a repair. With the current 'fix' from DG I suspect a lot of them will just sit in trailers not getting flown, or bought. Also, is this a problem with both the top and bottom spar caps of the wings or just one cap? Thanks for your information. Steve You have described a $20K repair on a product which might not be worth $20K right after the repair. I assume that you're replying to my post of 1:39 today - though it doesn't appear so in the Google view of r.a.s. Please let me know if otherwise. Yes, in the right hands that might be a $20K repair - I know a lot of folks who can manage that, and I'm sure they're salivating over the fallout of this situation. But if there's lots of them to do, a relatively modest investment in tooling can easily cut the costs down to around a third of that, possibly less. For example, it's virtually a no-brainer to build a scarf-router to precisely mill out the required chunk of wing spar. And the pre-fabbed skin repair panels are easy, the layup is dirt simple and takes about an hour to do four; with cure cycles you could probably yield 8 per day from a single wing mold set. |
#3
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Yes Bob, I was responding to your earlier post.
Thanks for your reply; there seems to be a lot more going on in the spar than I had realized. I was just guesstimating at the value of a DG 300 now vs. after a repair. With the current 'fix' from DG I suspect a lot of them will just sit in trailers not getting flown, or bought. Also, is this a problem with both the top and bottom spar caps of the wings or just one cap? Thanks for your information. Steve You have described a $20K repair on a product which might not be worth $20K right after the repair. I assume that you're replying to my post of 1:39 today - though it doesn't appear so in the Google view of r.a.s. Please let me know if otherwise. Yes, in the right hands that might be a $20K repair - I know a lot of folks who can manage that, and I'm sure they're salivating over the fallout of this situation. But if there's lots of them to do, a relatively modest investment in tooling can easily cut the costs down to around a third of that, possibly less. For example, it's virtually a no-brainer to build a scarf-router to precisely mill out the required chunk of wing spar. And the pre-fabbed skin repair panels are easy, the layup is dirt simple and takes about an hour to do four; with cure cycles you could probably yield 8 per day from a single wing mold set. |
#4
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just wondering how much a NEW set of wings, 808 profile with butt adaption and tongue/fork width to suit 300/303 series would be worth.
Mr DG would be tooled up already, the new specs could be added to the manual and the glider is upgraded. You Americans could then buy up the old 303 wings and bolt them to your beloved tinships for training! There is always an outside to the square. Bagger (diving for flamesuit, as usual) |
#5
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On Apr 18, 6:30 pm, Steve Davis
wrote: .. With the current 'fix' from DG I suspect a lot of them will just sit in trailers not getting flown, or bought. Steve, this all came out about ten days ago. Last weekend at the field there was quite a bit of chatter about it, and I had to answer a lot of questions about how I was planning on dealing with my 303. And the answer is, I'm so happy with the glider I just don't really care. Andreas is correct, this will not affect me until I decide to sell it, and that is some years down the line. The focus in this thread is on how to fix the problem; my interest is on how to test at the lowest cost. Let's say 50% of the gliders are affected, that means that the cost to fix half the gliders is exactly nothing. While the testing process is being worked out I'll be flying, and having fun. As it happens, I have the last plane (DG303 # 486) ever made by ELAN, and the 27th ACRO. It will be interesting to look back on this in a year or two. |
#6
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brianDG303 wrote:
As it happens, I have the last plane (DG303 # 486) ever made by ELAN, and the 27th ACRO. It will be interesting to look back on this in a year or two. Who made the final 25 units, and what is the source of this information? Jack |
#7
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Jack wrote:
brianDG303 wrote: As it happens, I have the last plane (DG303 # 486) ever made by ELAN, and the 27th ACRO. It will be interesting to look back on this in a year or two. Who made the final 25 units, and what is the source of this information? AMS Flight made the last 25, after they bought out ELAN's aircraft business and bought the production rights from DG Flugzeugbau... Marc |
#8
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Marc Ramsey wrote:
AMS Flight made the last 25, after they bought out ELAN's aircraft business and bought the production rights from DG Flugzeugbau... And they continued the defective construction techniques, in the same facility, probably using the same personnel? No wonder they are staying silent. Jack |
#9
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I doubt that you stay liable through bankruptcy.
DG is not Glazer-Dirks nor is it Rolladin-Schneider and when DG bought the assets of those bankrupt companies it didn't buy the liability of them. The liabilities, debts to suppliers, warranties, shareholders rights, employee compensation issues, etc... all were disposed of by the bankruptcy court. By buying the company name, assets and tooling etc...DG got the goodwill of the customer base and may have taken on the obligation to monitor the status of legacy product but it did not take on an obligation to provide free repair. Also, they seem to believe that the third option, the wings are strong enough with reduced operating limits is sufficient. Bob K. mentioned 'Hmmm... I wonder who that 'someone' might be. Whoever they are, they're pretty brave to get wrapped up in this mess.' This could also be applied to DG. If they specify an inspection and repair procedure for this mess does it imply that they are accepting some liability for payment and warranty if someone other than DG does the work? At 03:06 21 April 2007, Mart wrote: I read the report on the DG website and it all looks very nice except the last words; end of discussion. That rubs me the wrong way. As far as I know this is not a warranty issue but a building mistake and I think you stay liable for that, no time expire. It seems to me that some business will have an insurance to cover the loss for the pilots. I was at the Elan factory a number of years ago. They were building there the very first DG 1000. So there was defenitely a close business contact. If DG would have to pay they might go bankrupt.Due the previous bankrupty they might not be liable anyway. But Elan is a very big ski-factory. The gliders were made on the same terrain,behind the same fence. After seeing the gliders build I saw them build ski's by the 1000's. There is money there to compensate or fix the gliders. I think all the 300/303 pilots should put $100 in an account and have somebody find out who is liable. -- mart |
#10
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I too believe the restrictions on the 300 will scarcely be noticed by
the average pilot, but if someone is concerened (acro) their ship can easily be proof-loaded to 5.3 G's. Stan Hall wrote a good paper on just how to go about it, published in Soaring. Basically you mount the wing inverted on a sturdy test stand, secure it so it won't twist and then sand-bag that puppy to the flight limits, usually 5.3 G's. Then you know the wing is stong enough for anything it should see in flight if the ship is flown within the flight envelope. JJ |
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