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Post by Cybermortis on Apr 10, 2014 9:48:34 GMT
For number 2 I would add that the RC car would have to carry enough explosives to blow another car up, while maintaining enough performance to at least keep pace with it. I had a RC truck a few years back, and that could certainly have carried a pound or so of explosives...but not have done so while keeping pace with a real car. (Which in all likely hood it couldn't have done anyway).
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Post by the light works on Apr 10, 2014 14:39:54 GMT
I think they did already do ducking behind something to shield from a blast. - and in all honesty, it is a case of "better than being out in the open"
there is also the idea of shockwaves cancelling each other out. can you be equidistant between two equal explosions and not be as severely affected by the shock waves? - this would want relatively "clean" explosions to do well, as you would want piezo sensors to back up your burst discs, but it gives them a new dimension to work with.
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Post by the light works on Apr 10, 2014 14:41:26 GMT
I have an RC car that can exceed 30 MPH on its best day, and it is not an extremely high end car.
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Post by Cybermortis on Apr 10, 2014 14:50:29 GMT
That is an interesting question....
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Post by the light works on Apr 10, 2014 14:58:35 GMT
That is an interesting question.... It is the principle quoted in our rodeo sideshow stunts where a stuntman climbs into a box allegedly filled with dynamite and blows it up from the inside. |
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Post by Lokifan on Apr 10, 2014 15:52:46 GMT
I found the car chase sequence: Pardon my French!  I couldn't find a clip in English. |
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Post by memeengine on Apr 10, 2014 21:29:43 GMT
there is also the idea of shockwaves cancelling each other out. can you be equidistant between two equal explosions and not be as severely affected by the shock waves? Wouldn't that just double the effect? The shockwave from an explosion is an over-pressure wave. In order for one shockwave to cancel out the other, one of the waves would have to be lower than ambient pressure (by the same amplitude as the other was over). That won't happen - what you'd get is the two over-pressure waves meeting and the result would be double the pressure. Not only that, but unless you were infinitely thin, the shockwaves would strike you on either side before they reached each other - so you'd be squashed between them. |
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Post by chriso on Apr 10, 2014 22:28:27 GMT
there is also the idea of shockwaves cancelling each other out. can you be equidistant between two equal explosions and not be as severely affected by the shock waves? Wouldn't that just double the effect? The shockwave from an explosion is an over-pressure wave. In order for one shockwave to cancel out the other, one of the waves would have to be lower than ambient pressure (by the same amplitude as the other was over). That won't happen - what you'd get is the two over-pressure waves meeting and the result would be double the pressure. Not only that, but unless you were infinitely thin, the shockwaves would strike you on either side before they reached each other - so you'd be squashed between them. Yes and no. A shockwave isn't really a normal* wave at all in the physics sense, and doesn't behave like one. The air traveling in a shockwave is moving so fast the air ahead of it cannot "get out of the way" before the shock wave arrived. A very abrupt rise in pressure, followed by a slow return to normal pressure, are characteristics of a shock wave. And, as you said, this would not allow it to cancel itself out and return to ambient pressure. That being said, what will kill you is the pressure difference across your body, as when your arm is pushed to your back through your stomache it isn't very good for your health. If you could somehow keep the pressure where you are relatively uniform, there is a chance you might survive the explosion.** If I was going to try this, though, I would probably use a "low" explosive, rather then something like C-4. As mentioned, shock waves have a VERY abrupt pressure difference, and I doubt that you could get the timing precise enough to not die. A low explosive would give a small amount of time to build up pressure without subjecting you to quite as much shear*** as a high explosive would. Either way, though, the idea is absolutely crazy... but when has that ever been a barrier? *Meaning capable of being represented by an equation of the form Asin(kx-wt+phase) **You may later die from lung damage.... *** I have no idea if this is the proper terminology, but it sounds right. |
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Post by memeengine on Apr 11, 2014 6:17:09 GMT
Yes and no. A shockwave isn't really a normal* wave at all in the physics sense, and doesn't behave like one. The air traveling in a shockwave is moving so fast the air ahead of it cannot "get out of the way" before the shock wave arrived. True, it's more of an energy pulse than a wave, but we are somewhat stuck with the "shockwave" terminology. That being said, what will kill you is the pressure difference across your body, as when your arm is pushed to your back through your stomache it isn't very good for your health. If you could somehow keep the pressure where you are relatively uniform, there is a chance you might survive the explosion. However, unless you were infinitely thin, there would still be a pressure difference across your body as the shockwaves struck. So, for example, if you were standing side-on your arms would be pressed into each side of your torso. In addition, the shockwaves wouldn't just stop when they met, they'd pass through each other. So you'd have two pressure differentials travelling right across the body in opposite directions. On the plus side, unlike a single explosion, there probably wouldn't be any resultant momentum imparted to the body (so it wouldn't be "thrown" by the shockwave). I suspect in testing, even with low explosives, getting the shockwaves to arrive together and to be of equal magnitude, would be a significant challenge. |
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Post by silverdragon on Apr 11, 2014 8:29:29 GMT
Video, Drive AND control an RC car?...
No one has that much spacial awareness that they can do that.
Not even a rocket scientist.
DO NOT TRY THIS AT HOME dear readers, I am sure you know the score by now, we dont award anything for stupidity, especially posthumous awards for trying silly suggestions...
Now I challenge anyone to do that, and not just on a flat surface no hazard runway, in simulated "Live" traffic whilst chasing another vehicle that is on a random course.
Is Adam or Jamie up for that challenge?....
Even if we allow them to use that deserted army base and make it that the rest of the build crew throw random objects into the road for them to avoid to replicate "Live" hazards and real life....
There, I have a challenge, and it wont be that complicated to set up.
The actual car, the number of jumps that it did, and stayed "On course"?....
No.
They didnt do that in one take, did they?...
Halfway through, after maybe a mile of running, it "wheelies".... that was an electric car?... no, I dont think the batteries would last that long and give that kind of performance.... they were not even modern LI-Ion.
Can a remote car do that kind of speed?... yes, I have one that has been clocked over 40 mph, and again, its not a top end, mine is a monster-truck stunt special.
Mine also has the landing gear to handle large jumps... oil filled shock absorbers/dampers.... over 10ft in height, you are going to need them for any repeated jumps...
My car could do the stunts, the speed, but maybe not the distance.
On a full charge, I get maybe 20 mins play time, about 7 or 8 mins on full throttle.
No over to the Petrol ones, I easily get half hour out of them, even on full throttle....
I could get more, but they are such a laugh, I have to go sit down for a rest..?....
And they could do over the national speed limit ... but I never chased one to find out.
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Post by the light works on Apr 11, 2014 14:18:14 GMT
Yes and no. A shockwave isn't really a normal* wave at all in the physics sense, and doesn't behave like one. The air traveling in a shockwave is moving so fast the air ahead of it cannot "get out of the way" before the shock wave arrived. True, it's more of an energy pulse than a wave, but we are somewhat stuck with the "shockwave" terminology. That being said, what will kill you is the pressure difference across your body, as when your arm is pushed to your back through your stomache it isn't very good for your health. If you could somehow keep the pressure where you are relatively uniform, there is a chance you might survive the explosion. However, unless you were infinitely thin, there would still be a pressure difference across your body as the shockwaves struck. So, for example, if you were standing side-on your arms would be pressed into each side of your torso. In addition, the shockwaves wouldn't just stop when they met, they'd pass through each other. So you'd have two pressure differentials travelling right across the body in opposite directions. On the plus side, unlike a single explosion, there probably wouldn't be any resultant momentum imparted to the body (so it wouldn't be "thrown" by the shockwave). I suspect in testing, even with low explosives, getting the shockwaves to arrive together and to be of equal magnitude, would be a significant challenge. they tested the shockwave throwing things (people), and it didn't really work. the air in the shockwave isn't really moving - it just pushes and recedes, like a wave in water. the wavefront travels, but the water itself just oscillates. for the record, I am not cheering either way on this myth - it seems to be quite a stretch - but it is something that can be tested, has several variables to adjust, and can go from small scale to large scale; and it has the added bonus of twin explosions. |
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Post by the light works on Apr 11, 2014 14:21:31 GMT
Video, Drive AND control an RC car?... No one has that much spacial awareness that they can do that. Not even a rocket scientist. DO NOT TRY THIS AT HOME dear readers, I am sure you know the score by now, we dont award anything for stupidity, especially posthumous awards for trying silly suggestions...
Now I challenge anyone to do that, and not just on a flat surface no hazard runway, in simulated "Live" traffic whilst chasing another vehicle that is on a random course.
Is Adam or Jamie up for that challenge?....
Even if we allow them to use that deserted army base and make it that the rest of the build crew throw random objects into the road for them to avoid to replicate "Live" hazards and real life....
There, I have a challenge, and it wont be that complicated to set up.
The actual car, the number of jumps that it did, and stayed "On course"?.... No. They didnt do that in one take, did they?... Halfway through, after maybe a mile of running, it "wheelies".... that was an electric car?... no, I dont think the batteries would last that long and give that kind of performance.... they were not even modern LI-Ion. Can a remote car do that kind of speed?... yes, I have one that has been clocked over 40 mph, and again, its not a top end, mine is a monster-truck stunt special. Mine also has the landing gear to handle large jumps... oil filled shock absorbers/dampers.... over 10ft in height, you are going to need them for any repeated jumps... My car could do the stunts, the speed, but maybe not the distance. On a full charge, I get maybe 20 mins play time, about 7 or 8 mins on full throttle. No over to the Petrol ones, I easily get half hour out of them, even on full throttle.... I could get more, but they are such a laugh, I have to go sit down for a rest..?.... And they could do over the national speed limit ... but I never chased one to find out. I think mine ran on ni-cads, and it was still at 90%+ performance for 90% of the battery life. (its been in storage for years and the battery pack may be dead from old age)so 5 minutes at 30MPH would take it 4 miles, allowing for stops and corners and such. as for the actual operation - my memory is 20 years old, not having watched the youtube clip - but I thought there were two bad guys - one driving and one running the car. |
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Post by User Unavailable on Apr 11, 2014 14:32:48 GMT
Period explosives are expensive and hard to get hold of - or at least blackpowder is. (As Richard Hammond discovered the hard way there is only one place in Europe capable of making significant amounts of blackpowder, and that is in Spain). I was also thinking of the 1812 overture, since tradition usually involves using a lot of fireworks at the climax. While the MB theme is, of course, the more logical choice I suspect that classical music with a lower/slower pace might work better. If you tried to duplicate something with too fast a tempo the sounds of the various blasts would probably merge together making it impossible to pick out the tune. I think that in order to be considered plausible you'd want someone who has no idea what tune is being played to be able to identify it (or at least hum the song if they can't remember the name). Come to think of it this might be a perfect ending, as not only would it give them something impressive to end the episode on* but they could get both teams together - the team who set everything up and did the testing and the other team who have to try and guess what was being 'played'. (*As I said they could extend 'explosives' to include cannons, firearms and fireworks. The latter would allow an impressive light show, especially if they could perform this at dusk or at night. Naturally this probably wouldn't be suitable for the bomb range, since people live nearby, but they do have other options available. Black Powder in quantity may be difficult to obtain in Europe/UK, not so much over here in the USA. Black Powder and Black Powder substitutes are pretty easy to come by as we have millions of folks who commonly use them all the time. Re-enactors, hunters, pyro technicians, sport shooters, re loaders , the list goes on. They've used pounds of black powder already to test various cannon myths and fuse myths. It just a matter of ordering "more" from whomever supplies their powder. |
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Post by chriso on Apr 11, 2014 19:28:38 GMT
they tested the shockwave throwing things (people), and it didn't really work. the air in the shockwave isn't really moving - it just pushes and recedes, like a wave in water. the wavefront travels, but the water itself just oscillates. for the record, I am not cheering either way on this myth - it seems to be quite a stretch - but it is something that can be tested, has several variables to adjust, and can go from small scale to large scale; and it has the added bonus of twin explosions. Well, not much anyhow. In a true shock wave, the air itself does actually have a net displacement. That's the difference between a subsonic blast wave and a shock wave. The air in a shock wave is moving fast enough it doesn't send any ripples backwards.* On the explosion, I NEVER imagined doing this using two singular explosions. I would imagine that would stress the body similarly to being squeezed between two walls. I was thinking along the lines of having a ring of gunpowder around an object, at an equal radius, and setting the whole ring off at almost the same time using either electric ignition or some form of fast explosive. Timing would be the issue. Thinking about the problem, I wonder if having a large explosive a large distance away from the person or object being tested would be a good idea? It seems like that would allow the energy in whatever blast wave is being used, assuming its subsonic, to spread out more. Thus making being *infinitely thin* less of a concern. EDIT Going to add, I don't think this has a very good chance of working. But I do enjoy physics experiments, explosives, and being surprised. *I am of course ignoring the vacuum such a blast creates, as it is not usually as powerful as the original explosion. |
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Post by silverdragon on Apr 11, 2014 19:40:36 GMT
Can I just mention, in explosive pressure differentials, or ANY pressure differentials, there is no "Cancel each other out"...
There is "Storm"
When the two pressure fronts collide, there is what can only be described as a storm like action where the two fronts push each other, change direction, go up down sideways and around.
This is covered in fluid dynamics, [and actually happens inside a tanker when a vehicle changes from a left swing to a right swing or acceleration to stop or all four at varying intervals.][add an uneven road surface to that, and, well, its not comfortable...]
Anyway, if you are stood between two equal explosions and get hit by a [for instance] 20psi pressure differential from both sides, you dont get a 40psi differential, [where differential is against what was there before this happened]just a 20 blast, but, "between a rock and a hard place", you have nowhere to move to, so would be held there in that "Storm" until it all sorts its self out and dissipates.
It would knock the air out of you, then back in you, spin you about, and make a mess of your hair.
It may hurt as well.
To get an idea of this, get a tank with a wave machine at either end, get two large waves and aim them towards each other.....
And I mean waves, not ripples.
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Post by OziRiS on Apr 11, 2014 21:51:10 GMT
They did indeed do the tires myth, shooting at truck tires while the truck itself was on a rig. They also shot tires in the Bouncing Bullets episode to see if you would lose control of the car. One type of explosion I've always been a little curious about is those that have happened during colonoscopies. A pig should make a nice human analog and for visual effect a few feet of sausage casing strategically placed in a ballistic gel torso could be a holy crap moment (pun intended). There really is no way to supersize this though except maybe with a fire hose and an elephant analog.  There has been one death associated with "colonic gas explosions" according to a study mentioned in this article. io9.com/5945897/sometimes-people-explode-during-colonoscopies-heres-how-that-happens"...a survey of the medical literature conducted by Ben-Soussan's team turned up just 20 cases of colonic gas explosion between 1952 and October 2006, only one of which was fatal." I know it's probably not the "big boom" Jamie wants but it could add a little brevity to an episode devoted to explosions. Just gonna bump this one real quick as it didn't get any comments from anyone before going into the twin explosions discussion. I think this has some potential and I like it. It's been a while since we've seen a good medical myth with potential for gore  |
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Post by silverdragon on May 11, 2014 12:33:07 GMT
Is this request still valid?... 'cos I had a couple of ideas.......
Exploding Engine.
Take one normal average say two litre non turbo engine from an average family car and change the fuel...
I have heard and discounted a few myths such as along the lines of adding certain fuels (White spirit being one) to a petrol tank will cause the engine to explode as its far stronger than petrol.....
This I hear from those that watch "Top fuel" dragsters do the fireball and bits of engine at the start line and think they are just "normal" engines highly tuned?.....
You hear a lot from the other side of the bar when slightly merry "Enthusiasts" start theoretically improving their cars.
Right.
Ok...
So why didnt they run cars on White Spirit in the beginning?....
When Petrol as as scarce as White Spirit?...
Was it just that petrol is actually better than white spirit?...
So can we discount that?...
For the next one, and this I doubt, if you ran an engine on say Aviation gas without numerous modifications, would it run, run faster, or just explode?...
Same with "Top fuel" dragster fuel, will a "normal" engine from a family saloon even run on that kind of fuel?...without a LOT of tinkering and upgrades?...
Is there any liquid at room temp fuel that if used (added to the fuel tank) as a fuel would just explode a normal Petrol engine.
How about the liquid explosive part of TNT?...
Also, is there anything that if introduced into the engine intake as a gas would "Blow" the engine?... such as one I hear that says running it on LOX would be beneficial....
I always state that if you change the fuel you would have to re-map the ignition system, as even with pure LOX, the engine is set to run at 14:1, you cant increase the burn unless the fuel is there in the first place.
Next on the list is Oxy-Acetalyn.
If you just introduced the right mix into the air intake, would the engine even be able to combust such a mix?.. or will it explode.....
What we are looking at is an engine being run remotely blowing the pistons out through the sidewalls.
Can that be done just by altering the fuel.
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Post by silverdragon on May 11, 2014 12:39:01 GMT
"Your only supposed to blow the bloody doors off"
You know the scene already.....But in case you dont, its one of the one-liners most quoted from the Italian Job.
Can you ONLY blow the back doors off?....
Can you be THAT precise with explosives?....
And I ask that this be done in the spirit of the film, with period explosive technology that would be available....
(Not Military secret ones eve...)
Modern shaped charges and specialised demolition explosives that will cleanly remove the back door locks and hinges without even scorching the paintwork not to be used..... in the final cut.... perhaps they could use them as demonstrations of what could be done with modern explosives, but I would like to see what can be done with period explosives.
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Post by Cybermortis on May 11, 2014 14:10:13 GMT
Plastic explosives have been in use since WW2, and these are the basis for modern breaching charges. So in theory yes, period (60's) technology would have been up to just blowing the doors off.
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Post by the light works on May 11, 2014 15:20:17 GMT
for the Avgas question, it depends on the Avgas. Avgas for a piston engine airplane is gasoline with an octane rating around 105. an standard automobile engine will run just fine on it. a highly tuned automobile engine will be able to be tuned a little bit higher without experiencing engine knock.
as far as the exploding dragster engine, I will give you an anecdote I came up with as a kid:
"with my windup cars, I noticed that the tighter I wound them, the faster they went. but I also noticed if I wound them too tight, they broke."
the advanced faster burning fuels just allow them to spin the engine faster to get more horsepower out of the same size box of holes. superchargers just allow them to stuff more fire into the holes. the balancing act is getting enough fire into the box to make the car go fast without blowing the lid off the box.
testing the fuel limits of an automobile engine would certainly be entertaining and educational.
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