Northrop's HSF design would be refined into DP110, which was its submission for the Dem/Val RFP. The YF-23 was stealthier and faster, but less agile than its competitor. In July 1986, proposals for Dem/Val were submitted by Lockheed, Boeing, General Dynamics, McDonnell Douglas, Northrop, Grumman and Rockwell; the latter two dropped out of the competition shortly thereafter.