Car sucking and flattening episode

I like explosions as much as the next guy, but nothing really surprising in this episode.

When I saw how much ANFO they were using on the full scale test, I figured there would be nothing left to find. I think they used as much, if not more, than they did in the cement mixer and look what happened to it. I think they knew that from the start but just wanted to end with a big bang. And that they did.

As for the vacuum lifting the car, I saw problems with the octopus contraption from the start. There was no way to evenly distribute the loading across all the suction cups and if any one failed to stay attached, it reduced the available suction on all the others. It failed exactly as I thought it would. If they would have used some type of bellows arrangement on the boxes, they could have completely lifted the car using only the vacuum and wouldn't have needed the crane at all. Of course, they wouldn't have lifted it high enough to drop it, which I think was the whole idea all along.

umm... how could the vacuum have lifted the car without something to lift the vacuum?

I have no fear of accordians.

a bellows rig would have been heck to build, and I agree they were looking for an excuse to trash some cars.

the octopus rig would have had a better chance with a rear drive car - they are more evenly balanced.

I had to work overtime Saturday, but got the chance to watch this yesterday.

I was wondering if Jamie might have gotten a more even "push" on full-scale if he'd put a rim on the top plate and poured the ANFO in loose -- like a big explosive litter box. With the bags stacked in the center of the plate, I don't care what the math said there was going to be more force on the center and less on the edges. His small-scale tests all had an even layer of explosive and seemed to work better.

I think calling Adam's test "destroying a car" was a stretch, but it was still an interesting build.

I loved this episode! If for nothing else, seeing Jamie giggle like a school girl always puts a smile on my face

It was pretty obvious that the ANFO would completely decimate the car, but the small scale tests were cool and a proof of concept. I think if they'd done as Antigone suggests and distributed less ANFO more evenly (I love the "big explosive litter box" analogy! ), they might have gotten a better result.

As for the vacuum car lift, that presented the biggest fail so far of the season. Why? Because the octopus rig would have worked if they'd just paid attention to one minor detail and I'm kind of surprised the crane operator didn't catch it.

Any crane (or even forklift) operator worth his salt should know that lifting something off its center of gravity will result in it tilting from uneven weight distribution, which is exactly what happened with the octopus rig and exactly the reason it only got the car an inch off the ground. They were lifting at the geometrical center of the car, not at the car's center of gravity, which was painfully obvious (at least to me) once the back end got off the ground, but the front dipped. Not only did the front suckers carry most of the load, but they did it at an angle, meaning each sucker wasn't even carrying the load evenly. The cables that held them to the lifting frame were tugging more on the front end of each sucker than the back end, so of course they would eventually let go.

Moving the lifting point about a foot closer to the front would have made for a more even load, meaning that the back and front would have come off the ground at the same time, so the front half of the suction cups weren't carrying 65-70% of the load on their own and at an angle. That's what they were doing here and that's the only reason it didn't work.

Then again, it seems they did realise their initial mistake later on when they made the box suckers, because the lifting point was moved closer to the front of the car on that one. I just don't think they noticed until after they'd started building the new rig and didn't want to admit on camera that they figured out that's why the first one didn't work.

Either way, the box design was cool, a lot simpler and it worked, which I never would have guessed at the beginning of the show. Mistakes aside, how cool is it that a single vacuum cleaner has enough suction to carry an entire car?

Calculate the surface area of the car, multiply it by 14.7 and that's the maximum amount of force, in pounds, you could get from a pure vacuum.
Just guessing, I would think that would be enough to crush a car.

In todays world, where now you have govt interference of how powerful a vacuum can be (NMaximum wattage of motor to save power) you better have an old one.

Ok, so lets take this idea and work on it, see what I can think of here as possible problems.

You need a older not restricted power vac, Or like me, a "workshop vac"..
Vacuum sealing a car....
You may have problems with safety cages... that wont crush a car with any reasonable safety features?.

Well, not mine anyway, and not some modified's I have driven either...
Think "Roll cage"....

The frame on my own minor Toyota will take the whole weight of the car over the top of the Windscreen "A" frame.
At force.
As in even if it lands that way from height at speed, being a normal surface road of 30mph limit and a small say 10ft drop...
I knows this because I have see a wreck where one fell off a ramp, there was minor denting but the internal "safety cage" was more or less intact.
(I have even seen a car fall off the top deck of a transporter in a collision, and get restored back to road condition by some small paintwork and glass replacements...)(No it wasnt brand new, and yes it had road wear on it before they started..)

Any vehicle that has a NCap 5 star rating will have an internal safety cage, to an order that vacuum sealing in a bag wont crush it at 14lbs.


If you were to try this with a "Domestic" vacuum...

The best you could manage would be a partial vacuum which wouldnt be the full 14-15 lbs per square inch (Correct me if I am wrong) at sort of normal height above sea level, so maybe 5lbs ?... max out with my shop vac at 10lbs for a short period(It has had upgrades.... 'nuf said...)
5lbs per square inch would be at my estimate quite a lot less than my Roof rack can carry, as I know I have had eighth of a ton (maybe more?) up there in wood, and its a four point connection to the roof, that has maybe two square inch of rubber at the mounts...
Do the maths and you can see what kind of trust I have in my own Safety Cage, thats a lot of weight travelling down the door pillars innit?..
The tyres alone are at 30lbs per square, your not even going to pop my tyres in a vacuum bag.

More damage would be done in a vacuum chamber, as I am sure that would make the air in the tyres leak out a little... or a lot...

My guess is that even when you have got the full car empty inside of all air, the bag will break before the car will.

You ever see a car crusher in action?.. I am guessing they use a little more than 14lbs psi on the crush plates.

However, I would love to see this tried...

My above is of course rough knowledge, if you can prove me wrong, I wanna see that happen.

Typical y-2000 or later high safety rated car, I am guessing a domestic vac wont do the damage.
However if that bag could contain a full vacuum, things are going to strain a little... maybe the glass in the side windows is going first, front and back are load bearing toughened glass.

So think on this, if you could put a small kids paddling pool up on the roof of a car with say six or seven inches of water in it?...

If you internet search redneck swimming pool, you may find a few pictures of truck beds with waterproof lining sheets turned into a pool, with a foot-and-a-half of water plus people in them.
Ok, so thats the bed of the truck, and not the roof, but, its not killing the suspension, its not crushing it exactly is it?...

Something like say this,


Which I use for an example.

I have seen ideas for a roof-rack water tank, I have no idea if it went into production...
I objected to the idea because I believed that the fluid dynamics of having that much water above the centre of gravity of a vehicle would create stability problems when driving, I believe they then changed it into a cellular idea, but, I know I have had a five gallon bucket full on top of my car roof without problems.
I doubt that if I completely filled my car roof with five gallon buckets I would get away without damage?.. but crush the car, maybe not.

You're right TUM, it was basic MythBusters at its best. Something they had gotten away from.