The impetus for these feasibility studies came from a staff meeting at the headquarters of the Air Research and Development Command ARDC at Baltimore, on February 15, 1956. During the course of the meeting, General Thomas S. Power, Commander of ARDC, expressed-impatience with the failure of his "idea men" to propose any advanced flight systems that could be undertaken after the X-15. Work should begin now, he declared, on two or three separate approaches beyond the X-15, including a vehicle that would operate outside the atmosphere without wings. He suggested that a manned ballistic rocket might be "eventually capable of useful intercontinental military and commercial transport and cargo operation." But the main benefit of having an advanced research project underway, Power pointed out, was that the Air Force could more easily acquire funds for the "general technical work needed."42
Thus prodded into action, Power's staff quickly proposed two separate research projects. The first called for a "Manned Glide Rocket Research System" - a rocket-launched glider that would operate initially at an altitude of about 400,000 feet and a speed of mach 21. The other, termed "Manned Ballistic Rocket Research System," would be a separable manned nose cone, or capsule, the final stage of an ICBM. Such a vehicle could lead to the "quick reaction delivery of  high priority logistics to any place on Earth," as suggested by Power, or to a manned satellite. Power's staff argued that the manned ballistic concept offered the greater promise, because the solution to the outstanding technical problems, the most critical of which was aerodynamic heating, would result from current ICBM research and development; because existing ICBMs would furnish the booster system, so that efforts could be concentrated on the capsule; and because the ballistic vehicle possibly could be developed by 1960. Either program, however, should be pushed rapidly so that the Air Force could protect its own interests in the field of space flight!43
In March 1956, ARDC established two research projects, one for the glide rocket system, the other, known as Task 27544, for the manned ballistic capsule. ARDC planners shortly held briefings on the two proposed systems for its missile-oriented Western Development Division, in California, and for its pilot-oriented Wright Air Development Center, in Ohio. Other briefings were held for NACA representatives and for aircraft and missile contractors. Then, in October, Major George D. Colchagoff of Power's staff described the basic aspects of the two advanced systems to a classified session of the American Rocket Society's annual meeting in Los Angeles.44
Since the Weapons Systems Plans Office of ARDC Headquarters never received the $200,000 it had requested for its own feasibility studies, the command had to content itself with encouraging privately financed contractor research.45 In particular Avco, then trying to develop serviceable nose cones for the Thor and Atlas missiles, was urged to study the manned ballistic capsule. In November 1956, Avco submitted to the Research and Development Command a preliminary study embodying its conclusions on the ballistic approach to manned space flight. ARDC still was short of funds, so Avco and other corporations continued to use their own money for further investigations.46
While ARDC promoted these systems studies and sponsored extensive research in human factors at the School of Aviation Medicine in Texas, at the Aeromedical Field Laboratory in New Mexico, and at the Aeromedical Laboratory in Ohio, it also sought to gain acceptance for its ideas within the Air Force organizational structure. On July 29, 1957, the Ad Hoc Committee of the Air Force Scientific Advisory Board, meeting at the Rand Corporation's offices in Santa Monica, California, heard presentations from the Ballistic Missile Division on ballistic missiles for Earth-orbital and lunar flights, and from ARDC Headquarters on the two advanced flight systems then under study. Brigadier General Don D. Flickinger, ARDC's Director of Human Factors, stated that from a medical standpoint sufficient knowledge and expertise already existed to support a manned space venture.47
Although the industrial firms investigated mainly the manned ballistic capsule, NACA, following the traditional approach of building up to higher and higher flight regimes, centered its efforts on the glide-rocket concept for most of 1957. Since late the previous year, when NACA had agreed in principle to an ARDC  invitation to cooperate on the Manned Glide Rocket Research System, as they were doing for the X-15, small teams of engineers at the Langley, Lewis, and Ames laboratories had carried on feasibility and design studies.48 In January 1957 the Ames group reported its conclusions on a new rocket-powered vehicle for "efficient hypersonic flight," featuring a flat-top, round-bottom configuration. Interestingly enough, the Ames document contained as an appendix a minority report written by Langley aerodynamicists mostly from the Flight Research, Instrument Research, and Pilotless Aircraft Research Divisions - recommending that a nonlifting spherical capsule be considered for global flight before a glide rocket.49 "The appendix was widely read and discussed at Langley at the time" recalled Hartley A. SoulÚ, a Langley senior engineer, "but there was little interest expressed in work on the proposal." He continued:
. . . aside from the environment that limited the NACA mission to terrestrial transportation, the proposal was criticized on technical grounds. The report suggested that landings be made in the western half of the United States, not a very small area. The spherical shape was suggested so that the attitude would not be important during reentry. The shape was specifically criticized because the weight of material to completely shield the surface from the reentry heat would probably preclude the launching with programmed ICBM boosters. Further, the lack of [body] orientation might result in harm to the occupant during the deceleration period.50NACA study groups continued their investigations of manned glide rocket concepts through the spring and summer. In September 1957 a formal "Study of the Feasibility of a Hypersonic Research Airplane" appeared, bearing the imprimatur of the whole NACA but influenced primarily by Langley proponents of a raised-top, flat-bottom glider configuration.51
A few days later, on October 4, Sputnik I shot into orbit and forcibly opened the Space Age. The spectacular Russian achievement wrought a remarkable alteration in practically everyone's thinking about space exploration, especially about the need for a serious, concerted effort to achieve manned space flight. New urgency attended the opening of a long-planned NACA conference beginning October 15 at Ames, which was to bring together representatives from the various NACA laboratories in an effort to resolve the conflict in aerodynamic thinking between advocates of round and flat bottoms for the proposed hypervelocity glider. Termed the "Round Three Conference," the Ames meeting produced the fundamental concept for what would become the X-20 or Dyna-Soar for dynamic soaring project a delta-wing, flat-bottom, rocket-propelled glider capable of reaching a velocity of mach 17.5, almost 13,000 miles per hour, and a peak altitude of perhaps 75 miles.52
Although they had been working mainly on the hypersonic glider, as requested by the Air Force, the research engineers of PARD, in tidewater Virginia, also had been speading more and more time thinking about how to transmute missile reentry bodies into machines for carrying man in low Earth orbit. Their advocacy, along with that of other Langley workers, of a spherical capsule early  that year had indicated their growing interest in making the quantum jump from hypersonic, upper- atmospheric, lift drag flight to orbital space flight in a nonlifting vehicle. At the Round Three Conference, Faget and Purser compared notes with Eggers, perhaps the leading hypervelocity theoretician in NACA. Eggers related his own conclusions: for orbital flight the design giving the highest proportion of payload to total weight was the compact, low lift drag vehicle, having little or no wings, and embodying Allen's blunt-nose principle. He discussed the analytical studies of his semiballistic M-1, which had some lift but would, he estimated, weigh from 4,000 to 7,500 pounds. Eggers cautioned his NACA colleagues that a nonlifting, or pure ballistic, vehicle might subject the passenger to excessive deceleration forces.53
Faget and Purser returned to Langley convinced that a maximum concentration of effort to achieve manned orbital flight as quickly as possible was imperative.54 Obviously this meant that in the months ahead their research should focus on the ballistic-capsule approach to orbiting a man. Both the hypersonic glider, which called for progressing to ever higher speeds and altitudes, and Eggers' M-1, also too heavy for any existing booster system, would take too long to develop. The manned ballistic vehicle combined a maximum of simplicity and heat protection with a minimum weight and offered the best chance of getting a man into space in a hurry. Henceforth the aerodynamicists in PARD, and space enthusiasts in other units of the Langley laboratory, turned from NACA's historic preoccupation with winged, aerodynamically controllable vehicles and devoted themselves to the study of "a man in a can on an ICBM," as some in the Air Force called it.55
After Sputnik I, the aircraft and missile corporations also stepped up their research on the ballistic capsule; throughout November and December their design studies and proposals flowed into ARDC Headquarters. The most active of the firms considering how to put a man on a missile still was Avco. On November 20, 1957, it submitted to ARDC its second and more detailed study of systems for manned space flight, entitled "Minimum Manned Satellite." The Avco document concluded that "a pure drag reentry vehicle is greatly superior in satisfying the overall system requirements," and that the best available rocket for boosting a manned satellite into an orbit about 127 miles from Earth was the Atlas. Still unproven, the Atlas was to make its first successful short-range flight (500 miles) on December 17, 1957. An Atlas-launched satellite, according to the Avco idea, would be a manned spherical capsule that would reenter the atmosphere on a stainless-steel-cloth parachute. Shaped like a shuttlecock, the parachute was supposed to brake the capsule through reentry. Then air pressure would expand the parachute to a diameter of 36 feet, and the capsule would land at a rate of 35 feet per second.
Avco requested $500,000 to cover the expense of a three-month study and the construction of a "mockup," or full-scale model, of the capsule containing some of its internal systems. But because the Ballistic Missile Division was skeptical  about the drag-brake apparatus, and because ARDC was uncertain about Air Force plans in general, a contract was not awarded. Avco engineers, believing that the limiting factor in putting a man in orbit was not the capsule but the development of a reliable booster, focused on the Atlas and began holding discussions with representatives of Convair, builder of the Atlas.56
42 Memo, Major George D. Colchagoff to Lt. Col. R. C. Anderson, "New Research Systems," Feb. 16, 1956; Colchagoff interview, Washington, December 3, 1964; "Chronology of Early USAF Man-in-Space Activity, 1945-1958," Air Force Systems Command, 3-4.
43 Colchagoff memo. Since 1952 the Air Force had sponsored studies of the rocket-launched glider concept at the Bell Aircraft Corp. (Project Bomi). These studies had been instigated at Bell by Walter Dornberger who was intrigued by the antipodal rocket bomber proposed during the war in Germany by Sńnger and Bredt. See Sńnger, Rocket Flight Engineering.
44 Letter, David Bushnell to J. M. G., Dec. 11, 1964; Colchagoff interview; "Chronology of Early USAF Man-in-Space Activity, 19451958," 4-5.
45 "Chronology of Early Air Force Man-in-Space Activity, 1955-1960," Air Force Systems Command, 1.
46 House Select Committee on Astronautics and Space Exploration, 85 Cong., 2 sess. (1958), Astronautics and Space Exploration, Hearings, testimony of Arthur Kantrowitz, 509.
47 "Chronology of Early Air Force Man-in-Space Activity, 1955-1960," 2-6; Mae M. Link, Space Medicine in Project Mercury, NASA SP-4003 (Washington, 1965), 23-24; "Chronology of Early USAF Man-in-Space Activity, 1945-1958," 6. The Western Development Division was renamed the Ballistic Missile Division on June 1, 1957.
48 Minutes, NACA Executive Committee, Washington, Feb. 21, 1957, 7-8, NASA Hist. Archives.
49 "Preliminary Investigation of a New Research Airplane for Exploring the Problems of Efficient Hypersonic Flight," NACA/Ames Aeronautical Laboratory, Moffett Field, Calif., Jan. 18, 1957. This Ames proposal for a hypervelocity glider with a round bottom for heat protection should not be confused with Eggers' M-1 concept, which was planned as a much smaller manned satellite vehicle. The technical kinship between the two, however, is obvious.
50 Letter, Hartley A. SoulÚ to J. M. G., Aug. 29, 1965.
51 Letter, Crowley to Edward W. Sharp, Dir., Lewis, June 17, 1957; letter, Crowley to Reid, Langley, June 17, 1957; memo, Crowley to Ames, "Meeting of Round III Steering Committee to be held at NACA Headquarters, July 2, 1957," June 18, 1957; memo for Dir., Clotaire Wood, "Presentation to Air Force Headquarters on Round III," July 11, 1957; "Study of the Feasibility of a Hypersonic Research Airplane," NACA, Washington, Sept. 8, 1957.
52 Ibid., 6-24. The term "Round Three," as used by the NACA and Air Force, referred to the third phase of the research airplane program, the first beginning with the X-1 and extending through the X-2, the second being the X-15.
53 Eggers letter; Paul Purser, interview, Houston, Feb. 12, 1964; Faget, interview, Aug. 24, 1964.
54 Hartley SoulÚ recalled that during the Round Three Conference, Faget asked for the floor and declared that NACA had misplaced its research emphasis, that he would spend no more effort on the Round Three concept, and that henceforth he would go to work on orbiting a man as fast as possible. "For me," said SoulÚ, "Project Mercury was born with Faget's remarks. . . ." SoulÚ letter.
55 This was a phrase current in ARDC in 1956-1957, Colchagoff interview; Virgil I. Grissom, interview, Houston, April 12, 1965.
56 Astronautics and Space Exploration, testimony of Kantrowitz, 510; "Chronology of Early Air Force Man-in-Space Activity, 1955-1960," 14-15; "Chronology of Early USAF Man-in-Space Activity, 1945-1958," 8.