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How safe will the 4C be compared to other modern cars?

3K views 25 replies 16 participants last post by  badgers_nadgers 
#1 ·
With such light weight, and the lack of side airbags that other modern cars normally gets, how safe will the 4C be in the event of a collision when compared to it's competitors, like the Cayman?

Anyone care to speculate?
 
#6 · (Edited)
Forget its lightness for a moment. It's a much, much stronger material than steel or aluminium. If you've seen the nose cone of a formula 1 car in a head on impact it's resistance is almost beyond scientific belief. The very nature of the material, that you can add layers in areas where extra strength is needed and lay the weave in opposite directions makes it very, very versatile, if not a tad expensive to buy and produce.
 
#14 · (Edited)
Rigid is good for the saftey cell. The 4C's front and rear crumple zones are aluminium subframes. Also, carbon fibre is very good at absorbing vibration and impacts which is why it's used in high-end road and mountain bike frames and forks.

However, I believe that its main weakness is that it doesn't really show signs when it's about to fail unlike say an alloy chassis that would show cracks. I think an x-ray has to be used, but I'm not 100% on this.
 
G
#10 ·
That's why the front & rear structures will incorporate crash structures, they'll dissipate the energy away from the tub.

On the subject of carbon tubs, the first McLaren F1 was apparently driven away after its crash test the chassis was that strong.
 
#15 ·
It is about absorbing the energy of the collision (into shattering the plastic bodywork and deforming aluminium frames at front and rear), while holding the passengers so they do not strike any surfaces, and preventing any hard or sharp things intruding into the passenger compartment.

Did you see the episode of Richard Hammond's Wonders of Nature where he through a light bulb from the edge of space down onto a rocky mountain? The bulb was held tight in a rigid tube, surrounded by soft beads, inside another rigid tube. The outer cracked, the inner shifted, but the contents were intact when they found them, days later...

That is how cars are designed. Stiff outer, soft layers, hard and tight inners.

The factor they are all trying to manage is the 'deceleration', by spreading the impact over a few more milliseconds, the forces on the occupants are reduced massively. You can have a bit of fun plugging numbers into this model: Car Crash Example

Then their is the lightness issue: if you are in a lighter car, you have less energy to deal with (if you hit a solid object), or are more likely to rebound (if struck). That helps spread the energy dissipation over time as well.

Which leaves us with the immense strength of carbon fibre shells.

The simple comparison between carbon fiber, steel and aluminum can be understood using common forms of the high-strength versions of these materials.

Compare the mechanical properties, the modulus of elasticity (stiffness) and the tensile strength (strength under tension) of these three materials:

1. Carbon fiber T700S from Toray, a standard modulus high-strength fiber, in an epoxy 250 F-cure composite
2. Alloy steel AISI 5130, a low hardenability alloy steel with moderate strength and good toughness
3. Aluminum alloy 7075-T6, a standard aerospace aluminum alloy

Modulus of Elasticity Tensile Strength Density
MPa MPa g/cm^3
CF 120 2500 1.5
Steel 205 1275 7.9
Alu 71 570 2.8

So, CF, even at its current development stage, hugely outperforms aluminium and steel and is lighter, but is possibly *too* stiff for some designed to collapse structures.
 
#17 ·
I have a 3mm's thick piece of carbon fibre as an adjuster for my alternator , since the steel one cracked --- not on my road car though. It's slotted for the adjustment clamp and the holes each end are clamped using penny washers and so far it's not been a problem.
 
#18 ·
There is a myth that carbon fibre is fragile and prone to cracking and splitting.

Anecdotes that this is not so come from my road and mountain bikes are both carbon. I'm 210lbs, so they take a major beating when used. The only parts that have failed were aluminium. My record player tone arm is carbon fibre. My walking poles (ultradistance & mountain walker) are carbon fibre). My pocket knife (leatherman skeletool) has carbon fibre parts. I trust carbon fibre.
 
#23 ·
the likelihood is that the Q& ('lard shed on wheels') will either flip on its roof under heavy braking or snap off the road and hit a solid object. The sad truth for the roadtards who buy SUV's because they are "safer" is that they are not: they are MORE likely to have accidents, MORE likely to kill the occupants, MORE likely to kill pedestrians, and MORE likely to kill other drivers. They take about 50% longer to stop, so, when their massive bulk causes them to slide off a wet bend, they hit walls, houses and trees far harder than the 4C ever will.

And, given the agility of a 4C, it should be quite easy to avoid the shed driving roadtards
 
#26 ·
I'm not sure I'd be considering the safety features if I were in the market for a 4C, not that I ever really consider safety as a feature of any car.

If I were concerned about safety, I wouldn't consider any sort of roadster or convertible.
 
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