Martin MarsSecond in size only to the Hughes H-4 Hercules, the Martin Mars was the largest flying boat ever operationally flown by the US Navy. Planning for a much scaled-up four-engined Mariner had coalesced as the Model 170 of 1938, but it would be several years before the prototype XPB2M-1 flew. Powered by four R-3350s, this was intended as a long-range patrol bomber, but the aircraft quickly became the XPB2M-1R transport, with no armament but larger hatches and structural reinforcements to carry 13,000lb loads. The transport Mars could carry heavy loads and large numbers of priority personnel over ranges exceeding 4,000 miles, and the USN ordered twenty JRM-1 production models to carry out such missions.
The JRM-1s began to arrive in the summer of 1945, but the end of the war cut procurement back to six aircraft. One aircraft (the first Hawaii Mars) was lost shortly after its first flight, and the last (Caroline Mars) was completed to the improved JRM-2 standard. The JRMs were JATO-capable, with each inboard engine nacelle having attachment points for two bottles, and the outboards four each. Using the rocket boost, takeoff distance could be halved, depending on conditions.
The third JRM-1 was christened Hawaii Mars after its lost predecessor, and set records in 1946 by taking a 35,000lb payload to Hawaii, and then returning to California with 120 passengers and crew, with 100 of these being medical evacuees.
Not all JRM flights were over the Pacific; in 1948 the Caroline Mars set a seaplane record by flying over 4,800 miles nonstop from Hawaii to Chicago, landing on Lake Michigan.
During a April 1950 flight near Honolulu to test a new engine, the crew of the Marshall Mars had to make an emergency landing when an engine fire broke out. The crew and their rescuers attempted without success to put out the blaze, and the JRM burned, exploded, and sank.
VR-2 retired the surviving JRMs in 1956, but they were not scrapped, and three years later the fleet was sold for use as water bombers in Canada. Early on in the Mars' second career, Marianas Mars (CF-LYJ) was lost in a fatal crash on Vancouver Island, and the following year Caroline Mars (CF-LYM) was written off after taking damage from Typhoon Freda.
Martin Mars Bibliography
Photo: XPB2M-1 prototype just prior to completion Flight November 6, 1941 p.310
Martin Aircraft ad, showing the XPB2M-1 before completion, with a row of B-26s in the background. Aviation December 1941 p.6
Purolator Products ad, featuring a side view photo of the Mars prototype Aviation March 1942 p.40
Photo (small): "Mars Makes Initial Flight" Aviation August 1942 p.228
Ad for Holley Aviation Carburetors, depicting a pair of Mars with twin tails (one more than was ever built in that configuration) preparing to land. Aviation November 1942 p.84
Photo: Mars prototype taking off Aviation September 1943 p.139
C.H. Schildhauer "Global Air Transport And The Flying Boat's Role" Aviation April 1944 Inludes cutaway illustrations of the projected civilian Model 170-21 passenger and Model 170-22 freighter derivatives of the Mars.
Scholer Bangs "Martin Claims New Mars to have 10¢ Per Ton-Mile Operating Cost" Aviation News May 8, 1944 p.9
Ad for Martin Aircraft, showing cutaway artwork of the Mars in freight, airliner, and combo configurations. Aviation News July 3, 1944 p.6
Photo: salvaging the hull of Hawaii Mars from Chesapeake Bay following 5 August 1945 crash. All Hands September 1945 p.53
"Mars will fly Navy Pacific Island Routes" Naval Aviation News October 1946
"JATO Boosts Mars In Air In 37 Sec." Naval Aviation News November 1946
"New Mark by Marshall Mars" All Hands July 1949 p.42
"Mars sets cargo records - own marks eclipsed by Kodiak trips" Naval Aviation News September 1949
"Caroline Mars engine fire - big seaplane to overhaul after blaze" Naval Aviation News November 1950 p.18
"Mars to Move?" FlyPast April 1998 p.9
"American Airplanes of World War II" Edited by David Donald. p.185 - 1 photo of the XPB2M-1 prototype in formation with the JRM-1.