[karajorma]

Yeah but who's stupid enough to drive a carbon fibre car on the roads when everyone else is driving metal cars?

[Nuke]

to enforce the change over we could embed magnetically triggered mines in all the roads

[achtung]

to enforce the change over we could embed magnetically triggered mines in all the roads

Cars would still have an engine block.

[Roanoke]

id like to see more improvements to public transportation. the trains in the usa are a joke, so noone wants to ride on a train with technology, save from the diesel electric engines used (those came out in the 60s/70s), from the 40s. bank the curves for higher speeds, and use streamlined trains. bus systems are ridiculously overcrowded, at least all the bus systems ive used. nobody wants to ride the bus if its gonna be full all the time and if they have to wait more than 20 minutes for one.

for cars, we should be building them out of carbon fiber and running 4 cylinder engines. a carbon fiber body aside from being really light can easily be made in any hyper-streamlined shape you can think of. this gives you the ability to better streamline the cars, reducing their drag coefficients. less wind resistance and less weight means that little 4cyl engine is gonna give you the same performance of a 6cyl or better engine in a metal car. reduced mass also improves safety because less energy must be dispersed in collisions.

Carbonfibre is far too brittle and exotic to be used in road cars. Plus it add even more complication to the ridicilously complex on-board electronic systems.

[Nuke]

its not any more complected than molding fiberglass. carbon fiber is only brittle in its raw form. when laid out in varying angles its strength improves greatly. my point is go for power to weight ratio, not just power. also theres been some advancement in aluminum engines as well as ceramic ones. i dont see a problem with small light engines in small light cars. the heavyest thing in it should be the people.

[perihelion]

I think Roanoke is referring to survivability in an impact, and his point stands.  Carbon fiber composites (or whatever fiber you care to substitute) do not do nearly as well as metal at dissipating impact energy as deformation.  They do not have large plastic deformation ranges.  They bend a little bit and then fracture.  That's emphatically NOT what you want in a crumple-zone.  You want that to take a lot of deformation and dissipate kinetic energy to soften the blow to the passenger compartment.  If it just fractures, you haven't dissipated much of anything.

Having all vehicles on the road made of the same lightweight fiber-epoxy composites would help, but you still are going to be moving them at 70+ MPH and then suddenly stopping them.  The net exchange of momentum may be lower than with metal frame vehicles, but I think what would happen is you would end up with motors and passengers trying to occupy the same volume with rather messy results.

[Kosh]

Carbon Fiber? Pfffft. Transparent Aluminum FTW!!!!!!

[Nuke]

I think Roanoke is referring to survivability in an impact, and his point stands.  Carbon fiber composites (or whatever fiber you care to substitute) do not do nearly as well as metal at dissipating impact energy as deformation.  They do not have large plastic deformation ranges.  They bend a little bit and then fracture.  That's emphatically NOT what you want in a crumple-zone.  You want that to take a lot of deformation and dissipate kinetic energy to soften the blow to the passenger compartment.  If it just fractures, you haven't dissipated much of anything.

Having all vehicles on the road made of the same lightweight fiber-epoxy composites would help, but you still are going to be moving them at 70+ MPH and then suddenly stopping them.  The net exchange of momentum may be lower than with metal frame vehicles, but I think what would happen is you would end up with motors and passengers trying to occupy the same volume with rather messy results.

force = mass * velocity.

if you reduce the mass then you reduce the force. running a steel 6cyl might be rather unsafe, but an aluminum or ceramic 2 or at most 4 cylinder engine, or a tiny wankel rotory engine, and you have a car that could potentially weigh less than 500 lbs.

[Roanoke]

I think Roanoke is referring to survivability in an impact, and his point stands.  Carbon fiber composites (or whatever fiber you care to substitute) do not do nearly as well as metal at dissipating impact energy as deformation.  They do not have large plastic deformation ranges.  They bend a little bit and then fracture.  That's emphatically NOT what you want in a crumple-zone.  You want that to take a lot of deformation and dissipate kinetic energy to soften the blow to the passenger compartment.  If it just fractures, you haven't dissipated much of anything.

Having all vehicles on the road made of the same lightweight fiber-epoxy composites would help, but you still are going to be moving them at 70+ MPH and then suddenly stopping them.  The net exchange of momentum may be lower than with metal frame vehicles, but I think what would happen is you would end up with motors and passengers trying to occupy the same volume with rather messy results.

force = mass * velocity.

if you reduce the mass then you reduce the force. running a steel 6cyl might be rather unsafe, but an aluminum or ceramic 2 or at most 4 cylinder engine, or a tiny wankel rotory engine, and you have a car that could potentially weigh less than 500 lbs.

A 500lb car is never going to happen in todays markets. Cars are actually far heavier then ever. A standard mk4 Golf (previous shape, if you will) with an uremarkable 4-pot engine weighs over a 1600kg. Not sure what that translates to but when you add in all the gadgets people seem to like in cars it all adds up.
I still say CF is too exotic. Even modern plastics used in simple trim is costly to produce and even more so to dispose of. Carbonfibre, or something similar would probably become the staple in years to come, as metal overtook wood but i can't see it doing so in the next 10-15 years.
And don't get me started on all alloy engines in "normal" road cars!

[DeepSpace9er]

'smartskin' cars that absorb kinetic energy without causing damage to the internal components, and then flex right back to their natural shape.

[IceFire]

Just to be clear...an all alloy engine is different than the "all aluminum" engine in my 09 Corolla?  Just curious.

There was a news article going around the car sites about some company in Japan had a new carbon fibre process that was lightweight but cheap to produce.  Some questions about strength but I guess you could use it in non structural applications?  Apparently high quality lightweight steel is the option of choice right now...a number of new designs such as the new Mazda6 are lighter weight than their predecessors despite being larger.  Apparently anyways.  Step in the right direction.  Just need something to further increase the fuel economy...hybrid or whatever.

I was also reading that the rotary engine may make a big come back as a hydrogen engine.  Again speculation by a few people so it may not be feasible in the long run.

[Nuke]

i still think cars have too much surface area and therefore unnecessarily large drag force upon them thus robbing performance from them. look what this guy has done. theres also a book about him.

[Kosh]

I found a new report on global oil supplies, unfortunately it's all in German. Anyone know what it says?

[Roanoke]

Just to be clear...an all alloy engine is different than the "all aluminum" engine in my 09 Corolla?  Just curious.

Nope! the same.

[perihelion]

force = mass * velocity.

if you reduce the mass then you reduce the force. running a steel 6cyl might be rather unsafe, but an aluminum or ceramic 2 or at most 4 cylinder engine, or a tiny wankel rotory engine, and you have a car that could potentially weigh less than 500 lbs.

Force does NOT equal mass * velocity.  You are thinking of momentum.  Force = mass * acceleration.  And it doesn't matter a goddamn if the force exchange has been reduced by 75% if the material shear yield strength has been reduced by the same amount.  For my money, it will be reduced quite a bit more than that unless they are much further along on composite research than they were last time I checked.

Fiber composites have generated a lot of hype with their extremely strength-to-weight ratio.  They are very light for how strong they are... in a particular direction!  Fiber composites normally have their fibers woven into a pattern which maximizes tensile yield strength in one or two directions.  If you load that composite in the wrong direction, if you are loading across the fibers rather than along them, the material is only marginally stronger than the epoxy (or whatever resin is used) matrix, which is to say "not at all."

Further, as I already pointed out, fiber composites do not flex well.  They do not dissipate much energy in deformation.  They just snap.  I'll grant you my exposure to composites is mostly several years old, but I am not making this stuff up.  I ran tensile tests on carbon fiber composites as part of my lab requirement for Structure and Properties of Materials.  They are great if you load them only in tension in the direction they were designed to be loaded, but their strength is very directionally dependent.  Shear strength is a sick joke.  Guess which matters more in a car wreck?

[neoterran]

I take it a Hercules Mk II is NOT build from Carbon Fiber then ?

[Stormkeeper]

Titanium, probably. Lighter, yet stronger than steel.