Hi Scott,
I have a copy of Tony Chong’s book “Flying Wings & Radical Things: Northrop’s Secret Aerospace Projects & Concepts 1939-1994” and since you noted in a previous publication in Aerospace Projects Review that the N-31 version with a refueling probe and two Turbodyne engines doesn’t have a specific N-31 variant label in the May 1950 brochure in which it was illustrated, you can label the twin-turboprop N-31 variant shown in the drawing on page 42 as “Northrop N-31 (twin Turbodyne-powered study) to distinguish it from the baseline N-31 design with six J40s and the N-31A. I also wanted to ask if the paragraph on page 36 mentions the N-31B, N-31C, and N-31F proposals, because Buttler (2010) notes that the N-31B would have been an all-wing N-31 with four J40s in the wing and the N-31C was a 1948 proposal with two Turbodynes, while the N-31F would have been a photo-reconnaissance version of the N-31B
Buttler, T., 2010. American Secret Projects: Bombers, Attack, and Anti-Submarine Aircraft 1945-1974. Hersham, UK: Ian Allan Publishing.
Vahe David Demirjian says: