Car safety and NCAP ratings improvements!

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bobins
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Re: Car safety and NCAP ratings improvements!

Post by bobins »

Mandrake wrote:
It seems that side pole intrusion is really hard to get right, and that the battery pack structure in the floor in the Tesla reinforces the body against side impacts like nothing else...putting all that extra structure in the floor in an ICE car would just be dead weight that couldn't be justified, but in a battery powered car that requires that structure to protect the battery better side impact results is a very nice "free" benefit!
It must be really tricky to get the whole thing right ! You want deformation of the car to help absorb the forces involved in the crash, but you want that deformation to stop just before it knocks points off your NCAP rating.
Fifth Gear (TV motoring program) illustrated the point quite nicely a few years ago. They set up (along with European counterparts) a test where they drove (I think) a Smart car at about 70mph obliquely into some Armco barrier. The passenger compartment survived brilliantly as the car effectively bounced off the barrier due to its low mass - the problem was that the occupants could never have survived that impact due to the deceleration and deflection forces involved.

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Mandrake
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Re: Car safety and NCAP ratings improvements!

Post by Mandrake »

bobins wrote: It must be really tricky to get the whole thing right ! You want deformation of the car to help absorb the forces involved in the crash, but you want that deformation to stop just before it knocks points off your NCAP rating.
You want deformation but you don't want significant intrusion into the passenger cabin that is going to crush or dismember you. In frontal and rear impacts this is "easy" - make the passenger cabin very strong and make the ends crumple zones to absorb the impact. All current cars that get good NCAP ratings probably have this solved now, and its even easier on an electric car because the mass and strength can be centred in the middle of the car with no big heavy objects near the ends, thus good crumple zones at the extremities.

Not so easy on side impacts (especially a pole) though because there isn't really much of a crumple zone available - there is only a door width between you and the impact. I would argue that the Volvo above goes too far in the "impact absorbing" direction though as there is major intrusion into the passenger compartment, yes the deceleration is probably less but at what cost if you arm is crushed inside a crumpled up door or your neck is sliced open by a crumpled up B pillar/roof. To deal with deceleration you can use airbags of course.

In the Tesla example there is hardly any intrusion into the passenger compartment and an extensive array of airbags dropping down from the ceiling right along the side of the car which presumably helps with the deceleration issue. It must work as it got a 5 star rating for side impact surviveability too.

In fact it was the first car to ever get 5/5 in every category (not just 5/5 overall) in the US National Highway Safety Administration crash testing.

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bobins
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Re: Car safety and NCAP ratings improvements!

Post by bobins »

I've just been looking into what makes up an NCAP test - quite an interesting read !!!
The 'protocols' section is a good place to start : http://www.euroncap.com/en/for-engineers/protocols/
...and the 'Adult Occupation Protection' protocol is quite illuminating : http://euroncap.blob.core.windows.net/m ... p-v703.pdf

To put the 'Pole Impact' test into perspective, the various testing criteria involve......
Measuring the acceleration to the crash test dummy's (CTD) head, making sure there is no CTD head / pole direct contact, measuring the CTD lateral chest compression during impact, measuring the CTD abdomen lateral compression during impact, measuring the forces on the CTD pelvis during impact, measuring lateral forces on the CTD shoulder during the test, measuring how the side (head) airbags deploy, what area they cover, how they're constructed, whether doors open during the impact, and whether the unstruck doors can be opened after impact.

It's just a simple matter of getting that lot right and you can pass that test with flying colours !! :shock:

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Re: Car safety and NCAP ratings improvements!

Post by Mandrake »

Here's a real eye opener that dispels the myth that classic cars were built more solidly than modern (well, 90's) cars:



Those old fashioned vertical A pillars really don't stand up to crash testing do they... :shock:

I wonder how well something like a GS or CX would stand up to modern NCAP testing or whether it too would be obliterated by a modern car ??

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Re: Car safety and NCAP ratings improvements!

Post by Mandrake »

Can't find a 40% overlap test for a GS but did find a full frontal solid wall impact where it seems to do better than I would have expected - but no idea what speed it was tested at!



Funnily enough the only car I have ever had a crash in was in my 1977 GS - a head on frontal crash with another car with probably 60% overlap which I got out of and walked away from uninjured apart from a bit of shock and some minor whiplash. I think the speed I hit at must have been below 30mph by the time I had braked, although I was doing over 50mph before seeing the impending collision and braking. It folded all the front bumper and under tray around the engine and bent the front left wing all out of shape. It also pushed the front suspension chassis back on the mounting point on the left hand side by about an inch where they bolt together.

The engine was undamaged (still started and ran fine) as was the front suspension sub chassis itself and suspension arms, track rods etc ! =D> (it only moved the chassis relative to the body mounting point) A new front bumper and under tray, some panel beating of the front left wing, a new headlight and re-adjusting the position of the suspension sub chassis and it was back on the road again!

In fact I actually drove it home just after the crash after just bending the front wing so that it didn't drag on the tyre, with proper repairs being made later...
Last edited by Mandrake on 06 Feb 2017, 17:54, edited 7 times in total.

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CitroJim
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Re: Car safety and NCAP ratings improvements!

Post by CitroJim »

Mandrake wrote:Here's a real eye opener that dispels the myth that classic cars were built more solidly than modern (well, 90's) cars
Never a myth Simon, it was well known that old 'classics used to crumple up like paper bags... They had all the structural integrity of a biscuit tin and often compromised by rust...

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Re: Car safety and NCAP ratings improvements!

Post by mickeymoon »

Even older Saabs and Volvos wetentt particularly safe - sure, they were safer than a lot of cars about in their time, but they'd score a nice round zero on an NCAP test.

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Re: Car safety and NCAP ratings improvements!

Post by red_dwarfers »

There was a guy who posted a few photos of his GS on the G Section Facebook page just after he was rear ended in a queue of traffic a couple of months ago. I can't find the photos to link to them. I'm not sure of speed but although he walked away there was some definite crumpling of the boot and bonnet.

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Mandrake
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Re: Car safety and NCAP ratings improvements!

Post by Mandrake »

Crumpling of the boot and bonnet is exactly what you want, if it protects the passenger compartment.

I've sometimes wondered whether the massive independent front suspension subchassis in the GS (and CX) helps or hinders crash safety and likewise whether having a steel rimmed spare wheel under the bonnet helps or hinders!

Anyone know ?

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Re: Car safety and NCAP ratings improvements!

Post by RichardW »

There's no doubt modern cars have reduced deaths and injuries, and in surveys many people put safety at the top of their list for cars. However, the no 1 thing you can do to improve safety is not crash it, and this starts with improving your driving - and yet few of the people who put safety at the top of their list are prepared to spend a few quid and hours of their time improving their driving??

Ref the GS - the only test in the 70's was a direct frontal - and cars were built with strong battering rams in the front chassis to pass this. What it did to the occupants as the car decellerated is another matter! I remember watching a TV prog about car safety in the US, and one of the guys how started pushing for better crash protection said he realised something had to be done when the number of people killed in a year in the US exceed the total number of US deaths in the Vietnam war....

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CitroJim
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Re: Car safety and NCAP ratings improvements!

Post by CitroJim »

RichardW wrote:However, the no 1 thing you can do to improve safety is not crash it, and this starts with improving your driving - and yet few of the people who put safety at the top of their list are prepared to spend a few quid and hours of their time improving their driving??
I completely agree with that Richard...