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spudgun range, are we falling short?

A place to ask general spud cannon related questions.
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Unread postAuthor: MrCrowley » Tue Apr 05, 2011 12:47 am

What about gutting something like this:
http://www.trademe.co.nz/Home-living/Se ... 762313.htm

If it is like the previous one linked, I doubt it could be used as there is no way to "resize" it, whereas if it had one particularly big component which could be made smaller, it could work.
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Unread postAuthor: jackssmirkingrevenge » Tue Apr 05, 2011 12:56 am

That looks a bit too bulky. I suppose something like thiswould do just as well. I would incorporate a circuit that pulses the noise, in order to preserve battery like as well as creating a distinctive tone that would be easier to locate than a constant buzzing.
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Unread postAuthor: Technician1002 » Tue Apr 05, 2011 1:44 am

Small pizeo units can be quite loud. The come in back up beeper configurations. Just add a battery.
Image
Operates on 3-28 Vdc. Continuous tone. 103 db sound pressure. 1.14" diameter x 0.93" ABS plastic housing. Can be bulkhead mounted with tabs on 1.31" mounting centers, or can be mounted through a panel hole of 0.7" diameter via threaded bushing and panel nut. 5" wire leads. Black housing

It is LOUD.
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Unread postAuthor: MrCrowley » Tue Apr 05, 2011 1:57 am

Here's a couple from NZ:

http://www.surplustronics.co.nz/shop/pr ... P0110.html
http://www.surplustronics.co.nz/shop/pr ... P0127.html
http://www.globalpc.co.nz/Electronics/H ... S6108.aspx
http://nicegear.co.nz/electronics-gear/piezo-buzzer/
http://www.jaycar.co.nz/productView.asp ... BCATID=291
http://www.jaycar.co.nz/productView.asp ... BCATID=291
http://www.jaycar.co.nz/productView.asp ... BCATID=291

I guess most of them are the same but I thought maybe you whizz kids out there could find one that is particularly better than another for some reason.

edit: I may as well stick an ultrabright LED in the tail section as well, just in case it helps. Is there a particular colour that would be best to use?

edit 2: I'll also try the tungsten filled arrow if I have time (right in the middle of uni atm). Ten 1.6mm diameter, 175mm long tungsten rods are about $20 and weigh 10g each. I could probably fit about 60g worth in an arrow shaft with a final weight of around 80g I imagine.
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Unread postAuthor: CpTn_lAw » Tue Apr 05, 2011 2:36 am

jackssmirkingrevenge wrote:
JDP12 wrote:Personally, I'm more tuning into this discussion as much of the sabot projectile discussion is applicable for designing High penetration projectiles as well.




By the way, I triedthis sabot again but with the last disk made of 1/4" balsa instead of foam - no luck at 15x, it just blew out as splinters before the projectiles. Obviously it needs to be thicker :roll:



Have you tried extruded polystyrene ? (Or roofmat ?) I shot a bullet from this material yesterday at 2x from a 20 mm barrel, judging by the crazy sound it normally only makes at 10x + , i think it went supersonic, and thus held the pressure. It is almost intact, except for a little burnt mark and some aluminium foil from the burst disc in it.
I'll try to make a small arrow out of japanese food sticks and try the sabot with this. i'll let you know how it turns out.
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Unread postAuthor: Ragnarok » Tue Apr 05, 2011 6:49 am

Hotwired wrote:I'm in the market for a lithium battery'd camera personally.

Well, that'd be rechargeable lithium batteries. These were disposable AAs. More expensive than typical alkalines, but god damn, they last longer.

I bought four batteries well over a year ago, and I'm still on the second set of two - although I did get a new camera part way through the second set, so they're not exactly under heavy use now.

MrCrowley wrote:I may as well stick an ultrabright LED in the tail section as well, just in case it helps. Is there a particular colour that would be best to use?

The human eye is most sensitive to wavelengths of about 555nm - yellow green. However, red might be more contrasting to the environment and easier to see.

It might prove useful, but more as a "tracer" to get a rough landing location than as an actual beacon (because I'm imagining it'll bury itself).
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Does that thing kinda look like a big cat to you?
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Unread postAuthor: jackssmirkingrevenge » Tue Apr 05, 2011 7:19 am

MrCrowley wrote:I may as well stick an ultrabright LED in the tail section as well, just in case it helps. Is there a particular colour that would be best to use?


As Rag said it would provide a useful rough indication where the round landed. If you could narrow the path to a specific direction, it's just a question of walking along and you're bound to run into the projectile (or a hole :roll:) eventually.

I'll also try the tungsten filled arrow if I have time (right in the middle of uni atm). Ten 1.6mm diameter, 175mm long tungsten rods are about $20 and weigh 10g each. I could probably fit about 60g worth in an arrow shaft with a final weight of around 80g I imagine.


Awesome, good luck finding it :)

Have you tried extruded polystyrene ? (Or roofmat ?) I shot a bullet from this material yesterday at 2x from a 20 mm barrel, judging by the crazy sound it normally only makes at 10x + , i think it went supersonic, and thus held the pressure. It is almost intact, except for a little burnt mark and some aluminium foil from the burst disc in it.


Do you have anything other indication of power other than sound? I find that when a sabot disintegrates the sound is much louder as gas can bypass the suppressor and go straight out of the muzzle.

The human eye is most sensitive to wavelengths of about 555nm - yellow green. However, red might be more contrasting to the environment and easier to see.


I think colour is probably not as important as intensity, and perhaps a blinking light is more likely to attract your attention on the ground, though it would of course be less useful as a "tracer".
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Unread postAuthor: CpTn_lAw » Tue Apr 05, 2011 7:44 am

Well, it's a 20 mm projectile, weighs less than a gram, was pushed by a 2x shot and is still intact. i didn't see it coming out the muzzle, but after 3 meters in the air it was slow again, so that i could see it fall on the ground.
I'll do a highspeed footage when i get the time.
I think it deserves a try as a sabot.
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Unread postAuthor: jackssmirkingrevenge » Tue Apr 05, 2011 8:08 am

If you look at this foam only sabot shot, the sabot bits come out first followed by the relatively slow projectile - could this have happened?

Wooden sabots have potential, used for ballistic wound testing here at up to 3800 fps :shock:

Image
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Unread postAuthor: LeMaudit » Tue Apr 05, 2011 8:17 am

Are those bullets called "ballplast" (plastic ammo) used by the military for practice (at least in France) made of extruded polystyrene as well? I wonder...

I remember shooting those with a FAMAS, they where quite precise and flight strait. At 50m I put a group of 3 in an inch. And I'm not a master sniper :lol:
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Unread postAuthor: SpudFarm » Tue Apr 05, 2011 10:22 am

I haven't read the entire thread but I have got the idea of the content.

I saw JSR's video and remembered that I have a similar video that might provide some info.

I'l start drawing some sketches for sabots for hybrids and high pressure pneumatics.

[youtube]http://www.youtube.com/watch?v=JSiPpVnsvrE[/youtube]

Would be fun to fire something like the below for range. Should reach pretty far.

[youtube]http://www.youtube.com/watch?v=vfpfYp0ZowA[/youtube]

I'll see if I can come up with a good sabot for a penetrator/dart shaped round.
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Unread postAuthor: Zeus » Tue Apr 05, 2011 6:46 pm

Regarding piezos, they wouldn't work considering the 1kpsi behind them which would flatten the piezo-electric crystal.

Same as for any speaker, the diaphram would be burst. Unless you put it facing forwards which would affect range.

Really a lose lose situation. A small radio transmitter would be the best way to you I think.

I know this is somewhat away from where the topic has gone but I thought I'd better add it anyway.
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/sarcasm, /hyperbole
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Unread postAuthor: LeMaudit » Tue Apr 05, 2011 6:53 pm

I bought 2 thingies today on the local stores that I found loud enough. Both have a very high pitch tone. And both are a bit too big to fit the inside of the 18mm missile that was planned :(

1st is a personal alarm thingy that sound when you unplug a strap. Works with 4 small lithium battery. 115db, fast pulsing sound, rectangular 24x13x80mm.

2nd is a Pulsing Piezo Buzzer. wired to a small 12V alkaline battery, it's maybe a bit louder than 115db, fast pulsing too. diameter 29mm, length 24mm. one battery dia. 12mm, length 30mm. Bulkier, and I have to fix the battery somehow.

I tried a few smaller piezo (they had a good selection at the store), but the sound was really not that impressive. Inside the missile body, I think they would barely be audible even with holes in it.

The piezo diameter seem to be a bit smaller than the plastic container diameter but not that much. That would fit in a missile body diameter of 1 1/4" (32mm). It's the larger aluminium tubing I have at hand. And with a thickness wall of 1/16" (1.6mm) I'm afraid it would not survive the impact and crush. Anybody have an opinion/experience?

The personal alarm thingy may fit a smaller tube, maybe 25mm, but those 2 round recess you can see on the photo are not for the battery, they seem to be resonance chambers. I wonder if the internals would work outside their plastic container.

No big deal to try to destroy them, it was only a few $, but I wonder if someone would have some idea to share before I cut them open?

MrCrowley, using the piezo + aluminum tubing 1 1/4" (32mm), that would make a missile about 9" (230mm) long.
If I use the personal alarm, I think I can fit it inside a piece of 1" (25mm) steel pipe for the main part of the body with a bit of sanding, if more strength is needed than aluminium. That would make a 7 1/4" (180mm) length.

[edit]And I just read Zeus comment... damnit :lol:
okay, I'll make it hollow, put some sausage meat in it and bring a dog to the beach with you :D
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Unread postAuthor: Zeus » Tue Apr 05, 2011 7:01 pm

Actually, that's a very good idea. It would take a little time but training a dog to find a very strong smelling substance isn't too hard, especially if it's something the dog likes. (rotten meat or cow dung)

I'll have a dog in maybe 6 months, should have a bloody big hybrid by then, take maybe 6 months to train it (it'll only be a pup when I get it).

Catch a rabbit, dogs love rabbit meat, I'll have a homing projectile finder.
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Unread postAuthor: Lockednloaded » Tue Apr 05, 2011 10:15 pm

LeMaudit wrote:okay, I'll make it hollow, put some sausage meat in it and bring a dog to the beach with you :D


Even though thats probably sarcastic, it could be done with nearly any hunting dog. You can bring it within a ~200m radius (depends on the dog and strength of the odor) and it'll find it. A pointer or blood-hound would be the best choices IMO
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