15-Tonnes Infantry Fighting Vehicle

Kingdom of Thailand (1985-1993)
Infantry Fighting Vehicle – 1 Prototype Built

Thai Made, Thai Used, Thai ​​Success?

The 15-Tonnes Infantry Fighting Vehicle (Thai: รถเกราะสายพานหุ้มเกราะขนาด ๑๕ ตัน) was one of the Royal Thai Army’s very few projects to develop and produce a domestic Infantry Fighting Vehicle (IFV). It was an attempt to create a prototype to pave the way for national production and usage of a locally designed armored vehicle and to solve the existing problems faced with acquiring foreign vehicles.

Thailand’s Wish for Self-Reliance

After the US’ withdrawal from Vietnam in 1975, Thai military policy changed as well. The US reduced its military aid to South Vietnam and the other countries in the region. This had a drastic effect on every US ally, including Thailand. US aid had come in the form of financial assistance and military aid, being responsible for the transfer of various armored vehicles to Thailand, such as the V-100 Commando, M24 Chaffee, and M41 Walker Bulldog.

In response, the Royal Thai Army issued a self-reliance policy in 1980. With this policy, many branches of the Thai Army initiated research and development projects. For example, the Weapon Production Centre (Thai: ศูนย์อํานวยการสร้างอาวุธ) would develop a range of combat vehicles, such as a 7-tonnes Armored Wheeled Vehicle and the Commando reconnaissance vehicle in 1980. The Lopburi Artillery Center (Thai: ศูนย์การทหารปืนใหญ่ลพบุรี) built a 105 mm Light Artillery Self-Propelled Gun in 1982 and the Ordnance Department (Thai: กรมสรรมพาวุธทหารบก) licence produced the Italian-designed Armored Car 6614 in 1982.

Following the introduction of the self-reliance policy in 1980, the Weapon Production Centre (WPC) was responsible for the research and development of weapons. They started off by studying foreign armored fighting vehicles, focussing on tracked armored vehicles in particular. One of the considerations was the ability to produce designs in Thailand, just in case importing vehicles in the future would be too expensive or if foreign countries refused to sell.

This marked the beginning of an industry aiming to build combat vehicles within the country. This also allowed for the WPC to gain knowledge, expertise, and technological experience in designing, constructing, and solving technical issues that arose during research and testing of armored vehicles. This was a great guideline for further research and development of various projects.

If the research and development were successful, the Army would be able to produce armored vehicles. As a result, it would save funds which would otherwise be used to acquire foreign armored vehicles, which were difficult to obtain and expensive.

The 12-tonnes Light Tank

The 12-tonnes Light Tank (Thai: รถถังเบาขนาด ๑๒ ตัน) was the first tank WPC developed. The WPC thought they had the capability to continue research and developed tanks. Therefore, they requested for approval to research and develop of light tank prototypes that had a total weight of approximately 10 to 15 tons from the Royal Thai Army. At the same time that the Royal Thai Army approved the project, WPC had already finished developing a 12-ton light tank. All components were made and supplied within Thailand except for the widely used Detroit Diesel 6-cylinder 300 hp engines that were purchased from foreign countries.

During the development process of the 12-tonnes light tank, the WPC used mild steel for the prototype instead of armor steel. The WPC continued developing this light tank until it reached certain internal quality and performance standards. The resulting vehicle was a turretless hull. In 1982, this 12-tonnes light tank conducted its first field tests by running both on road and off-road. It drove around 1,000 km in total. The findings were that the 12-tonnes light tank had two major problems. First, its cooling system was underpowered, leading to overheating, and second, the suspension was inadequate. With these findings, the WPC implemented improvements and would continuously test and retest its design, improving it a little further after each test. By the time all of the testing had been conducted, the WPC discontinued the 12-tonnes light tank project because the budget needed for the development of a light tank project would be too large. The experience and information gained during this project was used to inform the future design and development of the new 15-tonnes IFV.

The 15-tonnes IFV

The 15-tonnes Infantry Fighting Vehicle (Thai: รถเกราะสายพานหุ้มเกราะขนาด ๑๕ ตัน) was developed by using a budget allocation from the Royal Thai Army. This time, the WPC had gained experience and know-how from the problems of the previous 12-tonnes design. For this new vehicle, they completely redesigned the drive train and chose new more suitable components. In 1982, the WPC selected a Cummins VT-903 C 8-cylinder, 4-stroke, 350 hp diesel engine and a Allison CLT.754 transmission system purchased from a foreign country. Other components were supplied locally, but the tank still used mild steel to reduce the cost of the prototype. The first prototype of the 15-tonnes Infantry Fighting Vehicle was finished in 1985.

The prototype entered testing after it was completed to check the performance of various components. After that, the tank was again tested multiple times to uncover any issues it may have had. Perhaps unsurprisingly, a significant number of problems were found. Engine and gearbox issues persisted because the Allison CLT.754 transmission was too large, the crew space was limited, and the engine was still underpowered. Possibly the biggest problem was the cramped interior space for carrying infantry, especially given that that was the primary purpose of the vehicle.

In 1986, the WPC received additional funding from the Weapon Research and Development Prototype Factory (WRDPF) (Thai: โรงงานต้นแบบการวิจัยพัฒนาอาวุธ รง.ตวพ.ศอว.ศอพท) to continue developing the 15-tonnes Infantry Fighting Vehicle. This enabled the WPC to install a new powerpack in the vehicle. The 500 hp Cummins 8 cylinder V model VTA-903T diesel engine and the General Electric HMPT-500 transmission were selected. In addition, many components, such as a new electric lighting system and ventilation inside the vehicle, were installed in the prototype. After the successful redesign, the WRDPF conducted a second trial with the 15-tonnes IFV with positive results.

The issue of the underpowered engine was fixed and the vehicle now had enough engine power spare capacity to mount armament turrets in the future. However, the suspension system was not strong enough to be able to take the extra weight due to the new, heavier powerpack, therefore the WPC started to redesign the suspension to be able to handle more weight. Later, in 1988, the WPC asked for more funding to improve the 15-tonnes IFV and they began to strengthen the suspension system by, among others, changing the wheel size and improving the track links. This project was finished in April 1989 without any trials. Just to improve the vehicle’s basis, it had taken 7 years of development starting from the first 12-tonnes lLight Tank program to complete the 15-tonnes Infantry Fighting Vehicle.

The 15-tonnes IFV in Detail

The 15-tonnes IFV was made out of mild steel plates with a maximum armor thickness of 16 mm on the front plate. There is no other information on the armor thickness of other parts of the vehicle. Taking into consideration the highly angled armor of the vehicle, it would have been able to deflect and protect against 7.62 mm and other small arms fire.

Hull and Interior

The frontal parts were covered with a high angle armor plate with a headlight on the top of each fender. In the lower front plate, there were towing points located on each side of the gearbox, with the small middle frontal plate as a gap.

There was a small square shape at the front left of the vehicle, presumably to provide ventilation for the driver. He was located on the left side of the vehicle. The driver had 3 periscopes in a circular hatch opening at the top of the frontal angled plate.

The engine compartment was on the right hand side of the front. The engine could be accessed by opening a four-hinge hatch to the right. There were three handles on the middle of the upper front plate to aid the crew to climb up the vehicle.

The exhaust system was located on the middle right of the hull, next to an engine inspection hatch. Attachments for tools were placed on the rear right side of the vehicle. A tow cable holder and spare tracks were located on the middle right of the vehicle’s hull.

There was a double door hatch for the radio operator in the middle top left of the vehicle. The gunner was located in the middle top of the vehicle, with a 12.7 machine gun at his disposal. Based on the available photographs, it is likely that this position was a fully rotating open-topped turret, not a fixed position. The gunner had some level of protection against small arms fire provided by a thin gun shield. A large double door hatch appears to have been placed on the rear of the roof of the vehicle, so that the infantry dismounts inside could fire from a safe position while the vehicle was maneuvering.

The passenger compartment at the rear was able to accommodate a full squad of 11 infantry. The rear plate of the vehicle most likely had a large door so that the infantry dismounts could enter and exit the vehicle. It also possibly had rear lights and a towing hook.

Mobility

The 15-ton Infantry Fighting Vehicle was powered by a Cummins 8 cylinder V model VTA 903T engine with a 500 hp output at 2,600 rpm, providing a power to weight ratio of 22 hp/t. The 15-tonnes Infantry Fighting Vehicle could go up to 65 km/h on road and 40 km/h off-road. With a 300 liter fuel tank which was likely located in the front of the vehicle, it had an operational range of 150 km.

The 15-tonnes IFV shared many similarities to the 12-tonnes light tank, having a drive sprocket located at the front and the idler at the rear. There were 5 road wheels per side and 3 the return roller on each side. The 15-ton IFV used rubber tracks.

Armament

The 15-tonnes Infantry fighting vehicle was armed with a 12.7 mm Browning heavy machine gun on the top of the vehicle. This heavy machine gun was able to defend the vehicle from enemy infantry attacks, provide fire support to the infantry, and could potentially take out lightly armored enemy vehicles and also a 7.62 mm M60 machine gun on the top back of the vehicle for its rear protection. However, this was very light armament for an Infantry Fighting Vehicle of the period, being more comparable to that found on most APCs. The vehicle lacked the anti-armor and anti-fortification capabilities typical of most IFVs.

Crew

The three-man crew consisted of a driver, a commander/radio operator, and a gunner. The driver sat in the front left of the vehicle. For visibility, he had 3 periscopes seeing towards the front. The radio operator sat right behind the driver. The exact radio model is unknown, but it is likely to have been an AN/PRC-77 . The gunner was positioned at the top of the vehicle, with some armor plate for an added level of protection.

The rear half of the vehicle could carry 11 infantry inside. It had a large top hatch for the infantry inside to be able to fire while still inside the vehicle and probably a back door for the infantry to exit the vehicle.

Testing and Cancellation

After canceling the 12-tonnes light tank and the first trial of the 15-tonnes IFV, WPC gathered valuable experience about developing armored vehicles and solving issues along the way. For the second set of trials in 1986, the WPC had changed to a new General Electric transmission that was smaller and more reliable and a more powerful Cummins 500 hp engine. With a new powerpack, the 15-tonnes IFV no longer had an issue with an underpowered engine. The main problem at this stage of the project was that the material used was not of a military type. The Royal Thai Army approved the cancellation of the project and canceled funding in March 1993.

Conclusion

After 7 years of developing a 15-tonnes Infantry Fighting Vehicle, the Royal Thai Army’s wish for self-reliance remained unfulfilled. Nonetheless, the project was a major lesson on the difficulties of AFV design and production and one of the rare attempts from countries with little experience in developing armored vehicles, such as Thailand, to begin research and development of an AFV. Since, Thailand has been able to develop the 8×8 Black Widow Spider armored wheeled vehicle project in 2015 and the Amphibious Armored Personnel Carrier (AAPC) in 2017 both of them are based on learning know-how from Singapore Terrex II.

Due to the cancellation of the 15-tonnes Infantry Fighting Vehicle, the Royal Thai Army ordered 51 Chinese Type 85 APC in 1987, which were delivered in 1988. This foreign APC fits the same role as the 15-ton IFV, since both of them were capable of carrying troops and providing fire support to the infantry. The Type 85 APC remains in service with Thailand to this day.

15-tonnes IFV Specifications
Dimensions	2.8 – 5.9 – 1.2 m
Total weight, battle ready	15 tonnes
Crew	3 (driver, gunner, commander)
Propulsion	Cummins VTA-903T 8 cylinder diesel 500 hp at 2,600 rpm
Suspension	torsion bar
Speed (road)	65 km/h
Range	150 km
Fuel capacity	300 liter
Trench crossing capability	1 meter
Armament	12.7 mm Browning heavy machine gun
Armor	16 mm
Production	1 prototype

Sources

BATTLEFIELD WEEKLY issue 376
ALL WARFARE issue 174
ALL WARFARE issue 126
ALL WARFARE issue 138
https://wpc.mod.go.th/Product/R-Dcompletnotproduction/IFV.aspx
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http://www.army-guide.com/eng/product3948.html