Update: USAF seeks information maritime strike weapon [F-35]

F-35 Armament, fuel tanks, internal and external hardpoints, loadouts, and other stores.
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element1loop

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Unread post01 Sep 2020, 04:57

madrat wrote:I'm not convinced LGB's hitting above deck have the same effect on a destroyer as that NK fishing trawler. For one, the destroyer isn't going to let the delivery come unabated.

SM-6 is an excellent example of a high plunging deck strike, basically hits like a battleship shell on steroids. One SM-6 could have sunk most WW2 cruisers (if not many WW2 battleships) at significantly longer ranges. SM-2 already proved to be a significant threat to ships, but SM-6 has a large performance bump over it.


I don't disagree, but 2 x 2,000 lb GBU based anything is going to make whatever that hits unserviceable for the duration, especially if an initial high-end antiship missile hits the right place, with next to no warning, and blows all the good bits into the water. The point is, you don't even need to sink the ship to make it a wreck, and you don't have to expend more than 2 modern antiship missiles to do so (one should be enough), then finish it off for $100K worth of wing-kits and GBUs.

Very much like the SM2 and SM6 options, and a PrSM moving-target option. But there's a reason for the one in the head, and two in the chest rule, it's to be sure the 'kill' does not resurrect, in this case 2 x 2,000lb JDAM-ER in the chest, to be sure.

[BTW, LGB is not going to be exploding on an upper deck plate, there are fusing options for LGBs, they can penetrate bunker concrete before detonation and JDAM-ER likewise comes in BLU-109 delayed fuse flavor, which will very much blow the keel apart on any class of ship, and with any desired angle of incidence, as per an SM2/6 strike.]
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marauder2048

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Unread post01 Sep 2020, 06:48

element1loop wrote:
[BTW, LGB is not going to be exploding on an upper deck plate, there are fusing options for LGBs, they can penetrate bunker concrete before detonation and JDAM-ER likewise comes in BLU-109 delayed fuse flavor, which will very much blow the keel apart on any class of ship, and with any desired angle of incidence, as per an SM2/6 strike.]


The typical issue is that at JDAM-ER ranges, impact velocities/angles aren't are that great.

And the laser seeker tends to reduce penetration depth since that's sensitive to nose design.

The turbojet version of JDAM-ER (which it looks like the Navy might be buying) wouldn't have
these issues since it could execute a powered dive.
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weasel1962

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Unread post01 Sep 2020, 07:43

Depends how much these costs.
https://tdi-engines.com/tdi-j85/

These weren't that cheap but made sense for those heavier class bombs.
https://www.pbsaerospace.com/our-produc ... t-engine-1
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Unread post01 Sep 2020, 08:08

weasel1962 wrote:Depends how much these costs.
https://tdi-engines.com/tdi-j85/

These weren't that cheap but made sense for those heavier class bombs.
https://www.pbsaerospace.com/our-produc ... t-engine-1


So Gray Wolf had an all-up-round target cost of $200,000.
.
Say TDI-J85 is $100,000, then you could see a powered JDAM-ER < $200,000.
(making some guesses about wing-kit cost).

JSOW-ER is projected at $500,000.

(From a 17 Oct 2012 NDIA preso)
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element1loop

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Unread post01 Sep 2020, 10:03

marauder2048 wrote:
element1loop wrote:
[BTW, LGB is not going to be exploding on an upper deck plate, there are fusing options for LGBs, they can penetrate bunker concrete before detonation and JDAM-ER likewise comes in BLU-109 delayed fuse flavor, which will very much blow the keel apart on any class of ship, and with any desired angle of incidence, as per an SM2/6 strike.]


The typical issue is that at JDAM-ER ranges, impact velocities/angles aren't are that great.

And the laser seeker tends to reduce penetration depth since that's sensitive to nose design.

The turbojet version of JDAM-ER (which it looks like the Navy might be buying) wouldn't have
these issues since it could execute a powered dive.


I had presumed RAAF's test range number included the need for terminal speed and high angles for BLU-109 bunker penetration. I'm pretty sure it would go through the bottom of a ship like it was tin foil if delaying the fuse long enough. But more speed is good against a ship that's still partially able to fire at a weapon.
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element1loop

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Unread post01 Sep 2020, 10:35



From link:

Max. starting altitude 13,123 ft
Speed range for startup 0 to 0.4 M
Max. operating altitude 29,528 ft


So after weapon release the weapon glides to below 13K feet and ~230 kt to start the engine then boosts back to under 30,000 feet then glides to the target. Thus no fuel left for terminal power dive with that one.
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wolfpak

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Unread post01 Sep 2020, 16:07

When penetrating the target the laser seeker will disintegrate but that's fine. It won't have an effect on the penetration of the warhead. It is external to it. It's merely threaded on the warhead body (ie; MK-84's, BLU-109's, etc.) so laser JDAM's are no less effective than the same bomb without the seeker with regards to penetration. As for speed remember that pesky formula from high school physics concerning speed of a projectile under the influence of gravity? As long as it's not a high drag airframe the impact velocity will be only marginally less than the velocity at launch from the aircraft. If anything you speed up from the acceleration of gravity not slow down.
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Unread post01 Sep 2020, 17:15

wolfpak wrote:When penetrating the target the laser seeker will disintegrate but that's fine. It won't have an effect on the penetration of the warhead. It is external to it. It's merely threaded on the warhead body (ie; MK-84's, BLU-109's, etc.) so laser JDAM's are no less effective than the same bomb without the seeker with regards to penetration.


This isn't accurate. Penetration is very sensitive to nose design; high CRH noses are generally required.
Sometimes that's not possible for cost or other reasons (see below). If you'll look at the advance penetrators
they've generally gone away from the fuze in the nose approach because it does inhibit penetration.

The same thing happens to SDB when they insert the laser seeker and replace the steel nosecone:
penetration is reduced (from memory) by 2/3rds.


wolfpak wrote: As for speed remember that pesky formula from high school physics concerning speed of a projectile under the influence of gravity? As long as it's not a high drag airframe the impact velocity will be only marginally less than the velocity at launch from the aircraft. If anything you speed up from the acceleration of gravity not slow down.


We're talking about the impact velocities of the weapons with glide kits at range is not all that great:
JSOW, with an L/D around 10 is around 700 fps. That's why they have to appeal to a two-stage
(shaped charge warhead + follow through) Or you have to trade range for higher impact velocities.
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Unread post01 Sep 2020, 17:17

element1loop wrote:So after weapon release the weapon glides to below 13K feet and ~230 kt to start the engine then boosts back to under 30,000 feet then glides to the target. Thus no fuel left for terminal power dive with that one.


Or you trade some range for a powered dive. You can make that tradeoff with a powered weapon.

Max. starting altitude 13,123 ft
Speed range for startup 0 to 0.4 M
Max. operating altitude 29,528 ft


That's also just a bad design; P&W TJ-150 can do pyrotechnic starts up to 35,000 ft.
The TDI engines are claimed starts somewhere in the 20,000 - 25,000 ft. altitude.
You can find other small turbojets in this class that have much higher altitude windmill starts.
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Unread post01 Sep 2020, 23:58

marauder2048 wrote:That's also just a bad design; P&W TJ-150 can do pyrotechnic starts up to 35,000 ft.
The TDI engines are claimed starts somewhere in the 20,000 - 25,000 ft. altitude.
You can find other small turbojets in this class that have much higher altitude windmill starts.


Yes, that's what I thought. These things must have an el-cheapo version of FADEC and some basic sensors to make them function better in marginal conditions.

Though I think you're incorrect with respect to a BLU-109 JDAM-ER penetrator depth being affected by the nose sensor kit. The sensor would be removed on impact, then the tip of the case will work as normal. I doubt there'd be a measurable attenuation (at least 21 ft through hardened concrete during tests). For the GBU versions the soft nose sensor and blunt GBU case would certainly curtail penetration.
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Unread post02 Sep 2020, 01:33

You can't compare a SDB to a 2000LB penetrator. They're different. What about a AUP? They were designed for laser guidance. A 20 lb seeker attached to the front end of any 2000lb warhead will have little measurable effect on the penetration capability of it. It's a matter of physics.
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Unread post02 Sep 2020, 02:02

wolfpak wrote:You can't compare a SDB to a 2000LB penetrator. They're different. What about a AUP? They were designed for laser guidance. A 20 lb seeker attached to the front end of any 2000lb warhead will have little measurable effect on the penetration capability of it. It's a matter of physics.


Of course, but I'm not comparing a GBU to SDB (which I understand penetrates 6 ft of hardened concrete no problem), the comparison was BLU-109 to Mk84 case. The GBU case's flatter nose will not not penetrate as well as the sharpened hardened BLU case, which was designed to penetrate.
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Unread post02 Sep 2020, 02:36

FYI
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12B8F51D-D5FC-4C04-9A94-1BE8286B7907.gif
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Unread post02 Sep 2020, 15:25

Sure hope Japan is following this discussion.

Given the type of destroyers and cruisers China's putting out to escort her carriers, they're going to need a damn good weapon to get through those air defenses (considered among the most capable in the world). I'm talking about their type 055 destroyers, in particular.
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Unread post02 Sep 2020, 16:58

wolfpak wrote:You can't compare a SDB to a 2000LB penetrator. They're different. What about a AUP? They were designed for laser guidance. A 20 lb seeker attached to the front end of any 2000lb warhead will have little measurable effect on the penetration capability of it. It's a matter of physics.


The B61-11 doesn't have a laser guidance system for this reason. The penetrators that did were
largely pre-GPS where the only guidance mode possible was laser.

The shape of the nose is crucial to penetration. That's plain from all the literature and the weapons the US
has deployed.
Last edited by marauder2048 on 02 Sep 2020, 17:15, edited 1 time in total.
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