In many places (copies of the Wikipedia entry), the interweb incorrectly states that "With time, the aircraft has come to be called 'Truculent Turtle'..." In fact, in press releases before the flight, the Navy was already referring to it as The Truculent Turtle as evidenced by a New York Times article dated the day that the flight began.
The name The Turtle and the cartoon character doubtless originated with the Navy/Lockheed plan, "Operation Turtle," to counter the publicity being garnered by the Army Air Force with long-range B-29 StratoFortress flights, one setting the long-distance record in November 1945. The Navy was concerned that the President and Congress might well overvalue the Army's ability to deliver the newly demonstrated atomic bomb and underfund the Navy's ship and airplane programs. "Turtle" was probably used by the engineers in recognition of the fact that the maximum-range cruise speed of a propeller-driven airplane, even high performance fighters, is slower than most people would think, only about 150 knots or 170 mph. They can cruise at higher speeds, of course, but not go as far.
The addition of Truculent was probably belated recognition that The Turtle did not convey the impression of long-range weapon delivery capability that the Navy wished to make with this record-setting flight even though this was not its stated purpose.
It was, no question, a publicity stunt. Few if any airplanes were as modified for speed records as The Turtle was for the distance record. Lockheed removed as much equipment as possible to minimize the empty weight and parasite drag and then added as many fuel tanks as there was space available until the aircraft gross weight was almost 50% greater than the maximum allowed operationally. In addition to new tip tanks, there were additional tanks in the outboard wing panels, the forward fuselage, and the aft fuselage. The standard internal fuel capacity of the P2V-1, not counting auxiliary tanks in the bomb bay, was 2,350 gallons. The Turtle's fuel capacity, including bomb bay tanks, was 8,541 gallons, well over than three times more.
Hal Andrews collection via Jim Sullivan (The lower radome was removed prior to the record flight and the tip tanks were dropped when empty.)
In order to accommodate an engine failure shortly after takeoff, a fuel jettison capability was developed to reduce the airplane's weight as quickly as possible in that event. The tip tanks were simply dropped. The fuselage tanks were ganged to a dump station manned by one of the relief pilots during the takeoff. In theory, once the P2V had climbed to 1,000 feet above the ground, he could empty those tanks while maintaining the center of gravity within an acceptable range and thereby reduce the gross weight to that permitting a climb before they lost more than 800 feet.
Even a new, well-broken-in piston engine burns oil. The engine oil capacity was therefore increased by 64 gallons. The oil in the tank added in the nose wheel well was pumped manually as required to one or the other of the standard 78-gallon tanks located in each engine nacelle.
Four JATO bottles were added for the takeoff. These minimized both the length of the takeoff roll and the time it would take to reach the minimum single-engine control speed. Another change was the substitution of heavier duty main landing gear tires because of the higher takeoff speed required at the higher gross weight. The resulting takeoff roll was 4,700 feet on a 6,000-foot long runway. (The normal takeoff distance was less than half that.)
JATO Takeoff Test at Lockheed Burbank
An excellent color video of the Turtle at Perth and the JATO takeoff is here: https://www.youtube.com/watch?v=8cyQklgmfzE
It would take almost 60 hours to burn this much fuel at the maximum range cruise speed. To reduce weight, the crew therefore consisted of only four pilots instead of the regular crew of eight, with two resting and two flying at any given time. The flight was not uneventful. The crew had to deal with bad weather crossing the equator northeast of Australia, turbulence and icing in the western US, and unexpected headwinds. The stated destination prior to takeoff was Seattle, Washington*, which would have set the record, but it seems clear that they intended to fly as far as they could, preferably all the way to Washington, D.C. However, after reviewing their fuel status and approaching Columbus, Ohio they prudently decided to land there after 55 hours in the air rather than pressing on to Anacostia where officials and family were waiting. That would set the record at 11,236 statue miles, almost halfway around the world.
New York Times
The flight had the hoped-for impact and specific comparison with the Army Air Force B-29 flights. On 2 October 1946, a New York Times editorial stated "The 7,916-mile record that it shattered was that made by the Army's Boeing Super-Fortress Dreamboat. A plane like the P2V can carry an atomic warhead from any point on the earth's surface to a point half-way round the globe."
Of course, the Times neglected to note that delivering a bomb to a target 12,000 miles away would be a one-way trip for a P2V, it couldn't be a very big bomb (the crew debated the last-minute addition of a 37-pound kangaroo), and the enemy would have a couple of days to get ready to greet it...
*Seattle, Washington was on the great circle route to Washington, D.C. as shown here.