Firefighting certainly wasn't what Glenn L. Martin had in mind for the design of the Martin Mars. Originally conceived as a bomber for long range missions and patrols, the production aircraft were redesigned and classified for long-range general transport because of the demonstrated heavy-lift capability of the prototype. The "Big Four", as they were affectionately known, established airlift and endurance records which remain valid today and they logged some 87,000 accident-free hours before being retired by the US Navy and sold to Flying Tankers. Mr. Martin would be very pleased to know his original intention of the Mars in a bomber role came to pass in their second career as waterbombers!

In 1959, the remaining Mars were to be sold for scrap. Dan McIvor, who represented a consortium of British Columbia forest companies, recognized their potential value as water bombers. A company called Flying Tankers Inc. was formed, and purchased and converted the "Big Four" for aerial firefighting. The Marianas Mars crashed near Northwest Bay, British Columbia on 23 June 1961 during firefighting operations; all four crewmembers were lost. Just over a year later, on 12 October 1962, the Caroline Mars was destroyed by Typhoon Freda while parked onshore. The Hawaii Mars and Philippine Mars had their conversions to water bombers accelerated and entered service in 1963.

The two surviving tankers are operated by Coulson Flying Tankers and are based and maintained at Sproat Lake near Port Alberni. On 25 October 2007, the Hawaii Mars ("Redtail") arrived at Lake Elsinore in Southern California, on a private contract, to assist with the firefighting efforts containing the California wildfires of October 2007. The Philippine Mars is undergoing "extensive maintenance and renovation" and will not be ready to fly again until 2010. As of 13 August 2009, the Hawaii Mars was in service fighting the La Brea fire east of Santa Maria in Southern California.

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The Martin Mars powered by four 18 cylinder 2,500-hp, Wright 3350-24WA Duplex Cyclone engines, can scoop water at better than a ton per second whilst "on the step" at a skim speed of 60-70knots, then lift off and return, to drop a payload upwards of 60,000 pounds from its bottom-drop system. The "Philippine Mars", on the other hand,employs a side-drop delivery system. 

Philippine Mars
White Tail - side drop system
Canadian Registration C-FLYK
S/N 76820

Hawaii Mars
Red Tail - bottom drop system
Canadian Registration C-FLYL
S/N 76823

During the fire season, the aircraft are kept in a state of readiness to meet the existing fire hazard conditions. They can be in the air in ten minutes and, based on historical data, each can make a drop every fifteen minutes. Working in tandem, this equates to 7,200 US gallons (27,276 litres) every seven minutes and each drop can cover an area of up to 4 acres (1.6 hectares). It has often been said that the Mars, with a 60,000 pound (27,216 kilogram) payload of foam, is like ""a huge wet blanket". The highly experienced Mars pilots, working closely with the Incident Commander, deliver the water or foam right where it is needed.
 
Each Mars carries 600 US gallons (2,270 litres) of foam concentrate - enough for 21 drops of a 0.4% solution which is the standard used although it may be decided to use more or less foam as dictated by the Incident Commander. The Mars are also equipped to deliver Thermo-Gel which when mixed with water forms a light gel by encapsulating the water droplets. This product provides a more even coating of the fuels as well as lasting longer on the ground.
 
Flying Tankers completed test and evaluation of Class A foam in 1986 and began using it with the Mars as a matter of routine in 1987. It has been estimated that the foam capability of the aircraft increases the efficiency of the Mars by at least 30%. The ability of the machines to drop massive amounts of foam lends itself particularly well to the suppression of urban/rural interface fires and the Mars have excelled in this regard.

The Mars carries a crew of four; Captain, First Officer and two Flight Engineers, all of whom work together as a team to get the job done - efficiently and safely. Since the loss of the prototype waterbomber in 1961, the Mars operation has been accident-free for both those flying the machines and those working on the ground. The strict flight procedures the crews adhere to ensure every effort is made to continue this enviable record. The Mars are maintained to the highest standards and undergo intensive repair and overhaul each year. It should suffice to say that the people who maintain them also fly in them - added incentive to do their work well!
 
The most frequently asked question regarding the Mars is "How do they pick up their water?". This part of the flying operation is, perhaps, the most demanding in terms of teamwork among the crew. The Captain executes a normal landing, keeps the the aircraft "on the step" and allows the speed to decrease to 70 knots. He then passes engine power to the Flight Engineer and selects the scoops to the "down" position. The ram pressure for injecting the water into the tanks is such that the aircraft is taking on water at a rate in excess of a ton per second. To account for this added weight, the Flight Engineer must advance the throttles to maintain a skimming speed of 60-70 knots to ensure the aircraft remains on the step. Pickup time is, on average, 25 seconds. When the tanks are full, the Captain will have the scoops raised, call for takeoff power from the Flight Engineer and carry out a normal loaded takeoff. Once airborne, the foam concentrate is injected into the water load (normally, 30 US gallons of concentrate into the 7,200 US gallon water load) where it is dispersed and remains inert until the load is dropped. Once dropped, the tumbling action causes expansion which converts the water load into a foam load. This process is repeated for each drop. In other words, this vital team work is carried out, on average, every 15 minutes per aircraft. For a Gel drop , the concentrate is injected during the scooping process to allow even mixing. 

 
http://www.martinmars.com/
Flying Tankers Inc

Photos: Andreas Barowski, Flying Tankers