Join Early Retirement Today
Reply
 
Thread Tools Search this Thread Display Modes
Old 07-01-2008, 09:21 AM   #21
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
 
Join Date: Sep 2005
Location: Northern IL
Posts: 18,263
Quote:
Originally Posted by jambo101 View Post
For those who might think these arent tough little cars..Smart car crash test
Look at this video that samclem and chinaco posted. You might feel differently about that.




look at about 0:55 to 1:10 for the best shot,

discussed at length in this thread - the 'brick wall' test is not the same as the 'hit another, larger vehicle' test.

-ERD50
__________________

__________________
ERD50 is offline   Reply With Quote
Join the #1 Early Retirement and Financial Independence Forum Today - It's Totally Free!

Are you planning to be financially independent as early as possible so you can live life on your own terms? Discuss successful investing strategies, asset allocation models, tax strategies and other related topics in our online forum community. Our members range from young folks just starting their journey to financial independence, military retirees and even multimillionaires. No matter where you fit in you'll find that Early-Retirement.org is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with our members, see fewer ads, upload photographs, create a retirement blog, send private messages and so much, much more!

Old 07-01-2008, 09:40 AM   #22
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
 
Join Date: May 2005
Posts: 13,259
Quote:
Originally Posted by ERD50 View Post
Look at this video that samclem and chinaco posted. You might feel differently about that.




look at about 0:55 to 1:10 for the best shot,

discussed at length in this thread - the 'brick wall' test is not the same as the 'hit another, larger vehicle' test.

-ERD50
and from what I have seen and heard on other videos... looks can be deceiving....

On a longer version of the first video... they said that more than likely nobody would have survived the 70 mph crash.... but they did reference the video you have and said that the smart punched a hole in the Mercedes before bouncing off.... the car going on its side would hinder rescue, but the passengers would more than likely have survived....
__________________

__________________
Texas Proud is online now   Reply With Quote
Old 07-01-2008, 09:43 AM   #23
Full time employment: Posting here.
jambo101's Avatar
 
Join Date: Oct 2007
Location: Montreal
Posts: 940
I guess crash results arent that relevant because i'll never buy one of these little Mickey Mouse cars.
__________________
"Second star to the right and straight on till morning"
jambo101 is offline   Reply With Quote
Old 07-01-2008, 10:09 AM   #24
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
 
Join Date: Sep 2005
Location: Northern IL
Posts: 18,263
Quote:
Originally Posted by Texas Proud View Post
and from what I have seen and heard on other videos... looks can be deceiving....

but they did reference the video you have and said that the smart punched a hole in the Mercedes before bouncing off.... the car going on its side would hinder rescue, but the passengers would more than likely have survived....
I don't know. As samclem was pointing out - the Smart Car had to come to an abrupt stop, and then got pushed backwards. I don't know how fast they were going in that video, I don't think they chopped any time between the :48 and :58 parts, so 10 seconds of acceleration? I'm assuming both cars were going the same speed, so maybe the Smart Car could get to 40mph in 10 seconds?

So the S-class slowed from X to 0 mph in Y feet, the SC went from X to 0 mph in negative Z feet. I don't think you can survive those forces. Anyone want to calculate the G-forces on a 150# occupant in the SC?

-ERD50
__________________
ERD50 is offline   Reply With Quote
Old 07-01-2008, 10:49 AM   #25
Thinks s/he gets paid by the post
 
Join Date: Jan 2008
Posts: 2,020
Assuming both cars are parallel to each other and horizontal to the earth and I remember anything from college...

v^2 = u^2 + 2as


edit: I suck at math.
__________________
Marquette is offline   Reply With Quote
Old 07-01-2008, 11:11 AM   #26
Give me a museum and I'll fill it. (Picasso)
Give me a forum ...
 
Join Date: May 2004
Posts: 11,615
Quote:
Originally Posted by ERD50 View Post
So the S-class slowed from X to 0 mph in Y feet, the SC went from X to 0 mph in negative Z feet. I don't think you can survive those forces. Anyone want to calculate the G-forces on a 150# occupant in the SC?

-ERD50
Back of the envelope computation of the collision:

Total time in contact = .08 seconds (assumes 6 feet of combined crumple space and an average velocity of 50 MPH. This is a wag, and likely conservative. If we assume both cars are going 60 MPH, then they have x number of seconds to cover the 6 feet of crumple space at a combined speed of 120 MPH. I assumed the average speed over this entire time time was just 50 MPH).

If, over that .08 seconds the Mercedes goes from 60 MPH to 0 MPH, then the deceleration forces in the Mercedes are 1100 fps^2, or 34 Gs

In the Smart car (60 MPH to -20 MPH) the deceleration forces are 1466 fps^2, or 46 Gs.

Again, just a wag. I'd love to see the instrumentation reading from the dummies in both cars.

The Smart Car benefits form the generous crumple zone provided by the Mercedes. In a Smart car, riding with your feet very close to the front bumper, hitting anything with less crumple space (truck bumper, another Smart Car, a wall) there's just no way to reduce the acceleration experienced by passengers as can be done in a larger vehicle. That intact body with the doors that open looks impressive on camera, but it's not much good if they find your head snapped off your neck and rolling on the floorboards.

[Later edit: Is see Marquette was crunching numbers, too. 6 G's sounds way too low for the occupants of either vehicle. Still, his approach assumes more distance for the Mercedes to "decellerate", which is probably Marquette's way of accounting for the rearward movement of the Smart car while the vehicle is still crunching. This is probably a more accurate model, and would significantly reduce the accleration in the Merc while also driving up the numbers in the Smart car. So, probably reduce my Gs for the Mercedes occupants by 50%, double the numbers for the Smart car.]
__________________
"Freedom begins when you tell Mrs. Grundy to go fly a kite." - R. Heinlein
samclem is offline   Reply With Quote
Old 07-01-2008, 11:24 AM   #27
Thinks s/he gets paid by the post
 
Join Date: Jan 2008
Posts: 2,020
Quote:
Originally Posted by samclem View Post
[Later edit: Is see Marquette was crunching numbers, too. 6 G's sounds way too low for the occupants of either vehicle. Still, his approach assumes more distance for the Mercedes to "decellerate", which is probably Marquette's way of accounting for the rearward movement of the Smart car while the vehicle is still crunching. This is probably a more accurate model, and would significantly reduce the accleration in the Merc while also driving up the numbers in the Smart car. So, probably reduce my Gs for the Mercedes occupants by 50%, double the numbers for the Smart car.]
I deleted my math because I think your approach is more sound.

However, I'm not sure I'm getting the same numbers.

edit: Here's my envelope... note, I wasn't adding the two speeds together as I wasn't sure if that was a correct assumption or if it was more correct to treat each car statically.

v^2 = u^2 + 2as
v=final velocity
u=initial velocity
a=acceleration
s=distance

v=0
u=26.82 m/s (60mph)
s=1.82 (6 ft)

Solve for a
a=-197 m/s2

g-force: a/9.80665 = -20 g
__________________

__________________
Marquette is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


 

 
All times are GMT -6. The time now is 12:39 PM.
 
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.