The Boeing-designed B-17 bomber was assembled also by Lockheed Aircraft Corp. and Douglas Aircraft Co., while the B-29 was assembled also by Bell Aircraft Co. and by Glenn L. Martin Company.
Pesawat pengebom Boeing B-17 juga dirakit oleh Lockheed Aircraft Corp. dan Douglas Aircraft Co., sedangkan B-29 dirakit juga oleh Bell Aircraft Co. dan oleh Glenn L. Martin Company.