Hate to say this to all of you but the car is RWD and if they want to do a 90 deg. turn stop the inside wheel and there you go. sorry to say that but to many or you are picking on the car.

I think this Myth is Busted. There is to much force on the line. On a side note I didn't think a want-to-be K.I.T.T car made a pretty nice looking bat car. Who thought a hub cap and wood bat wings and some flat black paint is all you need.

ebay anyone.

Everybody here with the exception of just a few have made very valid points. With consideration of just a few more variables, the myth could easily have been confirmed.

First, like many have said, the problem was not the cable, though to be fair, a fairly thick synthetic cable like Spectra cable would have made a big difference.

Second, the very first thing I thought of looking at the setup of the test was the location of the point at which the cable attaches to the car; it simply MUST be located at the center of gravity of the car, specifically on the y- and z-axes. As for the x-axis, the best point at which to tie in is the very side of the car on the inside of the turn. Physics tells us that tying in at any other point will not allow the car to remain tangent to the arc of the turn, no matter where the wheels are or whether the car is FWD or RWD (or even AWD).

Third, anyone who said that the instantaneous or impulse force exhibited when the line goes taut must be reduced to make this stunt work could not be more correct. All that must happen is that the shock of the cable going taut must be somehow absorbed... perhaps a mechanical device such as, say, a shock absorber...
Although, I must say the braking drum sounds quite plausible as well... or maybe even a disc brake?
Also, keep in mind that nothing says you couldn't implement a type of shock absorber AND a brake...

Fourth, some aim-forgiveness could be achieved by devising a way to eliminate the threat of having a cable fray on the sides of those I-beams. Perhaps Kevlar mesh could do the trick? Correct me if I'm wrong about its resistence to lasceration... similarly, any better suggestions out there?
Also, I recall one post that called for the modification of the structure; personally I would oppose the idea, just because it would be more impressive to build a robust, versatile rig, rather than one that could only work on schedule 80 such-and-stuff pipe, right?

Fifth, some added accuracy could be achieved by adding in-dash Batmanesque controls to the cannon? Maybe a solenoid valve could be fitted to it? It and the quick-release could be operated by the passenger, leaving only the maneuvering to the driver and nothing to an outsider.

Sixth, would it help to increase the firing angle of the cannon? This could allow the cable to actually wrap around the structure causing the hook to either catch a different corner or the cable itself, thereby reducing the stress on the attachment point (although I suppose this could have its drawbacks too; what does everyone else think?).

Seventh and finally, the smallest vital detail I can think of is that the run could be affected if the hook catches the first corner and the cable is caught by the very inside corner of the structure, thereby suddenly reducing the radius of the turn by a few (3-5) feet. This should be avoided, namely by activating the quick release immediately after making it sufficiently through the turn (before the cable would get caught on the inside corner). If this doesn't happen, it could create yet another instantaneous force that the shock absorber would have to deal with. We wouldn't want the myth to turn out busted after all this careful planning, right? Better safe than sorry, I figure.

That's all I can think of. I really truly believe that if all of these details are taken into consideration, there is no way that this myth will turn out to truly be busted! You guys really need to revisit this one!!

What if you used marine tow line like on tugs or CoastGuard boats its strong and is made to absorb and stretch a little at first then hold. Cables don't give. All the pressure is on one point so it will break fast and with less force.

What about the nitrogen cannon... nitrogen is cold... and with that kind of pressure it would be very very cold... kind of like using a can of air duster... lost some skin from one of those before. Wouldnt this lower the tensile strength of the rope/cable making it far easier to break/snap?

Did anybody notice they almost got nailed by the test of the cannon.I thought they had a safety guy that looks after them so they don't kill themselves.

It was said by Grant that there is 7000 lbs on the line. Does that count the force that is put on the lin when it comes to a sudden stop as it tries to swing the car around the corner? Maybe you should have power up KIT he turned 90 degree corners haha.

Here is another fun myth for you to try. build If memorry seves me didn't batman have a bulit proof cape?

Cable Position: For the most part the position of the cable attached to the car should have had a bit more calculation. If it's centered to the mass then the tires have to turn(spin) the car while the cable redirects it's foce (most ideal situation). If it's too far foreward the rear of the car is going to swing outword (Newtons 1st law) which you may need depending on the speed, too far back and the front is going to swing outward and resist the cars stearing (again Newtons 1st law) -- just like most everyone is saying --
Cable/Rope: Grants calculations for the strength was correct...
<test> tie the rope to the car and then directly to a static source with some kind of rotation so the rope doesn't wind around it, taught the line and see how fast you can go before the line breaks. I think they could have easily exceeded the 30mph they were shooting for. You can also test the position of the cable attachment to the car with this. I would have realy like to see this test done.
90 degree turn: again because of another variable that was not eliminated, the length of the cable and distance from the static source allowed the car to pass the 90 degree angle they needed and wound up looking like Adam and Jamie's Axel yank. The line needs to be taught at the 90 degree angle to eliminate the yank...
<test> Attach the rope/cable to the car and static source but have a wench or something winding up the slack, just have to prevent the line from being able to come back out, then precisely parallel (90 degrees) to the source the line will be completely taught and will start the turn.

"Busted"? Gave up too early leaving too many human errors in the calculations.
*** MUST REVISIT *** ...please!!!

quote:

Originally posted by webcity:
It was said by Grant that there is 7000 lbs on the line. Does that count the force that is put on the lin when it comes to a sudden stop as it tries to swing the car around the corner? Maybe you should have power up KIT he turned 90 degree corners haha.

Here is another fun myth for you to try. build If memorry seves me didn't batman have a bulit proof cape?

His cape wasn't bullet proof - his body armor was, however his cape is fire proof... he covered himself in his cape in front of an explosion, engulfing himself in the flames and came out a little smoky but fine.

okay here's my thought. since the cable snapped at the grappling hook i assume the reason may be that the tension on the cable was put onto only one "threa" of the cable; therefore i would suggest having the fired hook wrap around the "structure" ( maybe a pole would work better) two or three times thus resulting in a squeezing force instead of a pulling force. Also putting the cable (car side) on a pully-like rig that also contains a wrapped arrangement that would be directly attached to the frame of the car, and also possibly bald tires. have fun

Did they need the 10lb hook? maybe if the hook itself is going to take the full blunt of the force but as any super hero knows, this kind grapple needs to wrap a couple times so the line is what grips the object, then all the hook does is prevent the line from comming undone.

quote:

Originally posted by gambitj79:
His cape wasn't bullet proof - his body armor was, however his cape is fire proof... he covered himself in his cape in front of an explosion, engulfing himself in the flames and came out a little smoky but fine.

I do recall he used his cape to stop bullets from killing a child. This was in some old show that my dad has. This sho had the 1950s flahing computers.

I think you maybe right about his cape being fire proof too. Lets see them run a show on batman's cape and explosions how about the bat light can you really see that at night. the has to be over cast before that would work but thats way they came up with the bat phone right.

Technora all I have to say stronger than steel light as rope look it up

If the cable/rope was attached to the front of the car (in front of the front wheels) you would have a better chance of the cable/rope not breaking. The car is under-steering but some force of the front steering wheels is still trying to make the turn. Sooo... less tension on the cable/ rope needed to make the turn.

That car is a camaro. It wasn't meant to turn. Lol. And you would think batman would be driving faster than 30mph and the car would have better suspension.

Turning the Myth Mobile.
I just watched Super Hero show you did a very good Job on the cannon guys.
I was wondering why you mounted the rope anchor point behind the center of gravity though.
Cars are forced around a turn by the lateral forces from the tires.
Mounting the cable behind the CG would be trying to pull the car back to straight.
The rope was pulling the back of the car out and trying to drag the car sideways through the corner. Fighting the wheels not helping.
Wouldn’t you want to mount the rope as close to front of the car as you can?
That would make the front swing in on the corner like it was over steering.
That way the front will point were you want to go and the rear tires can keep driving, not dragging.

Finally got around to watching this episode. Overall, very entertaining. But I have some suggestions for a revisit if they ever try it.

First, the rope/cable. They used one "high-tech" solution that did not work, they went to the old standard that they should have know would not work. The 3/8" steel braided cable did not work for the axle-ripping myth, why would it work for this? There are materials out the that would work for this, though I would imagine they are rather expensive. My suggestion would be AmSTEEL Blue 1/2" with a tensile strength of 34,000lbs. A bit of stretch
to it, but not enough to allow the car to impact the far "building." If strobnger is needed, step up to the 3/4" version at 64,400lbs.

For the mounting location of the cannon...does not matter. What matters is the attachment point(s) of the cable. My idea here is to attach the cable to the car twice. Once at the top of each strut tower. For non-car-folks, inboard and above each wheel a bit...open the hood of any late model car...the bulge under the hood, near the hood hinges, usually has 3 or 4 smaller nuts surrounding one great big one. The rear should have something similar, though often harder to get to and not always as convenient a mounting setup...some vehicles would require a rather intensive fab job as they don't have struts in the rear. If the 3rd Gen F-Bodies have rear struts, this method would be handy in that you usually have nice neat studs to mount a plate, which can then have a clevis for the cable. These are already holding the entire weight of the car, even when stressed due to cornering, braking or accelerating. If no rear struts, then can still use the front towers, and rig something in th rear. Added benefit of having two strands of cable running to the grapple for added strength. It also allows you to ignore the center of mass calcs and related hassles, as it will inherently hold the car tangent to the pivot as long as both cable lengths are equal.

OK, now everyone shoot holes in my ideas .

OK you were trying to do a 90 degree turn with rope and cable that was super strong but you calculated the weight as if the cable would be attached close to the cars center of gravity. You placed the cable to far back. It should have been attached to the front of the car or right behind the front wheel. If you look at the geometry of how drifters drive you can see that they need to spin the rear end of the car to make the turns. Please retry the myth with the cable attached to the front. I promise you wont be disappointed.

In order to make the experiment work, the grapple would have to be placed over front the the axil of the car. The engine is the heaviest. So yes, the rope cable would have to be more towards the front. You have to account for inertia, and ther was too much weight that has past the axis, which overtaxed the lines. A Bull can be persuaded to turn if you tie a rope around the tip of the horn on the side in which you want the Bull to turn. But if you tie the rope around the Bull's neck, the Bull will drag you along with it. All cars that the steering and the front axil position is the best place to take any turn. Should one add a spring attachment to where the cable attached to the car, it would act as a shock absorber, and the cable, if more forward, might not have snapped. The 7k rope would have been more the enough to nudge the car the little bit the car itself couldn't handle. This experiment proved to me that if could have worked provided the Myth/Grant mobile was in the lane closest to the leftside curb to arc the turn instead of trying a 90 degree angle.

Since you're dealing with a horizontal pendulum the force needs to be applied at the center of gravity. A possible suggestion to take some of the instanteous force off of the cable/rope would be a coil spring similar to a truck spring. The present rig could be modified easily by bolting or welding an I-bolt to the frame of the car at the CG, attaching the spring, and running the cable through the spring.