range activated exploding projectile

[Ctrl_C]

Most of you have seen my spudgun by now. It has a 2" barrel and is pneumatic. Spuds are great and do a lot of damage but I'm looking for something better.

Imagine a smaller that golf ball sized moldable explosive, surrounded by tiny nails to make a spiny little grenade smaller than 2". Now imagine it has some very small electronics in it also: an accelerometer, an adjustable timer, and a small power supply. The whole thing is encased in paper mache' to make a nice mortar-like ball that fits the barrel perfectly. Now the idea is that you take the range of your target with a range finder, plug it into some simple projectile motion equations, and figure out how long the shell will take to get to the target. You open a little flap or something on the shell, set the timer, and fire. The countdown starts at the end of positive acceleration (when it leaves the barrel). As the shell travels down range, it counts down it's preprogrammed time and at the end, triggers a switch or relay to connect a circut with the ignitor, causing it to explode.

This idea could be improved upon with an electronic range finder. Instead of manually entering the time, perhaps the shell has metal contacts that touch other contacts on the inside of the barrel. The range finder relays the range into a microchip which calculates the time it takes for the shell to reach the target. This time is relayed from the chip to the shell via the contacts.

I am going to begin testing this sometime this summer, starting out with a simple fused design just to test its worth. If it proves effective, I will try the electronic version.

As always, any suggestions?

[Madog555]

thats a little complicated and expensive to just make it go boom. it would be a marvel though. i would probaly have a long string that pulls a pin out as it travels away to activate a simple imact initiation device. you could use a thin wire that is coiled on the back for compactness. it would be a good precaution to make sure all the shrapnel is on the front and sides. so it doesnt face u if it goes off ass the pin is pulled.

military greanades are activated by spinning in flight.

<small>[ June 20, 2002, 04:44 PM: Message edited by: Madog555 ]</small>

[xoo1246]

If you want it to explode on your target I would use impact detonators. You would have to have very consistent V0 on your spudgun/ cosistent design of your grenades and 500 other factors to make it work. I think it's overcomplicating stuff. I would rather spend my time developing safe(r) impact detonators and doing experiments, measurements and calculations on angle vs range (vs wind). But don't let me stop you.

[VX]

That’s a great idea. :)

However I was once going to make something similar, The circuit was a simple 555 monostable circuit. It was set to turn on and start counting when a reed switch was triggered as the projectile left the barrel of the cannon (a very powerful magnet was to be attached to the outside of the end of the barrel). The voltage was kept 'turned on' by use of a thyrister.

There were some issues with it though, the barrel must not be made of a magnetic material, and the magnet must be removed when loading the projectile.

I think that the main advantage to this design as opposed to yours is its simplicity. Also it is very cheap, the electronics for each projectile probably not costing more than £2. I think that a PP3 (9 Volt) battery is the most cost effective power source, and because of this the projectile would probable by elongated like a proper mortar shell. Finns could also be added for extra stability.

This design does not however take into consideration the speed of the projectile, distance from source or any other factor. This would be a big problem if you had a misfire.

On a simpler note, how about just using the same design as an 'airbomb' (firework) and using the lift charge to light a section of slow burning composition and have this leading into a primary charge (AP, HMTD etc) which in turn could be used to detonate a secondary explosive..... This is much less complex, but is a tries and tested method.

[Ctrl_C]

There's actually a funny story related to this. The original idea started out with putting a mortar type firework into the barrel and shooting it. My friend was going to light it, quickly load it, and I was going to throw the valve. Well, apparently this cheap ass chinese fuse burns a LOT faster than my stuff. He lit it and was trying to shove it down the barrel and 3 secs later: BANG!.

I knew the base charge had went off and the main was about to go off so I instinctivly ran into the nearby garage. Unfortunately, my friend didn't have such an advanced understanding of how fireworks work as I did. He just stood there, unhurt but shocked, and then the entire area for about 40 yards instantly burned brightly and created thick thick smoke as the burning stars whizzed past him and onto my porch, yard, picinic tables etc.

[A-BOMB]

Ctrl_C why not just use a radio transmitter and reciver setup. The transmitter has a adjustable range, the reciever is hooked up to a small relay, once the reciver is out of range of the transmitter the relay closes and boom.

[CyclonitePyro]

This reminds me of the OICW, that gay looking futuristic gun, wouldn't mind on though. Look here <a href="http://www.hecklerkoch-usa.com/pages/military/fwframeset.html" target="_blank">http://www.hecklerkoch-usa.com/pages/military/fwframeset.html</a>
That's is depressing, I bet the friendly UN Peacekeepers will be sporting these when they come to put me and others who think alike in FEMA centers. :mad:
Sounds like a fun project, it would be a little OTT for me but if you can do it then more power to ya.

[pyromaniac_guy]

a bomb....
althougha radio transmitter is a good idea, i dont like the idea of making the relay trip when the transmitter is out of range.... murphys law states that if you do something like that, you are much more likely to drop the transmitter, or have it's battery die after arming the projectile.... still a good idea though.... lets say you wanted to set off a remote charge.. you could laungh it with your spud gun, then set it off any time you want in the future, so long as you still have battery life left in the transmitter. i owuld caution against useing off the shelf transmitters though, as it would suck to have a 'round' go off in your pocket because someone drove by while pressing their garage door opener

[PYRO500]

I remember seeing a while back a baseball that you could throw and it would start and stop a timer when it was thrown/caught, the internal timer would calculate th speed (if it was thrown at the right distance) I was unable to find a patent on the specific device but it seemed simple enough and was about 5$.

[pyromaniac_guy]

the only problem with the use of a simple timer is that it makes no distinction between a misfire and a proper shot, ie if your projectile just pops out of the barrel, you arent going to ahve alot of time to duck and cover before things get very ugly. Thats one feature of the OP's idea that i kinda like, an accelerometer. this way you can build the thing with a fail safe... an accelerometer tell the time to start counting down, but a solid state relay that carries the initiation signal is not activated unless the accelerometer sees x g's....

[pyromaniac_guy]

also, if you had the funds and wanted to get REALLY devious....
you could use a small gps reciver.. they are making um to fit in a few cubic cm of volume these days.... see:http://em.tycoelectronics.com/micro/gpsnews.stm
you could make a large caliber spud gun, and sew up into a stuffed animal a reciver, antenna, battery pack, and explosive of choice... once the accelerometer tells the thing it ahs been fired an internal microcontoller polls the gps, and decided whent he thing has been picked up.... when that happens, BOOM! (the use of a gps removes the chance of a false fire due to the normal routes of failure for most motion mechanisms....) or if you wanted to get really selective, you could fire the thing onto the property of some person.. when they pick up the stuffed critter to take it inside, or to the garbage can, boom! such a device would be very expensive, and very complex, but it sure does bring up the possibility of a very target specific weapon

[nbk2000]

The South African army had an interesting idea they used for their cluster bomblets.

The bomblets were round balls covered with rubber that would bounce off the ground, back up into the air, before exploding. A simple impact switch would activate a .2 second delay that caused it to explode between 10 and 40 feet above the enemies heads.

And we recently got into the store these shotglasses that light up when they're slammed down on the tabletop. A very small spring is supported on one end, the other end free to swing above a contact plate. When hit with enough force against a stationary object, the free end of the spring bends down and touches the contact, completing the circuit.

This seems like an easily adapted impact switch. Just use a sufficiently stiff spring with some sort of support to prevent premature activation, like an ejecting pin that runs down the spring, and you're set.

[Anthony Privratsky]

A simple but effective hand grenade could be made to explode on impact no matter how it lands. Its a little of the subject of a mortar/rocket but effective. A person could just surround a HE with an impact sensitive explosive like ap, murcury fulminate or other. These could be made from a sphere of any kind.. prefferably a tennis ball. They wouldnt be hard to make and would be really fun to throw around.

<small>[ July 21, 2002, 01:18 PM: Message edited by: Anthony Privratsky ]</small>

[kingspaz]

well you just go and do some testing then <img border="0" title="" alt="[Wink]" src="wink.gif" /> ....thats a good idea in principle but a shitty idea in reality. having an HE with primary sorrounding it is lethal. one drop and its all over. you need somthing you can activate with the removal of a pin or somthing so when the pins in its not going to go off nomatter what.

[Anthony]

Not to mention it'd be rather unreliable. The primaries you mentioned aren't *that* sensitive.

[john_smith]

Talking about impact detonators, the simple primary based ones with no safeties are more threat to you than to whoever you plan to use em on, and military style grenade igniters are impossible to replicate without a completely equipped machine shop. However, what about building an electric one using a car alarm shock sensor? It would be easy to incorporate a simple delay activating the sensor/firing circuit about 0.5 sec or so after releasing the safety, and it would probably blow up quite reliably.
Edit: replace the alarm sensor with fuel cutoff shock sensor.

<small>[ July 22, 2002, 07:45 AM: Message edited by: john_smith ]</small>

[Ctrl_C]

I'm bringing this back up because I finished rebuilding my spudgun today. While I eventually plan on doing a range activated thing, I'm going to start off with an impact sensitive bullet for it. I need opinions on several things:

What type of explosive? Remember it has to withstand some pretty substantial acceleration so low sensitivity is a must.

What type of casing? It must fit in a 2" pvc pipe. I originally planned on using a mini nerf football (very aerodynamic w/ fins) that supposedly fits very well into a 2" pipe but they are discontinued. I was thinking possibly plaster. Lightweight, easy to cast, however, If it is shaped like a large bullet (I figure about 1' long total with a rounded front end), then the side walls around the explosive may not withstand the force of the massive air pressure wave hitting it.
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">
|--------x---------\
| x \
| EEEEEEEEEEEEE==P---
| x /
|________x_________/</pre><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">This is the basic idea, explosive cast in middle, with a small tube extending to the tip (also filled with explosive) and a primer at the end of the tube and a metal rod just sticking out of the bullet to transfer impact to the primer. Weak points of concern where x's are.

Remember, I'm trying to avoid metal as this round has to be as lightweight as possible.

<small>[ October 02, 2002, 08:55 PM: Message edited by: Ctrl_C ]</small>

[Eliteforum]

Might be a bit extream, but an idea.

First make a mould of your chosen design, then with a say plaster mould, fill it with melted plastic, then with another solid mould but about 5mm gap all the way around the other mould. push it in, and the excess plastic is pushed out.

Don't know how good this would work, or if it would work at all. But you could try it on a smaller scale perhaps?

[Asger]

About using AP in projectiles. I searched for this regarding small arms but it is not very common.

Though AP is somewhat sensitive, it is stil insensitive and stable enough to be filled into a cal.22 hollowpoint and making a projectile that explodes on impact. I tried it many many times working perfectly 99,9% of the time. Both from pistol and rifle.
If pressed firmly it will withstand a high acceleration without detonating. So if it is pressed good (take care) it should launch from your spudgun like a charm. But take really good care. You would obviously be dealing with larger amounts than that of a .22 drilled with a 2,2 mm drill.

Well my use in the .22 is very different from yours so I just mention this so you can compare my experiences to what you need yourself.

Take care.

(I really like to tell more about my experiences on this becaus ihave a lot, if any is interested. But I don't know where would be most appropriate.)

[Asger]

About your timing device. If you want something simpler than microprocessors for a start - then how about this :

In your grenade you have an electric flashbulb
from a one-use flashcube) - they are great for ignighting AP, black powder or bulletpowder. They are instant and require little power (unfortunately they are also static sensitive so take care).
Then you have a capacitor of moderate size (eg. 50V 100uF) They should be very small today and cheap.
And finally a simple circuit that detects the voltage on the capacitor. Once this voltage drops below say 10V the circuit dumps the rest of the charge into the flashbulb.´
You then put the grenade in your cannon. Charge it through some contacts to a voltage depending on the range from a table you made of voltages vs. timing vs. range. And finally arm it since the circuit will try to detonate as long as you are below said 10 V. You must take care of that little flaw.
You vill need a variable powersupply and a digital voltmeter.
Once you fire, the powersupply to the grenade is obviously cut and the capacitor is discharging from some rangedependant value towards the 10 V or whatever limit you set. You just need enough leftover charge to reliably set off the flashbulb.

The main thing is that you do some testing so you can reproduce timings down to few hundreds of a second. Actually I think this could be a problem. Mostly because the value of the resistor that discharges the cap. is somewhat temprature dependant.

<small>[ October 04, 2002, 10:14 AM: Message edited by: Asger ]</small>

[BoB-]

The problem with cast projectile casings is that if the explosive/detonator core is not perfectly centered then the flight can be unstable, as the round would be unbalanced. If you were able to center the core, then this would be ideal, you could cast the shrapnel into the casing, and/or use stronger casings, like bondo, or cement.

You could even attach some fins to some dowel and cast that into the rear of the round.

I've thought about using one of those home-manufactured spudgun darts like on spudtech.com, this would give you more room for electronics and added shrapnel. You could even use shaped charges. My guess would be that 1 1/4" endcaps would fit in 2" PVC.

<small>[ October 08, 2002, 05:07 PM: Message edited by: BoB- ]</small>

[Asger]

One can buy some quite cheap gadgets that has some LEDs that flash when said gadget is in the vicinity of a transmitting cellphone. Now I'm sure they can easily be modified to set of a flashbulb instead - so if you imagine you put this device into your spud-grenade and fire it towards an active (communication going on) cellphone, the grenade should detonate when it comes close enough.

Now I don't know the range wherein this device responds neither if it only responds to the phone while it is ringing or also while a conversation is going on. But I don't suppose such a piece of cheap electronics can tell the difference.

I will buy one soon and see what potential it has. Maybe one of you guys already have one.

But you get the picture : lure target into a deserted area, make a call to a cellphone carried by target (from a stationary phone ofcourse to avoid premature detonation) and fire the grenade towards target while target ansvers phone. For better successrate, add impact detonator to grenade too.

<small>[ October 23, 2002, 09:07 AM: Message edited by: Asger ]</small>