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Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/25/2016 11:55 AM

Ok.. not likely.. "At this stage of the investigation, preliminary review of the data and debris suggests that a large breach in the cryogenic helium system of the second stage liquid oxygen tank took place."

So? Did a valve open early? Don't tell me for a minute that it was some sort of O-ring.. again!

No that I've lead the post off topic.. The real reason I'm flummoxed this morning is because I learned that garbage bags are or have been filled with hydrogen for anti aircraft purposes.

I know I could google this up in a jif, but I thought I'd pass it on to the group.

My initial reaction was "If jet engines can have frozen turkeys tossed into them and be fine? How's a bag of gas going to stop so much as a hang glider? How would it ignite in the first place? Good luck getting enough of them in the air in the right time, place and quantity to be anything more than a nuisance."

How long would a garbage bad of helium float? and how high will it go?

My brother and I used to make epic NG soap bubbles and light them.

In the kitchen of course.. and yes the house is this standing. Mum didn't find until years later.

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#1

Re: Maybe space X encountered a garbage bag full of hydrogen?

09/25/2016 12:34 PM
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#2

Re: Maybe space X encountered a garbage bag full of hydrogen?

09/25/2016 1:23 PM

Like a fusillade of arrows.

Cheap, easy to make and no big loss if they float away.

Turkeys don't blow up when they hit the engine.

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#4
In reply to #2

Re: Maybe space X encountered a garbage bag full of hydrogen?

09/25/2016 3:39 PM

Does a frozen turkey traveling at a rate better than 1/2 the speed of sound contain more potential energy than a garbage bag full of hydrogen is the question?

Let me google that and get back to you.

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#5
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Re: Maybe space X encountered a garbage bag full of hydrogen?

09/25/2016 4:25 PM

The birds ARE NOT frozen.

That's a myth from long ago and it had to do with testing canopies of aircraft for bird strike resistance.

It's actually called a chicken gun, and the birds are room temperature.

We had a variation of this gun in our basement when I worked at Motorola Government in Scottsdale, AZ.

Our use was different in that we fired electronic artillery shell fuzes into 12" cubes of plywood to test the fuzes ability to withstand the shock of being fired out of a Howitzer and still work. These were nuke artillery shell fuzes.

There was another "shock start" test to determine if these fuzes could withstand the instantaneous transition from sitting still to turning at thousands of rpms as they were spun up by the rifling of the barrel. Interesting work.

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#6
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Re: Maybe space X encountered a garbage bag full of hydrogen?

09/25/2016 4:42 PM

I've never used a chicken gun before but a coworker made a 'cat cannon' once!

You see the was this story that moved into the workshop that just loved supervising everything. No matter what it was he was on it under iand in it even if could get him killed.

Nice friendly cat and knocked off mice 10x better than any of the bosses lame bait traps ever did so we didn't really want him to end up as a shredded furball on some piece of machinery.

Anyway one day we were cutting 8 - 10" dia tubing down to size for a repair project and Mr Cat was doing his usual top to bottom inside and out inspections to the point he was getting in the way.

One of the guys yells, "Hey! anyone ever seen a cat cannon before?"

So several of us turn to look in his direction just as he hits one of the tubes with a 2 - 3 pound hammer.

Sure enough. Cat Cannon! Mr cat came out of their like he had a 10# gunpowder charge backing him up!

It may sound cruel but it kept him from nosing around from then on. He'd sit on a chair or a shelf and supervise from there and no closer. In fact he lasted longer a that company than half the workforce including myself.

Now had we stuck the company owners head in the pipe and gave it a good whack maybe most of us would have still been working the today. Good lord knows a bit of brain damage certainly wouldn't have made his decision making any worse.

Simple fool Vs arrogant fool. Which one would you rather work for?

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#11
In reply to #2

Re: Maybe space X encountered a garbage bag full of hydrogen?

09/26/2016 10:29 AM

Re: "Turkeys don't blow up when they hit the engine."

Correct. Then, too, neither does > "a garbage bad of helium" < {copied/pasted}

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#12
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Re: Maybe space X encountered a garbage bag full of hydrogen?

09/26/2016 10:35 AM

Yet another reason why anonymous posters should be annihilated!

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#13
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Re: Maybe space X encountered a garbage bag full of hydrogen?

09/26/2016 10:50 AM

I think everyone should start posting anonymously and just fill the whole forum with trollish drivel and nonsensical attacks until they shut it down.

What good would an engineering forum be if every thread is nothing but anonymously posted crap from top bottom.

I mean they they gave us the ability to use it to post whatever we want to without having to put our normal screen names behind it so let use it!

What are they going to do? Kick everyone out? Delete everything? Hows that going to effect their forum rating?

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#14
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Re: Maybe space X encountered a garbage bag full of hydrogen?

09/26/2016 11:19 AM

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#3

Re: Maybe space X encountered a garbage bag full of hydrogen?

09/25/2016 1:29 PM

I think it's the IED/mine carried by the balloon that would be the threat, however these probably wouldn't stay airborne very long as the hydrogen seeps out....

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#7

Re: Maybe space X encountered a garbage bag full of hydrogen?

09/25/2016 4:58 PM

Helium is inert. How did that ever cause a fire?

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#8

Re: Maybe space X encountered a garbage bag full of hydrogen?

09/25/2016 5:22 PM
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#9

Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 1:50 AM

When I as in 10th grade, my younger brother would occasionally make acetylene balloons that would fly to about 200 ft, then explode in flames, I wasn't sure if it interfered with aircraft either.

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#15
In reply to #9

Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 11:41 AM

So, do you know why they exploded? How many seconds in sunlight was that? (hint)

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#17
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 12:10 PM

I really wasn't sure, at the time I thought as the balloon rose and the gas rose in temperature, gas leakage interacted with O2 outside the envelope and oxidation lead to spontaneous combustion. (?)

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#18
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 1:06 PM
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#19
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 1:08 PM

Did they light off their beans?

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#20
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 2:33 PM

Acetylene balloon + static electricity = Big Boom

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#23
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 2:51 PM

True that static potential increases as the balloon floats up. I was also thinking that some UV could penetrate the balloon and induce a concentration of free radicals that increases to the critical value after some seconds.

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#21
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 2:41 PM

Holy Fire Ball Batman, I'll bet Norman Frey thinks twice about doing that again!

He deserves an honorable mention survivors trophy at the next Darwin Awards Ceremony.

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#22
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 2:42 PM

Acetylene is heavier than air so it would have to have been mixed with hydrogen or helium...Then an ignition source, wouldn't take much....It's a wonder he survived....

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#24
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 2:54 PM

Where do you get acetylene to be heavier than air? The molecular mass is 26, whereas air is 28. Granted it is not all that bouyant, but it should float if the balloon is large enough. If the acetylene was made using the carbide process, and it got warm enough, it might be the moisture would be enough to make it rise even better.

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#25
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 2:54 PM

Nope. Acetylene has a nominal density at STP of 1.1 kg/m3 while air has a nominal density at STP of 1.2 kg/m3. It is barely lighter than air but it is lighter than air. Those balloons could not weigh very much for them to float.

Now who's....

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#26
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 2:57 PM

Dibs on that.

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#27
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 3:28 PM

Mc Donalds soda straws & dry cleaners plastic bags.

I wonder if the guy who wrote the alchemist hand book had a page on that ?

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#29
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 6:06 PM

That would be pure acetylene, not the kind found in welding tanks, and the density for air you are quoting is for dry sea level air, as you add moisture the density goes down, and as you add altitude it goes down further.....With the weight of the balloon I would concede they are ~=.... Not enough to float a balloon is the point....

However I think a demonstration is in order....hehe

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#31
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/27/2016 9:32 AM

Now, 10th grade was a few years ago. I do remember a few " launch " parameters.

The acetylene was welding gas, my brother liked to do oxygen/acetylene welding and cutting. He would get my mom to drive him to Cameron Welding to get his " bottles" filled, I think that Cameron may have been located in Buena Park, I don't remember what or who manufactured their process gas, I liked doing Arc welding, my brother used to criticize me because he said oxy/act welding took more finess and arc was the lazy way. These were the days when all schools had "shop" classes.

The balloons were launched in the early evening, (about 6-7pm) ( now remember, this was his project, not mine) ( I was more interested in solar energy-practical application) we were situated about 150' above sea level, and the launches were done in the summertime, so the sun came up early and went down later.

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#32
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/27/2016 9:46 AM

Are you certain the balloons were not filled with MAPP gas mixed with oxygen?

"MAPP gas" is a trademarked name, belonging to The Linde Group, and previously belonging to the Dow Chemical Company, for a fuel gas based on a stabilized mixture of methylacetylene (propyne) and propadiene. The name comes from the original chemical composition, methylacetylene-propadiene propane.

MAPP gas - Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/MAPP_gas Wikipedia

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#33
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/27/2016 10:12 AM

MAPP gas has a nominal molecular weight of 42 g/mol. It is about twice as heavy as air.

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#34
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/27/2016 12:30 PM

You need to mix oxygen with the acetylene to get a good pop...anybody who has worked with a torch knows that...FIRE IN THE HOLE!!!

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#28
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 5:05 PM

It would seem we have a urban myth on our hands.

For as long as I can remember ti I too have been told that acetylene gas was heavier than air.

High School shop class, multiple college welding and fabrication classes, my job at a welding supply store, most every welder and metal fabricator I have ever met.

"Don't let your unlit torch or a leaking line or fitting go. The gas will collect in a low lying area and before you know it . Boom!" Is what I was always told.

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#30
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Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 6:47 PM

Here's how you do it....you need helium balloons to lift the acetylene balloon....

Fairly awesome....

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#10

Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 10:25 AM

Barrage balloons work by not making a wall of balloons but a curtain of hard to see cables that tether the balloons. This is why the WWII barrage balloons were so big. They were lifting a heavy cable into the air.

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#16

Re: Maybe Space X Encountered a Garbage Bag Full of Hydrogen?

09/26/2016 11:44 AM

The cryogenic helium system is there to do two jobs: (1) keep the liquid oxygen liquid and at cold enough pressure, the vapor pressure is low, and (2) once coupled to heat, the system may be used to create additional pressure in the system to push oxygen into the rocket engine.

IF there was a large breach, this might also rupture the oxygen tank, and liquid oxygen is a strong fire starter in its own right, in other words contact is sufficient to initiate a flame chain reaction.

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