Reading level:

Martin Mars

Martin · Transport / Firefighter · USA · WWII (1939–1945)

Martin Mars — Transport / Firefighter
Open in interactive gallery →

The Martin JRM Mars (also called Martin Mars) was a U.S. Navy four-engine flying boat — the largest production flying boat ever built and one of the largest aircraft of WWII. Martin built 7 Mars between 1942 and 1947. The aircraft was originally designed as the XPB2M-1R prototype maritime patrol bomber but transitioned mid-war to a long-range Pacific transport role; the production JRM-1 / JRM-2 variants flew U.S. Navy trans-Pacific cargo and personnel transport from 1944 to 1956. Two Mars airframes were converted to civilian fire-bombing aerial tankers in the late 1950s and remained in service in British Columbia until 2015 — fighting wildfires in northwestern North America for over 50 years.

The Mars was enormous: 200 ft wingspan, 117 ft long, 165,000 lb maximum takeoff weight. Power: four Wright R-3350 Cyclone 18 18-cylinder radials (2,500 hp each — the same engine as the B-29 Superfortress). Maximum speed 222 mph; range 4,945 miles; service ceiling 14,600 ft. Payload: 30,000 lb of cargo or 133 passengers or 84 stretcher cases. The Mars was about twice the size of the contemporary PB2Y Coronado and approximately equal to the post-war Boeing 377 Stratocruiser airliner — the largest U.S. transport flying boat ever built.

Trans-Pacific transport service. The seven JRM-1 airframes (named after Pacific islands: Hawaii Mars, Marshall Mars, Marianas Mars, Caroline Mars, Philippine Mars, Pacific Mars, and Hawaii Mars II) flew U.S. Navy VR-2 Squadron's trans-Pacific transport route from California to Hawaii, the Philippines, and Japan from 1945 onward. Marshall Mars set a 308-passenger world record on 4 May 1946 (Marines and crew from San Francisco to Honolulu). Caroline Mars set a 33,500-lb cargo record. The fleet carried about 800,000 passengers and over 100 million tonnes of cargo across the Pacific 1945-1956 before retirement. Marshall Mars burned to the waterline in a 1950 fire; the rest were retired and most were scrapped.

Two airframes (Hawaii Mars II and Philippine Mars) were converted to civilian fire-bombing aerial tankers and operated by Coulson Forest Products in Sproat Lake, British Columbia from 1959 to 2015. The aircraft carried 7,200 imperial gallons (32,700 litres) of water and fire retardant — by far the largest aerial firefighting capacity in North America. Both were retired in 2015 after 56 years of fire-bombing service. Hawaii Mars II is preserved at the BC Aviation Museum in Sidney, British Columbia; Philippine Mars was sold to the U.S. Navy and is at the National Naval Aviation Museum at Pensacola, Florida.

For Kids — a shorter, friendlier version

The Martin Mars was a giant flying boat made for the American Navy. It was the largest flying boat ever built for regular service. Seven of them were made between 1942 and 1947. That is a very small number for such a famous plane!

The Mars was huge. Its wings stretched 200 feet wide — longer than most city blocks. It was 117 feet long and could weigh up to 165,000 pounds at takeoff. That makes it heavier than most large trucks combined.

The Navy used the Mars to carry cargo and people across the Pacific Ocean. It could carry 133 passengers or about 30,000 pounds of supplies. Four powerful engines kept it in the air. Each engine had 18 cylinders and made 2,500 horsepower.

Later, two Mars planes got a new job. Workers changed them into fire-bombers. They flew over forests in British Columbia, Canada, and dropped water on wildfires. They kept doing this important work until 2015.

The Mars could fly up to 222 miles per hour and travel nearly 5,000 miles without stopping. It could also fly as high as 14,600 feet. This amazing plane served for over 50 years in total!

Fun Facts

  • The Martin Mars had a wingspan bigger than half a football field!
  • Only seven Martin Mars planes were ever built.
  • The Mars could carry 133 passengers — about as many as a small airliner.
  • Two Mars planes fought wildfires in Canada for over 50 years.
  • The Mars used the same engines as the famous B-29 Superfortress bomber.
  • It could fly nearly 5,000 miles without stopping — that is almost the width of the entire Pacific Ocean!
  • The Mars weighed up to 165,000 pounds — heavier than a loaded freight train car.
  • The Mars started as a patrol bomber but became a transport and later a fire-fighter.

Kids’ Questions

How did the Martin Mars land on water?

The Martin Mars was a flying boat, which means its body was shaped like a boat hull. It could land right on the surface of lakes or the ocean. Special floats near the wings helped keep it steady in the water.

How did the Mars fight wildfires?

The Mars could scoop up water while skimming across a lake at high speed. Then it flew over a burning forest and dropped all that water on the flames. It could carry thousands of gallons at a time.

Was the Martin Mars the biggest plane ever?

It was the largest flying boat ever made for regular service. It was also one of the largest aircraft of World War Two. Many planes built after the war have since grown even bigger.

How long did the Martin Mars stay in service?

The American Navy used the Mars from 1944 to 1956. After that, two planes became fire-bombers and kept flying until 2015. That means the Mars was in service for over 50 years in total!

Variants

XPB2M-1R (prototype, 1942)
Single prototype built as a maritime patrol bomber. First flight 23 June 1942. Converted to transport configuration after Pearl Harbor changed U.S. Navy priorities.
JRM-1 (1944-1947, 6 built)
Production transport variant. Six built — Hawaii Mars, Marshall Mars, Marianas Mars, Caroline Mars, Philippine Mars, Pacific Mars. R-3350 Cyclone 18 engines. Trans-Pacific U.S. Navy service 1945-1956.
JRM-2 (1947, 1 built)
Single airframe built — Hawaii Mars II (replacing the original Hawaii Mars destroyed in a 1945 accident). Identical to JRM-1. Later converted to fire-bomber.
Mars fire bomber (Coulson conversions)
Civilian fire-bomber conversions of Hawaii Mars II and Philippine Mars. Operated by Coulson Forest Products from Sproat Lake, BC 1959-2015. Carried 7,200 imp gal of water/retardant.

Notable Operators

U.S. Navy (VR-2 Squadron)
Sole military user. Trans-Pacific transport service 1945-1956 from Naval Air Station Alameda, California to Hawaii, the Philippines, and Japan. Retired 1956 in favour of land-based aircraft.
Forest Industries Flying Tankers / Coulson Forest Products
Civilian fire-bomber operator 1959-2015 at Sproat Lake, British Columbia, Canada. Operated Hawaii Mars II and Philippine Mars. Retired both airframes 2015 after 56 years of operation.

Frequently Asked Questions

Was the Martin Mars the largest aircraft ever built?

The largest production flying boat ever built. Larger one-off aircraft existed (the Hughes H-4 Hercules Spruce Goose at 320 ft wingspan, the Antonov An-225 Mriya at 290 ft) but the Mars at 200 ft wingspan was the largest aircraft to enter regular production and in-service service. Seven Mars were built; the Hughes H-4 was a single airframe.

Did Martin Mars fight wildfires?

Yes — for 56 years. Two Mars airframes (Hawaii Mars II and Philippine Mars) were converted to civilian fire-bombing aerial tankers in 1959 and operated by Forest Industries Flying Tankers / Coulson Forest Products at Sproat Lake, British Columbia. They carried 7,200 imperial gallons (32,700 litres) of water and fire retardant — by far the largest aerial firefighting capacity in North America. Both were retired in 2015.

How many Martin Mars were built?

Seven airframes total: 1 XPB2M-1R prototype (1942) + 6 JRM-1 production (1944-1947) + 1 JRM-2 (1947). The original Hawaii Mars (1944) was destroyed in a 1945 accident; Hawaii Mars II (the JRM-2) replaced it.

What records did the Martin Mars set?

Marshall Mars set a 308-passenger record on 4 May 1946 (Marines and crew from San Francisco to Honolulu). Caroline Mars set a 33,500-lb cargo record. The Mars fleet carried about 800,000 passengers and over 100 million tonnes of cargo across the Pacific 1945-1956 — the most-prolific Pacific transport aircraft of its era.

Are any Mars preserved?

Yes — both surviving airframes. Hawaii Mars II is preserved at the British Columbia Aviation Museum in Sidney, British Columbia. Philippine Mars was sold to the U.S. Navy in 2016 and is at the National Naval Aviation Museum at Pensacola, Florida. Both are static displays; neither is airworthy.

Sources

See Also