[paul cotter (OP)]

Watching the recent events in Syria with the reckless firing of weapons into the air, I wonder where these projectiles return to the ground and with what energy. The path will be roughly parabolic and in the absence of air the return energy will match that of dispatch. Air resistance will result in significant loss of energy, still I would not want to be on the receiving end. Any ideas on how dangerous these returning projectiles will be?

[alancalverd]

The terminal speed of a 9 mm bullet is around 250 ft/sec. This is considerably less than the muzzle velocity of an AK47 (1000 - 1500 ft/sec) but dangerous if not always lethal.

[paul cotter (OP)]

That is faster than I would have guessed and could definitely do damage.

[Petrochemicals]

It does more than damage paul, the A rabs are well known for celebratory gunfire and thus deaths.

https://en.m.wikipedia.org/wiki/Celebratory_gunfire

 Not sure of the maximum velocity, ak47 bullets, like all warfare rifles are metal jacket points to conform to the Geneva convention so you would need to find it's resistance.

[vhfpmr]

This thread reminds me of a day I walked through a hail of clay pigeon shrapnel, you'd think someone would have the sense not to hold a shoot over a public right of way, really.

As I keep pointing out to cyclists who like to refer to the difference in kinetic energy between a car and a bike, kinetic energy isn't really a very useful metric for gauging the potential to cause harm: the kinetic energy of a 72kg cyclist travelling at 12mph is exactly the same as Dirty Harry's Magnum 44 (1037J, 16g & 360m/s, to save you looking it up).

Energy lost on impact is a big step in the right direction but even that doesn't cut the mustard, as a simple thought experiment demonstrates. If a stuntman jumps from a skyscraper, the outcome will be very different depending on whether he lands on the pavement or an airbag, even though the terminal KE and total dissipated energy are the same in each case.

What differ are contact area and modulus of the materials, hence stopping distance & acceleration, hence force & pressure.

[alancalverd]

This thread reminds me of a day I walked through a hail of clay pigeon shrapnel,

Good example! Wartime advice to country housewives was to prepare a few shotgun cartridges by consolidating the shot with candle wax, thus not merely irritating an enemy parachutist at 25 yards but completely disembowelling him with a single shot.  If in doubt, use the second barrel to decapitate.

[paul cotter (OP)]

I would not have thought paraffin wax would be strong enough for this job. I have definitely heard of this, many many years ago, but I thought something more resilient than paraffin wax was used- to be honest I can't remember.

[alancalverd]

If you have a shotgun, a classic physics demonstration is to replace the shot of a 12-bore cartridge with a candle, and fire it though a blackboard. I recall seeing this done at a Royal Institution schools lecture many years ago, but Health and Safety have now banned blackboards!

[paul cotter (OP)]

That really is a shame, Health and Safety interfering with science. I will have to inform BC about this as I was arguing with him about how H&S was making life difficult, no lead in solder, etc. Could we not fire a black candle at a white board?? (joking, of course). I don't own a shotgun or any type of gun, so it is all hypothetical.

[vhfpmr]

I recall a farmer demonstrating the difference between a rifle and a shotgun. He fired both into a thick wooden board from about 2' away, and they both made a neat hole in the front the size of the bore. On the back, the rifle hole had a couple of small splinters, and the shotgun hole had a patch about 3" diameter split away.

[Bored chemist]

H&S was making life difficult, no lead in solder, etc.

That's the environmentalists.

Could we not fire a black candle at a white board?

Sure.
But do a proper risk assessment first.
Also, you will need some sort of firearms license.

HSE very seldom banned anything.
They just said that if you wanted to do it, you had to document that you could do it safely (and that there was a benefit beyond the residual risk).

This thread reminds me of a day I walked through a hail of clay pigeon shrapnel,

Good example! Wartime advice to country housewives was to prepare a few shotgun cartridges by consolidating the shot with candle wax, thus not merely irritating an enemy parachutist at 25 yards but completely disembowelling him with a single shot.  If in doubt, use the second barrel to decapitate.

Be careful; you might be committing a war crime.
https://en.wikipedia.org/wiki/Attacks_on_parachutists

[paul cotter (OP)]

Apologies,BC, mea culpa.

[alancalverd]

Be careful; you might be committing a war crime.
https://en.wikipedia.org/wiki/Attacks_on_parachutists

which reads, inter alia....
 

However, firing on airborne forces who are descending by parachute (i.e. paratroopers) is not prohibited.

So it is incumbent on the farmer's wife to distinguish between aircrew and airborne ground troops, and also between legitimate civilian passengers and spies.

Furthermore

In 1977, this practice was finally outlawed in an interstate armed conflict by Additional Protocol I to the 1949 Geneva Conventions:[1]

Article 42 ? Occupants of aircraft

No person parachuting from an aircraft in distress shall be made the object of attack during his descent.
Upon reaching the ground in territory controlled by an adverse Party, a person who has parachuted from an aircraft in distress shall be given an opportunity to surrender before being made the object of attack, unless it is apparent that he is engaging in a hostile act.
Airborne troops are not protected by this Article.

So everyone inside a serviceable enemy aircraft is a legitimate target, but some of the survivors of a damaged aircraft may not be.  Being naive, I would have interpreted flying over Britain whilst displaying enemy insignia as

  apparent that he is engaging in a hostile act

no matter what his duties and status may have been whilst airborne. 

[paul cotter (OP)]

Hi BC, a little update on a subject we had previously discussed. Recently I ran out of regular 60/40 solder and I needed to order a fresh supply. Looking at the website of the local RS franchisee, Radionics, I was greeted with "ONLY FOR PROFESSIONAL USERS" which may or may not have been displayed the last time I made a purchase. I decided to look for an alternate supplier but got the same silly nonsense everywhere I looked. I had noticed that a company I use for printer cartridges had a suitable solder on their website, replete with "ONLY...................." so I decided to try to place an order. Within a couple of days it arrived by post(postman was not wearing a hazmat suit!) and stuck on the spec was more "ONLY..........". At this point in my life I am purely a hobbyist and no way could my use be described as "professional". I reckon no retailer is taking any notice of this silly rule and i'm sure I could have obtained from any of them.

[Bored chemist]

I would have interpreted flying over Britain whilst displaying enemy insignia...

So would I.
But the case in point wasn't someone flying. They were descending by parachute and the status of the plane was left undetermined.

You seem to have read my post ...

Be careful; you might be committing a war crime.

as if it said "Stop! You will be committing a war crime".

Do you see the difference?

[alancalverd]

I see the difference in theory quite clearly.  You have ignored the practical problem:

Anyone inside the aircraft is a legitimate target, so you shoot at it, rendering it incapable of continuing normal flight. Some or all of the occupants elect to parachute from it.

Some of the parachutists (spies, infantry) are legitimate targets under the convention, and others (civilians, aircrew) are not.   

[Petrochemicals]

https://www.amazon.co.uk/Electrical-Soldering-Circuit-Repairing-Essmetuin/dp/B0C8JQWRB7/ref=sr_1_6?dib=eyJ2IjoiMSJ9.aQmMyP7olosXzni-BRYiCw901I-XMkWfqGF693YUlKwnwjpQHndQFokCIBWDntTpOiMthhkvQlxfcJMQFiToR3zFN6196iPd5EOYSNvbMiUQGbl85jMj0IW13zx3Y3gEp87hZlUatjdy8flrdffbN4UFqlYFMLEKt04REbd0CErL-Rlxp8b8D7KCSZXBe8hnrziVmefXqC91E227QKoyIBHWBjKEagqlqEg2XTOvid1FrgmCmsPFyMZS5GSSzldp6h_4UJf8VixnCCcTZpjeKu5erZnrdyReyXSynLbE7Sv6H0QVnG8ZOH0KuUbXTZ75vE0j29FiI1PY0nh5zOKEBdbxMe5vZx99gA_NddY26vsN-7VZBAN1gsOvcgIKG-gj66pqpuIFB3tg2mJhaLoQ3J5bERgI919kTGa1Up603mhXA8G_eCHq3Pg4EaxJN9Mu.g5_DszXW4zUcAjAc5wJLVo4u80iiAEmckvTBIjjOcsE&dib_tag=se&keywords=60%2F40+solder&qid=1734776356&sr=8-6

[paul cotter (OP)]

Yea, no silly warning notice with this placement, most likely because it is an American company. The cost however is over twice what I paid for my purchase, so this is not a viable route for me.

[Petrochemicals]

Yep I find ebay amazon and especially the Chinese supply chain play by entirely different rules, which is a bit unfair, they will also increase the price with our merit too, you probably can get asbestos insulation if you look. Was that a quantisized price including p+p Paul?

[paul cotter (OP)]

Not quite sure what your question is, Petro. The Amazon ad was 50grams for ?9 +?5.5 p&p. I bought 100grams for ~7euros + 3.5euros p&p. Big difference. PS: the forum software is turning pounds sterling to ?