I know that the Martin 216 has been mentioned in several sources pertaining to the B-52 competition, but in my opinion it's wrong. The Martin models listing states that the Model 216 was an "eight engine 500,000 lb flying aircraft carrier" that could lift "1/2 million pounds at take-off." I suppose that refers to what Mr. Pelletier designates as the Model 216-1 pusher flying wing of 1944. As to the Model 216-2 bomber, I find it surprising that it retained the same basic model number, but if what Mr. Pelletier wrote is accurate, then the number was reused for a completely different, heavy bomber design. But does that mean it could be a B-52 contender?
Now speaking of the B-52 competition, what we know of Martin's contender is that it's listed as the Model 236 of 1946. The very interesting point here is that the Model 236 was Martin's entry in a forgotten 1945 competition for a medium, not heavy, bomber. Indeed, the USAAF issued two near-simultaneous competitions in 1945: one for Light Bombers (LB), to which Martin responded with their early Model 234 design (straight-wing XA-45), and one for Medium Bombers (MB), to which Martin submitted their Model 236 design in April 1946 (other known contenders being Consolidated Vultee and Boeing). The winning designs of both competitions received project designations MX-838 and MX-839, respectively. And guess what? MX-839 is the project designation for the B-52 program, which surely is no "medium bomber"... Therefore, in the same way that MX-838 was changed and amended along the way from straight-wing attack to swept-wing ground-support bomber, MX-839 evolved from straight-wing medium bomber to swept-wing heavy bomber.
Back to Model 216-2. It is clear that it is a heavy bomber from the start. So it could not have been submitted in the MX-839 competition, which even though it ultimately resulted in the B-52, wasn't a heavy bomber competition from the start.
