Engine compartment vehicle the LVTP5, Troop commander vehicle
Later modifications to the LVTP5, the LVTH6, and the LVTR1 resulted in a change of the designations. They now became the LVTP5A1, the LVTH6A1, and the LVTR1A1. The most obvious identification feature for the modified vehicles was the superstructure on the rear deck over the engine compartment vehicle the LVTP5. This superstructure housed the modified air intake and exhaust system.
In 1966, FMC modified two LVTP5A1 vehicles to use the air-cooled AVDS-1790 diesel engine. Like the LVTE1, these vehicles could be identified by the absence of the recessed radiator compartments on the sides and the armor plate covers for the cooling air intake and exhaust valves on the rear deck. They were designated as the LVTPXD1.
The LVTP5 family was successfully employed in Vietnam. However, by this time, a new development program was in progress that would produce its successor.
THE LVTP7 FAMILY
Design studies for an improved LVT started in 1964 and in February 1966, engineering development began at FMC. The first of 12 prototypes of the new vehicle, designated as the LVTPX12, was completed during the Summer of 1967. It was vastly different from the LVTP5. Assembled from 5083 aluminum armor plate, the level of protection was approximately the same as that ofthe M113 armored personnel carrier. The LVTPX12 was a front drive vehicle with a ramp in the rear. The interior was divided between the crew and personnel compartment and the engine compartment vehicle the LVTP5.
The engine compartment vehicle the LVTP5 was located in the center at the forward end of the hull. It housed the General Motors 8V53T diesel engine with the HS-400 transmission. The liquid-cooled V8 engine developed 400 gross horsepower at 2,800 rpm. The semiautomatic transmission had four speeds forward and two in reverse with hydrostatic steering. The front mounted drive sprockets drove the 21 inch wide, single pin, steel tracks.
A torsion tube-over-bar suspension supported the vehicle on six dual road wheels per side with an adjustable idler at the rear. In water, the LVTPX12 was driven by two water-jet propulsion units at the rear. These units were connected by drive shafts through two power transfer assemblies to the power take-off on the transmission. Water-jet deflectors on the propulsion units steered the vehicle in the water (U.S. Army).
The driver, assistant driver, vehicle commander, troop commander vehicle, and 24 troops were accommodated in the crew and personnel compartment. The driver rode in the left front on the port sponson with the troop commander vehicle just behind him. The driver and the troop commander each had a cupola with seven vision blocks around the hatch. In addition, the driver had an M24 infrared periscope and the troop commander had an M17C periscope. The latter permitted forward vision over the driver's cupola.
The vehicle commander was located in the weapon station at the right front on the starboard sponson. The weapon station was armed with an M139 20mm gun and an M73E1 7.62mm coaxial machine gun. It was fitted with six vision blocks and a periscope. The assistant driver was seated on the port sponson behind the troop commander vehicle. The 24 troops were seated in three rows of eight. A seat was attached to each side wall and the third was in the center. All of these seats could be stowed away to provide a clear space for cargo. A large cargo hatch was in the hull roof above the crew and personnel compartment.
The LVTPX 12 had a maximum speed of 40 miles per hour on land and 8.4 miles per hour in water. The cruising range on land was about 300 miles and the endurance in water was 7 hours. The combat loaded weight was 48,500 pounds.
Like the LVTP5, the LVTPX12 was intended to provide the basis for a family of vehicles. Initially, four variants ofthe basic vehicle were proposed. These were the LVTCX2 command vehicle, the LVTRX2 recovery vehicle, the LVTEX3 engineer vehicle, and the LVTHX5 armed with a turret mounted 105mm howitzer. However, the latter was never built.
The LVTPX12 prototypes were tested at Aberdeen Proving Ground, the Yuma Proving Ground, Fort Greely, and in Panama. High surf tests were carried out at Camp Pendleton and Monterey, California. One ofthe specification requirements was the ability to operate in a 10 foot high plunging surf. Under high surf conditions, the vehicle frequently was fully submerged for 10 to 15 seconds.
After successful completion ofthe test program, the vehicle was type classified as the LVTP7 and the first production vehicle was delivered in the Fall of 1971. The first U. S. Marine Corps units were equipped with the LVTP7 in 1972.
On the production LVTP7, a new electric-hydraulic powered weapon station was installed for the vehicle troop commander. It was armed with a single .50 caliber machine gun M85 and fitted with nine vision blocks for a 360 degree view. An 8 power optical sight was provided for the machine gun. The combat loaded weight of the LVTP7 had increased to 50,350 pounds, but the performance remained the same. FMC produced 971 LVTP7s starting in 1971.