We are comparing the 73-86 F250 4x4 gas truck to the 97 and up F250 4x4 truck both regular cab longbeds, what do you think your chances of survival are in these vehicles if we were to have them collide with each other.. at different speeds 40 mph 65 mph speeds like them.. who would win? would it be the crumple zones and airbags or the more solid vehicle?


Ray

heres a video of a f150 from the 70's crashing the f25o is more solid built with the leaf sprung front end

http://youtube.com/watch?v=3ReZ0C_UF-8

 

Greythorn, I don't believe you understand the dynamics of impact forces, nor do you understand what the rate of deceleration does to the human anatomy. I believe you are equating the damage to the truck (less vs. more) as correlating to the injury of the occupant. Actually because of the deceleration factor, they are inversely proportional. A rapid stop without "crumple or give" to the body structure transmits the impact forces directly to the occupant, either through the safety belt/harness or more unfortunately, through the steering column, windshield, dash panel, and header of the roof panel.

The newer body structures are designed to dissipate the impact energy as it crumples so that it is not transmitted to the occupants. The crumple zone is primarily designed from the a-pillar forward, to leave the cab intact. However, there are secondary "crumple zones" (if that's what you would like to call them) built into the interior trim and the steering column to cushion the blow. On top of that, the air bags are designed to deploy to further decelerate the body mass before it strikes a rigid object.

The key to survival is the rate of deceleration. Slower = Better. Keep in mind that without restraints that during a 30 mph impact the truck decelerates quickly (milliseconds actually, but the newer Fords with crumple zones add a few critical milliseconds as the front structure is collapsing), while anything unattached to the vehicle continues travelling at 30mph until it hits something to stop it. (Hopefully for our body it's the restraints and the airbags.) It's that impact that occurs in the interior that transmits the G-forces to the body. Then finally the rapid deceleration of the brain as it impacts the inside of the cranium that kills. Not the vehicle hitting another vehicle.

The only advice that I can give you in your 1975 Ford is to not get into a high speed accident. Secondly, make sure that anything heavy in the cab is secured, and any payload in the bed is restrained so it cannot come throught the back of the cab. And since the truck is rigid enough that it will likely survive a crash better than you will, you might want to consider who you will leave it to in your will.

Dale

 

Good notes A Farm. In a vehicle crash you have several impacts;

The truck hitting whatever
Your body hitting the inside of the truck
Your internal organs (such as brain, heart, etc) hitting your skeletal system (bones).

The newer the vehicle, the better the tend to absorb impact and energy (most do).

Seat belts and airbags also cushion and absorb.

 

Not even close. The newer vehicle is safer for the occupant. I can't add a thing to Aberdale Farm's post. Judging from his credentials, he knows what of he speaks.

 

Very well said Dale.

Tim

 

Well put Dale, I've been trying to say that in the other thread, but guess I never got my point across. Obviously you know what my vote was

 

i've never understood peoples distrust of new safety features....it just does't make sense to me.

 

I feel it centres around (and no disrespect to you here Ray) a misunderstanding about how they actually work

 

I've seen a lot of wrecks.

In older cars, there is much less damage to the car and much more damage to the people.

In newer cars, there is much more damage to the cars, and much less to the people.

Mike

 

The talk here is supposed to be about F250 vs F250 crashing into each other not into a block of cement in a lab.. Crush zone work both ways, absorbing the impact of the older ford F250 also into the newer f250 causing more damage to the newer one. keep this conisdered.. and NO cement block theory. real world theorys.

keep um comming

Ray

 

no disrespect taken, and I know how safety features work.. but how do they work in the real world against something over 30mph that is not a block of concrete and is going at a good rate of speed also.. 2 45 mph vehicles heading into one another.. would you be less dead with airbags?

Ray

 

You do stand a better chance with the air bags, the newer steering columns, safer seat belts.

One other thing here to consider, I don't know the weights of the two vehicles, but I figure they could differ as much as a ton or so between two models so differant in age.

When two objects collide head on, at the same speed and same mass, they will both come to a dead stop at the point of intersection. Now, if one is going faster, the slower one would be pushed backwards, and the faster would still have some foward velocity immediately after the crash, however, the change in velocity would be equal for both vehicles

(i.e. 1 car doin 40, hits a similiar car doing 60 head on, after the crash, the 40mph car will bedoing 10mph in reverse, and the 60mph car will be doin 10mph in its previous direction)

Now, if truck A and truck B are both doing 50 and hit head on, but truck A weighs 2 tons and truck B weighs 4 tons, then after the crash truck A is doing 16 mph in reverse and truck B is still traveling foward 16mph. What this means is that the delta V (change in velocity) is much lower for Truck B than Truck A, for truck B, this is the equivilent of hitting a wall at 34 mph, but for Truck A, it was like hitting a wall doing 66mph, which means that the damage to occupants of Truck A is MUCH worse than that of Truck B, assuming similiar safety features inside the trucks. (The numbers for weight are hypothetical, the speed after the crash is assuming no loss of energy....which is a bad assumption in a car crash, but it does illustrate the point, more realistically, the speeds would be about 10mph and -10mph and not 16...initially)

This is one of the reasons that in head on collisions, provided no roll over or rolling on top of, Trucks tend to come out better than Cars, because of their mass and momentum, they tend to win the fight and force the car backwards whereas they maintain some of the foward momentum


now with the diff. in masses, I am going to go on a limb and say that there is prolly less than a 15% diff in the weights of the two trucks? Which means that the delta Vs will only be slightly differant, and therefore the safety features in the newer truck are gonna be the most important factor even if the older truck weighs say 1/2 ton more, or maybe even 1 ton more. I give it to the newer truck hands down

 

If they have equal mass, but different absorbtion capabilitys that will make it different. its not simple as cut and dry, weight + momentum >< weight momentium, there are other factors to consider.

Ray

 

Ataullya s far as the delta V, yes, it is that cut and dry for the initial impact, There are three things that affect the initial impact, Mass, Velocity, and Direction. The normal 4th thing that affects an impact is not much of an issue on the INITIAL collision, that is frictional forces, that would determine how far the vehicles will travel after, but for the amount of energy each vehicle takes on its own, Mass and Velocity/Direction

 

Well it depends then.

You have a lot of energy to dissipate - and the majority has to go into deformation.
Say you hit an old car that is just as stiff as the old F-250, you are going to be much safer in the new F250, because it is going to deform, and increase the time elapsed of the crash.
You hit a newer car which absorbs the majority of the impact in deformation there won't be a huge difference in safety, the newer F250 will be better, but it will be marginal.

Bearing in mind, this is overlooking the things on newer vehicles like softer interiors, airbags, pre-tensioned seatbelts and all the other improvements.



So just aim for the new cars