anyone else watching “myth busters”?

[betty.k]

i just got on to this show a couple of weeks ago, i wanna join their crew!!

if you dunno what i’m on about it’s a show on sbs, monday nights at 7:30 or 8. they take a popular rumour and find out for sure if it’s true, eg: does using a mobile phone while refueling your car cause explosions?

on that topic i think they missed a vital point. when they put the phone in the chamber full of petrol vapour they only rang the phone without it being answered.
to the best of my knowledge when a tactile (or any mechanical) switch is depressed electricity will arc between the 2 contacts just before contact. the myth busters claimed it was impossible to cause ignition with a phone but i think they should have pushed the buttons on the phone while in the chamber.

whatta you reckon:question::8ball:

[micro_Amps]

AKAIK, mobile phone use can cause ignition of fumes by the RF waves bouncing off multiple metallic objects (eg car, bowser, service station roof etc.) concentrating them and causing minor sparks. Same reason you dont put metallic objects in the midrowave.
Just what I’ve heard thats all.

[TallduDe]

yeah great show i missed that episode but they should have rigged it to answer dont ya think?

i still like the episode where they put those high power rockets onto a car and set em off!

a good show also on cable but without the ozzie guy comentating instead the original yank talking.

[z-beam]

so true betty! i didnt think about that one…

a few things that have been on cable/satelite that you can look forward to: baloon flight with helium and a pool chair, ice projectiles/jfk majic bullet theory.

that rocket car was awesome… possibly the fastest r/c ever, well maybe for its weight anyways!

betty watch em but dont join em… hasnt it occured to you how camp those two are?

[Pork_Hunt]

Man don’t worry about your mobile at a pump, when you hit the starter motor of your car you get a much hotter, better spark then any 3.6v mobile phone will ever throw. Dropping it, and the subsequent sparks off the metal termianls MAY pose a risk, but no greater than, for example, dropping your keys.

[Admin]

Very interesting show… and I was watching it a few weeks ago, and they were in front of their stores shelves… sitting on top is a vintage Tamiya Audi Quattro box…. and some of the drawers had marked on them things like “RC parts”, “Tamiya Tiger Tank parts” etc etc…. typical RC geeks… lol…

Alex

[bithed]

…great show…its on discovery channel here…Its on just before Odessey 5 which isnt too bad…

…I keep forgetting to watch it too…i saw the mobile phone one…missed them dropping a coin off a high building…exploding breast implants…i LOVE their workshop…

[betty.k]

man i’d wet myself if they asked me to come and play with them in their workshop!

@zbeam, i think you’re right but that’s cool! at least they’ll keep things neat!:D:8ball:

[bithed]

…they might let me in but they would let me out until id cleaned everything up..lol…

[z-beam]

they sure do know alot about creating latex/silocone manequins…:shock:

@bithed, is this how your woman treats you as well?:smiley2:

[bithed]

hell yeah beam..i have a little room in the house..EVERYTHING i own is in this room..from underpants to soldering iron baby…ANYTHING of mine is OUTSIDE this room and im not actually USING it then it is removed immediately, sterilized, hidden from my son and then disposed of in the next days rubbish unless i can rescue it..lol…and you guys think im kidding..lol…

[z-beam]

nope i dont think youre kidding bit, where did micro r/c come from? japan! why? space is at an insane limit.

at least you got a room to stash your gear dude! im probably one of the lucky ones because me and emma share a double garage for all things unused… some of my mates live in apartments half the size of that space!

[sg219]

I love this show!!

Did anyone see the one where they put dead pigs in a car and sealed it up for, I think it was 30 days, but may have been longer.

The smell was sooo bad that they had to move the car away from the shop.

[z-beam]

ewww:dead:

[trash]

Yep, the show has been around for a while, but I’m glad SBS is showing it so I keep on working out ways of stealing it from foxtel. 🙂

The mobile phone at petrol pumps has always been complex bollocks. About 2 years ago I had some dip shit stop the pump on me and it was about $1.80. So I finished the call after 5 minutes and went in and paid for the $1.80 and went to the next station down the road.
We had a safety OH&S email sent to us with this exact same kind of urban myth rubbish. When I approached the safety officer explaining that this email was as much bullshit as the “wearing contact lenses while arc welding” email. He got stroppy and accused me of being a young punk smart arse trouble maker. Which is a valid claim, but my RF engineering experience over rides his ability to post emails without thought.
I even offered to blow up my mobile phone in the name of science but I was quickly dispatched.

A second email on the subject was posted about a month later and it included a video (which I still have). After viewing it a second time is was instantly recognisable as a static discharge and the cause was from the driver’s seat/clothes.

It was from a different person (a boss), but they aggreed that the video which has a woman getting back into her car was caused by static, not by her answering her phone. He subsequentially sent around another email explaining that he and I believed it was more dangerous to suggest that mobile phones were at fault and mask to real cause of static electricity. The solution was “Not to re-enter your car until you have finished fueling the vehicle. (That was 6 months ago)

Tuesday morning I went to the safety officer’s desk and asked him which of my arse cheeks would he like to kiss ?

What does amuse me is how ard it was to ignite petrol fumes. Even the fire brigade guys were over reacting to the expected fireball. I would have been standing well back with them.

Here is the myth in it’s pure form:
lets disect it: sorry uA 🙂

“AKAIK, mobile phone use can cause ignition of fumes by the RF waves bouncing off multiple metallic objects (eg car, bowser, service station roof etc.) concentrating them and causing minor sparks. Same reason you dont put metallic objects in the midrowave.
Just what I’ve heard thats all.”

The last sentence acts like an active protien that validates it’s existance like a virus and gives it an excuse to live and propagate.

There isn’t any truth in the previous sentences.
mobile phones can cause ignition of fumes: No
mobile phones can cause ignition by RF: No
mobile phones can cause ignition by other means: possible, but unlikely .. shorted batter catching fire ?
by RF waves bouncing off multiple metallic objects: RF usually bounces of metal and other non metalic objects depending on frequency.
But this does not start fires or cause sparks.
Even increasung the transmitter power to 1kW of a BIG microwave oven will still not cause objects to spack because they are ‘reflecting’ signals.
To sugest that objects in a random environment could focus RF or any other energy is so astronomically impossible. Think of it like “the kindergarten death squad”. (20 kids with mirrors and one target) It just doesn’t happen randomly.

concentrating them and causing minor sparks:
concentrated RF or high power RF doesn’t behave any different to low power RF. The laws of physics don’t change just because you have more of something. (apart from gravity)

Sparks in a microwave are cause by objects being in the ‘near field’. The whole oven is a faraday cage which contains the near field. The maths start to get complex as wave fronts add and subtract everywhere.
Sparks only occur for one of 2 reasons.
Firstly the metal (or conductive) object has to be resonant. A dipole would be a classic example, but edges edges of metal sheets etc can also be resonant. If you look at a dipole voltage and currents, you will see the ends of the antenna have high voltage and the center has high current.
Sparks will be caused by a breakdown between two antennas side by side that flash over and in the center of the dipoles the current will cause the metal to heat and melt also a source of heat for fire.
A CD in a microwave is a classic example.
As the aluminium foil is vapourised and cut, the edges are detuned and no longer spark, but the areas that are resonant continue to sequentiall burn until the whole CD has no more resonant parts.

[micro_Amps]

Well there you go, bugger me, and bugger urban myths. Another one bites the dust.

:DuA

[trash]

Strapping a jato to a car … I wasn’t sure about that one. I’ve seen jato’s used on Herc’s and a video of them being used in reverse to ‘short’ land (crash) hercs.
Still, it was a hell of a lot of fun to see a raido controlled 1:1 scale rocket powered car !
YEAH BABY !!! 🙂
Another myth busted, though I would have loved to see that car fly !

[PandaBear]

The 1:1 RC on Monster Garage is more fun.

At least they didn’t just drive in a straight line!!! 🙂

[trash]

Bugger the “RC” !!
Which is more fun… skootin’ down Sydney Harbour in a Hovercraft or controling one while you stand on the beach. 🙂

[PandaBear]

Even Hollywood stuntmen wouldn’t be stupid enough to dare driving a JATO car.

… not when the “myth” includes finding remains of the original car flat as a pancake in the side of a mountain, 30′ up.

[betty.k]

well i dunno about you guys but i wanna make me a tree cannon!!:p:8ball:

[TallduDe]

same!!!!

this show is one of my fav’s. wish i could blow up a tree.

[trash]

6 pounds of black powder. I pissed myself laughing … flashback to Hungary … “Common Borris, put more of the powder in there, we’ll show them tartars who’s da boss !”
Of course the tartars came along and saw the hungarians blow themselves up …. but they were laughing so hard that even their horses couldn’t ride straight and they had to call it all off 🙂
I’ll stick to steel for my cannons, or PVC for potato cannons.

Got to love the size of their marx bridge though.
Some serious voltage being generated there. I can think of a few people with tounge studs that I think need to be struck by lightening. 🙂

[jamiekulhanek]

A guy i know made a goldball gun with PVC pipe 🙂

One of my dads friends made a potato gun and ‘tested’ it on his fence :), he didn’t try it again 😀

[trash]

Spud guns are ok, they’re a lot of fun and not that scarey. I’ve even seen one built to fire 600ml coke bottles which gets a giggle.
Compressed Air is an excellent accelerant, but it increases complexity.

If you want to throw heavey stuff, a trebuchet is the weapon of choice. I have a design for a small catapault that I’ve been meaning to build for many years. It’ll throw a waterbomb a good 200 metres.

[jamiekulhanek]

My sisters ex had a fantastic slingshot, took 3 people to operate, but was great for firing waterbombs/pinecones/other objects for huge distances!

[merc-blue]

i would love to buy one of them hunting sling shots to take out pidgeons with .. lol

[TallduDe]

http://www.trebuchet.com/

always wanted to get one off that site.

[betty.k]

i remember another series on sbs years back that consisted of people re creating ancient feats of engineering with only the tools of the time, eg: making one of the stonehenge structures and they made a full size trebuchet too. fricken ingenious machine!!:p they sure can fling a rock hard!:shock::dead::8ball:

[jamiekulhanek]

Quote:

i remember another series on sbs years back that consisted of people re creating ancient feats of engineering with only the tools of the time, eg: making one of the stonehenge structures and they made a full size trebuchet too. fricken ingenious machine!!:p they sure can fling a rock hard!:shock::dead::8ball:

I remember that program quite well, they made a bridge atleast 100′ long over a river from grass!!

[trash]

This forum needs a steam catapult for bit cars !
opps, just gave away an idea for the next comp 🙂

[z-beam]

Quote:

I remember that program quite well, they made a bridge atleast 100′ long over a river from grass!!

was that the one where the made the woven grass matt and floated it on the water so that you could run across the surface using the waves to support you?

whats this about a new competion?:question:

[novin]

ce?

novin

[z-beam]

huh? what you trying to say novin?

[novin]

was trying to figure out what you guys are talking about, didn’t read page one, only page x2 x3. read page one, now it makes sense )

novin

[Author]

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