XM1018

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XM1018
Non-lethal projectile variants
general information
caliber 20 × 28 mm G
Sleeve shape Belt sleeve
Dimensions
Sleeve shoulder ⌀ approx. 21 mm
Sleeve neck ⌀ approx. 21 mm
Floor ⌀ 20 mm
Cartridge bottom ⌀ approx. 21 mm
Cartridge length 92 mm
Weights
total weight 92.13 g
Technical specifications
Speed ​​v 0 240 m / s
Lists on the subject

The XM1018 High Explosive Air Bursting (HEAB) ammunition was developed by ATK Integrated Defense Systems for the Objective Individual Combat Weapon (OICW), also known as the HK XM29 . The grenade was designed to detonate with impact, delay or air ignition in order to develop an optimal effect depending on the target situation. In the opinion of those responsible for the project, however, the effect of the grenade was not sufficient, so the XM1018 grenade was a reason to discontinue the OICW program.

history

With the start of the tender and phase 1 for an Objective Individual Combat Weapon in December 1994, the two company consortia also began developing the grenades. The target was a 50% annihilation probability at 500 m for people outdoors and 35% for people under cover. A group of 9 exposed, protected soldiers should be able to be fought with 18 rounds. In the long term, the probability of destruction of the grenade should be increased to 90% up to a distance of 750 m. In phase 2, the demonstration of critical technologies in ammunition, fire control and the weapon itself was completed by both teams in February 1996. The prototype of the safety mechanism, which was designed as a microsystem , was produced for the first time. In phase 3, which took place between January 1997 and 1998, both concepts were tested:

  • ATK / HK / Brashear LP : The grenades had a detonation unit in the middle and two small warheads made of hot isostatic pressed steel at the front and rear to ensure that the area was completely covered with fragments. The drive took place conventionally with a propellant charge, which was housed in a cylinder case. The grenade weapon was designed as a gas pressure loader.

The heads of the Joint Service Small Arms Program decided in April 1998 for the design by Heckler & Koch, Brashear and ATK; On the one hand because of the higher performance in terms of range and precision, on the other hand because the design had an integrated thermal imaging device. ATK received $ 8.5 million to build seven prototypes and 4,700 rounds of 20mm ammunition to reach phases 4 and 5 of the project. On August 4, 2000, the group received an additional $ 6.946 million to begin pilot production. The subsequent development was then limited to improving the MEMS Safety and Arming Device according to STANAG 1316, as well as increasing the destruction performance and reducing costs. In the future, a price of 30 US dollars per shot should be achieved.

The first successful series of tests took place in January 2002. Over 180 rounds were fired to confirm the airburst accuracy, the safety system and the effectiveness at ranges of 100, 350 and 500 meters. On February 12, 2002 test shots were carried out with the non-lethal projectile variant, smoke was used as payload and marker charge. The styrofoam placed five meters behind it showed only negligible impressions.

In the opinion of those responsible for the project, the 20mm XM1018 grenades were not effective enough, which was a reason to discontinue the OICW program in 2004. It was decided to use a larger caliber of 25 mm with the HK XM25 . The XM1018 could not achieve the desired effectiveness against open and covert targets, which was partly due to the fact that OICW shooters had a "considerable margin of error " (literally: sizeable margin of error ) when shooting at targets under cover. In other countries they seem to trust soldiers to have a steadier hand; the South Korean Daewoo K11 continues to use 20 mm caliber shells.

overview

The effectiveness of grenades depends solely on the splinters they send out. The faster and heavier these are, the greater their destructive power. The more numerous these are, the higher the hit rate at a greater distance. In practice, this results in a conflict of objectives because the volume and surface area are limited: a thicker wall increases the mass of fragments, but reduces the volume of explosives. Larger fragments allow a constant volume of explosives, but reduce the number of fragments. As a result, an explosive that is as powerful as possible and a wall material that is as heavy as possible is the best choice, but cannot always be realized for reasons of cost.

Sliver pattern of the XM1018

Secondly, the structure of the projectile is also decisive: the intrinsic speed of the rear fuses results in a forward-facing, conical splinter pattern. The side and the rear area are almost splinter-free. In the case of head detonators, the fragment image is inverted. Here a cone-shaped area in front of the floor is almost free of splinters, but the side and rear areas are affected. Depending on the target location, one or the other structure can be advantageous: For people outdoors, rear fuses are more advantageous, the grenade then detonates shortly before the target, which is hit by the fragment cone. In the event of impact ignition, the effect on the hit object is better. Head fuses are better for enemies in cover, as people standing at right angles to the flight path, for example behind an obstacle or window frame, can be hit more effectively. In the case of contact ignition, on the other hand, the environment can be better split up.

The well-known 40 mm grenades , for example, are all head fuses, as they hit the ground very steeply. The upward-pointing rear of the grenades can thus better cover the surroundings with splinters. Due to the deep detonation point, the effect is limited, especially when the enemy is on the ground. Air-igniting grenades can therefore be smaller as they can work more effectively. For the XM1018, the ignition unit was relocated to the middle of the grenades to get the best of both worlds. While the front warhead produces small fragments because the grenade's own speed is added up, the fragments of the rear warhead have a lower initial speed due to the grenade's own speed, which is why larger fragments were chosen to keep the kinetic energy roughly the same.

technology

construction

Structure of the XM1018 shell

As mentioned above, the electronics sit in the middle of the grenade. This consists (from front to back) of the actual ignition electronics, which take up around 33% of the electronics volume, and the fuse, which is designed as a microsystem and requires around 20% of the electronics volume. The remaining electronics space is used by the battery. The safety microsystem had come a long way to withstand the 45,000g launch and the 40-foot drop test. The first prototypes were made from 1996, experimenting with rotors, springs and anchors. ARDEC built a 200 µm thick model with inertial drive on a nickel plate, while Sandia National Laboratories designed an electro-mechanical model on a 2 µm thick plate made of polycrystalline silicon. The end product, also manufactured using the LIGA process , ultimately consisted of two micro-springs, which were built into the grenade at right angles and radially. Due to the centrifugal force of the rotation, they are stretched during flight, so that an unlocking slide is released and can move into the ignition position, thereby closing the electrical circuit for the ignition. The grenade can now be detonated by the electronics when the target point is reached.

Air ignition of the grenade

When the trigger is pulled, the TA / FCS transmits the necessary information to the 20mm grenades. The programming is carried out contact-free via induction coils , which are located outside on the chamber of the titanium tube and in the grenade. If the grenade is supposed to explode in the air, the electronics count the rotations that the grenade makes to maintain its gyro stabilization. The grenade is fired when the necessary number of rotations has been made, which was programmed into the grenade by the TA / FCS before firing. In addition, security was built into the microelectronics: Eight seconds after being fired, the grenade definitely exploded so as not to pose any further danger.

A total volume of 12 milliliters is available for the front and rear warheads. In order to achieve a good effect despite the cramped conditions, the walls of the warhead were manufactured using hot isostatic pressing (HIP). ATK used a special powder mixture of steel, stainless steel, high-speed steel , a titanium alloy and refractory metals . The manufacturing process began with the pressing of pellets, which represent the fragments. These were then glued together in a second step using HIP. As a result, despite the mass production, it was possible to generate a consistent fragment image or to adapt the warhead design flexibly to new threats. As with the 25 × 59 mm grenades LX-14 was probably used as the explosive . This consists of 95.5% HMX , the remaining 4.5% are thermoplastic polyurethanes and binders.

In 2000, the development of a non-lethal variant of the projectile began. The first concept was to integrate a LIDAR into the projectile nose and small brake rockets into the stern behind the payload. If the laser radar reported contact, the braking process should be initiated and the payload should be released. Ultimately, they agreed on a more practical and cheaper approach: a rear detonator with a small explosive charge, and in front of it a layer of tungsten powder that hurls the payload forward. The mass of the tungsten powder also decelerates the ignition unit. With the air-igniting CS gas variant, tests were also carried out to determine whether the CS was more effective as a powder or as a solid block with a decomposing charge, but the test results were inconclusive. Other payloads were rubber bullets and stun grenades .

variants

A total of six projectile variants were planned for the HK XM29 , of which only the HEAB variant, which was later designated as the XM1018, and the practice and CS ammunition (TP or CS) were almost ready for series production. The color scheme of all bullet variants is not known, but a similar ammunition family in caliber 25 × 40 mm is planned for the HK XM25 , whereby the color choice is mostly identical.

  • High Explosive Air Bursting (HEAB): A programmable, air-igniting high-explosive grenade. The color scheme is yellow.
  • High Explosive Dual Purpose (HEDP): A multi-purpose grenade with a shaped charge , fragmentation jacket and contact ignition. The color scheme is red.
  • Training / Practice (TP): A training grenade without a warhead. The color scheme is blue.
  • Anti-Personnel (AP): A non-lethal rubber bullet. The color scheme is unknown, possibly purple.
  • CS Gas (CS): A programmable, air-igniting gas grenade. The color scheme is green.
  • Stun (?): Flash grenade, possibly programmable. Color scheme and details are unknown.

Web links

Individual evidence

  1. ↑ a b Erik C. Webb: AN ANALYSIS OF THE TRANSITION OF THE OBJECTIVE INDIVIDUAL COMBAT WEAPON (OICW) FROM ADVANCED TECHNOLOGY DEMONSTRATION TO ACQUISITION PROGRAM ; NAVAL POSTGRADUATE SCHOOL, March 2002 (PDF; 651 kB)
  2. ↑ a b US Army TACOM ARDEC: MEMS Safety and Arming Device for OICW ; August 13-16, 2001 (PDF; 1.8 MB)
  3. ↑ a b sistemasdearmas: XM-29 - SABR
  4. ↑ AAI / JSSAP: Firestorm Objective Individual Combat Weapon (OICW) , February 18, 1998 ( Memento of December 10, 2006 in the Internet Archive ) (PDF; 1.8 MB)
  5. ↑ Thomas G. Harris: INTERACTIVE SIMULATION TRAINING SYSTEM FOR THE OBJECTIVE INDIVIDUAL COMBAT WEAPON SYSTEM , USAWC STRATEGY RESEARCH PROJECT (PDF; 375 kB)
  6. ↑ a b c Global security: XM1018 High Explosive Air Bursting (HEAB)
  7. ↑ a b Penstate Applied Research Laboratory: The Objective Individual Combat Weapon Non-Lethal Munition , October 10, 2002 ( Memento of July 28, 2012 in the Internet Archive ) (PDF; 6.3 MB)
  8. ↑ National Defense: Experts Question Lethality of OICW Warhead , June 2001 ( Memento of February 20, 2013 in the Internet Archive )
  9. ↑ Camilo A. Sanchez: Non-Lethal Airburst Munition (s) for Objective Individual Combat Weapon , August 15, 2001 ( Memento of December 2, 2011 in the Internet Archive ) (PDF; 1.1 MB)