The Class III designs for Nova were intended to use advanced propulsion systems, advanced materials and be fully recoverable. Shown below is a NASA briefing chart on Nova Class III designs from September 1963 showing three Class III designs. The first is an airbreathing SSTO concept… a conical vehicle with rocket engines at the rim, and a ;large duct wrapped around them. This produced an ejector effect, in theory greatly increasing thrust at low airspeed. As velocity increased, fuel could be injected directly into the duct, turning it into a ramjet. The ramjet would of course be use for only a relatively brief portion of the flight, so the duct would be dropped not long into the flight, presumably to be parachute recovered in the ocean. The other two designs are substantially more conventional, though both used plug cluster engines.
You can download a 4.4 megabyte JPG file of the artwork; the link is HERE. To access it, you will need to enter a username and password. The username: the first word in the body of the text on page 12 of APR issue V1N6. The password: the first word in the body of the text on page 14 of the same issue. Note that both are case sensitive.