Front engine safer than rear?
Discussion
XJ Flyer said:
As for the safe analogy you're not actually attached to the safe.In this case the safe is a few feet away acting as an armoured bulkhead which hopefully uses the opposing car as it's crumple zone.
How is this safe held a few feet away? Via a crumple zone (in which case the crumple zone hasn't been totally consumed?) or via rigid links (in which case the few feet makes absolutely no difference)Edited by XJ Flyer on Wednesday 27th August 22:11
Finlandia said:
XJ Flyer said:
scenario8 said:
I promise you "most people" wouldn't have a clue what most of that post meant at all.
Possibly.They would probably also be the same people who think that a small shopping hatch would survive a square on head on collision with a big old school Volvo.In exactly the same way as it would in an offset head on collision with same. XJ Flyer said:
Finlandia said:
XJ Flyer said:
scenario8 said:
I promise you "most people" wouldn't have a clue what most of that post meant at all.
Possibly.They would probably also be the same people who think that a small shopping hatch would survive a square on head on collision with a big old school Volvo.In exactly the same way as it would in an offset head on collision with same. Would you mind explaining the 1962 Caddy vs the 2002 Caddy, in a straight head on? Link posted a page back.
XJ Flyer said:
Not assuming the driver of the longitudinal engined car knows the weakness and does everything possible to turn an offset collision into a square on one.While in the case of a rear engined car there obviously won't be that choice/chance.
jesus, who the hell do you have traffic collisions with?In any case, unless you've ever seen a rear engine come loose or crumple the passenger cell in front of it in a front impact - then the energy involved in stopping it went through the same parts of the car anyway.
paranoid airbag said:
XJ Flyer said:
Not assuming the driver of the longitudinal engined car knows the weakness and does everything possible to turn an offset collision into a square on one.While in the case of a rear engined car there obviously won't be that choice/chance.
jesus, who the hell do you have traffic collisions with?Finlandia said:
Racing is a totally different story and has nothing to do with road cars.
Would you mind explaining the 1962 Caddy vs the 2002 Caddy, in a straight head on? Link posted a page back.
In the case of the old Caddy it seems obvious that the square head on format produced better results penetration wise than offset.However it seems obvious that the newer Caddy's ability to resist deformation and penetration of it's bulkhead area outweighed the ability of the older Caddy to crumple.Hence the older Caddy lost on energy transfer to occupants.Would you mind explaining the 1962 Caddy vs the 2002 Caddy, in a straight head on? Link posted a page back.
As for Bangers that isn't exactly racing it's more about destroying road cars by colliding them.Somehow I don't think there will be many people mixing it with these with a modern shopping trolley let alone a late model 911.But the option is there for anyone who'd want to try.
www.youtube.com/watch?v=XUOLfLQjsoU
Banger racing is the complete opposite of what you want in a road crash. In a road crash you want the car to absorb the impact of a high energy collision through a one off deformation to protect the occupants. In banger racing you want minimum damage to the car over a large number of low energy collisions, at the expense of the driver seeing higher g levels
Mave said:
Banger racing is the complete opposite of what you want in a road crash. In a road crash you want the car to absorb the impact of a high energy collision through a one off deformation to protect the occupants. In banger racing you want minimum damage to the car over a large number of low energy collisions, at the expense of the driver seeing higher g levels
The important point being that those arguable higher G's are survivable.While those supposedly 'low energy collisions' aren't as low energy as they might seem.As I said 'if' it's all about ability to crumple,as opposed to the combination of the ability crumple and to penetrate and the ability to withstand penetration.Then there'd obviously be no problem with putting a few modern shopping trollies,let alone a 911,up against a few Westminsters on the banger track.
XJ Flyer said:
The important point being that those arguable higher G's are survivable.While those supposedly 'low energy collisions' aren't as low energy as they might seem.
Well 2 cars head on at 50mph have 8 times the energy of one car at 25mph hitting a near stationary car so no, I don't think those banger crashes are particularly high energy. Put 2 of those bangers together head to head at 50mph and those g levels which are survivable on the track quickly become unsurvivable at road speedsMave said:
XJ Flyer said:
Mave said:
XJ Flyer said:
Although it is obvious that having as much metal as possible out front in addition can only help.
Not really, you want the crumple job to do it's job, not have a big stiff lump of metal keeping the peak deceleration high...XJ Flyer said:
Hence the rigged Volvo v shopping trolley stunt in which no surprise that's exactly what happened in the case of the unfortunate Volvo when he offset pitted the Volvo's front wing and bulkhead/A post structure against the combined strength of the transverse engine and bulkhead structure of the shopping car.Which had it been a square on hit involving the same combination in the case of the Volvo most likely would have had a very different outcome.
Why are you saying the test was rigged? Surely an offset collision is far more common than a square head on?In WW2 fighter pilots were generally pleased to have circa 2.4 m long engines, and bullet proof windscreens in `front' of them.
At the end of the day it probably doesn't matter, where a car has its engine in a serious crash, its still going to hurt.
Cars can produce the `illusion' that they are rock solid, tough, and safe, but in a `proper' crash, they should really be regarded as being made of tin foil.
Many years ago my Dad had a head on crash with a drunk driver who had fallen asleep at the wheel and drifted over to my Dads side of the road. The gear lever in my Dads car was found protruding from
from the middle of the rear seat. The engine and transmission had moved back through the car, but my Dad got out of the crash reasonably unscathed, with just a few cuts and bruises. The engine and transmission passed between the front seats, so the only person who might really have suffered had they been in the car would have been someone sitting in the middle of the rear seat.
The Traffic police who investigated the crash did say that if the gearbox tailshaft had got any further back it may have penetrated the fuel tank, and started a fire, as my dad (eventually) had to be cut out of the car. that could have resulted in a whole different outcome
from the middle of the rear seat. The engine and transmission had moved back through the car, but my Dad got out of the crash reasonably unscathed, with just a few cuts and bruises. The engine and transmission passed between the front seats, so the only person who might really have suffered had they been in the car would have been someone sitting in the middle of the rear seat.
The Traffic police who investigated the crash did say that if the gearbox tailshaft had got any further back it may have penetrated the fuel tank, and started a fire, as my dad (eventually) had to be cut out of the car. that could have resulted in a whole different outcome
I guess the problem with these sorts of debate is that it's easy enough to come up with a scenario in which any one of the configurations is best, and hard to find information on the frequency of different tyres of accident to the degree of accuracy required to know which category it would fall into. I seem to remember reading somewhere that a huge proportion of fatal accidents are small (<10%) offset collisions in which the engine location probably wont make any difference at all.
This is why I've always been rather dubious of things like NCAP which simply run a single or small number of collision types - it's too easy to engineer the cars to pass the test rather than to actually perform well in a variety of situations.
This is why I've always been rather dubious of things like NCAP which simply run a single or small number of collision types - it's too easy to engineer the cars to pass the test rather than to actually perform well in a variety of situations.
Pan Pan said:
Probably just a gut reaction to the question, but to use an analogy, if I was at a fort about to be attacked by the Indians, would I prefer to have a big heavy wall in front of me, or behind me?
A more accurate question would be whether you'd rather have a big wall in front of you AND one behind you, or two in front of you. 
DonkeyApple said:
Pan Pan said:
Probably just a gut reaction to the question, but to use an analogy, if I was at a fort about to be attacked by the Indians, would I prefer to have a big heavy wall in front of me, or behind me?
Depends. Are there any French about?
As noted before in a `proper' crash it will largely be a matter of luck regardless of where the engine is, if the occupants of a car survive.
In a `proper' crash the bodies of most cars, even advanced highly sophisticated ones, might just as well be regarded as being made out of tin foil.
Weight certainly does have an influence, which is why F1 cars, and even racing Caterhams seem to fare reasonably well in major crashes. because there is far less energy to disperse.
I saw a huge Caterham crash at Castle Combe some years back, where the car tumbled end over end, heaven knows how many times before it finally hit an earth bank at speed. The driver got out and walked away from it.
In a `proper' crash the bodies of most cars, even advanced highly sophisticated ones, might just as well be regarded as being made out of tin foil.
Weight certainly does have an influence, which is why F1 cars, and even racing Caterhams seem to fare reasonably well in major crashes. because there is far less energy to disperse.
I saw a huge Caterham crash at Castle Combe some years back, where the car tumbled end over end, heaven knows how many times before it finally hit an earth bank at speed. The driver got out and walked away from it.
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