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Air Cushioned Patrol Boat

The PACV ("Patrol Air Cushion Vehicle") was a patrol hovercraft made notable by its involvement in the Vietnam War under the flag of the United States Navy and, later, Army. The system was trialed with good results but limited to just seven total production units made up of four USN PACV trial vessels and three slightly-modified craft for the Army under the designation of "ACV", or "Air Cushion Vehicle" (some sources state only six total PACVs/ACVs were produced). The series became known by the nickname of "Pac Vee", noting its USN "PACV" designation. The Viet Cong feared the capabilities of the PACV/ACV to the extent that they gave it the rightful nickname of "Monster".

Though often betrayed by her operating noise, the PACV/ACV made up for it through speed and firepower and was known as Monster by the Vietcong.
The PACV maintained its origins in an original hovercraft design produced by the British firm of Saunders-Roe. Saunders-Roe had a long history of producing both aircraft and marine vehicles since its founding in 1929. A merger with Westland Aircraft (later Agusta-Westland) ended Saunders-Roe officially as a company by 1964 but the merger gave birth to the British Hovercraft Corporation. The American PACV was developed from the original Saunders-Roe/British Hovercraft Corporation product SR.N5 under the Bell Aerosystems brand. Bell Aerosystems designated their new militarized product as the SK-5. As actions in the Vietnam War were ramping up, the US Navy took note of the machine and decided on a small purchase of these new machines for evaluation in the Theater. Her sailors trained on the waters off Coronado, California near San Diego. Refinements to the design were made based on feedback.

Categorized as a hovercraft, the PACV was capable of skimming the water's surface, able to build a fair amount of forward speed in the process and possess agility quite uncommon to any surface patrol vessel.

Displacement was near 15,600lbs and the PACV featured a bow-to-stern length of 38 feet, 10 inches. Its beam was a reported 23 feet, 9 inches. Maximum speed was listed at 60 knots while a range of 165 nautical miles was possible. The PACV as accurately described as "one-third helicopter, one-third airplane and one-third boat".

The PACV took on a wide and stout external appearance, primarily characterized by her wide-span upper hull and inflated air cushion skirt.

The crew cabin lay in a centralized nacelle just behind the bow and running to about amidships. The GE turboshaft turbine engine was fitted just aft of the crew compartment and powered an elevated three-bladed Hamilton propeller with variable pitch and full reversibility. The propeller system forced air between two vertical tail fins connected via a horizontal plane and allowing for smooth lateral movement as well as forward propulsion. Vertical lift power was supplied to the PACV through a centrifugal 12-bladed blower fan of 7-foot diameter comprising the horizontal lift system. This arrangement served the PACV well and allowed the nimble system the ability to cross over marshland and muddy surfaces with relative ease and at speed.

The crew cabin was windowed along all sides but the rear (this area taken up by the powerplant).

 A radar array was affixed to the top of the cabin. The dorsal gunner emplacement was situated above the cabin and ahead of the radar array. The pilot sat in the forward area of the crew cabin, offset to the right with a commanding view of the forward action. The radar operator was seated opposite him, maintaining a position in the forward-left portion of the crew cabin. Entry and exit was primarily through a flip-up hinged door system fitted to the front of the cabin, splitting the seating areas of the pilot and radar operator. The upper hull worked well as a surface for transporting passengers and gear.

It was not uncommon to see the PACV painted with "shark teeth" along the forward portion of the skirt - this obviously a psychological play against the Viet Cong they would be fighting.
Armament was centralized around a single (or double) Browning M2 .50 caliber machine gun set up affixed to a rotating mount above the crew cabin. This armament was complimented by .30 caliber M60 general purpose machine guns fitted to the sides of the craft. Additionally, 40mm grenade launchers and additional M60 machine guns could be fitted in remote-controlled emplacements at the stern. Beyond that, the PACV crew had access to whatever personal weapons they would take along on a given mission including rifles, automatic weapons and grenades. In addition to the base crew's weapons, the PACV could also make use of any armament brought onboard by its passengers. Many-a-passenger preferred to ride on the outside of the craft with guns at the ready. This made for easier disembarking and allowed the passengers to bring their weapons to bear in support of the crew. In all, this collection of armament options made for one lethal waterborne system on par with other patrol craft operating in Vietnam at the time.

The first PACV were sent and deployed to Vietnam waters sometime in 1966 and were utilized to good effect across the Mekong Delta.

 PACVs operated as experimental evaluation units tied to Task Force 116 and making up PACV Division 107. Combat engagements soon led to additional armoring being added to help support the crew and the delicate subsystems of the PACV. The PACV fought on, out of Moc Hoa, until being recalled for their overhaul in early 1967. These USN PACVs were eventually relegated to state-side duties with the US Coast Guard after their tours in Vietnam had concluded.

Initial actions revealed the PACV to be an effective weapon against the Viet Cong, particularly across soft and wet terrain where no other USN and US Army vehicles could go.

If there was a negative in the legacy of the PACV, it was in the amount of noise being generated from her turbine engine. Thusly, the reach of the PACV was limited to some extent. Additionally, the internal components of the PACVs showed themselves to be too complicated for the daily rigors of riverine warfare in Vietnam where both environment and combat actions could render its subsystems inoperable with relative ease. However, the speed, traversing capabilities and firepower of the PACV were second to none and these benefits - at least for the time being - outweighed the inherent deficiencies in the system. The PACV proved effective in engaging the enemy through sheer force and served well in blocking known supply lines, policing enemy waterways, serving in the fire support role and useful in the extraction of allies in need or special forces operatives.

The US Army teamed up with Bell to develop its own version of the Navy PACV. The resulting design became the ACV which sported a longer and wider appearance and reinforced side decking.

The forward access door was widened and weapons-carrying capabilities were enhanced. The US Army operated their ACVs with an equal level of success against the Viet Cong throughout the "Plain of Reeds" and undertook missions in the training, reconnaissance, supply and assault roles - often serving in pairs for best effect with aerial coverage of a given operation served by helicopters. Army ACVs operated with the US 9th Infantry Division and deployed out of the Dong Tam area (and later Ben Luc). The ACV deployed to Vietnam in May of 1968 as three examples with hull numbers ACV 901, 902 and 903.

ACV 901 and 902 were fully-loaded attack variants complete with the dorsal .50 caliber machine guns, side-mounted M60 machine guns and a 40mm automatic grenade launcher while ACV 903 was set up as an armed transport fitting only the M60 machine guns. ACV 901 was eventually put out of commission for a period of eight months due to an accident leaving the three vessels to served concurrently only in late 1969. ACV 901 and 902 were eventually destroyed in January and August of 1970 respectively while ACV 903 eventually returned state-side to be put on display at the Transportation Museum.

Despite its combat usefulness, the PACV/ACV program was ultimately dropped. The PACV/ACV was a unique vehicle requiring its own unique training.

 Twenty-four personnel made up one operating unit and training spanned some 14 days each month, requiring at least one PACV/ACV to be left behind during this period. ACV crews were called to train their own replacements. Additionally, the mechanical requirements of the PACV/ACV in regards to regular and combat-related maintenance required much attention, with logistical support having to come from long distance state-side sources.

PACV-4 is the only known surviving PACV system. She completed two tours in the Vietnam War before going on to serve in the Canadian Coast Guard during her post-war years.

Specifications for the PACV / ACV (Pac-Vee / Monster)

Length: 48.55ft (14.80m)
Beam: 25.26ft (7.70m)
Draught: 0ft (0.00m)

Surface Speed: 35kts (40mph)
Range: 190miles (306km)

Armament Suite:
In addition to any crew-served weapons (M16, M79, M60 GPMG, etc...), the PACV was fitted with the following:

1 OR 2 x 12.7mm machine guns in forward rotating dorsal rotating position
1 x 7.62mm M60 general purpose machine gun in port side mount.
1 x 7.62mm M60 general purpose machine gun in starboard side mount.

1 OR 2 x 7.62mm M60 general purpose machine gun in remote-controlled stern position(s)
1 OR 2 x 40mm grenade launchers in remote-controlled stern position(s)
Complement: 4
Surface Displacement: 10tons

Engine(s): 1 x Rolls-Royce Marine Gnome gasoline turbine developing 900shp driving a BHC 12-blade centrifugal lift fan propeller and Dowty Rotol 4-blade propulsion propeller (SR.N6 Mk 1).

Monday, October 27, 2014

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Tuesday, September 23, 2014

M47 Patton Main Battle Tank

The M47 was the U.S. Army's and Marine Corps' primary tank, intended to replace the M46 Patton and M4 Sherman medium tanks. The M47 was widely used by U.S. Cold War allies, both SEATO and NATO countries, and was the only Patton series tank that never saw combat while in US service.

Although roughly similar to the later M48s and M60s, these were completely new tank designs. Many different M47 Patton models remain in service internationally. The M47 was the last US tank to have a bow-mounted machine gun in the hull.

The M47 Patton was an interim solution developed during the Korean conflict, though it was a system that did not see action in that war.

The M47 Patton tank saw a short life in frontline service, being replaced promptly by the M48 Pattons as early as 1953 (the M47s entered service in 1951.
Because of their short life, they did not see any combat service in the Korean War, where only some M46 Pattons (200) saw service.

The M47's, much like their M46 Patton counterparts, served more as a stop gap than a final solution.

They would be replaced from frontline service as soon as the M48 Pattons became available. Unlike the M46 however (which was basically a modernized WW2-era M26 Pershing), the M47 held only a few of the M46/M26 features, and the beginning of the 'true' Patton series of tanks would have to wait for the introduction of the M48.
The M47 Patton featured a crew of five (later to be decreased to four after the assistant driver position was deleted), a 90mm main gun and increased ballistics protection for the crew.

A modernization program in the 1960's increased the life of the weapon system, more notably for the export nations that took on the US interim design.

The M47 Patton pictured above was used by the 1st Division Troops during the occupation of Germany after World War II.

Like the M46, the M47 is also named after famed World War Two US General George S. Patton, Jr.


  • M46E1 - pilot model, M46 hull with T42 turret, fitted with the M36 90 mm Gun, and was longer to incorporate a radio, ventilator, and featured a stereoscopic rangefinder; only one built
  • M47 - main production version, M46 hull modified with redesigned glacis, reduction from five to three track return rollers per side, longer mufflers on rear fenders; 8,576 built
  • M47M - The product of an improvement program started in the late 1960s, the M47M featured the engine and fire control elements from the M60A1. The assistant driver's position was eliminated in favor of additional 90 mm ammunition. Not used by the US; over 800 vehicles were produced for Iran and Pakistan
  • M47E - Spanish M47M austere version (kept original FCS).
  • M47E1 - Second Spanish upgrade batch with rearranged main gun ammunition storage and crew heater. Both new and upgraded M47Es. 330 converted.
  • M47E2 - 45 built. M47E1 with Rh-105 105mm gun and improved FCS (still electromechanical). Passive night vision for driver and commander. All M47 series MBT in Spanish service retired 1993.
  • M47ER3 - Spanish armored recovery vehicle. 22 built.
  • Sabalan - An Iranian upgraded version of the US M47M, It has side skirts and a newly built turret fitted with a 105-mm gun, laser range finder, new fire control system and communication equipment.

Designation: M47 Patton (Patton 1)
Classification Type: Medium Tank
Contractor: Detroit Tank Arsenal / American Locomotive Company, USA
Country of Origin: United States
Initial Year of Service: 1951.

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Tuesday, August 26, 2014

Combat Rubber Reconnaissance Craft F470

Zodiac of North America announced the EVO 7 Futura Commando 470 (F470) Combat Rubber
Raiding Craft (CRRC) will begin delivering to military customers in August 2007. Special Operations Forces, U.S. Navy SEALs and RECON Marines use Zodiac EVO7s to launch from submarines or air-drop from helicopters and Lockheed C130 Hercules transports. This new, lightweight F470 is a completely new-and-forward-thinking design in the realm of inflatable boats, designed specifically and from the outset with multi-mission capabilities and to accommodate varying engine sizes as needed.
The impressive F470 Combat Rubber Raiding Craft is set to make Special Forces groups that much more special.
The Zodiac H2P deck supports engine sizes up to a 55-horsepower (41 kW), two-stroke engine with a pump jet propulsor which consists of a shrouded impeller instead of the traditional exposed propeller. Impellers are rotating devices that force liquids, gases and vapors in a desired direction. This design reduces the risk of serious injury to personnel within the water near the vessel when compared to that of an open propeller system. Likewise, an internally-fitted propeller system also reduces the risk of the propulsion system sustaining damage if an impact occurred during a mission, sometimes happening far away from a supply ship. Tear resistant Duratane protects the floor system from damage. The H2P deck system reduces the empty weight of an F470 by 63 pounds, results in a smaller stowed footprint of the vessel is just 2'6" x 4'11". Reducing weight by 1/4 made room for additional gear for SOF operators and increased the speed of the craft by 2 or 3 knots. Less weight allows SOF support units to transport more boats and a single operator simply turns on a SCUBA tank to inflate the entire EVO 7 in less than 2 minutes.

The EVO7 features a high-pressure air deck system that uses a rigid aluminum deck, an improved hard deck that does not use a thrust board.

Its chief advantages are stealth, versatility, and generally robust good sea keeping. Its buoyancy gives it the ability to operate in relatively high seas for such a small light craft. The raft has eight airtight chambers, the main hull (or gunwale) contains five connected chambers which are separated by internal baffles and valves. This connected air value system makes sure that a single leak will not result in the loss of major pressure throughout the entire hull with air being shared between the eight chambers. For some comfort, additional chambers (called speed skags) are located on the sides to allow some cushioning. For stability, a chamber running the length of the bottom of the craft (producing a "V" shape) is utilized for shock absorption. A wood transom at the stern provides a mount the outboard engine(s) and is also strong enough to support a machine gun. A bow line is attached for docking the boat plus a righting line to be used to flip the boat upright if it capsizes.

The boat can be used for "blue" or "brown" water missions, inserting up to ten lightly-armed Special Forces team members onto beaches, piers, oil rigs and vessels as required.

The assistant coxswain is charged with keeping contact with other vessels boats via hand signals and helps out the coxswain as needed. The remaining six-to-eight passengers make up the team. The fire team normally straddles the gunwale to make a low silhouette in avoiding detection, leaving room on the deck for mission-applicable weapons and equipment. At its core, however, the CRRC offers little-to-no protection to its occupants and is itself vulnerable to small-arms fire - making operations in the dark of night a necessity - especially when stealth and the element of surprise are concerned.

A coxswain (acting as commander of the vessel) sits at the stern of the boat and controls the tiller arm, attached to an outboard engine while the assistant coxswain sits nearby.

 This small boat maintains over-the-horizon raid capability to conduct amphibious short-notice missions. Launched at night and in all types of adverse weather conditions while using stealth in such adverse surf zones to support an advance force through special operations makes the craft quite unique. On top of all this, careful planning covers all navigational issues while an excellent set of swimmer skills is showcased by highly-trained and select personnel and all are trained in crew water survival safety.

The number one priority for the modern military is undergoing a planning evolution to fulfill a mission need. The execute order is given and no longer than six hours is expected to elapse from the beginning of the craft-launching phase.

This boat was undoubtedly designed for a special breed of warrior beyond the standard infantryman.

Length: 15.6ft (4.75m); Beam: 6.2ft (1.89m); Draught: 2ft (0.61m)

Surface Speed: 18kts (21mph)

Complement: 10; Surface Displacement: 1 ton

Engine: 1 x outboard engine delivering 55 horsepower; two- or four-stroke engines with pump jet propulsion containing a shrouded impeller.



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