GT40 Crash Test 1967

[buddaben]

Recieved the following correspondance & Picture from an ex-Fird engineer I mat at a car show in Oklahoma.

Ben Miller,

As I promised you at the car show in OK. here is the photo of a early GT-40 we crashed into a fixed barrier at the Ford Dearborn Test Track in 1967. We conducted this test after we installed a roll cage to see if we couldn̓t help the driver when an accident occurs. We hit the barrier at 41 mph and the spray you see over the vehicle represents fuel, (gas), we use Stoddard Solvent as it very close in weight to fuel but has a very high flash point. As you can see the front tires crush the rockers panels, housing the fuel cells, causing the fuel cells to be pressurized. The fuel is then forced up the filler necks and blows the fuel caps. In our crash the front sheet metel is forced back over thç fuel caps directing the fuel over the vehicle. We didn̓t have a fire as the engine was not re4uired to run in our test. We found the vehicle to be quite sturdy and but the crash dummy was in fact hurt. There is a accompaning letter about a friend of mine that was a special test driver at the time you might fmd interesting.

You have a real collectors car and you should be very proud of it, I enjoyed talking with you and maybe someday we will meet again.

Regards

Bill Holbrook

06/11/2004

[Steve Toner]

That's only 41MPH???

[Mark Worthington]

Note to self: don't drive a GT40 into a solid object at any appreciable speed.

WHile that looks pretty bad, remember that most of the damage appears to be to the extreme front of the vehicle, and GT40s have lots of front overhang and not much chassis strength up there. The thing in that image that worries me is the atomized fuel all over the place.

[MBelcher]

The picture of the GT 40 crash test is pretty dramatic. Keep in mind, however, that this is roughly the equivalent of an 80 mph impact into a stationary vehicle of equal weight. The impact also produces 86 percent more energy than a 30 miles per hour barrier impact.

Passenger cars, where weight savings is not quite as big an issue, are barrier tested at 30 mph. The chances of a fatal injury are increased dramatically when the speed is increased to just 35 mph. That five mph increase requires a dissipation of 37 percent more energy.

Fortunately for those who race, few impacts involve a 4000 lb. concrete/steel barrier, or the equivalent. Unfortunately, for those of us who will be driving our cars on the street, we have to be much more aware of that possibility. To borrow a phrase from the old “Hill Street Blues” program, “let’s be careful out there.”

[Lee]

That same picture, and a few others showing the car after the crash are published in 'Shelby GT40' by Dave Friedman. A very good book, with lots of old colour photos, and those pictures are in a section dealing with the death of Ken Miles late in 66. A very sobering chapter.
It also includes a similar recount of the story by Bill.

This also leads to the question of which chassis was used? And what became of it. I don't think Ronnie Spain got to the bottom of it in his old book, but perhaps someone out there now knows the story?

It appears to be of the early Mark 2s - chassis GT1.., but which one?

[Pete.]

Wow that fuel spray is very scary!! Memo to myself, fit a
good onboard fire extinguisher system. Investigate foam filled fuel tanks..

[Bill Bayard]

What a sobering photo! I wish that some of the replica
manufacturers could incorporate new, safer technology into these cars, without compromising the look, handling, etc.
Anybody have any ideas for a retrofitted, more crash proof front end? There has to be a way to deflect the front wheel to tank impact. I know that the new GT doesn't have sill tanks, but has there ever been a car built with sill tanks, that has some sort of adequate tank protection? I could live with a couple of hundred extra pounds, if it would save my life. You'd need an entire fire department to put out a fire from that much fuel catching ablaze. Even with fire extinguishers and foam filled tanks, you'd still have a major problem, in such a crash.

There are some pretty slick engineers on here. Any thoughts
from the slide rule and pocket protector contingent?



Bill

[Tony Hunt]

There are two things that worry me about a GT40 crash:
1. What happens when you hit something designed to withstand impact from a taller vehicle. ie the possibility of taking the car off at about windscreen level against something really solid like the side of a truck. . . .
2. The amount of front crushing that takes place. I wouldn't have liked to have had my feet and legs anywhere near front wheel area of that car. GT40s don't have crumple zones!
The lesson here, as with all high performance cars, is to do everything possible to use the agility of the car, its superlative acceleration, roadholding, cornering ability and braking, to stay out of trouble in the first place.
I don't think crash survivability is that high, and I am aware of driving much more defensively in my 40 than when hammering around in the family Sludgemobile.
Should cars be crash-protection boxes, like Volvos, brick-built s***houses, like 4WDs, or crash-avoiders? I think the two former categories give a false sense of security, and have always personally opted for the latter, so far, with no major accidents.
OK, some Jeremiah is going to flame me for being irresponsible, not wanting to take elementary precautions to protect the car's occupants and so on, but that's not the point of this present discussion. I'm all in favour of crash survivability being built in, but if you did that to a GT40 it would look like a Volvo!

[MK -IV J6]

Fuel systems have come a long way since 66 and people like Fuel Safe and ATL can help you there with a system with check valves that will act IMO better then the caps on this car did.
A 4 liter SPA dual zone fire system is a must.
A stronger tub will help. Andretti had a 145mph off in a MK-IV at LeMans and walked away.
That said you do not want to have a crash in one of these and should always drive VERY safely. VERY.

[Bill Musarra]

Bill,
Only one problem with your senario, You would have to crash,,, on a runway,,,, with the fire crew standing by.... Otherwise you are crumpled and crispy bacon. On a lighter note I have hit an immovable object (stoped 1980 Chey pickup driven by a good-ol-boy) with a Lotus Esprit (85). These cars as well as the GT40 are so low, you go under them much like a spatula under an egg (pardon my analogy). So you have the equivalent of a crumple zone in that you don't actually stop until you meet the rear axel or equivilent low object, which gives you about 2 or 3 extra feet to come to a hault. Of couse the opposite is true for low retaining walls.
Bill

[Bill Bayard]

All good points, safety, fire system, etc, but I was thinking along the lines of somehow deflecting the front wheels outward, so they didn't crush the tanks. That wouldn't help your legs much, but you might not become well done bacon. Perhaps angling the rear of the wheelwells?

Bill,

Do you have any photos of what's left of the Lotus? I had a

1971 Elan, which I wrecked years ago. There wasn't much

left of it, but I did walk away, by some sort of miracle.

It looked like the 917 crash in the movie LeMans...body

parts flying everywhere! Fortunately that fuel

tank was in the rear!


Bill

[Trevor Booth]

From the slide rule department.
The notable feature of the crash test is the rupture of the fuel cap allowing escape of fuel. A foam filled tank will go a long way to prevent this occurrence. The foam whether 10% or 15% will retard the velocity of the fuel and hence the energy to rupture the cap. A screw in type cap below the traditional QR cap will not allow fuel to escape. It is also to be noted that the vehicle had bag tanks which perform particularly well in a frontal impact. If you have a rigid alum tank it may well rupture in any event. Foam filling will reduce the energy level of the fuel in an impact situation. IMHO any side mounted tank should be of the fuel cell type. The crash test would have produced a decel in the order of 25-30g and when you look at the wheel posn the tub does not appear to have suffered a great deal of deformation. An overhead shot of the impact would indicate the level of deformation more clearly than a side view. On the subject of crash worthiness for replica vehicles it is not difficult to evaluate with the power of modern computers by non linear analysis, however the cost is high. It is not feasible to retrofit some form of crash worthiness device to an existing vehicle. The energy of a frontal impact is absorbed throughout the whole of the vehicle, modern day vehicles crumple under the back seat and rear passenger area floor to absorb some of the energy. Rear engined cars have a unique set of circumstances in as much as you have a veritable block of cast iron behind you which suddenly becomes 20-30 times it's mass ( rushing out to have a look at those engine mounts :-))). IMHO tube framed vehicles are unlikely to exhibit the same amount of crashworthiness as a mono tub. The whole purpose of crashworthiness is to limit the amount of energy imparted to the occupant. Some of the injury criteria are, deceleration of the head 75-80g for 3 milliseconds, compression load on the femur - 10 Kn (~1000 kg, 2300lbs). compressive deflection of spine relative to sternum - 75mm,
Tension in the neck - 3300N (~330kg). Any more than this and you may not survive!! It is not uncommon for car makers to crash 5-6 cars cars before they get it right.
Hopefully a video of a computer modelled chasssis rail is attached. This was broken down into 8000 elements for modelling.

[Mike Dozier]

Trevor

Thanks for the explanation.
I think Bill's concern was rupturing the fuel tanks with
a suspension member. No one is suggesting adding crumple zones to reduce impact energy to the occupants....just
not practical.

If the method of fuel system failure is the tank and cap design, we should all look at retrofitting our cars to dramatically improve our chances. And as Jim says...add
a fire system....just might save your life.

MikeD

[Bill Bayard]

Mike,

That's exactly what I was suggesting. Not adding crumple zones or massive intrusion beams,
but diverting the front wheels outboard, in the event of a front end collision.
In theory, that would give you a couple of more feet of
crunch zone, before anything began pushing on the tanks.
Granted, there's not much in that crunch zone to slow things down,
just curious if anybody had an opinion as to whether that would make a positive or
negative influence on fire potential.

Bill

[BenL]

I had foam filled fuel tanks, but the modern US gasoline additives ate the foam (the car previously lived in Australia).

[Kalun D]

The originals and the replicas were never made to be crash worthy. Just look at the new GT which is 10 percent larger, which part of the reason I'm sure is crashworthiness.

ERA has a plastic fuel cell.

Add foam to aluminum tanks, Speedway sells it among others.

Consider a better gas cap either under the flip one or eliminate the neck and put a flush cap right on the tank.

Fire system, possibly with nozzles right in the fuel tank compartments, as discussed by Lynn.


Drive with eyes in the back of your head.

[Mike Dozier]

Hi Bill

Did you get your injection system sorted yet?

On the subject of preventing fuel loss in a head-on,
besides foam and upgrading the cap design, what about
a simple piece of steel plate mounted in front of the tank?
Would that significantly reduce chances of a front puncture?

MikeD

[Bill Bayard]

Hi Mike,

Still sorting the injection system. I am getting very close to being back on the road, but I've thought that for a while now. "Getting frustrated" is putting it mildly! I hope to be up and running again soon.

Wouldn't the steel plate just be a more solid object pushing on the tank? If a plate were angled 45 degrees
outward toward the rear of the wheelwell, a collision might take the wheel right off, but the plate might also lessen the wheel's impact on the tanks. The wheels would give the tanks a "glancing blow", rather than a direct hit. My 0.02.

Bill

[Mark Worthington]

Mike, I don't think the concern is puncture of the fuel tank, rather it is compression of them which causes the fuel to "hydraulic" and find the path of least resistence out of the tank. In a replica, this is likely to be the filler necks. One of the things I'm doing to my RF is to put some additional aluminum paneling inboard of the filler necks in an effort to keep fuel out of the cockpit. I will also fit an extinguisher system.

Another consideration is how a space-frame would compare to a monocoque in a crash test. My RF has a fair amount of chassis rails between the back of the front wheel well and the front of the fuel tanks. I suspect the space-frame chassis may behave better in a frontal impact, at least in terms of protecting the fuel tanks.