Courtesy Photo | Concept of a CH-47 in a gunship configuration for airborne artillery support. This...... read more read more
The year was 1966, and for several years the Soldiers in Vietnam had been using the same howitzer that their fathers had used in World War II. The M101 (known in World War II as the M2) was a 105-mm howitzer that was known for its accuracy and destructive power. So, why, in the middle of a war in the jungle, was the Army changing these well-known and tried-and-true fire breathing monsters with a lighter M102?
Many disliked the change. Some of the arguments included concerns over cost or ease of use. While these arguments may have been true, in theory, they did not outweigh the benefits in a changing war where tactics were constantly evolving. What’s more, they also didn’t account for combat in such an austere environment.
In 1963, the weapons laboratories at Rock Island Arsenal had started extensively researching improvements to existing weapon systems in Vietnam. There were two main weapon systems developed amidst several fire support systems between 1961 and 1973. However, the most significant contributions to artillery were the modification of the XM102 howitzer and the XM6 Air Mobile Firing Platform.
Climate, Terrain, and Mobility
Two words can be used to describe the climate in Vietnam: hot and wet. Vietnam’s climate is dominated by rainforest and monsoon climates. Most of the country is defined as either tropical savannah or temperate hot summer conditions. Terrain is defined as either jungle or marshland.
Much like the rest of the northern hemisphere, temperatures generally increase with southward progression. Temperatures in Hanoi average around 82 degrees Fahrenheit and increase over 90 degrees in Saigon (modern Ho Chi Minh City). Hanoi, on average, sees around 66 inches of rain, but the central part of the nation sees over 100 inches of rain. Likewise, rain falls almost daily year-round across the center of the nation from south of Quang Ngai to north of Dong Hoi.
The climate, coupled with the dense tropical rainforest and swampy marshlands meant that mobility of mechanized units was impacted significantly. Heavy artillery tended to get stuck in mud or be unable to overcome the thick brush. Quick movement of equipment was cumbersome to impossible at times. Transportation required movement by air or sea in many instances, as ground transport was likely to succumb to the same fate as the heavy equipment pieces it was to carry.
With an enemy as tenacious as that of the Viet Minh and Viet Cong, accomplishing the mission without mechanized support and artillery would prove difficult.
Stabilizing the Weight
The two chief natural obstacles to fire on the ground in Vietnam were stability and mobility. Stability suffered from multiple points of failure, including sinking or getting stuck in mud, tipping over, or poor terrain-to-target proximity. Howitzers and guns were heavy, and the use of tanks and mechanized units were hindered significantly by the density of brush and trees. Heavy reliance was placed on air support and artillery barrages.
Lightweight howitzers tended to tip over, jump, or move when fired from solid surfaces. The M101 was no different. Thus, the production of the XM102 aimed to fix this issue with the development of a new carriage design. The carriage utilized a wishbone trail which increased rear-weight while managing the center-of-gravity of the gun in such a way that it would not jump when fired. The lightweight nature also allowed the gun better mobility in swampy areas and allowed it to be air deployed or moved by helicopter. However, the gun was still susceptible to sinking or getting stuck. This was unavoidable in a climate such as Vietnam’s.
According to a May 1973 publication from Armament Command (ARMCOM) the manufactures for each key component of the XM102 were varied. Rock Island Arsenal produced the M37 Recoil Mechanism and the M31 Carriage, Frankford Arsenal produced the fire control system, and Watervliet produced the gun tube. The prototypes were completed in 1962 with production beginning in 1964. Over 1,100 M102 were produced from 1964 to 1973. The need was defined as “a towed, lightweight (3,000 pounds or less) 105-mm Howitzer capable of delivery by parachute, helicopter, and assault landings of an airborne operation.”
The May 1973 publication also described the XM6 Artillery Firing Platform as being “deliverable by a CH-47 [Chinook] helicopter” and was designed to be used “with the M102 105-mm howitzer in inundated and soft ground areas found in Vietnam.” The first of 38 XM6 platforms were produced between September 1967 and December 1968.
In September 1967, six prototypes were sent to Vietnam as proof-of-concepts. These prototypes, along with their production models, were designed to handle the weight of the howitzer, crew, equipment, plus 30 rounds of ammunition. The tests proved very successful, and additional orders were made in May 1968. By the end of the year, all 38 platforms had been completed. Each platform weighed approximately 8,000 pounds and was capable of being deployed over densely swampy areas and even small ponds of water.
The XM102 and XM6 components were capable of being moved together via the same helicopter sling. The two created a weight of around 11,000 pounds with the XM102 accounting for only 3,000 pounds. By comparison, the M101 weighed almost 5,000 pounds on its own.
Taking Artillery to the Skies
In the late 1950s, the Army started experimenting with heavy air-to-surface deployment weapons. This consisted of providing artillery support from the air using helicopters as a firing platform. Chief among the candidates for the mounting of howitzers or large guns was the UH-1 Huey. In a 1965 rendering, a heavily modified Huey airframe was shown with an additional front-placed cupola, a recoilless 105-mm gun launcher, and air-stored 105-mm ammunition.
The concept underwent several transformations and iterations before eventually settling on two helicopter platforms for deployment. The first, H-21 Shawnee, proved to be far too lightweight to handle the backpressure from even a recoilless rifle. The second, the CH-47 Chinook, was ultimately selected as the best candidate for the program. The UH-1 was a non-starter due to its limited lift capacity.
According to ARMCOM’s publication, the original concept called for a weapon system like the XM70 115 mm rocket launcher with a rotary-equipped loading mechanism. The same publication states that the concept was modified to use the XM204 (a design built for this application) 105-mm howitzer instead. In 1972, Boeing released a technical design study that researched the feasibility of mounting two XM204 howitzers on a CH-47 helicopter. The concept from the following year proposed one XM204 on each winglet, plus an additional XM204 mounted on the rear ramp of the CH-47.
These concepts underwent multiple stages of iterations attempting to overcome the problems of backpressure from the blast and stability. ARMCOM also stated that the range and hover time of the helicopter would be reduced by about 20 percent. Stability was supposed to be provided by rocket thrusters. However, the reduction in range, the cost of the modifications, juxtaposed to the performance and the rise of more accurate airborne rocket systems made the deployment of such a system irrelevant. The requirement for airborne artillery support eventually was covered by wider adoption of the AC-130 gunship and augmented Close-Air-Support (CAS) from the A-10 Thunderbolt II.
Nevertheless, the studies in mounting of artillery systems to the airframe of the Chinook allowed for better understanding of the load limits of the airframe. Weight reduction of artillery and carriages meant more systems could be slung and moved into place for deployment. This extended beyond artillery by the end of the war, with numerous theater rocket and missile systems being modified to be sling-transported by helicopter into position. The sling-transport of artillery systems meant that ground transportation could also be lighter, enabling more efficient transportation of materiel.
Other firepower developments
Coupled with the small arms deployment on the UH-1 Huey and the door gun positions on other helicopters, small arms development focused on the M60 machine gun and the M16 rifle. The XM16 rifle grew out of the Special Purpose Individual Weapon (SPIW) program in the Small Arms Laboratory at Weapons Command (WECOM).
The SPIW program aimed to create a modular rifle capable of taking multiple forms of ammunition to include flechettes, grenades, and standard 5.56 mm ammunition. Multiple prototypes were produced at Rock Island Arsenal before the XM16 was selected. The subsequent production was originally supposed to be short lived, paving the way for the Future Rifle System (FRS). The FRS eventually evolved into the M4.
Conclusion
Vietnam was a brutal conflict that cost the lives of many and brought the war the closest to the American Public as conflict ever had been. It was also the catalyst for modernization. The M1 Garand, the Sherman Tank, and the M101 were no longer staples of the battlefield. The Army was forced to modernize and adapt to a rapidly changing, rapidly deteriorating, austere environment fraught with unknown perils and obstacles. This coupled with an enemy that knew no rules of engagement created a need for new and innovative technologies and doctrine to accomplish mission objectives.
Whether it was providing artillery support from the rear or the air, whether CAS was required from a fixed-wing plane or a helicopter, and whether a Soldier was equipped with the modern weapon or not, the U.S. Army adapted and overcame insurmountable obstacles. At home, the industrial base and the brilliant minds in weapons laboratories thought of ways to ensure Soldier’s requirements were met.
Today, these lessons learned continue to be used to teach the next generation of warfighters and train and educate the future of innovation in technology and warfare doctrine.
| Date Taken: | 01.06.2025 |
| Date Posted: | 01.06.2025 13:55 |
| Story ID: | 488720 |
| Location: | US |
| Web Views: | 110 |
| Downloads: | 0 |
This work, Supporting fire: Stabilizing firepower in a swamp, by Mark Struve, identified by DVIDS, must comply with the restrictions shown on https://www.dvidshub.net/about/copyright.
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