Thank you, James
In spite of being somewhat unorthodox, not a great success. Thus cancelled.
Quote from wikipedia:
The XP-54 was unique in numerous ways. The pressurized cockpit required a complex entry system: the pilot’s seat acted as an elevator for cockpit access from the ground. The pilot lowered the seat electrically, sat in it, and raised it into the cockpit. Bail-out procedure was complicated by the pressurization system and necessitated a downward ejection of the pilot and seat in order to clear the propeller arc.[1] Also, the nose section could pivot through the vertical, three degrees up and six degrees down. In the nose, two 37 mm T-9 cannon were in rigid mounts while two .50 cal machine guns were in movable mounts. Movement of the nose and machine guns was controlled by a special compensating gun sight. Thus, the cannon trajectory could be elevated without altering the flight attitude of the airplane.
The Swedes may have had a bit more success with a similar configuration, the SAAB J21.
The SAAB was also unique: A reasonably successful conversion into a jet powered version, the J21R.
But that's another story.
New quest-ion: This lovely little seaplane