Forum: F-35 Armament, Stores and Tactics

Penetrate faster, harder with new AFRL weapon By Stephen Trimble on February 20, 2011

http://www.flightglobal.com/blogs/the-d ... ith-n.html

"My trip to Brazil has been unexpectedly delayed by an unplanned, extended pit-stop in Caracas, where my Boeing 767 is currently parked with a flat tire. If you detect a note of innuendo in the headline, it's the lack of sleep talking. Meanwhile, what better way to spend my first day in Venezuela than blogging about new bunker-busters! Meet the US Air Force's latest unintentional metaphor of a missile:

An Air Force Research Laboratory fact sheet with a 2011 time-stamp for public release approval tells us that a 2,000lb-class weapon with 5,000lb-class penetration capability could be available within three years.

"Future fighters will be able to deliver bunker-busting capabilities currently associated with the bomber fleet," the fact sheet says.

I found the fact sheet for the High Velocity Penetrating Weapon (HVPW) in the AFRL munitions directorate booth at the Air Warfare Symposium a few days ago. The document reveals the USAF has shifted its focus on next-generation penetrator technology on a couple of different levels.

Force is a function of mass multiplied by velocity. Mass is the key design point for the free-falling, 5,000lb GBU-28 bunker buster and the 30,000lb Massive Ordnance Penetrator.

For the next generation penetrator weapon, the AFRL appears to have shifted the focus to velocity. Packing a solid rocket propulsion system "with mission tailored boost and terminal velocities, intelligent fuzing and optimized explosive," the HVPW blasts into bunkers using speed in place of raw mass.

But the HPVW also may reflect a shift from previous interest in an air-breathing, high-speed penetrator, such as the Mach 3.0 Lockheed Martin revolutionary approach to time critical long-range strike (RATTLRS) demonstrator.

Like RATTLRS, the HPVW is designed to be carried inside the Lockheed Martin F-35's internal weapons bay, but will also enable "other fighter/bombers", the fact sheet says.

It's clear the USAF is in the market for a new penetrator weapon for the next generation bomber. Gen William Fraser, chief of Air Combat Command, actually confused the air force's message in his opening remarks at the symposium on 17 February. Fraser said that the next generation bomber would leverage several existing technologies, and he included the Massive Ordnance Penetrator on the list.

I asked Lt Gen Jim Kowalski, chief of Global Strike Command, about that the next day. He clarified that Fraser means the next generation bomber will leverage the bunker-buster effect of the massive ordnance penetrator, but not necessarily its mass. In the aforementioned force equation, that implies a shift toward higher speed, although Kowalski declined to confirm that theory."

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The Air Force Wants A New Bunker Buster Bomb For the F-35

http://defensetech.org/2011/02/20/the-a ... -the-f-35/

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Sounds similar to the Kinetic Energy Missile concept from the late 80s.

OK, I'll bite.

So what would the current 4-5k pound bomb, modified with this same multiplying busting effect have then? Equivalent to 10,000 lb worth of bunker busting?? Wow... I guess i'd just be more worried as a bad guy, with an F-15 dropping a 10,000lb equivalent buster, than an F-22/F-35 dropping a 5k equivalent... But that's just me. Wink

I hope Stephen enjoys a well deserved holiday in beautiful Brazil.

geogen wrote:

OK, I'll bite.

So what would the current 4-5k pound bomb, modified with this same multiplying busting effect have then? Equivalent to 10,000 lb worth of bunker busting?? Wow... I guess i'd just be more worried as a bad guy, with an F-15 dropping a 10,000lb equivalent buster, than an F-22/F-35 dropping a 5k equivalent... But that's just me. Wink

I hope Stephen enjoys a well deserved holiday in beautiful Brazil.

You'd have to steap an awfully big motor onto the back of such an already large weapon to get the same high velocity performance. Does the F-15E even have a hardpoint rating for such a large weapon?

I'd be surprised if they do...

And if the targets heavily defended the F-15 doesn't have much hope of getting near it to release such a weapon yet the F-35 does.

Quote:

Force is a function of mass multiplied by velocity.

I thought it was acceleration and mass. Ya know, F = ma. Kinetic energy would involve velocity, K = 1/2 * m * v^2. Correct me if I'm wrong, I'm looking at my physics book right now.

So the USAF wants to get added potential energy from a rocket motor instead of relying solely on mass?

1st503rdsgt wrote:

Sounds similar to the Kinetic Energy Missile concept from the late 80s.

Yep. 1986/87 I believe. There were 2 versions, one for fielding on ground platforms, and a lighter version for AC. The missile made it into some HUMVEE platforms, only.

The MOP weighs 30,000lbs of which 5300lbs is explosive filler. Most of the weight is in the heavy casing w/c provides its punch-through capability. With the new bunker-busters, strike fighters will now pack the punch of heavy bombers like the Spirit and Lancer.

The author said, "Force is a function of mass multiplied by velocity. Mass is the key design point for the free-falling, 5,000lb GBU-28 bunker buster and the 30,000lb Massive Ordnance Penetrator."
I always thought force=1/2 mass times velocity squared. If physics hasn't changed, and I remember the formula correctly, the big dog is velocity--that's why the "high velocity" was added to the penetrator. Squaring that high velocity adds exponential? force to the penetrating blivet. See the specs. on BKEP? (ballistic runway cratering munition) for similarities...
Anyway, its a good idea.

Force is mass x acceleration. Momentum is mass x velocity. Kinetic energy is one-half mass x velocity squared.

And potential energy is weight x height, where weight is mass x gravity.

Isn't the overall problem with these bunker busters a "potential" energy problem from the start? If the aircraft cannot support enough potential energy, then it will never transition into enough kinetic energy, right? I'm trying to test my physics knowledge here and see if two semesters worth (PHYS 1 and 2) taught me anything. Any experts out there?

AFRL Moves Ahead on Bunker-Buster for F-35 by Graham Warwick, Jul 06, 2012

http://www.aviationweek.com/Blogs.aspx? ... db096866b8

"The US Air Force Research Laboratory has awarded two more contracts under the High Velocity Penetrating Weapon (HVPW) program to develop technology for a rocket-boosted bunker-buster that can fit inside an F-35.

Lockheed Martin has been awarded $1.7 million and MBDA $1.3 million, but what they will do for the money has not been revealed. In January, Raytheon received an $11 million contract to develop GPS-degraded guidance technology for the HVPW, including anti-jam GPS, angle-of-attack sensing and RF seeker....

...As conceived, the HVPW is a solid-rocket-boosted 2,000lb-class weapon with the penetration of a 5,000lb gravity bomb, design for internal carriage in an F-35 and also able to increase the load-out on other bombers and fighters...."

MORE at the JUMP - BLAST! Very Happy

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http://www.aviationweek.com/Portals/AWe ... %20FCC.jpg

Hope the following helps somebody out there visualize why adding a rocket motor to an earth penetrator - like with the old Durandel anti-runway device - is a sound idea for a given bomb size. Consider:

Acceleration - a change in velocity. Drive at a constant 65mph speed, A=0. Brake and you accelerate in a negative direction. Hit the gas pedal and you accelerate in a positive direction. Think scalar values plus a direction for rate of change. (I was taught never ever to use the term "deceleration". It's just acceleration in a direction.)

Velocity - speed. *Exponential* effect on kinetic energy. The greater the velocity for a given mass, the greater the object's energy by a square of the speed. Add two units speed, get four units contribution, add three units speed, get nine units contribution etc.

Mass - the object, in this case a bomb. Mere *linear* effect on kinetic energy, e.g., add one kilogram, get one kilogram's contribution, add two kilograms, get two kilograms contribution etc.

Kinetic Energy - has two constituents: mass and velocity.

Key concerns for a successful earth/bunker penetrator are kinetic energy (good), the bomb's friction with the earth/bunker (bad), and inertia (tendency of an object to remain moving without change).

To increase the bomb's kinetic energy (good), the most practical means is to speed it up (square) rather than to beef it up (linear). Accelerate the bomb to max velocity attainable.

Once the bomb is up to max velocity (A=0) it will stay at that value unless some other force acts on it. This is the bomb's inertia.

Friction caused by the bomb-earth interaction is the other, "opposing" force. Friction is a function of surface area and changes inertia opposite the bomb's direction of travel. Thus friction reduces kinetic energy quickly.

Friction doesn't significantly change the mass. So to keep the kinetic energy as high as possible for as long as possible to punch through earth and bunker as deeply as possible you increase the bomb's mass as much as possible for a given bomb size (surface area) and a given speed curve (high speed then slowing down).

The bomb's inertia will change more slowly versus the frictional force the heavier you make your bomb. But you want to get the bomb going as fast as possible in the first place before the friction starts operating on the bomb. And that's why you stick a rocket up it's keester. 0.02

Forum: F-35 Armament, Stores and Tactics

Another Weapon for F-35? - HVPW