flak monkey
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| posted on 24/5/05 at 08:48 PM |
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Ali chassis on Ebay
Spotted this today: (Yes I know its Marc from MNR selling it  )
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=100921&item=4551975923&rd=1
Is this one of those made by MK a while back? ISTR discussion about it on several occasions.
Might be ok for a race/sprint car thats going to be checked regularly, wouldnt use it on the road though....
David 
Sera
http://www.motosera.com
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nick205
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| posted on 24/5/05 at 09:34 PM |
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The description refers to it as a Formula 27 chassis. Either way I agree about using it on the road 
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marc n
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| posted on 25/5/05 at 07:23 AM |
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yep chassis defintely f27 38mm round tubular durol chassis, looks pretty impressive
think the mk one was done in inch by inch box in standard alloy
best regards
marc
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Triton
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| posted on 25/5/05 at 07:48 AM |
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Not convinced an ali space frame is such a good idea....one shunt and it's a goner
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JAG
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| posted on 25/5/05 at 08:16 AM |
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One word - FATIGUE - aluminium will always fatigue and crack eventually can't be avoided.
It works OK in aircraft because most parts are 'lifed' in hours and replaced/scrapped after that time expires.
[Edited on 25/5/05 by JAG]
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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NS Dev
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| posted on 25/5/05 at 11:17 AM |
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There are a number of offroad racers that lead much harder fatigue lives than a "second" road car ever will and have tubular alloy
spaceframe chassis.
An aeroplane's fuselage and airframe are not routinely replaced (don't know whether they are lifed but some 747's have been around a
long time if they are!)
I know about the MK ally chassis but as was said, that was a replica of a steel one!!!!! You have to tailor the design to suit the material, look at
an F1 car or mountain bike FFS!!!!!!!!!!!!!
Maybe thinking before answering would be good.
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flak monkey
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| posted on 25/5/05 at 11:40 AM |
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quote:
Originally posted by marc n
yep chassis defintely f27 38mm round tubular durol chassis, looks pretty impressive
think the mk one was done in inch by inch box in standard alloy
best regards
marc
Ahh, I wasnt aware of the difference between the F27 and locost chassis. It sounds as if the ali problems have been addressed and dealt with by using
the larger, stiffer tubing. It is a good buy at the price its sitting at at the moment.
The MK ali chassis wasnt meant to be used on road, and would be pretty useless as discussed before.
There are plenty of ali chassis cars (Elise for one) around. But most of them are not technically space frames (the Elise is a ladder frame) as it is
hard to get both the required strength and lightweight from an ali spaceframe, but relatively easy in a ladder frame due to the ability to use much
larger section tubing.
Any chance of some pics Marc, just out of interest more than anything.
I wasnt out to bring up the whole ali chassis debate again, as its been done to death. I was more curious than anything.
Cheers,
David
Sera
http://www.motosera.com
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JAG
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| posted on 25/5/05 at 12:20 PM |
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quote:
Maybe thinking before answering would be good
What an amazing lack of technical understanding you have
Over engineered Aluminium chassis will last a long time - but fatigue will get them in the end.
Aluminium has zero fatigue limit and will eventually fatigue no matter what the stress levels.
The 747, like all aircraft, has a recommended life and is regularly inspected for cracks and other fatigue damage.
Check your facts before spouting ill informed rubbish 
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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Staple balls
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| posted on 25/5/05 at 12:39 PM |
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JAG, do you have any accurate numbers to back up what you're saying, assuming say 6061 or 7005 T6 alu*, properly welded and treated?
and of course in various different configurations, compared with steel of many flavours.
I figure, if you want a decent fight about this crap, it may as well have some proof to it.
*picked out of the hat due to many years of mountain biking on frames made of these alloys
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NS Dev
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| posted on 25/5/05 at 12:46 PM |
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Just looking at the 6061 frame of my mountain bike that I came to work on this morning..........................better nip up the corridor and get the
dye penetrant aerosols out then!!
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flak monkey
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| posted on 25/5/05 at 12:46 PM |
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Steels between ~0.3 and 0.6% C show a fatigue limit if loading is loads are kept below a certain level. Which means cyclic loadings can go on forever
and it will never fail. Other steels do not have fatigue limits and will eventually break due to fatigue.
Most if not all ali's do not have a fatigue limit. And most will fail under much fewer cycles than steel.
(Materials courses can be handy sometimes )
You can ignore HT on most chassis as when you weld you destroy the effects of any HT on the surrounding area. Of course if you can heat treat the
whole chassis without resulting in any distortion etc, then that problem wouldnt exist.
An ali chassis designed correctly will not have too many problems. But it will more than likely fail before a steel one due to fatigue.
David
Sera
http://www.motosera.com
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Staple balls
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| posted on 25/5/05 at 12:48 PM |
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quote:
Originally posted by NS Dev
Just looking at the 6061 frame of my mountain bike that I came to work on this morning..........................better nip up the corridor and get the
dye penetrant aerosols out then!!
pfft.
i spent the best part of 18 months landing 4-12' drops on a 7005 frame (a 21" planet x compo) oddly enough, it's still going
strong.
[Edited on 25/5/05 by Staple balls]
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spunky
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| posted on 25/5/05 at 12:56 PM |
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Taking my bike on the track on Friday, should I check for stress fractures before I go.......
John
The reckless man may not live as long......
But the cautious man does not live at all.....
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Liam
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| posted on 25/5/05 at 02:57 PM |
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Well maybe you ought too!
A seriously used ally downhill frame is generally considered to have a life of only 3-5 years. Not too sure about road racing ally frames, but
i'd have thought only about 10,000 miles. But then you'd have to be a serious racer to cycle a frame to the point of failure in that time
(assuming no bad crashes). You and me could probably keep a decent ally frame for many years, or at least as long as our commitment to ride lasts!
I dirt jump on a 7005 frame and it feels bulletproof, but i'd always check it after a bad landing. My friend had a similar frame and broke a
headset bearing and the steerer tube on a bad landing without damaging the head tube/gussett at all. (But i'd still feel better with a steel or
Ti frame!)
As NS Dev says it is the design that is important. An ally aircraft fuselage can be designed to last 30+ years despite the material. Similarly for a
car chassis. The important thing is that an ally structure is stiff as any bending will fatigue the ally very fast.
As for an ally copy of a locost steel chassis - that is definately NOT stiff and will fail relatively quickly. That F27 frame seems much better but
who knows its fatigue life? Probably not even the designer.
And that's the problem with one off ally car chassis - unless the design is rigorously analysed and tested (which it mostly isn't) you
never know the date it will start falling apart around you on the road. This is NOT the case with aircraft and, to a slightly lesser extent, bike
frames.
Liam
[Edited on 25/5/05 by Liam]
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Liam
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| posted on 25/5/05 at 03:08 PM |
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Huh huh!!
Just read the add...
"One of only 3 ever made."
"Believed to be the only one left now."
Says it all!!
Liam
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mookaloid
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| posted on 25/5/05 at 03:26 PM |
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Just to say I have seen Marc's chassis and I have to say it looks very impressive. It is clearly designed with the material used in mind.
Could make a very interesting hill climb car, mmmmmmm.... now there's a thought!!
Cheers
Mark
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marc n
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| posted on 25/5/05 at 03:29 PM |
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heres one
 
Rescued attachment alloy-chassis-1.jpg
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marc n
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| posted on 25/5/05 at 03:30 PM |
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and another
 
Rescued attachment alloy-chassis-2.jpg
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marc n
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| posted on 25/5/05 at 03:31 PM |
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and another
 
Rescued attachment alloy-chassis-3.jpg
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marc n
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| posted on 25/5/05 at 03:31 PM |
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another
 
Rescued attachment alloy-chassis-4.jpg
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marc n
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| posted on 25/5/05 at 03:32 PM |
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finally
 
Rescued attachment alloy-chassis-5.jpg
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ned
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| posted on 25/5/05 at 03:39 PM |
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sure i've seen one of that design on ebay before, i remember the rear irs bulkhead plate arrangement..
Ned.
beware, I've got yellow skin
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kb58
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| posted on 25/5/05 at 03:46 PM |
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I you bend a piece of steel back and forth slightly (staying in the non-elastic mode) you can do it a really long time. Now do the same with
aluminum. The very act of bending the aluminum causes it to work-harden, to get more and more brittle, finally reaching a point where it will crack
at the welds.
And AFAIK the Elise aluminum frame is *not* welded, either bonded or riveted... as are aircraft frames. The welding is what does it in.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Liam
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| posted on 25/5/05 at 03:51 PM |
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quote:
Originally posted by mookaloid
Just to say I have seen Marc's chassis and I have to say it looks very impressive. It is clearly designed with the material used in
mind.
Yeah crikey, that's bitchin!! Nicely made. Wonder if its any lighter than a steel chassis though?
P.S. Got me a price for them brake lines yet marc? I wanna do the brakes soon.
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marc n
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| posted on 25/5/05 at 03:59 PM |
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gonna wade throught the emails tonight
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