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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marauder2048

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Unread post02 Sep 2020, 17:12

garrya wrote:FYI


You do realize that's the warhead and not the overall penetrator? When JDAM'ed it looks
like this. Note the pointy bit at the end.
blu-109.png
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wolfpak

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Unread post03 Sep 2020, 01:46

The US used laser guided weapons in combat during Desert Storm. They were mounted to both blast fragmentation and penetrator bodies. The historical record is full of photos of demolished harden aircraft shelters and other structures that received hits from BLU-109 based weapons. They all were laser guided. They hit penetrated reinforced concrete or steel blast doors. These were the GBU-10I, GBU-24 and GBU-27's. At the end of the war the GBU-28 ws used which had a modified GBU-27 guidance unit. Additionally the GBU-15/AGM-130 electro optical glide bombs had BLU-109 variants in addition to the MK-84 ones. It was the performance of the GBU-24's and '27's that lead to the development of the SBD. They discovered that these weapons would not only penetrate the roofs of the HAS's but also the floor before exploding. That's why they sized the SBD as they did to have enough energy to get thru the rood and then explode. There is no need to heave the floor if the explosion destroys the aircraft in the shelter. The key point is that they all had laser guidance packages which we still use today that did not interfere with penetration and proved to be highly effective.

During this time the F-111 and F-15E units were also plinking tanks using the blast fragmentation MK-82's with a laser guidance package creating what we know as a GBU-12. Once again this blast frag warhead with a laser guidance package consistently penetrated the armor on the tops of the turrets of Iraqi T-72's causing massive secondary's tossing the turret assemblies from the chassis. Once again no interference from the guidance package only this time the warheads weren't even penetrators. There is video and photos to support this.

Finally during the Falklands campaign of 1982 several British Frigates were damaged and or sunk using the MK-82 delivered using the MK-1 eyeball from Argentine A-4's. In this case there were reports of duds because the fuses with the arming vanes on their noses did not have enough turns to arm the weapon because of the close low altitude deliveries. This saved several ships but please note that the fuse pocket didn't have a nose plug because the fuse was in it. No different than the LGB's above.

So to summarize laser guidance packages based on actual combat experience don't impede penetration of US warheads.
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marauder2048

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Unread post03 Sep 2020, 04:16

wolfpak wrote:The US used laser guided weapons in combat during Desert Storm. They were mounted to both blast fragmentation and penetrator bodies. The historical record is full of photos of demolished harden aircraft shelters and other structures that received hits from BLU-109 based weapons. They all were laser guided. They hit penetrated reinforced concrete or steel blast doors. These were the GBU-10I, GBU-24 and GBU-27's. At the end of the war the GBU-28 ws used which had a modified GBU-27 guidance unit. Additionally the GBU-15/AGM-130 electro optical glide bombs had BLU-109 variants in addition to the MK-84 ones. It was the performance of the GBU-24's and '27's that lead to the development of the SBD. They discovered that these weapons would not only penetrate the roofs of the HAS's but also the floor before exploding. That's why they sized the SBD as they did to have enough energy to get thru the rood and then explode. There is no need to heave the floor if the explosion destroys the aircraft in the shelter. The key point is that they all had laser guidance packages which we still use today that did not interfere with penetration and proved to be highly effective.


Penetration depth depends heavily on the shape of the nose since it's fundamentally about two things:

a. pounds-per-square inch (PSI).
b. velocity

That means developing small diameter, heavy, pointy things since that helps with PSI and...drag.

The only way to guide penetrators in the period you describe was through front-mounted guidance
systems/and or some kind of command guided arrangement. Consequently, they were draggier,
not-all weather and couldn't penetrate as well.

But because penetrators need to be guided due to impact angle and velocity requirements
they used what was available.

Now that's no longer necessary you are seeing laser and optical guidance disappear because they did impair penetration.
And the things the older weapons penetrated were not particularly hard by modern standards (3000 psi).

SDB was developed with no laser guidance; as a result it has excellent penetration for a weapon
in its class. Laser guidance was an afterthought that destroys its ability to penetrate. It will similarly
degrade other weapons in its class or larger


The JDAM penetrators you see today do not use front-mounted laser guidance with the occasional exception.
SDB does not use it if it is needed to penetrate its design target set
MOP has no laser guidance.
B61-11 has no laser guidance.

The forthcoming A2K penetrator will not feature laser guidance
The forthcoming A5K penetrator will not feature laser guidance


wolfpak wrote:Finally during the Falklands campaign of 1982 several British Frigates were damaged and or sunk using the MK-82 delivered using the MK-1 eyeball from Argentine A-4's. In this case there were reports of duds because the fuses with the arming vanes on their noses did not have enough turns to arm the weapon because of the close low altitude deliveries. This saved several ships but please note that the fuse pocket didn't have a nose plug because the fuse was in it. No different than the LGB's above.


Completely irrelevant; that was low-level skip bombing. And the bombs that did the damage
were as often as not, MK 17s...not Mk-82s. The MK 17s are perfectly serviceable penetrators for
the thin hulled British frigates.

https://aquellasarmasdeguerra.wordpress.com/2013/03/05/bombas-en-la-guerra-de-malvinas/
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element1loop

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Unread post03 Sep 2020, 07:55

mixelflick wrote: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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garrya

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Unread post03 Sep 2020, 11:29

marauder2048 wrote:
You do realize that's the warhead and not the overall penetrator? When JDAM'ed it looks
like this. Note the pointy bit at the end.
The attachment blu-109.png is no longer available

I know but iirc, pointy nose is not necessary the best for penetration especially at a slanted angle. The issue is that very pointy nose tend to slide when they impact at an angle.Thus, even for Apds-t round the plastic aerodynamic cap is pointy but the penetrator isn't. So I think the pointy part is only plastic, the actual steel case is blunt. Furthermore, GBU-57 doesn't have a pointy nose

5CD8BACA-5AE0-4A5F-92E5-4E767F9FF526.jpeg


12D0B4A0-36AA-4EB9-BC69-088630F27AA2.png
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marauder2048

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Unread post03 Sep 2020, 15:42

garrya wrote:I know but iirc, pointy nose is not necessary the best for penetration especially at a slanted angle.


That's why most penetrators have angle restrictions and its why they needed
to be guided in order to conform to those restrictions.

garrya wrote:GBU-57 doesn't have a pointy nose


Which is why I posted the slide that explains why the GBU-57 has the nose it does:

"Button" nose for carriage


Like anything, there are going to be tradeoffs in penetrator design that may preclude ideal nose designs.
The same thing applies to APFDS: getting pointy tips that can survive multi-Mach impacts against armor is hard.
And armor tends to be sloped so you want a tip that's also less sensitive to deflection/ricochet.

But you generally see modern air dropped penetrators with noses that are closer to the ideal because they
are guided and get to chose to the impact angle.
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Unread post03 Sep 2020, 16:12

Here's the penetrator design for Conventional Prompt Strike.
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wolfpak

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Unread post03 Sep 2020, 20:46

Blunt shapes make the best penetrators as they reduce the likelihood of ricochet. All projectiles have limited entry angles Modern laser and GPS guidance systems use a PID type control to limit the entry angle. You don't want ricochet or slap-down.

So was the performance of laser guided weapons a fluke during Desert Storm?

Curious why they have a tri-mode seeker on the SDB-II? Won't it interfere with that warhead?

The publicly quoted ranges for Paveway II and III weapons imply low drag airfoils. Please clarify why you suggest that they are high drag?

What's the difference between skip bombing and any other delivery means once the project enters the target.
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Unread post03 Sep 2020, 21:14

wolfpak wrote:Blunt shapes make the best penetrators as they reduce the likelihood of ricochet. All projectiles have limited entry angles Modern laser and GPS guidance systems use a PID type control to limit the entry angle. You don't want ricochet or slap-down.


Blunt shapes do not make the best penetrators; see the CPS design. Where's the anti-ricochet there?
See the A2K designs

wolfpak wrote:So was the performance of laser guided weapons a fluke during Desert Storm?


It struggled against certain target types. So they developed new ones.

wolfpak wrote:Curious why they have a tri-mode seeker on the SDB-II? Won't it interfere with that warhead?


It's not a penetrating warhead; it's a multi-purpose shaped charge.
The seeker will get crushed and compressed against the target, then the charge will fire.

Since it's a shaped charge, its effects are independent of velocity; that's *NOT*
true of any of the other penetrators we've been discussing aside from:

JSOW-C/C-1/C-1-ER which uses shaped charge in conjunction with the follow through
charge. JMEWS will be the same.

wolfpak wrote:The publicly quoted ranges for Paveway II and III weapons imply low drag airfoils. Please clarify why you suggest that they are high drag?


They are not the basis for penetrator designs moving forward. JDAM is.

wolfpak wrote:What's the difference between skip bombing and any other delivery means once the project enters the target.


Aside from velocity, proximity, hull thickness? And you are cool with being completely wrong about the bomb
types (and shapes) used there right?
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Last edited by marauder2048 on 03 Sep 2020, 21:43, edited 2 times in total.
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Unread post03 Sep 2020, 21:17

Here's the TACMS-P penetrator (before and after). Clearly blunt is better.
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Unread post03 Sep 2020, 21:31

The Turks didn't get the memo on blunt ends.

32_neb-640x375.png



Even the modern Paveway penetrators are sub-caliber pointy things.
unnamed.png
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wolfpak

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Unread post03 Sep 2020, 23:13

Thanks. Being an engineer for over forty years, a registered Professional Engineer since 1982 and the owner of an engineering firm since 1989 I am always interested in the interpretation of engineering problems by non-engineers. It has been enlightening. Thanks again!
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Unread post03 Sep 2020, 23:17

wolfpak wrote:Thanks. Being an engineer for over forty years, a registered Professional Engineer since 1982 and the owner of an engineering firm since 1989 I am always interested in the interpretation of engineering problems by non-engineers. It has been enlightening. Thanks again!


Naturally, those with excellent technical backgrounds resort to slinging their credentials around rather
than presenting evidence, analysis and arguments.

I've got a far better background than you but I don't need it to produce it to show that you are utterly wrong
about modern penetrator designs. That trend is obvious and founded on the fundamentals of
penetration dynamics and improvements in guidance.

The only arguments for lower CRH noses is for penetrator stability or to reduce tip heating.
They are still pointy ogives but less pointy.

Feel free to look at the NAP study
https://www.nap.edu/download/11282

Or like any paper on penetration. Here's one I found it 30 seconds.

https://www.researchgate.net/publication/259515946_Response_Of_Granular_Media_To_Rapid_Penetration
It's on soil but the graph would be the same for other media.

A CRH of zero is blunt: it's bad. Higher is better.

crh-penetration-depth.png
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Unread post04 Sep 2020, 01:28

Nor did RAAF

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Unread post08 Sep 2020, 15:41

The pointy end cap is just there for protection of the threads on the boss. You can see the fine line separating the end cap from the bomb body on the photo you submitted. Note that the laser seeker for the GBU-55 will thread into the same boss.

https://www.bulletpicker.com/bomb_-2000 ... -blu-.html

Here's a definition of a Boss:

https://en.wikipedia.org/wiki/Boss_(engineering)
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