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Sparky
Joined: 08 Dec 2003
Posts: 19083
Location: PDX9/9/14 5:34 PM |
I thought you meant a gal that age....
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LeeW
Joined: 13 Jan 2004
Posts: 453
Location: near Baltimore, MD9/9/14 6:04 PM |
Wow Nick... I have to question your friend's estimate of 200 days before a ski "starts to go dead". I have been skiing for over 35 years and have known at least 2 dozen or more professional instructors, several ski industry tech reps, a dozen or more ski shop mechanics and managers, and several elite level racers who were good enough to race at Europa Cup and US Ski team level.
Of course, the useful life of a ski is going to depend on what terrain one is skiing and how much one is skiing bumps, ice, thin cover, and on how often they need to fill gouges and sharpen edges. I have not known a full-time instructor (working all week at a big resort) that ever got more than 1 season on a pair of skis and most high level skiers notice a deadening of rebound and ice holding ability in the ski at somewhere between about 60-80 days at which point they relegate the ski to early and late season "rock skis" until they are ready for the dumpster.
I might concede 100-120 days if someone is skiing deep powder or easy groomers with deep base all the time, but 200 is up there.
I know Mr irons is an accomplishd skier of much experience... I'd be interested to hear his take on ski life.
Last edited by LeeW on 9/10/14 6:01 AM; edited 1 time in total
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walter
Joined: 11 Jan 2004
Posts: 4391
Location: metro-motown-area9/9/14 6:11 PM |
F16 vs 787, the big leap
the viper was designed in the mid 70s...the composites used in that are a garnish. no major structural elements are made of CF or any composite. the 787 relies almost entirely on composites for major structures -- the main wing spar, for example. the entire fuselage, exterior skin and all of the inner structural ribbing and interior structural bits are composite. +50% of a 787's weight is composite, and since composite is lighter than alloy that's a whole lot of CF structure! a viper is made of <5% composite by weight.
the viper and its ilk were a good start getting the industry familiar with composites, but the 787 represents +30 years of progress and its structure light years more advanced than a viper.
like erik, i'd not hesitate to take a ride on a 787...given the interior is alot more well-thought-out than more mature stuff, i'd actually *prefer* to fly in one!
no idea how this affects whether CF bikes fatigue or not!
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ErikS
Joined: 19 May 2005
Posts: 8337
Location: Slowing boiling over in the steamy south, Global Warming is real9/9/14 8:31 PM |
The stabs, though not anywhere as big a structure that the 787 is are in fact large load bearing structures for a small fighter.
The carbon almost looks machined on the stab. You are correct that it is old tech but my main point is that those carbon bits have lived on the world's most prolific fighter and has done VERY well.
I know that carbon bike bits have been around long enough that I don't hesitate to use them.
Back in the day of the Spynergy RevX, nope back then I would not touch carbon bits.
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walter
Joined: 11 Jan 2004
Posts: 4391
Location: metro-motown-area9/9/14 8:44 PM |
anyone remember fiber-flight spokes?
Crrrrunch!
True, viper stabs are essential flight surfaces despite their small size...looks like a fair bit of aluminum is inside .... today that and the structural load-bearing pivot/shaft (?) would be made of CF as well.
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ErikS
Joined: 19 May 2005
Posts: 8337
Location: Slowing boiling over in the steamy south, Global Warming is real9/9/14 11:50 PM |
What is slang called "stab" are the tailplanes on this cutaway. Yep, they do have an Al structure internally. I suspect that much of the 787 has some Al internally.
None of the Viper structures are totally carbon. I have seen stabs destroyed in fires and they come apart in strips, the resin burns up and layers of carbon fall down in long strips and sheets. It is not something you want to get on you, that is for sure.
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Jesus Saves
Joined: 16 Jun 2005
Posts: 1150
Location: South of Heaven9/10/14 7:43 AM |
If I remember correctly, the primary motivation to use a carbon composite in the 787 is to reduce weight which in turn reduces fuel consumption. The amount airline companies spend on fuel is one of, if not the most significant operating cost. Boeing pushed/accelerated this initiative several years ago, circa, when oil became $$ (retail gas doubled in price to $4/gallon, IIRC).
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KerryIrons
Joined: 12 Jan 2004
Posts: 3236
Location: Midland, MI9/10/14 7:15 PM |
Skis again
quote:
All the large structures have a honeycomb core which is very different from a bike or the foam in a ski.
Some of us here will remember Hexel skis, with their honeycomb cores. I never skied one but they were popular for a few years. The company had aerospace roots IIRC so I don't know if they were just leveraging what they knew or thought they really were bringing something to the party. They weren't really high performance skis (IMO) and so never really got put to the durability test that an expert or racer would give them.
I would agree that 200 days would be pretty good for skis unless the owner was quite light or stayed off the rough stuff. 100 seems more in range. My K2 Mod Axis skis are still skiable (probably 80 days on them) but both converted themselves from continuous edges to cracked edges (both skis developed one crack right under the boot). I think people who ski 20 days a year are more likely to "wear out" a ski due to base damage than softening. And just like with bikes, "new skis" are the holy grail for lots of people.
There's an easy test for ski softening - you just put the skis base to base and hold the bottom ski horizontal. You can tell how much camber is left. We don't have any such easy test for bikes.
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Sparky
Joined: 08 Dec 2003
Posts: 19083
Location: PDX9/10/14 7:36 PM |
I always likes wood core skis. The faster I got the more I like them.. But as a qualifier, last time I skied was the day in Feb 2006 I came home with the Tib/Fib fractures.
No clue what tech has entered into the equation since then. Skis I got in 2001-2 are Dynastar and very shaped with cracked edges which cut frozen crud really well as I recall.
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