[s-cars] Teen cars

Wed Dec 9 11:40:19 PST 2009

Structural strength does not of course mean safer - years ago Mercedes cars
were famous for having dead occupants and perfectly working the doors.
Structural strength coupled with deformable zones = safety.  Manage the
decel.

It's been a while since I perused the SCCA GCR, but when last seen the cage
could be mild steel but the roll hoop needed to be chrome moly.  The tricky
part of using 4130 is that the high carbon content requires an extra
annealing step to prevent brittleness in the welds.

PJM

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of Taka Mizutani
Sent: Wednesday, December 09, 2009 1:05 PM
To: LL - NY
Cc: erikaddy at yahoo.com; s-car-list at audifans.com
Subject: Re: [s-cars] Teen cars

I think you're trivializing the advances in automotive design and research
over time- we did not have as much crash data 30 yrs. ago as we do now-
black boxes in cars among other things have helped engineers understand
real-world crashes a lot better than before. There were no such devices back
then.

Actual structural strength has increased- I don't know where you're getting
your info, but structural rigidity of cars has increased tremendously- that
may be from optimization of strength/weight ratios, but nevertheless, cars
are a lot stronger now than they were in the past.

Also, the computing power of 30 yrs. ago vs. now is a joke- my cell phone
has far more computing power than probably any computer built 30 yrs. ago.

Automotive engineers understand better what is needed to protect the
occupants now than they ever did in the past. Advances in crash test
dummies, testing of a much greater range of size/weight/shapes of dummies,
etc. has helped.

My point still being that no car of 30 years ago can provide the type of
crash protection and survivability of a current automobile. Don't compare
apples to oranges- race cars now are much, much safer than they were 30
years ago. None of the Group B rally cars would pass tech for WRC today- the
rollcage and impact protection standards are much more stringent now. BTW,
SCCA does allow 4130 cromoly steel for roll cages, not just mild steel.

Taka

On Wed, Dec 9, 2009 at 12:10 PM, LL - NY <larrycleung at gmail.com> wrote:

> It's action/reaction. Since the earth cannot hit the car any harder than
> car can hit the earth going at the same rate, the effect is that the
barrier
> acts like the car is hitting something of equal mass to itself. Due to the
> relatively small force on the earth, it essentially does not accelerate.
An
> Escalade would. Backwards, but not by much. An equal mass car would
> accelerate backward at a greater rate than the Escalade.
>
> That was the concept of that allowed the barrier crash to be practical,
the
> car would only be compared to hitting something of the same mass, which
> allows for a uniform, within class tests. Makes things much simpler for
the
> tester, no multiple crashes nor methods of applying those crashes to get a
> relative idea of vehicle crash performance. Newton's 3rd law is one of the
> more difficult concepts to grasp, so perhaps the NHTSA site can help with
a
> better explanation that I can do at the moment.
>
> And, in terms of engineering, new materials, modelling methods, etc, what
> those techniques have done has allowed better *optimization* of material
> for a given strength, not the actual strength of the structures
themselves.
> It is entirely possible to emulate the boron steel crash structure of the
> modern car (think standard racing roll cages, which for at least the SCCA
> MUST be made of mild steel) at the expense of typically weight. FEA
existed
> when I was in college, and I learned the fundamentals of it, and that was
> just shy of 30 years ago. It had been used primarily in the aircraft
> industry for years already (where materials optimization was much more
> important than in cars, although it's obviously trickling down due to
> economy/emissions concerns). The greatest change in terms of engineering *
> capability* (as opposed to actual application) I've seen in automobile
> safety, really does lie in the interior safety devices, (airbags, interior
> impact design, anti-submarine devices), as the space frame concept has
> existed for quite awhile. Whether or not it was profitable enough for
> manufacturers at the time to do the "safety thing". From marketing
> literature at the time, I do know that Saab actually was applying aircraft
> engineering principles in their perimeter frame, which I do know from
> personal experience existed in their cars frames from the 99 series up to
> GM.  As for the UrS, I don't personally know, so I will accept that I *
> could* be entirely wrong on the Mini/UrS point. However, if one had to
> rely on empirical evidence alone, then the only way we could be sure is to
> test every car on car combination. What the video did state was that their
> results should result in a re-examination of the mass/mass concept being
the
> primary factor as a matter of principle for multi-vehicle crashes (it
still
> matters not in single vehicle crashes), it didn't state that this was a
> total principle to apply in all cases. Sure, a well designed smaller
vehicle
> can "win" vs an older heavier vehicle. But, what if (again, I don't think
we
> can fairly say all) the heavier vehicle had a better design (I don't
recall
> 740's ever being exceptional in this area, from my recollections of CU
> magazine, even all Volvo's aren't necessarily equal) which is entirely
> possible. If we had to do it empirically, we'd have to crash every one.
>
> LL - NY
>
>
> On Wed, Dec 9, 2009 at 11:33 AM, Taka Mizutani <t44tqtro at gmail.com> wrote:
>
>> Again, you're wrong- offset crash tests into a concrete mass are
>> effectively infinite mass, far more than an Escalade. How do you explain
>> that one?
>>
>> Also, how do you figure that the engineering in a 30+ year old design is
>> better than 30 years later? There was no FEA or other computer modeling
back
>> then, steel alloys were not as advanced and safety systems were not as
>> advanced. Comparing an old car to a new one and saying the old car is
safer
>> is simply foolish.
>>
>> I will not discuss how a Saab 99 will do against an Audi Coupe GT, that's
>> not what the original discussion was about.
>>
>> Taka
>>
>>
>>
>> On Wed, Dec 9, 2009 at 10:37 AM, LL - NY <larrycleung at gmail.com> wrote:
>>
>>> One thing not being taken into account (boron steel, non-withstanding)
is
>>> design. Saab used a similar, for the lack of a better term, perimeter
>>> frame
>>> on the 99/900 series. It's a rather complicated section tubular frame
>>> that
>>> surrounds the sides of the passenger compartment, very similar to what
>>> the
>>> Impreza "perimeter frame (which is the boron steel section), but it's of
>>> rather heavy section tubing on the Saab (I was able to inspect it when
>>> doing
>>> body work on the car). WHAT boron steel (and other higher tech
materials)
>>> allows for is to make the perimeter frame considerably lighter than the
>>> likely heavier similar design/construction framework on the Subaru. As I
>>> recall, the failings of the Saab 99 series (up until about '78, when
they
>>> finally installed a proper collapsing steering column) was in frontal
>>> barrier crashes, where Saab's attempt to "hinge away" the steering
column
>>> didn't quite work in barrier tests. Seemed to work better in more "real
>>> world" situations.  My point is side penetration of the 99/900 would be
>>> MUCH
>>> better than a CGT or 4K, from my estimations, as a former mechanical
>>> engineer, and I think passenger compartment *integrity* would be
>>> reasonably
>>> contemporary. *Survivability*, without the impact mediators such as side
>>> airbags and curtain airbags, as with any vehicle without them, would be
>>> less
>>> than contemporary, however, as our bodies would still flop around
>>> (greatest
>>> issue, head and neck injuries) inside the mostly intact passenger cell.
>>> Hell, that's even an issue with the UrS, (mAC) however, in
>>> vehicle/vehicle
>>> crashes, mass will always win, which is why Mini still looses (no matter
>>> how
>>> well it does in single car crashes) when it takes on a 'Sclade. Still,
>>> the
>>> slicability of the CGT/4K (and it's corresponding lightweight, I think
>>> they,
>>> even in quattro form, are outweighed by a Mini) pretty well regulates it
>>> to
>>> be comparatively less safe in terms of crashability, assuming an
accident
>>> can't be avoided.
>>>
>>> LL - NY
>>>
>>> On Wed, Dec 9, 2009 at 10:07 AM, erikaddy at yahoo.com <erikaddy at yahoo.com
>>> >wrote:
>>>
>>> > Not a leap at all.  The construction in a mini will destroy the late
>>> 70s
>>> > tech in the cgt (or any other car from that era).
>>> >
>>> > I wasn't suggesting a mini for a teen, I just used that for
>>> illustration as
>>> > it is a small car available in the US.  You were mentioning the
>>> construction
>>> > of the cgt in terms of safety and I'm saying almost any 2000+ car
makes
>>> a
>>> > cgt look like a death trap.
>>> >
>>> > Erik Addy
>>>
>>
>>
>
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