Surface-Fired Chemical Tanks?

April 24, 2018
(rough, incomplete)

Chlorine barrel bombs as shown over the years often have a metal harnesses seen attached or nearby in pieces. These make some sense in the allegation that they're dropped from government helicopters. This is one way of attaching fins to help it fall the right way, and even little rolling wheels to make pushing it out of the chopper a easier. (see wheels attached here, in the napping cylinder linked to the alleged chemical attack in Douma on 7 April. - yellow box. Credit: Andrew).

But also note how it remains loose around the cylinder - not unlike the welded-on collars used to attach exterior fins to standard "Hell Cannon" shells, which are modified propane tanks of a much smaller size than these yellow ones.
--
Petri Krohn on Twitter:
The #harness around the #DoumaGasMassacre cylinders is needed to fire the #chlorine cylinder from a #HellCannon.
Similar harnesses were used in early Hell Cannon variants.

How did the rooftop cylinder escape from its corset? Or were both pieces planted?

--
If chlorine tanks of this size could be fired, it would be with a much bigger weapon, with a much wider, yet very thin-sided firing tube. As far as I know, no one has seen such a weapon. It seems entirely possible, but unknown (as far as I know, which isn't that far).

Neither tank shown in the Douma attack appears to have really fallen or flown into place, instead seeming planted. The damage to the tanks is too little to suggest much of a fall, and the damage at the buildings seems to be from something else in each case.

I don't know of any prior cases in the area suggest such tanks being fired in. If so, the devices used for that should be found soon, if not already. If not, then probably such a weapon doesn't exist there, so let's not allege it and get people expecting that.

Other places, Aleppo and Idlib, where rebel military industry is more evolved, it seems they probably have been firing these things around. I don't mean to make a detailed study, but I'll start with one case as a good example, and maybe add a few more in time.

Sarcastically, I replied to Petri:
https://twitter.com/CL4Syr/status/988728051776217089
But in the real world we can see these fall with massive force, straight down from way up, smashing trough floor after floor of buildings straight down, only stopping in shreds.
Case in point Khan al-Assal 22/8/2017
https://www.youtube.com/watch?v=o5ZeRxyc4h0

(graphic updated here to show normal artillery angles vs. helicopter drops (basic idea).)

Notes:

red = impact area (app. hole punch #1 and only)

pink circle = apparent impact point (not 100% certain, but I think that's where it hit - rough patch there, an plaster tends to fall off at impact point and below. Possible re-bar segment impact on far right, same level, just above window frame)

pink lines = trajectory to there, and apparent bounce to resting place

orange - angle of flung debris that chipped the walls

Normal helicopter barrel-bomb-type drops are done by hovering over the selected target and dropping the weapon straight down. If they did it while flying at speed, from a very low altitude, this kind if angle and force might be possible. But it's just very, very unlikely, this was dropped from an aircraft.

It's also possible this thing was planted, but they picked a poor site for their case if so, and the whole scene makes sense to me as a surface-fired gas cylinder. Here, perhaps a slightly looser harness than in Douma, able to fit round the firing tube? That's not obvious to me. But look at that incoming angle!

Update 4/29, Skipping some maths but adding anyway: Considering if it were at usual height, but speeding at 100mph...
https://twitter.com/Mare_Indicum/status/988747040984186880
100mph is 44 m/s. Terminal velocity at least  200 m/s for random orientation. Yes a smallish angle and if I could recall my geometry course I'd be able to tell you what. But air resistance will slow the 44 m/s a bit so it'll be steeper than you might think. 15-20 degrees? (guess)
https://twitter.com/Mare_Indicum/status/988750044823212032
calculates under 12
https://twitter.com/MichaKobs/status/988756061237673989
Just take a triangle of vertical 200 (increasing) and horizontal 44 (decreasing) to estimate a possible angle.
https://twitter.com/CL4Syr/status/988759192986050560
That I could do easily and did. Average slope (pink) measures 12 degrees on the protractor. Realistic curve added here (red) comes out more like 6 or 7 degrees from vertical at impact. The true curve should be a bit different but similar, well under 12 degrees. And that's for a helicopter speeding along at 100mph. Normally if you want your barrel bomb to fall on that school or that one basement-trapped family, you hover over it and drop straight down, let gravity provide your accuracy. Higher speeds could increase the angle, and obviously so could a lower altitude, albeit within range of rebel surface fire. But what would it take besides speeding low to take the 6-7 degrees and turn it into more like 60 degrees? It's impossible. There was simply no fall from a helicopter or any other aircraft. Surface firing is the only other option.

Some think the Khan al-Assal cylinder was planted there, but I don't think so, and I just noticed this: the 7 or so torn short segments of rebar on the far side of the hole and the long, ladder-like flung segment prove it was a long-bodied object like this, flying in endwise, that tore the rebar. It was going almost between the rebar on its width axis, and against it the other way, over that long a span (in red). That's not consistent with this falling in horizontally - too small a hole. But the hole is too big and the tearing of the grid is wrong for a normal, nose-down vertical drop, which we can already see wasn't the case. It came in at whatever angle gets that yellow bar fitting through that hole about the red bar's width. Probably about the same angle as all the other damage suggests. So it was not just planted, nor dropped from a hovering or a speeding helicopter. Surface firing is the only other option, however exactly it was done.

Update 4 April, 2019: Did a HTS-Nusra Front drone filming one their attacks capture a full-sized cylinder with fins flying past? The scale isn't clear, but the shape is like that - not like regular propane-tank HC shells. It lands with a powerful blast that could, to an expert, say the basic size and volume of this projectile. If it's as bag as it seems, and that video is genuine (seems like it to me), they're proven to be launched sometimes.

Charles Wood, Showing the projectile: "I'm pretty sure this projectile is a full size gas cylinder fired from a hell cannon"
https://twitter.com/Mare_Indicum/status/1108145676481785856

Linking to video
https://twitter.com/Mare_Indicum/status/1108213343775412224
Video (edited re-post, not original)
https://www.youtube.com/watch?v=rB4xDbogIgM
Al-Nusra Drone Footage Tunnel-bomb Captures Hell Canon Shell Nearly Taking Out Own Drone.

My notes and image
https://twitter.com/CL4Syr/status/1108726268483137538

We've seen it in flight, but not being launched. So the method is still speculation. Kariii with another thought on how it could be done:
https://twitter.com/kraaiiii/status/1108453134119170048