Monday, June 29, 2020

One of Those “That's Funny” Stories

Every so often you see stories in the news that make you say, “that's funny” and then disappear.  You wonder what's really going on but while you'd expect more followup stories, those just don't show up. 

There was a story like that over the weekend but today I'm only seeing it on PJ Media.  The Associated Press reported on Friday that a huge explosion had occurred that rattled Tehran and lit up the horizon. The site of the blast was a region where many nuclear experts believe Iran conducted high-explosive tests relating to its nuclear program. 

The explosion happened in the Alborz mountains, just east of the city and appear to have come from the Khojir Missile Base in Iran. There is some Twitter back and forth about it, saying that the Iranian regime is trying to say it was somewhere else, when open source, commercial satellites clearly show some differences at the Khojir Missile Base.

If that's what happened, 5,000 liters (about 1,300 gallons) of propane could make quite a boom, but propane isn't typically used as a rocket fuel.  That's not to say that it couldn't be used with the proper design trades, just that generations of actual rocket scientists have looked at the trades and don't consider it a worthwhile fuel.  If it's the only fuel you have, it can burn, it's just not as good a rocket fuel as methane.  The most up-voted answer at that previous link is:
Propane, with ~5-7 bar vapor pressure at ambient temperatures would require a pressure tank (not acceptable on a rocket due to mass), or needs to be cooled to at least -42oC. This combines disadvantages of cryofuels and complex hydrocarbons, giving a very small specific impulse rise over RP-1, and while rather large, still insufficient boiling point rise above methane. 
In my limited perspective the pieces don't add up here.  I think it's entirely possible that thousands of liters of propane went boom, I just don't think that it's likely they're developing rockets based on it.  I'm assuming that if there was any indication that was nuclear, somehow that news would leak out, but there are uses for other explosives in a nuclear warhead that could also have gone boom.  I'm left where I started, with a “that's funny.” 


  1. meant "funny" as in "peculiar", and not ha-ha.

    Yep, I've seen many stories like that and often wonder why they weren't followed up on.

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  2. Wonder if they were doing bio-research instead of nuclear research. Hmmm...

    Propane would more likely be used in either bio or chem research, bio for the fuel purposes, chem for the chemical compound usage.


  3. Nope, nope, it never happened and anyway it wasn't here. As someone who had a small (very) part in spy satellite optics, I say GOTCHA.

  4. They could have just been using propane as fuel for housekeeping purposes. A thousand gallons would be a bit much for cooking, but just right for fueling a big furnace.

  5. Propane can be feedstock for all sorts of chemical products, and it's cheap and relatively easily handled. Was the detonation just a big "ooops" or was it sabotage? We'll likely never know.

  6. Propane fueled BLEVEs (Bulk Liquid Expanding Vapor Explosions) give you a fairly large bang.

  7. All you have to do is liquify the propane. This is done in millions of household installations everywhere in the US. In a home installation, the pressure inside the propane tank is generally 150 to 200 psig, depending on ambient temperature. These are quite low pressures. Even your municipal water main operates at about 60 psig.

  8. Propane, smopane. This is what I found funny peculiar over the past few days.
    1. This explosion story.
    2. TWO Iraqi raids on Iranian backed targets in Iraq.
    3. Rising tensions in Israel. Which Palestinian group is Iranian backed?
    4. Increased radiation levels blamed on the Russians.
    5. Iran issuing an arrest warrant for Trump.
    Anyone want to try and connect the dots on those?
    I will suggest:
    1. Israel did it.
    2. Someone suggested Iraq tamp down on Iranian actions in Iraq.
    3. Iran was fomenting unrest in Israel. Led to #1.
    4. The weren't no "propane" explosion.
    5. Iran is trying to move the spotlight off the explosion and the illegal activities it exposed.
    Any thoughts?

  9. Sorry, can't edit.

    1. Israel did it to disrupt some research project. Nuclear?

    4. That weren't no "propane" explosion. Maybe the propane blew up, but there was something else there that needed to be eliminated.

    1. We're on similar trains of thought. I discount #2 because the Iranians and Iraqis have been at each other's throats for ages. That old Shia vs. Sunni hatred. Iraqi forces trying to kick Iranian forces out doesn't surprise me even the tiniest bit and nobody needs to suggest to Iraq to do it.

      I considered that the radiation being seen in Europe might have come from Iran, but I don't think prevailing upper level winds blow SE to NW. Remember there was a similar story in 2017 and that turned out to be an isotope used for medical studies. Probably urine from a couple of thyroid cancer patients. Summary here.

      In this case, it's easy to say the Mossad did it with no evidence at all. Just because Israel has been throwing any wrench they can find into Iran's nuclear programs since Iran started. I notice, though, that Iran didn't reflexively blame Israel or the US, like they do for everything.

      That leads to something like your second numbers 4 and 5. This wasn't a propane explosion - at least not just a propane explosion, and from what I can hear, it's more like Iran saying, "nothing to see here; move along, move along".

      Another thought is that this facility, like most of Iran's secret work, is in underground tunnels. I wonder how much of that collapsed and how many people were trapped underground?

  10. I'm curious about the "requires pressure tank" and is thus not used for rockets. Starship uses methane and their tanks will be tested to 8.5 bar before human flight will be allowed, which is above the 5-7 bar range in your quote (though propane goes to ~12 bar at 100 degrees F).

    The other thing is, why do we believe this was propane? Liquid methane can be stored in similar tanks, and it is true that it's more suited to rocketry than propane. Elon Musk is running around showing everybody in the world how well methane works as rocket fuel.

    1. All I know is what they tell us. That picture says it was propane.

      I've read some about propane-fueled rockets and the answer was pretty much, "too much bother for any possible benefit".

  11. One thing that is a problem with propane as a fuel is that propane is heavier than air while methane is lighter than air i.e. it will evaporate. Propane will lay in a shallow spot waiting for a spark.

    1. And so does butane, though many people think it is safe and propane is not.