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Unread postAuthor: Crna Legija » Tue Jan 31, 2012 4:13 am

jrrdw wrote:@Crna Legija: A dedicated race/high performance shop would probably do it for you but those guys are never cheep. Do it the way feel safe or can prove it to work safe for you.


That wont work for me because I want to put it in my daily driver and it very illegal to have a line locker in Australia, if they install one on a road registered vehicle they could be up for $50,000 of fines, but today I did find someone that showed me witch ports need the valve installed. I ordered them on eBay should be hear in a month or so.

ill definitely test the system out well before using it, it will also have two switches and a led to show it's on.
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Unread postAuthor: MrCrowley » Tue Jan 31, 2012 4:19 am

jackssmirkingrevenge wrote:https://share.sandia.gov/news/resources/news_releases/bullet/

:shock:

Have they actually tested it in the field yet (accuracy at long ranges)? I saw a lot of talk about computer simulations and field test for various parts of the patent...

If it's as good as they say it is, I can't wait for some better videos to come out.
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Unread postAuthor: POLAND_SPUD » Tue Jan 31, 2012 6:34 am

https://share.sandia.gov/news/resources/news_releases/bullet/
wait why would they attach an led to it?? aparently they haven't tested it yet


I saw a lot of talk about computer simulations and field test for various parts of the patent
link plzz

ohh and what sensor do you need to sense a reflected laser beam ??
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Unread postAuthor: MrCrowley » Tue Jan 31, 2012 6:46 am

POLAND_SPUD wrote:
I saw a lot of talk about computer simulations and field test for various parts of the patent
link plzz

I'm talking about the article jsr linked, that they appear to have only tested certain functions of the bullet's patent in field tests, not its full functionality at ranges and accuracies predicted in the computer simulations.

I might be wrong but they weren't very clear.
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Unread postAuthor: jackssmirkingrevenge » Tue Jan 31, 2012 6:50 am

POLAND_SPUD wrote:ohh and what sensor do you need to sense a reflected laser beam ??


Tired of hitting your greenhouse :D
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Unread postAuthor: POLAND_SPUD » Tue Jan 31, 2012 7:45 am

jackssmirkingrevenge wrote:
POLAND_SPUD wrote:ohh and what sensor do you need to sense a reflected laser beam ??


Tired of hitting your greenhouse :D

Image

nahh I am just curious if one could fabricate something like that... small RC servos would probably fit inside a 1" PVC pipe, so would a microcontroller, so the only questions is - wtf do you need to sense a reflected laser beam?
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Unread postAuthor: jackssmirkingrevenge » Tue Jan 31, 2012 7:58 am

:D

POLAND_SPUD wrote:nahh I am just curious if one could fabricate something like that... small RC servos would probably fit inside a 1" PVC pipe, so would a microcontroller, so the only questions is - wtf do you need to sense a reflected laser beam?


Well I guess it works the same way a heat or visual guidance system works, but looking for a laser spot as opposed to a heat signature or shape.

It's a bit like the software driving a sentry gun. What you want is something that can locate a particular spot and send signals to the servos to always put the spot on the centre of the screen.

This is how it worked on the first models:

this article wrote:Precision Guided Munitions - Texas Instruments GBU-10, 12, 16 Paveway

The Paveway "smart bomb" was the first laser-guided weapon to gain wider application and distinguished itself during the Vietnam conflict.

The Paveway is a modular guidance kit comprised of a Computer Control Group and Airfoil Group Assembly fitted to a standard Mk82, 83, 84 demolition bomb or SUU 54 cluster bomb. It functions as a semi-active laser-seeking ballistic projectile and requires no electrical connections with carrying aircraft prior to release.

The CCG consists of a laser energy sensor, a guidance command computer and a control actuator/control surface assembly (see diagram). The laser sensor is mounted in a gimballed, aerodynamically aligned (ring airfoil - it aligns the sensor assembly with the weapon's velocity vector) assembly. Laser light reflected off a target passes through a protective nose window and an infrared filter and is focussed by an aspheric lens on to a four-quadrant silicon photoelectric sensor. The sensor is slightly shifted along the longitudinal axis of the assembly so it lies in front of the focal plane of the lens and the image of the laser spot is slightly defocussed. If the spot is perfectly aligned with the weapon's velocity vector, all quadrants are equally illuminated. If the spot lies off-axis it will illuminate each quadrant differently. Each quadrant generates electric current proportional to its illumination. Voltages proportional to these currents are then amplified and fed into a mixer network which compares the signals and generates up/down, left/right commands - these are then fed into the guidance command computer.

Paveway uses a non-proportional 'bang-bang' guidance where control surfaces are not deflected proportionally to the guidance error, but are driven to the limit of their deflection; the guidance commands being up, down, left, right and no command. The computer receives the outputs from the sensor assembly and, after selecting the correct pulse code, it compares the outputs to select the appropriate control commands. Control actuation occurs if the difference between two channels exceeds a level given by the minimum guidance error; if not, the control fins are set to trail.


It conceivably be cooked up (with some help from arudino perhaps ;D) but again, this is something that will put you on a watch list...
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Unread postAuthor: Technician1002 » Tue Jan 31, 2012 10:34 am

^^^^^ a cheap source for a 4 quadrant detector is the laser pickup assy from any dvd or cd player. They are used as part of the focus servo. A pickup diode array has 6 diodes. 4 in the center are the main pickup. 2 more are used for tracking the recorded line.

http://books.google.com/books?id=cqYBIuYBUvsC&pg=SA3-PA59&lpg=SA3-PA59&dq=cd+player+focus+circuit&source=bl&ots=bwCX2n40xX&sig=FAw-ugPKRFLpB8VcZxq7WFl4q30&hl=en&sa=X&ei=ZgkoT-TCMYeyiQL14vzKAQ&ved=0CE8Q6AEwBQ#v=onepage&q=cd%20player%20focus%20circuit&f=false

This shows the light pattern on the main detector of the focus servo. Diagonal pairs are used for focus. All 4 are added for the detected data. Adjacent pairs can de uded for tracking in a 4 diode detector. Most often two more diodes are used for tracking in a 6 diode detector to track the line.
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Unread postAuthor: Daltonultra » Tue Jan 31, 2012 3:00 pm

POLAND_SPUD wrote:
https://share.sandia.gov/news/resources/news_releases/bullet/
wait why would they attach an led to it?? aparently they haven't tested it yet


Actually, the picture in the article shows why they attached the LED: They were using it basically as a tracer, to track the bullet as it went down-range in function testing, and as a power indicator to show that the tracking electronics are operational in flight. The path left by the LED on a slightly long exposure picture shows the bullet correcting during flight, and confirms that the controls are active. So yeah, they actually have tested full functionality. Next step would be impact testing, to confirm the lethality of the round.


BTW, sorry about my little snit, before. Brakes are serious business, and I get a little bent out of shape about incorrect advice being given about them. Even so, I shouldn't have jumped on jrrdw that hard. I was having a straight-up BAD day.
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Unread postAuthor: MrCrowley » Tue Jan 31, 2012 4:14 pm

Daltonultra wrote:So yeah, they actually have tested full functionality. Next step would be impact testing, to confirm the lethality of the round
Isn't that a contradiction? I would include the terminal ballistics of a bullet as a key functionality of the design :wink:

Furthermore, just because they were able to test a key part of the design (a self-correcting bullet in that LED photo) doesn't mean they tested its accuracy at long ranges. They make no mention of how accurate it was at long ranges except for in computer simulations. So I can only conclude they haven't properly tested its full functionality in the field.

Don't get me wrong, having successfully tested in the field the main part of the design, the self-correcting part, is quite an achievement. I just want to see some statistical graphs and analyses showing a comparison the accuracy of their design at long ranges to normal bullets.
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Unread postAuthor: POLAND_SPUD » Tue Jan 31, 2012 5:30 pm

but again, this is something that will put you on a watch list
now that you mentioned it I think it wasn't the best idea to post comments along the lines of
'ohh it would make an awesome cruise missile'
in like a bunch of vids of FPV RC planes on youtube :roll:
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Unread postAuthor: jackssmirkingrevenge » Wed Feb 01, 2012 1:12 am

POLAND_SPUD wrote:now that you mentioned it I think it wasn't the best idea to post comments along the lines of
'ohh it would make an awesome cruise missile'
in like a bunch of vids of FPV RC planes on youtube :roll:


:D

look what happened to these little shìtes: http://thelede.blogs.nytimes.com/2012/0 ... ter-jokes/

Back to the guided bullet, I think they're going about it the wrong way.

It's guided, so the high velocity in order to get the flat trajectory to ease aiming is unnecessary. I would aim for high subsonic at most, in a streamlined and dense platform for good velocity retention. Lower speed means less stress on the electronics, so lower cost and more reliability.

Instead of relying on kinetic energy that decreases with range, why not have an explosive warhead that will affect the target roughly the same at any range?

In order to be most effective, the thing should look more like a miniature Hellfire than a bullet with fins and actuators.

Something conceptually like the Switchblade: http://defense-update.com/products/l/sw ... 22010.html - but unpowered and fired from something like a 40mm grenade launcher.
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Unread postAuthor: Daltonultra » Wed Feb 01, 2012 3:12 am

jackssmirkingrevenge wrote:Back to the guided bullet, I think they're going about it the wrong way.

It's guided, so the high velocity in order to get the flat trajectory to ease aiming is unnecessary. I would aim for high subsonic at most, in a streamlined and dense platform for good velocity retention. Lower speed means less stress on the electronics, so lower cost and more reliability.

Instead of relying on kinetic energy that decreases with range, why not have an explosive warhead that will affect the target roughly the same at any range?

In order to be most effective, the thing should look more like a miniature Hellfire than a bullet with fins and actuators.

Something conceptually like the Switchblade: http://defense-update.com/products/l/sw ... 22010.html - but unpowered and fired from something like a 40mm grenade launcher.


That link made my antivirus light up like a Christmas tree... Gave me a warning about an exploit.

OK, let's break it down.

Velocity equals range, not just ease of aiming. The more velocity you have at the muzzle, and the more you retain, the longer your effective range, regardless of whether the round is guided or not.

The problem of acceleration stresses on the electronics is purely a development issue, which they appear to have solved, so that's out of the way.

Explosives would require more room in the round, making it larger. A larger round would require a larger propellant charge to achieve the same range. That would also require a larger, less-portable rifle. Also, explosives are a HECK of a lot more expensive than steel or titanium or whatever alloy they're using. Plus you'd need room for a detonator mechanism, which adds even more complication and weight.

Finally, fins or wings generate much more drag than the strakes and cone-shaped tail section of the round they developed. And the drag would multiply with each correction, shortening the range. Not to mention the massive amounts complication you'd be adding.

The steerable cone they're using needs two tiny actuators. A wing would require either an actuator or a spring to deploy it, another actuator for each control surface, pins and hinges... you're talking about multiplying the number of moving parts several times, and it would also require much more complex guidance. All of this yet again adds up to a much bigger launching system than a simple man-portable rifle.

You'd probably be right about it requiring something the size of a 40mm grenade launcher to get it downrange, but the charge required to match the range of current .50BMG rifles would mean the launcher would absolutely have to be either vehicle or tripod mounted, as the barrel would have to stand up to firing pressures higher than WWII 37mm flak cannons.

So, basically, in the search for a better sniper rifle, you've actually invented a field artillery piece with rounds that cost a hundred thousand a pop, and have a fiendishly high chance of failure due to complication.

The round they came up with looks very simple and robust, with very few moving parts. And it's only slightly larger than a current .50BMG round.
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Unread postAuthor: jackssmirkingrevenge » Wed Feb 01, 2012 4:51 am

Daltonultra wrote:That link made my antivirus light up like a Christmas tree... Gave me a warning about an exploit.


Hmm... well, here's a video:

[youtube]http://www.youtube.com/watch?v=VdRjYkEU-N4[/youtube]

Velocity equals range, not just ease of aiming. The more velocity you have at the muzzle, and the more you retain, the longer your effective range, regardless of whether the round is guided or not.


Through, but my point though is that you can achieve range by using a 40-50º launch angle and an optimised streamlined projectile.

The problem of acceleration stresses on the electronics is purely a development issue, which they appear to have solved, so that's out of the way.


... but less acceleration means lower spec electronics, meaning a cheaper round more likely to be manufactured and used.

Explosives would require more room in the round, making it larger. A larger round would require a larger propellant charge to achieve the same range. That would also require a larger, less-portable rifle.


True, but you wouldn't need to fire it as fast, so I think recoil would balance out.

Also, explosives are a HECK of a lot more expensive than steel or titanium or whatever alloy they're using.


... but probably only a small fraction of the cost of the guidance system.

Plus you'd need room for a detonator mechanism, which adds even more complication and weight.


Explosive rounds are practical down to 50 cal, so it's not that much more complication and weight.

Finally, fins or wings generate much more drag than the strakes and cone-shaped tail section of the round they developed. And the drag would multiply with each correction, shortening the range. Not to mention the massive amounts complication you'd be adding.


It could look the same as the prototype in terms of external design, why not.

You'd probably be right about it requiring something the size of a 40mm grenade launcher to get it downrange, but the charge required to match the range of current .50BMG rifles would mean the launcher would absolutely have to be either vehicle or tripod mounted, as the barrel would have to stand up to firing pressures higher than WWII 37mm flak cannons.


50 BMG AMRs are limited to a relatively flat trajectory. If you have the opportinity to shoot at 45º, you don't need to go anywhere near as fast as they do in order to get to 2000 yards or so.

So, basically, in the search for a better sniper rifle, you've actually invented a field artillery piece with rounds that cost a hundred thousand a pop, and have a fiendishly high chance of failure due to complication.


I doubt what I proposed would cost much more, indeed it could actually cost less because of the lower spec electronics required. All I've added is the explosive charge, which is used in countless other weapons to high degrees of reliability, and it's travelling slower so if anything it should have a higher chance of hitting the target as the system has more time to compensate.

The round they came up with looks very simple and robust, with very few moving parts. And it's only slightly larger than a current .50BMG round.


The bullet is much bigger than a 50 cal, and there's no word on how heavy it is and the size of cartridge it would need, or indeed the recoil forces involved.
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Unread postAuthor: POLAND_SPUD » Wed Feb 01, 2012 7:26 am

Hmm... well, here's a video
lol so I was right...
someone has thought it would make an awesome weapon

I think that the vid you posted shows something that will actually be adopted soon... now let me get back to the thing we're discussing now...
It's guided, so the high velocity in order to get the flat trajectory to ease aiming is unnecessary. I would aim for high subsonic at most, in a streamlined and dense platform for good velocity retention
I agree completely...
since it is laser guided you probably need two ppl: one to fire the gun and one to illuminate the target
something like a terminally guided grenade launcher would work much better and would be much more practical IMO (even assuming its max range would be lower)


ohh and why spend $$$ on something that will be used so rarely? if one really needs better accuracy at longer ranges you can use these
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