Maxwell Hunter's ultimate goal was to shake things up and achieve better, simpler ways for man to travel to space. He believed that following an "airplane" design paradigm of a single-stage craft that could return to earth intact and be fully reusable would bring down costs, allowing far greater access to space travel.
For nearly 40 years, from the RITA single-stage nuclear rocket at Douglas in 1959 to the StarClipper expendable tank design at Lockheed in 1966 and the X-Rocket single-stage-to-orbit in 1985, Max continually pursued single stage designs and aircraft-like operations as the keys to vastly improved, economical space transport.
In his seminal essay, "Single Stage Spaceships Should Be Our Goal!", he lays out the reasons and challenges.
THE ULTIMATE vehicle for manned space travel within the solar system is the high-performance single-stage spaceship—a vehicle that could travel from earth to points in space and back time after time in the same way that jet transports travel from point to point on the face of the earth, stopping only to be serviced and refueled. In fact, only with the development of a spaceship of this simplicity, economy and versatility of operation can we foresee the economic feasibility of really large-scale manned space operations with whatever permanent manned bases on the moon or planets are necessary...
If one examines the reasons for the high cost of space travel, he is usually impressed with how hopeless everything seems. Large installations such as Cape Canaveral are evidently necessary, and expensive pieces of hardware are placed almost beyond recovery at various points in space and around the planet. Furthermore the very high velocities required in space flight would seem to involve such tremendous energies that one would expect everything to be fantastically expensive anyway...
A really high-performance rocket is capable of making fundamental improvements in this picture. If the performance of single-stage rockets can be made high enough, one can begin to think of reusing equipment exactly as in transport airplane practice. Except possibly for safety provisions surrounding the engine, there is no reason why a single-stage nuclear rocket should be any more complicated than a standard transport airplane and NO reason why it should be much more expensive in production. The temperature inside the reactor (and in the exhaust jet) will be substantially higher than that to be found anywhere near a normal transport aircraft. On the other hand, the rocket accelerates out through the atmosphere slowly, and hence is never subjected to the severe external environmental factors faced by supersonic aircraft. Should aerothermodynamic loads on unpowered re-entry prove too severe, a really high-performance rocket could re-enter the atmosphere on jet thrust. The high reactor-core temperature, hence, is really the only major vehicle difference.
In my opinion most people tragically underrate this point. Five-stage rockets of the large man-and-cargo variety tend to spawn large, complicated launching systems, fantastic numbers and types of engines, vast real estate developments, and similar complicating phenomena. As a matter of fact, one of Hunter's additions to Parkinson's laws is: "The management structure (total number of companies and agencies) involved in large manned rocket programs is at least directly proportional to the gross weight times the number of stages of the vehicle." We must not be blind to the fact that we need only develop a single adequate propulsion system to have a simple, reliable vehicle that might be no more difficult to prepare for the next flight than the average, equally complicated, transport plane.