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Soft Recoil Technology

Artillery weapons have been used for hundreds of years. These weapons have been continuously developed to improve accuracy, effectiveness, and efficiency. When an artillery weapon is fired, the energy of the round must be absorbed by the weapon’s structure and eventually transmitted to the ground.


The recoil system is a necessary accessory of the gun. It is defined as an assembly of components whereby the forces acting on a gun and its related mount during a firing cycle can be controlled and limited to certain parameters by one or more recoil mechanism. When the gun is fired the gas thrust generated tending to move the gun rearward is very large, and if the gun is mounted rigidly without any recoil system, it would be impossible to build a mounting strong enough to resist the stresses without rupturing or overturning. To reduce the stresses to reasonable values, and to ensure stability of the equipment, the gun must be allowed to recoil relative to the mounting. This is achieved by an elastic link between cradle and Ordnance. This link is called Recoil System.


Modern artillery systems incorporate recoil mechanisms to modulate the forces associated with these firings to a level that can be effectively and reliably supported by the structure. With some recoil mechanisms, the energy of the round is dissipated by throttling fluid over the length of the recoil. The minimum level of this modulating force is directly proportional to the length of recoil.


Recoil system

Function of the Recoil System in the Gun
The recoil system has following functions to perform in the gun:
 To absorb the recoil energy smoothly in a convenient distance to bring the ordnance to rest
 To return the ordnance to the firing position
 To hold the ordnance in the fully run-out position at all angle of elevation
 Enhance the stability of the gun
 To enhance the accuracy of the gun.


The recoil system consists of buffer for absorbing and dissipating part of energy of recoil, a recuperator for storing part of the energy to be used subsequently for returning the gun to the firing position; and control plunger for controlling run-out or smoothen the last stages, and ensures that the gun returns quietly to its firing position, and a replenisher to feed the buffer to take care of any leakage. The recoil system affects the accuracy, stability and the rate of fire of the gun. It also reduces the Trunnion pull of the gun according to the length of recoil. Trunnion pull reduces with increase in length of recoil of the gun.


Presently hydro-pneumatic type of recoil system is in vogue in all gun system for its consistent performance, but change in terrain changes its performance. To make it independent of weather condition/terrain conditions non-Newtonian fluid (Hydraulic) is under exploration for the use.


There are many types of recoil systems but few have got futuristic relevance in the futuristic combat system. For futuristic development for next three decades following types of recoil system will be more relevant and appropriate for the combat system. These are – curvilinear recoil system and adaptive recoil system based on soft recoil mechanism and non-Newtonian fluid (e.g. Electro-rheological (ER) and Magneto-rheological (MR) fluid).


Soft Recoil system

In a soft recoil system, the recoiling parts are accelerated forward prior to the firing of the round by an internal gas spring. When the round is fired, nearly half of the energy of the round is used to stop the forward motion of the recoiling parts and the remaining energy is used to force the recoiling parts rearward, recompressing the gas spring. The recoiling parts are then captured by a latch in preparation for the next firing. This use of momentum exchange and energy conservation by the soft recoil technique results in recoil force reductions as high as 75% when compared to conventional recoil systems.


Although the soft recoil technique offers considerable advantages, there are some drawbacks associated with the cycle. Among these are: (1) A different run-up velocity is required for each of the different zones/charges being fired to maximize the benefits, (2) If the round fails to fire during the run up (known as a misfire), the buffing load required to bring the forward velocity of the recoiling parts to zero may be high enough to cause some weapon instability, and (3) If the round fires prematurely from the latch position (known as a “cookoff”), the conventional recoil-style buffer rearward of the latch point may induce sufficient forces to cause the weapon to slide rearward or become unstable.



The Hawkeye is a 105mm, Humvee-mounted artillery piece that’s made by AM General and Mandus Group. AM General makes Humvees, while the Mandus Group makes the a soft-recoil howitzer, which allows the cannon to fire from a lighter platform.


Mandus Group, is an innovator of artillery solutions based on soft recoil technology, headquartered in Rock Island, Illinois. In addition to the revolutionary mobile light artillery system, that leverages a patented soft recoil technology that can be integrated into multiple mobility platforms, their product portfolio includes innovative systems that have proven very successful in assisting government agencies to reduce maintenance time and expense on equipment.


The groundbreaking self-propelled Humvee Hawkeye howitzer system incorporates soft recoil technology that reduces loads and the weight of stabilizing structures by as much as 50 percent compared to conventional recoil systems. The merging of the soft recoil 105mm weapon system with the iconic, rugged, and proven Humvee has resulted in a dynamic platform that not only provides faster and more accurate firing but also maximizes rapid deploy-and-redeploy, “shoot and scoot” capability, with a crew half the size of traditional towed artillery systems.


It was lauded as a more mobile light artillery platform by Capts. Joseph Schmid and Adam Wilson in the May-June issues of “Fires,” the professional journal of the artillery community. “For example, we can reasonably assume a brigade will perform large amounts of artillery air assaults to move guns over non-trafficable ridgelines, high peaks and dangerous valleys,” they wrote. They compared the transport options with the current M119A3 for light artillery versus using lighter platforms such as the Hawkeye.


“… a battery commander can sling-load two full howitzer sections (one towed M119A3 and one prime mover per section) with four CH-47 Chinook helicopters. However, with the Hawkeye platform, a brigade can double its ability to project indirect Fires forward in support of a maneuver formation by sling-loading one Hawkeye SPH under each CH-47,” they wrote.


AM General and Mandus Group’s Soft Recoil Technology to Be Tested with the United States Army, reported in May 2021

A press release provided by AM General listed on Cision PR Newswire, May 18, 2021, announced that they recently received a firm-fixed price contract by the US Army for HUMVEE 2-CT Hawkeye Mobile Howitzer Systems (MHS) for the U.S. Army’s characterization test. The MHS has Mandus Group’s soft recoil technology integrated onto AM General’s M1152 two-door cargo truck. Click this link to read the full press release.


Soft recoil could not only make it possible to fit relatively light vehicles like Humvees or medium tactical trucks with up to 155mm guns, but make light artillery more survivable in the bargain.


Regis Luther, AM General’s chief technology officer, says that SRT can enable the carriage of heavier guns on light vehicles because it reduces recoil shock by up to 60%, diminishing the chances of recoil-induced rollover and cushioning the recoil-induced fatigue load to vehicle chassis.

On Hawkeye, the system combines external stabilizers that look like the legs you’d see splayed out behind a backhoe or in front of a heavy tow truck with a hydraulic system internal to the howitzer barrel. The external stabilizers quickly retract for stowage when the vehicle is in motion and are lowered hydraulically when it’s time to fire the gun.


Firing of the howitzer is softened by the configuration of the gun barrel and SRT hydraulics, Regis Luther, AM General’s chief technology officer, explains. “Just prior to firing, the gun barrel is in a retracted position. As it is [commanded] to fire [the barrel] moves forward to near the end of its travel. When the round fires, there’s a large returning force and the hydraulics shift from moving the barrel forward to catching it and slowing the rebound of the firing force.”


“The range of motion is longer than with a non-soft reoil weapon,” Luther says. The effect is that the vehicle moves less while the gun moves more. The technology makes it possible to actually place the guns directly on smaller, elusive platforms rather than towing them behind light or medium tactical vehicles. “SRT gives us the ability to shoot-and-scoot in about half the time,” Luther asserts.


“Towed artillery is pulled behind a prime mover thanks to its weight. When they fire, they have to disconnect it from the [tow vehicle] and fire it in-place. With the Hawkeye with the 105mm, we only need to put down the stabilizers, aim and fire the weapon. When you’re done, you re-emplace the weapon, pull up the stabilizers and move. It cuts several minutes off the firing time.”


In the time it takes for adversaries to locate the source of the rounds landing on them, the Hawkeye has already moved to another location. Owing to the blast radius of typical enemy counter-artillery, even as little as a quarter-mile away is sufficient to be survivable Luther says. SRT also enables firing larger charges than otherwise possible. Integrating the gun with a single platform enables greater stealth and hiding capability than a vehicle/towed-artillery piece combo. The agility of a single platform traversing off-road terrain is also better than towing. “Hawkeye can be moved moved by air, train, ship or other transport and it takes up less room because the trailer and the truck are combined into one. It’s just more deployable,” AM General’s CTO adds.


Thanks to dedicated suspension-tuning, adding a howitzer with SRT does not appreciably raise the Hawkeye’s center of gravity or affect its weight according to AM General. The company claims to have fired over 100 test rounds at various distances and targets from Hawkeye which it says has also completed extensive reliability testing. AM General is touting the scalability of its SRT integration which could enable carriage of guns up to 155mm on medium tactical vehicles. The company’s Brutus 6X6 truck prototype sports a 155mm howitzer with soft recoil technology, a combination that could potentially replace the 155mm guns typically towed behind 8X8 Stryker vehicles. The AM General/Mandus team has reportedly offered Brutus as a candidate for the Army’s new wheeled howitzer, meant to accompany highly mobile Stryker vehicles into battle.


Applying the tech to other platforms like the Army’s Mobile Protected Firepower (MPF) light tanks could also be on the cards. “We’re looking at mortars up to 81mm and applications up to the M1 Abrams [tank] 120mm main gun. Soft recoil technology applies to anything that fires in a similar manner and it has the same affect on the [platform]. You’re bringing the prime mover down by one vehicle size or perhaps two,” Luther says.


For all the potential that integrating SRT might bring, there appears to be little awareness of the technology within the Army writ-large. Neither Army headquarters nor its Program Office for Combat Support and Combat Service Support (PEO CS & CSS) was aware of which Army entity is doing the characterization tests of the Hawkeye.


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