The plane shown is XB-29 serial 41-18335, the third of three prototype Superfortresses, which also carried Boeing Model No. 345. The first two aircraft had been ordered by the Army Air Corps in August, 1940, with the order for the third prototype being placed that December.
|There is a tradition at Boeing, which continues to this day, of shooting portraits|
of all their new models with Mount Rainier in the background. Note the three-
bladed props - production aircraft were equipped with four-bladed propellers.
Killed in the crash were all eleven on board, including Boeing Chief Test Pilot Edmund "Eddie" Allen (who also served as chief of Boeing's research division), test pilot Bob Dansfield, and a number of other senior Boeing flight test engineers and senior staff. Another 21 people on the ground, including a firefighter, were killed as well.
After the crash, a congressional investigation led by Senator Harry S. Truman resulted in a scathing report which revealed that Curtiss-Wright, the manufacturer of the engines, was using substandard parts. As a result of the report, the Army took over the flight test program from Boeing, with the two XB-29s and fourteen YB-29s soldiering on.
Also as a result, 41-18335 received upgraded engines and a number of other improvements to help prevent future fires. When originally ordered, the plane was given the name The Flying Guinea Pig, but at some point, she was affectionately named Gremlin Hotel by her crews (in the photo at this link, from the Museum of the U.S. Air Force, you can just barely make out that name painted in small letters on the nose of the plane).
The gremlins had their time with this plane as well. On May 23, 1943, during a high speed taxi test in which Col. Leonard "Jake" Harmon intended to take the plane to flying speed, but not leave the runway , it was found that plane tipped to the right when he moved the control wheel to the left, with the right wingtip scraping the runway. He managed to use engine power to recover, and the plane became airborne for a short time before Harmon set it down on a parallel taxiway. After an investigation, it was found that the aileron cables had been connected backwards, causing the ailerons to move in the opposite direction as intended. The "official" first flight didn't come until late June, after the first of the YB-29s had taken to the air.
After the initial phases of flight testing were complete, Gremlin Hotel was also used to set up the production line at Boeing, and later crashed during further flight testing.
The Museum of the U.S. Air Force also has another photo of the plane with Mount Rainier, at this link.
A fascinating article about the crash - and the art museum that came to be as a result - can be found at this Seattle Times link.