Advanced Propulsion Concepts - Project Outgrowth

This technical report, titled 'Advanced Propulsion Concepts - Project Outgrowth' (AFRPL-TR-72-31), was published in June 1972 by the Air Force Rocket Propulsion Laboratory. It documents the findings of an ad hoc group that conducted a study during the 1970 calendar year to predict major propulsion developments for the subsequent 30 to 40 years. The study was initiated and directed by Donald M. Ross, then Deputy Director of the laboratory, and edited by Franklin B. Mead, Jr. The report's primary objective was to encourage creative thinking among scientists and engineers regarding propulsion beyond conventional chemical rocketry. The document is divided into two main parts: Part I covers chemical propulsion, including inherent limitations, propellant ideas (such as liquid ozone and stultene), and system ideas (such as infinitely staged rockets and nozzleless motors). Part II covers non-chemical propulsion, including thermal propulsion (electrothermal, nuclear fission, and fusion), field propulsion (electromagnetic thrusters, Alfven wave, and antigravity), and photon propulsion (antimatter and solar energy). The report also includes a chapter on 'Unique Concepts,' specifically the Air-Scooping Orbital Rocket (A-SCOR). Each section provides an analysis, identifies shortcomings, and offers conclusions and recommendations for future research. The report emphasizes that while many of these concepts are theoretically sound, they often face significant engineering, material, or economic hurdles. The report explicitly mentions that the study included an examination of 'Unknown Sciences,' noting that 'psychic forces' such as psychokinesis were discussed in Appendix I to illustrate the extent to which unrestricted thinking was applied. The document concludes that while no single concept warrants a crash development program, certain areas, such as A-SCOR and superconducting particle accelerators, merit further investigation.