Tag Archives: Wright Aeronautical Division Cyclone 18 825C18BD1

19 May 1949

Martin JRM-3 Mars, Bu.No. 76822, Marshall Mars. (U.S. Navy)
Martin JRM-3 Mars, Bu. No. 76822, Marshall Mars. (U.S. Navy)

19 May 1949: Martin JRM-3 Mars, Marshall Mars, United States Navy Bureau of Aeronautics serial number (Bu. No.) 76822 flew from the Alameda Naval Air Station on the east shore of San Francisco Bay, to San Diego Bay, a distance of approximately 450 miles (725 kilometers). On board, in addition to the flight crew of 7, were 301 passengers.

The Associated Press wire service reported the story:

NAVY’S BIG FLYING BOAT MARSHALL MARS CARRIES 301 PERSONS

SAN FRANCISCO, May 19—(AP)—The Navy’s big flying boat Marshall Mars carried a record load of 301 passengers—plus seven crewmen—on a flight to San Diego today.

It had never carried more than 269 passengers before.

The 1:52 p.m. takeoff, from the naval air station at Alameda, across the bay, was uneventful.

Today’s passengers are personnel of Air Group 5, Alameda Naval Air Station, who are being transferred to San Diego. Mattresses on the floor were provided for men unable to find seats.

Wilmington Morning Star, Friday, 20 May 1949, Page 1, Column 4.

Four Martin JRM-3 Mars flying boats in formation. (U.S. Navy)
Four Martin JRM-3 Mars flying boats in formation. In the foreground is Philippine Mars, Bu. No. 76820. The second airplane is Marianas Mars, Bu. No. 76821. (U.S. Navy)

The Martin JRM Mars was a large four-engine flying boat transport built by the Glenn L. Martin Company for the U. S. Navy. Only five were built, four designated JRM-1, with the last one being a JRM-2. Each airplane was given an individual name derived from the names of island chains in the Pacific Ocean: Marianas MarsHawaii MarsPhilippine MarsMarshall Mars and Caroline Mars. These airplanes were used to transport personnel and cargo between the West Coast of the United States and the Hawaiian Islands. All were upgraded to JRM-3.

The Martin JRM-3 Mars had a normal crew of 4, with accommodations for a relief crew. It was designed to carry 133 combat troops or 32,000 pounds (14,515 kilograms) of cargo. It was 117 feet, 3 inches (35.738 meters) long with a wingspan of 200 feet (60.960 meters) and height of 38 feet, 5 inches (11.709 meters). The flying boat had an empty weight of 75,573 pounds (34,279.3 kilograms) and a loaded weight of 90,000 pounds (40,823.3 kilograms). The maximum takeoff weight (MTOW) was 165,000 pounds (74,842.7 kilograms).

A NASA publication states, “A zero-lift drag coefficient of 0.0233 and a maximum lift-drag ratio of 16.4 made the JRM the most aerodynamically efficient of any of of the flying boats. . . .”

The Martin Mars was powered by four air-cooled, supercharged, direct-fuel-injected, 3,347.662-cubic-inch-displacement (54.858 liter) Wright Aeronautical Division R-3350-24WA (Cyclone 18 825C18BD1) (also known as the Duplex-Cyclone), a two-row 18-cylinder radial engines with a compression ratio of 6.70:1 and water/alcohol injection. This engine has a normal power rating of 2,000 horsepower at 2,400 r.p.m at 5,500 feet (1,676 meters) and 1,800 horsepower at 2,400 r.p.m. at 15,000 feet (4,572 meters). The engine’s takeoff power rating is 2,500 horsepower at 2,900 r.p.m. 100/130 octane aviation gasoline was required. The engines drove four-bladed 16 foot, 8 inch (5.080 meter) Curtiss Electric variable-pitch propellers through a 0.4375:1 gear reduction. (After modification to the JRM-3, the propellers on the inboard engines were reversible.) The R-3350-24WA is 6 feet, 8.58 inches (2.047 meters) long, and 4 feet, 6.13 inches (1.375 meters) in diameter. Its dry weight is 2,822 pounds (1,280 kilograms).

The JRM-3 had a cruise speed of 190 miles per hour (305.8 kilometers per hour) and a maximum speed of 221 miles per hour (355.7 kilometers per hour). The service ceiling was 14,600 feet (4,450 meters) and its range was 5,000 miles (8,046.7 kilometers).

On 5 April 1950, Marshall Mars had an engine fire and made an emergency landing off Diamond Head, Hawaii. The crew was rescued but the airplane exploded and sank. The wreck was discovered on the sea floor in August 2004.

The remaining airplanes were later converted to fire fighting airplanes in Canada. Only two remain.

Martin JRM-3 Mars Bu. No. 76822, Marshall Mires, burning off Diamond Head, Oahu, Hawaiian Islands, 5 April 1950. (U.S. Navy)
Martin JRM-3 Mars, Bu. No. 76822, Marshall Mars, burning off Diamond Head, Oahu, Territory of the Hawaiian Islands, 5 April 1950. (U.S. Navy)

© 2017, Bryan R. Swopes

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5 April 1950

Martin JRM-3 Mars Bu. No. 76822, Marshall Mars, burning off Diamond Head, Oahu, Hawaiian Islands, 5 April 1950. (U.S. Navy)
Martin JRM-3 Mars Bu. No. 76822, Marshall Mars, burning off Diamond Head, Oahu, Hawaiian Islands, 5 April 1950. (U.S. Navy)

While on a test flight following an engine change, a United States Navy Martin JRM-3 Mars seaplane, Marshall Mars, Bu. No. 76822, suffered an engine fire (inboard, left wing) and made an emergency landing at Ke’ehi Lagoon, off Diamond Head, Hawaii, 5 April 1950. The airplane’s crew was rescued but the airplane exploded and sank.

The wreck was discovered on the sea floor in August 2004 at a depth of approximately 1,400 feet (427 meters).

The Martin JRM Mars was a large four-engine flying boat transport built by the Glenn L. Martin Company for the U. S. Navy. Only five were built, four designated JRM-1, with the last one being a JRM-2. Each airplane was given an individual name derived from the names of island chains in the Pacific Ocean: Marianas MarsHawaii MarsPhilippine MarsMarshall Mars and Caroline Mars. These airplanes were used to transport personnel and cargo between the West Coast of the United States and the Hawaiian Islands. All were upgraded to JRM-3.

Four Martin JRM-3 Mars flying boats in formation. (U.S. Navy)
Four Martin JRM-3 Mars flying boats in formation. (U.S. Navy)

The Martin JRM-3 Mars had a normal crew of 4, with accommodations for a relief crew. It was designed to carry 133 combat troops or 32,000 pounds (14,515 kilograms) of cargo. It was 117 feet, 3 inches (35.738 meters) long with a wingspan of 200 feet (60.960 meters) and height of 38 feet, 5 inches (11.709 meters). The flying boat had an empty weight of 75,573 pounds (34,279.3 kilograms) and a loaded weight of 90,000 pounds (40,823.3 kilograms). The maximum takeoff weight (MTOW) was 165,000 pounds (74,842.7 kilograms).

A NASA publication states, “A zero-lift drag coefficient of 0.0233 and a maximum lift-drag ratio of 16.4 made the JRM the most aerodynamically efficient of any of of the flying boats. . . .”

Martin JRM-3 Mars, Bu.No. 76822, Marshall Mars. (U.S. Navy)
Martin JRM-3 Mars, Bu.No. 76822, Marshall Mars. (U.S. Navy)

The Martin Mars was powered by four air-cooled, supercharged, direct-fuel-injected, 3,347.662-cubic-inch-displacement (54.858 liter) Wright Aeronautical Division R-3350-24WA (Cyclone 18 825C18BD1) (also known as the Duplex-Cyclone), a two-row 18-cylinder radial engines with a compression ratio of 6.70:1 and water/alcohol injection. This engine has a normal power rating of 2,000 horsepower at 2,400 r.p.m at 5,500 feet (1,676 meters) and 1,800 horsepower at 2,400 r.p.m. at 15,000 feet (4,572 meters). The engine’s takeoff power rating is 2,500 horsepower at 2,900 r.p.m. 100/130 octane aviation gasoline was required. The engines drove four-bladed 16 foot, 8 inch (5.080 meter) Curtiss Electric variable-pitch propellers through a 0.4375:1 gear reduction. (After modification to the JRM-3, the propellers on the inboard engines were reversible.) The R-3350-24WA is 6 feet, 8.58 inches (2.047 meters) long, and 4 feet, 6.13 inches (1.375 meters) in diameter. Its dry weight is 2,822 pounds (1,280 kilograms).

The JRM-3 had a cruise speed of 190 miles per hour (305.8 kilometers per hour) and a maximum speed of 221 miles per hour (355.7 kilometers per hour). The service ceiling was 14,600 feet (4,450 meters) and its range was 5,000 miles (8,046.7 kilometers).

A U.S. Navy Martin JRM Mars. (Glenn L. Martin Co.)
A U.S. Navy Martin JRM Mars. (Glenn L. Martin Co.)

© 2017, Bryan R. Swopes

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18 March 1945

LaVerne Brown, Director of Flight Test, Douglas Aircraft Company, in the cockpit of the first XBT2D-1 Dauntless II prototype, Bu. No. 9085. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)
LaVerne Ward Browne, Director of Flight Test, Douglas Aircraft Company, in the cockpit of the first XBT2D-1 Dauntless II prototype, Bu. No. 9085. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)

18 March 1945: At the Naval Airplane Factory, El Segundo, California (at the southeast corner of Los Angeles Airport, now best known as LAX), Douglas Aircraft Company Director of Flight Test LaVerne Ward (“Brownie”) Browne took the prototype XBT2D-1 Dauntless II, Bu. No. 9085, for its first flight.

He later commented, “I wish I could tell of some dramatic incident that occurred. There wasn’t any. I just floated around up there for an hour and a half and brought her down. But I did do something that’s unprecedented, I believe, for a first trip. The airplane handled so well that I put it through rolls and Immelmanns to check it for maneuverability.”

The first prototype Douglas XBT2D-1 Dauntless II, Bu. No. 9085. In this photograph the airplane has a propeller spinner. (San Diego Air and Space Museum archive)
The first prototype Douglas XBT2D-1 Dauntless II, Bu. No. 9085. In this photograph the airplane has a propeller spinner. (Douglas Aircraft Company)

The XBT2D-1 would be ordered into production as the Douglas AD-1 Skyraider.

Designed by Douglas’ Chief Engineer, Edward Henry Heinemann, the XBT2D-1 was a single-place, single-engine attack bomber capable of operation from the U.S. Navy’s aircraft carriers. The prototype was 39 feet, 5 inches (12.014 meters) long with a wingspan of 50 feet, ¼ inch (15.246 meters) and overall height of 15 feet, 7½ inches (4.763 meters). The airplane had an empty weight of 10,093 pounds (4,578 kilograms) and maximum weight of 17,500 pounds (7,938 kilograms).

The first four XBT2D-1 prototypes were powered by an air-cooled, supercharged, direct-fuel-injected 3,347.662-cubic-inch-displacement (54.858 liter) Wright Aeronautical Division R3350-8 (Cyclone 18 779C18BB1) twin-row 18-cylinder radial engine rated at 2,100 horsepower at 2,400 r.p.m., and 2,400 horsepower at 2,600 r.p.m., for takeoff. The next 20 airplanes built utilized the R3350-24W (Cyclone 18 825C18BD1) which had a takeoff power rating of 2,500 horsepower at 2,900 r.p.m.

Test pilot Brown in teh cockpit of Douglas XBT2D-1 Dauntless II Bu. No. 9085 during a test flight. (Douglas Aircraft Company)
Test pilot LaVerne Brown in the cockpit of Douglas XBT2D-1 Dauntless II Bu. No. 9085 during a test flight. (Douglas Aircraft Company)

The XBT2D-1 had a maximum speed of 375 miles per hour (604 kilometers per hour) at 13,600 feet (4,145 meters) and normal cruise speed of 164 miles per hour (264 kilometers per hour).

The first XBT2D-1, Bu. No. 9085, was sent to NAS Patuxent River, Maryland for further testing. The second, 9086, went to NACA Ames at Moffet Field, California, where it underwent testing from 11 March 1946 to 4 September 1947..

The second prototype XBT2D-1, Bu. No. 9086, was tested at the NACA Ames Research Center, Moffet Field, California, from 11 March 1946 to 4 September 1947. (NASA)
The second prototype XBT2D-1, Bu. No. 9086, at the NACA Ames Research Center, Moffet Field, California, 18 June 1946. (NASA)

3,180 Skyraiders in 11 variants were built at the Douglas Aircraft Company’s El Segundo, California, plant from 1945 to 1957. The attack bomber was widely used during the Korean War and the Vietnam War. It was utilized for many purposes but is best known for its close support missions during combat rescue operations. After 1962, the AD-series aircraft still in service were redesignated A-1E through A-1J.

Douglas XBT2D-1 Dauntless II at Los Angeles Airport, circa 1945. (Douglas Aircraft Company via Tommy H. Thomason)

The most numerous Skyraider variant was the AD-6 (A-1H), of which 713 were produced by Douglas. The AD-6 was 38 feet, 10 inches (11.836 meters) long with a wingspan of 50 feet, 9 inches (15.469 meters) and overall height of 15 feet, 8¼ inches (4.782 meters). Its empty weight was 11,968 pounds (5,429 kilograms) and gross weight was 18,106 pounds (8,213 kilograms). The maximum takeoff weight (MTOW) for the AD-6 was 25,000 pounds (11,340 kilograms).

Douglas AD-4 Skyraider of VA-195 taking off from USS Princeton (CV-37) circa 1950–52 (U.S. Navy)
Douglas AD-4 Skyraider of VA-195 taking off from USS Princeton (CV-37) circa 1950–52 (U.S. Navy)

The Douglas AD-6 was powered by an air-cooled, supercharged, direct-fuel-injected, 3,347.662-cubic-inch-displacement (54.858 liter), Wright Aeronautical Division R-3350-26WA (Cyclone 18 836C18CA1) twin-row 18-cylinder radial engine, with water/alcohol injection. This engine has a compression ratio of 6.71:1. The R-3350-26W has a Normal Power rating of  2,300 horsepower at 2,600 r.p.m., and a Takeoff/Military Power rating of 2,700 horsepower at 2,900 r.p.m., using 115/145 aviation gasoline. The engine drives a four-bladed Aeroproducts constant-speed propeller with a diameter of 13 feet, 6 inch (4.115 meters) through a 0.4375:1 gear reduction. The engine is 4 feet, 7.62 inches (1.413 meters) in diameter and 6 feet, 6.81 inches (2.002 meters) long. It weighs 2,848 pounds (1,292 kilograms), dry.

The AD-6/A-1H Skyraider had a cruise speed of 198 miles per hour (319 kilometers per hour) and a maximum speed of 322 miles per hour (518 kilometers per hour). The ceiling was 29,400 feet (8,961 meters) and its combat radius carrying 2,000 pounds (907 kilograms) of ordnance was 275 miles (443 kilometers).

A U.S. Marine Corps Douglas AD-2 Skyraider of VMF-121 parked at airfield K-6, Pyongtaek, South Korea, 1952. The hard points under the wings are fully loaded with bombs.
A U.S. Marine Corps Douglas AD-4 Skyraider, Bu. No. 127874, of VMF-121 is parked at airfield K-6, Pyongtaek, South Korea, 1952. The hard points under the wings are fully loaded with bombs. The aircraft is painted overall glossy sea blue. (Navy Pilot Overseas)
Douglas AH-1H Skyraider 52-137593 (U.S. Air Force)
Douglas AH-1H Skyraider 52-137593 of the 602nd Special Operations Squadron. (U.S. Air Force)

The AD-6 Skyraider was armed with four 20mm AN-M2 autocannons, with two in each wing. The guns fired explosive projectiles with a muzzle velocity of 2,850 feet per second (869 meters per second), and had a rate of fire of 600–700 rounds per minute. The AD-6 could carry 8,000 pounds (3,629 kilograms) of bombs, rockets, gun pods and external fuel tanks from the 15 hard points and pylons under the wings and fuselage.

A Douglas A-1H Skyraider of the 6th Special Operations Squadron dive bombing a target during a close air support mission, Vietnam, 1968. (U.S. Air Force)
A Douglas A-1J Skyraider, 52-142016, of the 6th Special Operations Squadron dive bombing a target during a close air support mission, Vietnam, 1968. (U.S. Air Force)

Many United States Navy and Marine Corps Skyraiders were transferred to the U.S. Air Force. The Air Force retained the Navy’s Bureau of Aeronautics serial numbers (“Bu. No.”) but added two digits corresponding to the fiscal year in which each airplane was contracted. This resulted in serial numbers similar, though longer, than customary in the Air Force and Army numbering system.

The oldest Skyraider in existence is XBT2D-1 Bu. No. 9102. Formerly on display at NAS Oceana, Virginia Beach, Virginia, the airplane was transferred to The Intrepid Sea, Air & Space Museum in New York City for restoration and preservation.

This is the Douglas A-1H Skyraider flown by LCOL Jones, 1 September 1968. Though it was extensively damaged by anti-aircraft gunfire and the subsequent fire, 52-139738 was repaired and returned to service. On 22 September 1972, -738 was shot down over Laos. It was the last Skyraider shot down during the Vietnam War.
Douglas A-1H Skyraider 52-139738, 1st Special Operations Squadron. Lieutenant Colonel William A. Jones III, commanding the 602nd Special Operations Squadron, flew this airplane on 1 September 1968 during a Combat Search and Rescue mission for which he was awarded the Medal of Honor. On 22 September 1972, -738 was shot down over Laos. It was the last Skyraider shot down during the Vietnam War. (U.S. Air Force)

LaVerne Ward Browne was born at Orange, California, 9 December 1906. He was the third child of Edwin J. Brown, a farm worker, and Phebe Alice Proctor Brown. He studied law at the University of Southern California (USC).

“Mystery Plane” poster. (Monogram Pictures Corporation)

In 1928, Brown learned to fly at the Hancock College of Aeronautics, Santa Maria, California. He then worked as a pilot for Transcontinental and Western Airways, flying the Douglas DC-2. He was also commissioned as a second lieutenant in the United States Army Air Corps Reserve.

Browne married Miss Dorothy Leonore Bach at Los Angeles, California, 28 January 1926. They had a daughter, Barbara May Browne, born 6 December 1926, but later divorced. One 12 June 1933, Browne married Harriette Fitzgerald Dodson at Norfolk, Virginia.

From 1931 to 1941, under the pseudonym “John Trent,” Browne performed in sixteen Hollywood movies, including “I Wanted Wings,” with William Holden, Ray Milland and Veronica Lake. He played the character “Tailspin Tommy Tompkins” in four: “Danger Flight,” “Sky Patrol,” “Stunt Pilot,” and “Mystery Plane.”

Browne worked for Douglas Aircraft Company from 1942 to 1957. He died 12 May 1966 at Palos Verdes, California, at the age of 59 years.

“John Trent” (LaVerne Ward Browne) portrayed “Tailspin Tommy Tompkins” in four Hollywood movies. (Monogram Pictures Corporation via IMDb)

© 2017, Bryan R. Swopes

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