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Author Topic: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles  (Read 53485 times)

Offline marauder2048

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #180 on: August 27, 2017, 02:57:26 pm »
It is quite a popular option outside the US. The Israeli Spike series, except the Spike NLOS which uses a wireless link, are all FOG missiles. The new Spike II is especially impressive looking.

Much shorter range than FOG-M and most of the newer Spike II LR versions use an RF datalink.

this was the last completely new tactical missile to enter US Army service.

That would be Griffin.

Offline Void

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #181 on: September 09, 2017, 07:02:41 pm »
Whether the guidance signal travels over fibre or over wireless does not change the nature of the guidance system. A better term would probably be TV-guided. "Fiber optic guidance" is a misnomer in that sense, just like "wire-guided". The US experimented with the same kind of wireless "FOG" guidance with the FMTI missile.

And as for the Griffin, it was sold on very the premise that it wasn't a completely new missile, but one that reused components from existing missiles as much as possible.

Online Mach42

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #182 on: September 09, 2017, 10:29:40 pm »
As an aside, there are rumours of Hanwha Defense Systems teaming up with Lockheed or Raytheon to modify the K21-105 for the MPF program. Hanwha will have a presence at AUSA this year so addition information may be forthcoming then. Seems like a less capable, but low cost and low risk design.

Offline bobbymike

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Offline marauder2048

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #184 on: September 12, 2017, 11:29:47 pm »
Whether the guidance signal travels over fibre or over wireless does not change the nature of the guidance system.

Sure it does; fiber permits much higher bi-directional data rates and much lower latency
which in turn makes things like performing automatic tracking and aimpoint selection on the
launcher-side readily doable.

FMTI was shorter range and fire-and-forget; the 2-way RF datalink had a much lower data rate and, AFIAK,
was mostly for LOAL fratricide avoidance.



And as for the Griffin, it was sold on very the premise that it wasn't a completely new missile, but one that reused components from existing missiles as much as possible.

It was sold on that premise but it really is a new missile particularly the more recent blocks.

Offline Void

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #185 on: September 13, 2017, 04:02:15 am »
Wireless has a lower minimum latency than fibre. EM waves simply travel faster through air than glass. The bandwidth available is higher in fibre true, but the bandwidth available in microwave or MMW links like the Spike-NLOS and FMTI use(d) is far in excess of what is actually needed for the relatively low-resolution video and missile data. The FMTI wasn't especially short range for its size either, it was tested to 8km (not trivial for a TOW-sized missile with a rocket motor) and had the potential for significantly greater range. And of course, the wireless Spike NLOS has a range of ~25km and seems to work quite well.

The attraction of fibre is the same as the attraction of wire in older missiles: The link is more reliable, especially at long distances, and it is largely immune to hostile interference. The principles of TV guidance did not change when it occurred to someone to link the weapon to the launcher by a fibre optic cable; TV guidance was already well established when optical fibre entered the picture as a potential alternative to radio links.

As for the Griffin, it is not alone in that regard. The Javelin has also been mostly rebuilt, there is a nice picture I don't have right now showing all the components that have been replaced since it entered service and it is almost the entire missile. As has the TOW. And the Hellfire. But they are still not completely new missiles. This isn't even my own observation. US tactical missiles which are not derived from existing missiles have been pretty consistently axed.

Offline Kadija_Man

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #186 on: September 13, 2017, 05:14:23 am »
All this is very interesting.  However, what it does not explain is why the US Army has been so resistant over the years to the use of optical fibre guided weapons.   FOG-M was quite capable but it was abandoned after the US Army didn't want it.  EFOGM was also abandoned.  Either would have allowed a light armoured vehicle which was quite capable of killing any MBT to be in service decades ago.   

Offline marauder2048

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #187 on: September 13, 2017, 02:52:15 pm »
Wireless has a lower minimum latency than fibre. EM waves simply travel faster through air than glass. The bandwidth available is higher in fibre true, but the bandwidth available in microwave or MMW links like the Spike-NLOS and FMTI use(d) is far in excess of what is actually needed for the relatively low-resolution video and missile data. The FMTI wasn't especially short range for its size either, it was tested to 8km (not trivial for a TOW-sized missile with a rocket motor) and had the potential for significantly greater range. And of course, the wireless Spike NLOS has a range of ~25km and seems to work quite well.

Propagation delay through the medium is not the major driver for the latency difference.
It's the protocol overhead of making RF datalinks reliable, full-duplex, LPI/LPD/jam-resistant etc.

FOG-M and its derivatives were not low-resolution which was the whole point.
Spike NLOS RF and FMTI are both predominantly F&F missiles with a MITL datalink
for LOAL.

The principles of TV guidance did not change when it occurred to someone to link the weapon to the launcher by a fibre optic cable; TV guidance was already well established when optical fibre entered the picture as a potential alternative to radio links.

Auto-tracking and automatic target handoff correlation (along with CCDs) revolutionized TV guidance in the late 70's.
But it was impractical (certainly at cost) to realize those gains over RF.

But they are still not completely new missiles. This isn't even my own observation. US tactical missiles which are not derived from existing missiles have been pretty consistently axed.

The slide-deck predates Griffin. And by the definition above FOG-M wouldn't have been
considered new because it used TOW's motor.

Offline marauder2048

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #188 on: September 13, 2017, 06:38:08 pm »
All this is very interesting.  However, what it does not explain is why the US Army has been so resistant over the years to the use of optical fibre guided weapons.   FOG-M was quite capable but it was abandoned after the US Army didn't want it.  EFOGM was also abandoned.  Either would have allowed a light armoured vehicle which was quite capable of killing any MBT to be in service decades ago.

My view is that the theme has been:

Fire-and-Forget approaches (especially with IFTU) tend to kill or relegate FOG even in the non-US offerings.

In the 80's, only Army Air Defense had the budget for FOG-M  and primarily as an anti-terrain masked helicopter weapon. 
Even then, a surface-launched AMRAAM was considered for that role.

In the 90's, Longbow Hellfire consistently outperformed EFOGM.

I could see FOG making a comeback in the ISR role though.

Offline Void

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #189 on: September 14, 2017, 05:50:35 am »
Propagation delay through the medium is not the major driver for the latency difference.
It's the protocol overhead of making RF datalinks reliable, full-duplex, LPI/LPD/jam-resistant etc.

But this is not a fundamental characteristic of a wireless link. The amount of interference it would be expected to encounter, intentional and unintentional, and the degree of covertness required would be application specific. For a given set of requirements, fibre may well prove to offer no meaningful advantage.

FOG-M and its derivatives were not low-resolution which was the whole point.
Spike NLOS RF and FMTI are both predominantly F&F missiles with a MITL datalink
for LOAL.

The video format of the FOG-M was RS170. Calling it high resolution is a bit of a stretch. The current Spike-NLOS provides CCD, IIR and SAL feeds simultaneously, which was beyond any hardware that existed in the FOG-Ms time.



The Spike-NLOS can function autonomously, semi-autonomously with man-in-the-loop lock-on of the automatic tracked or under full manual control. This is the same set of guidance options as the FOG-M.


Offline bobbymike

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Offline marauder2048

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #191 on: October 01, 2017, 04:32:51 pm »
Propagation delay through the medium is not the major driver for the latency difference.
It's the protocol overhead of making RF datalinks reliable, full-duplex, LPI/LPD/jam-resistant etc.

But this is not a fundamental characteristic of a wireless link. The amount of interference it would be expected to encounter, intentional and unintentional, and the degree of covertness required would be application specific. For a given set of requirements, fibre may well prove to offer no meaningful advantage.

And the application we are talking about in employing an AT/anti-helicopter weapon over a comparatively
long range  against a high-end opponent potentially in a post-nuclear attack environment. So yeah it's fundamental.


And the video format of the FOG-M was RS170. Calling it high resolution is a bit of a stretch. The current Spike-NLOS provides CCD, IIR and SAL feeds simultaneously, which was beyond any hardware that existed in the FOG-Ms time.

That video format did not provide sufficient contrast for the autotracker so they bumped it to 875 lines/10 MHz video bandwidth
(roughly RS-343). For the daylight camera alone (+ telemetry) that required a downlink data rate of 80 Mb/sec. 
There was provisioning for infrared or lowlight as well which would have added to the downlink data rate
requirements but it was still well within the link budget of single mode fiber even at range and with
micro/macro bending induced signal losses.

FMTI, some two decades later, could do ~ 20 Mb/sec downlink over MMW RF but in full-on LPD/LPI/AJ mode the operator
would see a frame rate of ~ 1 Hz.  Of course for a predominantly F&F weapon that's still tactically useful but
it shows the protocol overhead impact on a real RF datalink.

The Spike-NLOS can function autonomously, semi-autonomously with man-in-the-loop lock-on of the automatic tracked or under full manual control. This is the same set of guidance options as the FOG-M.

As we've said before,  the modern Spike-NLOS are predominantly fire & forget.

Offline Void

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #192 on: October 01, 2017, 07:02:34 pm »
And the application we are talking about in employing an AT/anti-helicopter weapon over a comparatively
long range  against a high-end opponent potentially in a post-nuclear attack environment. So yeah it's fundamental.

Fighting the Warsaw Pact is not the sole possible mission of FOG-like missile. And even if it had been procured that mission would have been irrelevant to the wars it would have actually been used in. Sensitivity to ECM is not a major concern when engaging Taliban fighters planing IEDS or ISIS weapons teams, yet these are the sorts of things TV guided "FOG" missiles are needed for in reality.

That video format did not provide sufficient contrast for the autotracker so they bumped it to 875 lines/10 MHz video bandwidth
(roughly RS-343). For the daylight camera alone (+ telemetry) that required a downlink data rate of 80 Mb/sec. 
There was provisioning for infrared or lowlight as well which would have added to the downlink data rate
requirements but it was still well within the link budget of single mode fiber even at range and with
micro/macro bending induced signal losses.

FMTI, some two decades later, could do ~ 20 Mb/sec downlink over MMW RF but in full-on LPD/LPI/AJ mode the operator
would see a frame rate of ~ 1 Hz.  Of course for a predominantly F&F weapon that's still tactically useful but
it shows the protocol overhead impact on a real RF datalink.

A missile that is restricted to F&F in the presence of hostile ESM/ECM is still quite suitable for the wars that are actually fought against non-state and "hybrid" opponents and the man-in-the-loop capability in a benign electronic environment is quite valuable against those same enemies. Which goes right back to what I said before, wireless is entirely suitable for a TV guided weapon in certain applications.

As we've said before,  the modern Spike-NLOS are predominantly fire & forget.

We? Are you multiple people posting on the same account?

You keep saying this, yes, but you have provided no indication you are correct, and what I can find contradicts what you are saying. So you aren't very convincing.

Jane's Defense Weekly described it:
Quote
Known as the Pere ('Savage'), the resulting vehicle is comparatively well armoured and has the mobility to keep up with the IDF's armoured divisions. It still has a crew of four: a commander, two gunners, and a driver. Once ordered to fire on certain co-ordinates, the crew launches a Tamuz towards the location, uses the live feed from the camera carried in its nose to identify a target as it approaches and then manually guides the missile towards it.

The manual guidance system restricts each Pere to having only one missile in the air at any given time, although a battalion of vehicles working together could potentially fire volleys at an enemy tank formation.

And video, both quality and rate, seem entirely sufficient for acquiring a target remotely. I won't pretend Jane's is always right, but then where is the contradiction?

Offline marauder2048

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Re: Army Wants 'Air Droppable' Light Tank & Ultra-Light Vehicles
« Reply #193 on: October 01, 2017, 10:28:42 pm »
Fighting the Warsaw Pact is not the sole possible mission of FOG-like missile. And even if it had been procured that mission would have been irrelevant to the wars it would have actually been used in. Sensitivity to ECM is not a major concern when engaging Taliban fighters planing IEDS or ISIS weapons teams, yet these are the sorts of things TV guided "FOG" missiles are needed for in reality.

And Anti-tank isn't the sole possible mission of Javelin as it has been used against IED and mortar teams.
But like FOG, it's an expensive way to kill personnel.

FOG isn't needed for that case either: cheap SAL/GPS munitions directed by a platform EO/IR sensor
can be used freely in permissive environments; that's much cheaper than FOG since you don't
destroy the expensive EO/IR bit with every use and the EO/IR on the platform will be superior
to anything you can affordably mount on a missile.

And you need the platform EO/IR sensor to spot the targets in the first place
since FOG type missiles are too expensive to use just for scouting.



A missile that is restricted to F&F in the presence of hostile ESM/ECM is still quite suitable for the wars that are actually fought against non-state and "hybrid" opponents and the man-in-the-loop capability in a benign electronic environment is quite valuable against those same enemies. Which goes right back to what I said before, wireless is entirely suitable for a TV guided weapon in certain applications.

Or you just carry a mixed load-out of F&F-only weapons and a bunch of your cheap SAL/GPS weapons
as is actually done. 


As we've said before,  the modern Spike-NLOS are predominantly fire & forget.



We? Are you multiple people posting on the same account?

You keep saying this, yes, but you have provided no indication you are correct, and what I can find contradicts what you are saying. So you aren't very convincing



You posted inaccurate info on FOG-M and then talked about Pere which was retired as obsolete neither of which help your argument:
the Israelis burned through the inventory of the RF guided versions and won't replenish them.

Offline bobbymike

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