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#81 Blunt Eversmoke

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Posted 20 November 2017 - 0050 AM

Okay, so the CG/RPG-16 approach is not enough for what most members of This Grate Sight envision. Guidance is needed.

Let me divert from guidance system approaches and ask one simple question:

 

While whatever sensors and computers used for missile guidance are becoming cheaper day by day, this trend is less pronounced with the provisions to physically direct the missile on its way to the target.

Given that we want cheap, and given that most in this discussion don't want to go over 72 mm (many say, better even 57 mm), how to achieve this?

Dragon comes to mind, anything else?..



#82 KV7

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Posted 20 November 2017 - 0442 AM

Okay, so the CG/RPG-16 approach is not enough for what most members of This Grate Sight envision. Guidance is needed.

Let me divert from guidance system approaches and ask one simple question:

 

While whatever sensors and computers used for missile guidance are becoming cheaper day by day, this trend is less pronounced with the provisions to physically direct the missile on its way to the target.

Given that we want cheap, and given that most in this discussion don't want to go over 72 mm (many say, better even 57 mm), how to achieve this?

Dragon comes to mind, anything else?..

Unguided or inertial guidance has the bonus of fire and forget which you cannot get otherwise in a cheap platform. And I still think it would be nice to have something you can use to lob HE. Then maybe you can sell partly it on the basis you can ditch an LMG team or similar from the inf squad.

Otherwise beam riding is good, but not dirt cheap.



#83 Chris Werb

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Posted 20 November 2017 - 1320 PM

I think soft launch would be possible if the missile had recorded the direction in which it had to fly and simply had to assume that direction after launch - a bit like an unguided torpedo fired on a compass bearing that is not the direction the torpedo tube is pointing. Minimum range is also an important consideration. I'm not sure how cheap inertial would be though - I believe N-LAW is very expensive. Here is a soft(ish) launch inertial LAW in use:

 



#84 KV7

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Posted 20 November 2017 - 1527 PM

You could maybe hot launch it using the Armbrust system or similar, adapted for more than one shot use.


Edited by KV7, 20 November 2017 - 1530 PM.


#85 lastdingo

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Posted 20 November 2017 - 1548 PM

Yeah, I wrote a bit about Picket.

http://defense-and-f...irect-fire.html

 

I hardly ever see info on it anywhere - only remember two Jane's sources featuring it (and one website that used to copy Jane's contents featured it as well).

 

You guys can find any error of thinking in that link?

I ask because you're pretty much spiralling towards it.



#86 Blunt Eversmoke

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Posted 21 November 2017 - 0020 AM

 

Okay, so the CG/RPG-16 approach is not enough for what most members of This Grate Sight envision. Guidance is needed.

Let me divert from guidance system approaches and ask one simple question:

 

While whatever sensors and computers used for missile guidance are becoming cheaper day by day, this trend is less pronounced with the provisions to physically direct the missile on its way to the target.

Given that we want cheap, and given that most in this discussion don't want to go over 72 mm (many say, better even 57 mm), how to achieve this?

Dragon comes to mind, anything else?..

Unguided or inertial guidance has the bonus of fire and forget which you cannot get otherwise in a cheap platform. And I still think it would be nice to have something you can use to lob HE. Then maybe you can sell partly it on the basis you can ditch an LMG team or similar from the inf squad.

Otherwise beam riding is good, but not dirt cheap.

 

Nah, I am asking, what means are preferred to physically control the missile IF it is at all guided. Winglets, tails and so on AND the electric motors to move them as well as batteries for those might take up too much space in a missile of a small calibre. Would what Dragon used (electrically-ignited small powder charges) be better?



#87 TTK Ciar

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Posted 21 November 2017 - 0147 AM

Battery energy density has gotten a lot better since Javelin's time (from 70Wh/kg in 1989 to 265Wh/kg today). I think you can get away with just a lithium-polymer battery, switching logic (which literally can be the size of a pinhead), a single solenoid and two control rods (one pushed when the solenoid actuates in one direction, the other pushed when it actuates in the opposite direction) for thrust-vectoring vanes -- one for roll, the other for pitch. Yaw would effectively be achieved by rolling the projectile 90deg or 270deg and then changing pitch.

The whole assembly should tuck between the nozzle and fins at the rear of the projectile, but I haven't tried it yet.

#88 KV7

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Posted 21 November 2017 - 0256 AM

If we want to be cheeky, spin stabilisation is a form of inertial guidance.



#89 lastdingo

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Posted 21 November 2017 - 0415 AM

Battery energy density has gotten a lot better since Javelin's time (from 70Wh/kg in 1989 to 265Wh/kg today). I think you can get away with just a lithium-polymer battery, switching logic (which literally can be the size of a pinhead), a single solenoid and two control rods (one pushed when the solenoid actuates in one direction, the other pushed when it actuates in the opposite direction) for thrust-vectoring vanes -- one for roll, the other for pitch. Yaw would effectively be achieved by rolling the projectile 90deg or 270deg and then changing pitch.

The whole assembly should tuck between the nozzle and fins at the rear of the projectile, but I haven't tried it yet.

 

Frankly, minute charges sound simpler to me.



#90 KV7

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Posted 21 November 2017 - 0504 AM

 

Battery energy density has gotten a lot better since Javelin's time (from 70Wh/kg in 1989 to 265Wh/kg today). I think you can get away with just a lithium-polymer battery, switching logic (which literally can be the size of a pinhead), a single solenoid and two control rods (one pushed when the solenoid actuates in one direction, the other pushed when it actuates in the opposite direction) for thrust-vectoring vanes -- one for roll, the other for pitch. Yaw would effectively be achieved by rolling the projectile 90deg or 270deg and then changing pitch.

The whole assembly should tuck between the nozzle and fins at the rear of the projectile, but I haven't tried it yet.

 

Frankly, minute charges sound simpler to me.

Better to make it variable, you could use variable flow orifices on a compressed tank of oxidiser, then selectively boosting part of the solid fuel rocket.



#91 TTK Ciar

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Posted 21 November 2017 - 1736 PM

Apologies if this comes up twice. I'm posting from my MIL's place and the site's security did something weird the first time.

Frankly, minute charges sound simpler to me.

Thinking about it, it could be. It adds a lot more parts, but no moving parts (whereas the solenoid-based rig adds seven parts, five moving), and chemical fuel is fairly energy-dense. The weight of the charge pans worries me a bit, but I'm going to fiddle with the numbers and see if it's that bad.

Rather than putting them all around the missile for purely lateral adjustments, rings of charges near the ends of the missile would allow for changes in direction. That would make a top-down attack path possible, which is of interest to me.


#92 lastdingo

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Posted 22 November 2017 - 0309 AM

I suppose the minute sharrges should be forward of CoG. This makes fighting gravity by body lift & minute charge thrust easier for a predicted line of sight missile.

 

I don't think top attack is needed for general issue infantry weapons. The BMP-x upper glacis has a tricky angle, but other than that the only targets that (almost) require top attack are modern MBTs that show their front 60°. Dedicated MBT busters may have that, but everyday carry weapons/munitions fo teh ifnantry (preferably HEDP) don't need it. They rather need confined spaces qualification and a small visual firing signature.



#93 Chris Werb

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Posted 24 November 2017 - 1633 PM

The way the Finns do it is to issue late model M72s as an anti BMP/MTLB weapon, N-LAW as MBT buster and SPIKE (indirect fire capable) as an ATGW. What they appear to lack is a longish range HE/HEDP thrower like the Carl Gustav M3/4 and a specialised anti structure munition like LASM or Matatdor.



#94 Chris Werb

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Posted 24 November 2017 - 1638 PM

 

Yeah, I wrote a bit about Picket.

http://defense-and-f...irect-fire.html

 

I hardly ever see info on it anywhere - only remember two Jane's sources featuring it (and one website that used to copy Jane's contents featured it as well).

 

You guys can find any error of thinking in that link?

I ask because you're pretty much spiralling towards it.

 

 

One of my favourite defence blogs. I wonder who writes it? :) :) :)



#95 lastdingo

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Posted 24 November 2017 - 1716 PM

Guess what? It's one of my favourites, too! :D



#96 Chris Werb

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Posted 26 November 2017 - 0735 AM

Given that inertial guidance would give a flat trajectory and that you might well be shooting at infantry in relatively flat terrain, timed airburst might be really handy. To keep it cheap, it could be manually set using whatever laser rangefinder or other method was handly - that would be mu slower than an integrated FCS, but would keep the FCS cheaper. As for a sight., there are now very good, rugged red dots out there that are much, much cheaper than the ACOG used on the N-LAW. These have NVG compatible settings and 50k hour battery lives. If you wanted magnification, a cheap flip to side magnifier would suffice.



#97 lastdingo

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Posted 26 November 2017 - 0836 AM

Personally, I think airburst is overrated.

 

Most of the time you'd use it against infantrymen in a building room. There would likely only be two enemy infantrymen in the room, and the room would typically be fairly small (not a big hall).

Airburst allows to shoot through the window (requires that the PD/PDSQ fuse can be deactivated) and explode about one metre behind. HEDP is no good for frag in forward 120° or so - that zone would be affected by blast more than frags.

 

Now look at the alternative; a PDSQ fuze on a rocket that's being shot through the window AFTER the window was opened (shot to pieces) by bullets. The rocket would explode on the rear wall. It would frag the rear of the room, and affect infantrymen right next to the window by blast (and frags of the disintegrated solid fuel rocket, but no predictable frag pattern).

 

Instead of airburst you can simply change the HEDP warhead such that it has some more frag effect rearwards, which may add 200-300 grams (judging by the weight of hand grenades with 5-10 m lethal radius depending on standard used). The HEDP would not have dedicated frags in the rear 45-60° cone to minimise the minimum safe distance for the shooter. The size of the explosive charge should provide satisfactory blast effect inside a room in that area, though.

Moreover, you can rarely lase the distance to a trench accurately. Trenches should have some above-ground background that minimises contrast (such as bushes), but that doesn't need to be directly behind; 2-5 m behind makes accurate distance-setting very hard.

 

The airburst scenario of hostiles in trenches or hostiles taking cover behind above-ground cover looks relatively unimportant to me by comparison. Most such cover would enable them to pop up, shoot, disappear, pop up someplace else, shoot, disappear, rinse and repeat.

 

I suppose we can and should limit airburst to weapons that should have a good FCS anyway; portable infantry guns such as Carl Gustaf (one per platoon), AFVs with guns 40 mm or bigger,



#98 Chris Werb

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Posted 26 November 2017 - 0951 AM

Personally, I think airburst is overrated.

 

 

 

Yes, I take all your points. Best keep it to a simpler fusing option, though optional between superquick/PD and fractional delay for penetrating ;ightly constructed buildings, light vehicles etc. would be good.



#99 lastdingo

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Posted 26 November 2017 - 1215 PM

 

Personally, I think airburst is overrated.

 

 

 

Yes, I take all your points. Best keep it to a simpler fusing option, though optional between superquick/PD and fractional delay for penetrating ;ightly constructed buildings, light vehicles etc. would be good.

 

 

A site that I linked to twice has this quote:

 

 

A fuse which can be set to a short delay (enough to penetrate doors, windows and soft vehicles) or point detonation super quick modes by electromagnetic induction.

:D

Clarification; the induction thing is for the programming of the fuse mode, not for the fusing (delay would be classic mechanical, PDSQ would be HEAT-typical piezoelectric).

It might even be possible to use a mechanical setter which would be more robust in face of EMP, but its design would be more tricky. Mechanical fuse setting is usually done outside of a tube or chamber.



#100 Chris Werb

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Posted 29 November 2017 - 1546 PM

Grate minds think alike :D






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