rwdfresno wrote:I haven't heard of anyone in the civilian world considering doing this. Of course the experiences of North American and the NA-98X were obviously not very successful. It is hard to say if the wing separation was due to the stress of the additional speed, the increased stress on the wing attach points due to the enlarged aileron and increased roll rate, or perhaps a combination of things.
This bothered me, so I went looking for my documents from NAA.
I will try to upload them in the future, I have transcribed the following for your understanding of the circumstances of the crash of the Experimental B-25 NA98X.
From my notes received directly from North American Rockwell a number of decades ago.
B-25H-NA98X #43-4406 – Pratt & Whitney R 2800 Engine
This “one only” aircraft was a test bed for the more powerful Pratt&Whitney R 2800 engine. The first flight of NA98X was flown on March 31, 1944. The NAA pilot was Joe Barton and the NAA flight engineer was Jim Talman. A person named Johnson was also aboard but his affiliation and duties are unknown. This first flight lasted one hour. There were sixteen more company test flights before the aircraft was turned over to the USAAC for evaluation.
A Major Ritchie was the Army Air Corp pilot and his flight engineer was Lt. Wey. Ritchie would fly the next thirteen test flights.
Recollections from NAA period engineers state that the Major put the more powerful aircraft through excessive flight stresses which far exceeded the operational combat requirements of an aircraft such as the B-25. He did not heed warnings to stay within red line warning boundaries.
One source claimed that Major Ritchie conducted tests that would have taxed an average fighter. A company armament engineer wanted to fly a mission or two to test the top turret modification of some sort but was advised by flight test supervision to stay out of the aircraft as long as Ritchie was at the controls.
Major Ritchie made his original, plus two additional flights, on April 22, 1944 which totaled 4:35 hours. On April 23 he totaled &:30 hours and on four of the five flights this day Sq. Leader Hartford teamed as flight engineer. On April 24 Major Ritchie, With Lt. Wey at his side, would make five flights totaling 6:40 hours.
Disaster would strike however. Returning from the 29th test flight (1:20 hours) on that 24th of April, Ritchie approached Mines Field (as it was known then and where the Inglewood plant of NAA was located) at a very high rate of speed (estimated at above red line). Evidently, structural fatigue had begun to set in on earlier flights through Ritchie’s excessive demands on the design integrity of the B25. As he made his high speed run at a runway landing approach altitude. The horizontal stabilizers were struck by disintegrating outer wing panels and gave way and the aircraft instantly came apart and crashed, killing both Ritchie and Wey. Heavier pieces, such as engines, etc., were strewn over a large area of ground adjacent to the plant and many other pieces that had flown through the air came to rest on the camouflaged screening covering the plant and the adjacent outdoor final flight line area.
The total flight test hours for NA98X totaled 40:15 hours. Total time for Major Ritchie was 18:50 hours over a period of three days. Company time totaled 21:25 hours over a period of twenty-two days including eight days of down time.
The flight time figures are from official NAA flight test records and the only comment on the flights made by Major Ritchie are simply recorded as “Army Air Corp Tests”.
References: Spivak, Holton, Ferren, and others.