quote:

Originally posted by hbchad:
For off road recovery we have switched to samson amsteel blue rope. I'm sure there are many others like it. 3/8" steel cable has a breaking strength of 14,400lbs. Amsteel blue 3/8" rope has a break strength of 19,600lbs at half the weight of steel.
...
This myth cannot be called busted on the premise that strong enough cable isn't available. We now have synthetics that are stronger than steel and not that expensive. The mythbusters should use them.

All good, but I just checked its specs at <http://www.samsonrope.com/index.cfm?rope=192>, and it will stretch only about 1%. So shock absorption would still be needed in the system.

I remember hearing someone say something about the tension on the cable would be about 7000lb..But even with a line that supports much more weight it still snapped like a rubberband. One problem that I noticed is that it always snapped where the grapplng hook was connected. I might have a solution.
Maybe if the grappling was connected to a oilfeild wireline cablehead. I work for a company called Baker Atlas. We do perforating and logging on oil and gas wells. The seven conductor wireline that we use is rated for strengths of 8000lb. to 16000lb., but to save the wrap of cable on the hoist from damage we use a cablehead that is built into the line and will pull out of the socket at 1/2 of the max strength of the line.
If there is a way to connect the grappling hook much the same way as our cablehead is connected, there might be a better shot at getting the line not to snap at the connection point. If your interested in knowing more please contact me. nwr2339@gmail.com

They should have used plasma rope. I don't know why they never thought to use that for the 90 degree turn myth. It's way stronger then steel and can pull really heavy ships. Plasma rope can pull up to a million pounds or even more. I will not except this myth being busted without using the plasma rope. One other myth I have problems with is the lighter myth. I don't know why they didn't you metal lighter. Metal does hold in gases and when it can hold the gas it explodes. Where do I go for old myths?

I agree, they needed to use a plasma rope and also they need to use some kind of dampener on the the rope or cable.

Perhaps they should use the same cable that was used on the Toyota Tundra commercial, It didn't break when the container was dropped off a cliff.


hummmmn!!!! Maybe this test says something about the plausibility of that commercial.

first off the placement of the cable attachment on the car was way too far back, the car is front heavy and as such will affect the turning radius, also, if the distance between the car and the steel object is not exact, then the cable will be too short or too long, in the mythbusters case, it was too long, which caused the steel cable to whip, and break.
thirdly the fact that they couldnt make the turn at 30mph and then tested it at that speed, goes to show that even if it did work, wouldnt be of much use, they are only going 30mph, not really a good speed if one is trying to escape

~keavy
JTN RI

Wow. You guys gave up way to easily on this myth... it definitely deserves another shot.

A few ideas...

About the car:
I bet that batman being the tech guru he is would have all the best technologies incorporated into his batmobile, you guys
came way short... I know that the old camaro is a perfect car to recreate a batmobile visually but it is everything but fitting for this myth...

-it is a RWD, you guys need an AWD which will dramatically improve your turning capabilities; camaros were made to go straight not turn

-you guys need to upgrade the suspension; this can either be done with sport shocks and springs which will lower the car and give it even
better turnability and responsiveness or by adjustable coilovers; you might also need to get better, stronger/lighter strut bars and control
arms which will too help with this myth; batman would surely have only the best, besides have you ever noticed how low the batmobile is? hello? it is not only for looks people!!!!!

-the car needs to be a lot lighter; camaros are heavy; you need to cut down on the weight so that the force is not as great when the turn
is attempted; i imagine batman's car would be really light, somewhere in the 2000lb range if not lighter, not 3300lb (i assume its a V8);
get rid of the seats and unnecessary electronics; even the exhaust, ac, alternator and the cooling system (if you do not plan on longer trips) are not necessary - that will save you lots of weight; make it so it is
only made up of the frame, drivetrain, and the suspension

-also remember about tires and lightweight wheels; depending on how you want to approach this myth, whether it is making the turn primarly with the help of the grappling hook or by helping the car hydroplane; slick and wider tires will provide you with incredible traction while thin and worn out ones will help you
skid around the turn (uncontrollably)

About the line and positioning of the cannon:

-the position of the cannon is very important here; behind the passanger door is not the best place to put it; what would make sense, especially in an AWD car is to put it closer to the front wheels, maybe in front of passenger door; this way when the grapple is shot out of the cannon and hooks, it will jerk the front of the car helping it enter the corner sharper and quicker; while the front tires are likely to skid (but they will still keep on going forward so that the car should center, unlike the camaro), the rear ones will keep on going straight and therefore help center the car and
complete the turn; with the camaro you just jerk the front of the car and hope that the RWD will put you back on the road... not going to happen

-when it comes to the line, I saw a couple of helpful posts, you might want to try out some
of the suggested ideas, they seemed reasonable; my suggestion is that you find something
that is more flexible so that the force is distributed over time and the line is not torn

Well thats all.


Thanks and Best of luck.

quote:

Originally posted by orcan:
I love you guys, instead of dealing with the problem at hand you find a whole bounch of other problems. lol

A super car might have "super handling" but that doesn't mean it can make that turn. I think the turning ability of the vehicle doesn't have much of a factor here. It's all about the car being spun around on the cable.

I still stand by my point that, the cable broke, nothing else really matters after that. Untill they find a way to keep the cable from snapping all these other things don't really matter.

Also it looked like Grant had done a whole bunch of small scale experiments with that model he was holding. I know I certaintly would! lol They probably would've shown that where the CG was the correct position for the cable. Unfortunatetly they decided not to cut it in, which they should've.

Yes i agree that a stronger line would help but still, if you put the launcher behind the cars center motion in this case between car doors, then its equivanent to attaching the caint to rear bumber and driving flat out until the line is taught, the car wont spin. By putting the launcher in a spot in front of the center of motion, the front end of the car will receive the resistance of the rope/line while the rear will still be driven forward by the engine. and because the line is attached to the right side, the line will pull the car to the right, causing the car to spin. its the same concept the its easier to tighten a already tight nut with a rachtet wrench rather than with say a nut driver (like a screwdirver). The back portion of the car is the driving force, and the front part is being pushed by it, so it is the stearing or controling force. its harder to change motion when force is put closer to the driving force(the rear), but it is easier to change the motion if the force is put near the stearing force(the front). I heavier line would partially solve the problem, but it would still take more force then needed to make the car spin, or pull a small 90 degree arch which is needed. By lessening the amount of force put on what ever line or cable they use, you solve the problem of the cable snapping. increasing the strencht of the rope would also help, but the main problem solver would be lessening the force put on it, which moving the launcher to the front portion of the car would do.

The way I see it, the reason the cable snapped it was attempting to jerk the car when at the start of the turn. If the shock isn't absorbed by something, either the cable will give, of the frame of the the car.

I would like to see it done again with the launcher mounted on a slide rail in the car, and some very heavy duty springs pre-compressed to about 10x the car weight with about one foot of movement to absorb the shock when the cable first goes taunt.

This set up should be able accelerate the car sideways up to at least 7.7m/s(17.3mph) in a single jerk without breaking it, and using a cable rated for 10x the car's weight.

I think that it can be done. I think that if you take the first rope you used . Then braid it. It will be stronger. I would love to is this done again. Revisti PLEASE...........

you sould braided the rope that was stronger than steal or use more ropes tied to gether then i will get off your back

1. Use a very light weight car. Perhaps a golf cart.

2. Due to Newton's 3rd law, which caused the inital firing of the canon to fall on the floor, I bet the car will have a difficult time transitioning into the straight after the cable is released. The car will pull away from the center of rotation upon cable release.

another thing that I wander about

would it make a difference where the grapling hook is mounted?

ok yes i does make a difference where the grappling hook is mounted and before you guys make a statement, read some of the replys on the previouse pages because i guarentee they will answer 80 percent of ur questions.
2
Batman didnt ride a golf cart did he
3
braiding would work but then the cables would endure friction on eachother, which creates heat, which weakens the cable.
4
yes i think a spring would be a verry good idea, just like if you put a frog in boiling ater it will hop out but if you put it in cold watter and raise the heat it will boil to death, gradually increasing the force on the cable would prevent the extra force put on when the line jerks taught, good idea but no sliding mechanism, because batman's car didn't have that. and that would cause a very unstable weight shift, possible breaking the cable, spring, or een the car if its at the right time.
remember its not seeing if its possible to make the turn, it seeing if its possible to make the turn with a batcar size vehicle, which would be something along the lines of say a camaro or mustang, a long bodied coupe.

i think that you have a point spitfire but if you were to make it work like many other myths adam and jamey do. i think that:
1 the cable is a bad choice and rope or nylon stap is a better choice because of strech.
2 a good swing of a car could only be made with a two point hook to the car so you could control angle of the car with the front catching first but the rear cannot swing out. that way the tires help corner.
3 the rope has to hook quick to pull car into corner in time. that is probaly the hard part. i wounder how many time they tried this to get those few results.
did batman have all that? he sure made it look easy! grats myth busters

yeah I am stating to think it may make a difference based on where the pivot point is ((Where the grapling hook is mounted from))

and it may change the forces the cable has to take if it is mounted in front or middle instead of the rear like it appeared to have been

I think they should have keept doing it, getting slower every time untill they fail. That would have made a much better show. So adam Jamie you guys might want to re-visit this myth. O and By the way , keep up the good work guys!!!

no. if they put it in the front they would get ripped around the turn. and if they put it in the back, they would get pulled to the left and run into the "cardboard cities". they have to put it in the focus point of the car to get the coorrect amount of force to make the turn.

hey, what about chain?
i dont know if that might be to heavy though

My question is did they rely *solely* on the cable or did they steer into the turn. Certainly if they had used teh wheel and the cable together they should be able to turn much more sharply than with the wheels alone.