john smith wrote:
The XB-28 appears to be a competitor for the XB-26 Maurader.
The designs appear similar, possibly due to specifications.
Was there also and XB-27?


The Martin XB-27 and North American XB-28s competed for an August 1939
request for a high altitude medium bomber that was intended to
supplement the B-25 and B-26. Due to improvements in medium altitude
bombing the requirement was dropped. A second N.A. aircraft, XB-28A,
was built as a possible high altitude reconnaissance aircraft, but was
not bought either.

(Info from Lloyd S Jones' U.S. Bombers, 1974