rec.autos.simulators

I remember after the Earnhardt accident I think it was you mentioning a
buddy who ran some numbers and said the actual accident energy was similar
to a 30 mph head on crash.  I was just wondering due to hearing it was
mentioned in RPM Tonight it was like a 75 mph to 0 head on crash when you
worked the numbers and removed the angle.  Just kinda wondering if that
seemed true. Nascar was reporting his car was going between 156 mph and 161
when he made contact with the wall and I thought I heard like a 22 degree
angle into the wall.

I did notice something also on the tape.  He never lifed period end of story
and well had to have been killed at impact since the car was getting
wheelspin from the rear tires all the way along the wall. Not smoke from a
sliding tire, but smoke being pushed out the rear of the car from wheel
spin.

--
David Robinson

If autocrossing was easier it would be called road racing.

I know, I'm not Doug Milliken but I thought I'd clear up the 75MPH thing

   My mother was rearended while at a dead stop by an 80 year old couple going
about 60 mph.  The couple planted there faces into the windshield, but walked
away.  So did my mother (she ran back to help them, although her neck still
bothers her today, 15 years later.)  It sure didn't look like Dale hit the wall
very hard, but snapping a seatbelt and hitting the wrong thing in the car the
wrong way can kill you, even at 25mph.  I believe that had the seatbelt not
snapped, he'd have walked away.  

  You could be going 300 mph and hit a wall and survive...  If you hit it at an
angle.  The speed directly towards or away from the wall is what counts.  To be
specific:

 Sine(angle of impact) * speed = impact speed

  The impact speed is what does damage.  At 1 degree angle, at 300 mph, you'd
only impact the wall as though you were going 5 mph straight on.  Also, it's
important to note that the direction his car was travelling when it hit the
wall is what to base a calculation on, not the direction it was facing.  

  I know I wasn't asked, but imo, he'd have lived had the seatbelt not broken.
That 80 year old couple walked away from a seatbeltless impact that was
effectively only 10-20 mph slower with nothing but ***ied noses.  The didn't
even know they hit the windshield.  Had their heads impacted something harder
than the windshield (their face prints were visible), they probably would have
died.  With a helmet and a full racing harness, they'd have been jolted hard,
but would have been just fine.

Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://www.racesimcentral.net/

  I didn't notice that, but at such an angle I doubt he would have sped up from
160 mph to anything much higher in such a short time.  I doubt that would have
changed things.
Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://PerformanceSimulations.Com

I am sorry but I think the belt thing as not a contributing factor to his
death.  The seperation of the spine from the brain really is what did him
in.  That would have happened with or without the belt breakage. Without the
belt breakage he would have been held more firmly in his torso, thus its
deceleration being more rapid then it was.

Well will never know for several reasons. I did not hear any quoted loads on
making the belt Dump as they call it, and there is no way to accurately
recreate the iccident to determine the actaully loads and directions of
those loads.

Dave

Dave

  Oh, ok.  >I am not saying he speed up I am saying from the moment he
contacted the

  Oh, ok.  That's odd.  
Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://PerformanceSimulations.Com

  To me, that's sort of like saying, "falling off the ladder didn't hurt, it
was hitting the ground that broke my leg" :-)  Not trying to make light of the
investigation or Dale's death, but it seems tough for me to believe a broken
seatbelt was "not a contributing factor to his death".  Of course, I wasn't
there and don't have any special info that wasn't in the news or anything...

  > That would have happened with or without the belt breakage. Without the

  I disagree.  Would you rather get stopped by a racing harness that's designed
to "give a little" (stretch) and distribute the load more evenly over a larger
area of your torso, or fly directly into a hard, immovable steering wheel,
possibly head first at who knows what angle?  Didn't somebody on this newsgroup
awhile back take a ride in one of these cars in the "Petty Driving Experience"
or something similar?  I recall the person being shocked at how low you sit in
the cars, right infront of the steering wheel.  He/she said that one driver
actually raced by looking "through" the wheel.  If this is the case, it seems
likely that in an impact with no seatbelt, the driver would be brought to rest
by the steering wheel alone, and probably hit it with your upper torso and
head.  I believe a racing harness will stop you more gently than a direct
impact with a rigid steering wheel or other***pit piece, wouldn't you agree?

  As I mentioned before, if the effective impact speed was what you (or
whomever) quoted (75 mph into a parked car?), the crash might have been
perfectly survivable with a racing harness.  We've all seen harder hits than
this one on TV, haven't we?  The driver usually shakes it off and walks away.
I still think of the 80 year couple that rearended my mother at a similar
effective speed (maybe 10-15mph slower).  They had no seatbelts and required no
hospitalization.  It's important to note, however, that they were stopped
mainly by the windshield and upper dashboard.  The 80 year old driver didn't
hit the steering wheel with his head or neck.  Surely that could have caused a
spine/brain seperation?  With a seatbelt, his head would never hit anything,
but would be brought to rest relatively gently with some whiplash (in
comparison with slamming into a steering wheel or windshield).  He was lucky,
as it didn't hit anything anyway (except the windshield, which had both of
their face prints.)

  Perhaps a possible impact with the steering wheel is what caused the bent
wheel in Dale's car someone else talked about recently?

 >Well will never know for several reasons. I did not hear any quoted loads on

  Maybe so, although I think a lot could still be determined from the video.
Anyway, I don't know many details of the crash, so my mind can still be
changed.

Todd Wasson
---
Performance Simulations
Drag Racing and Top Speed Prediction
Software
http://www.racesimcentral.net/

I never got the post with the original question (poor newsfeed the last few
weeks).

My friend was working from broadcast video with all the problems
associated with NTSC.  I'd go with any analysis that NASCAR had done,
they would have access to the original video (better quality)
as well as data on the actual location of the camersa(s) relative
to the track, etc.

-- Doug Milliken
   Milliken Research Associates Inc.

Sorry for delayed reaction...just got this tonight<sigh>

Actually, these days a lot of accidents are re-created.  There are even
companies that specialize in "accident reconstruction", they use
engineering simulation (not simulaTORS) and also do staged crash tests.
Most of this work is done in connection with accident litigation (court
cases).  I visited one place that specialized in motorcycle crashes and
they had a "cart" that they could use to position a motorcycle accurately
in mid-air, at any angle, then they did a staged crash into an appropriate
object, with high speed cameras running (to show the jury a slo-mo replay).

I hear that the full accident report can be downloaded from NASCAR.com.  A
friend took a look (I haven't yet) and said there were plenty of
interesting things there to study.  I'm guessing that the press summaries
leave a lot out, and some probably add their own 'spin'??

-- Doug Milliken