Titan II Makes the Grade, But Not Paraglider

What had been Project Gemini's greatest concern - whether Titan II could function as a booster for manned space flight - was soonest laid to rest. [167] Titan II Missile N-25 was launched 1 November 1963 from the Atlantic Missile Range, the 23rd in the series of test flights conducted by the Air Force Ballistic Systems Division (BSD). It furnished the first real proof that Titan II would do for Gemini. Missile N-25 was equipped with the standpipes on its oxidizer lines and mechanical accumulators on its fuel lines that the revised theory had predicted would suppress the severe length-wise bouncing (Pogo) that threatened Titan II's role as a manned booster. The November flight proved it worked. The devices installed in fuel and oxidizer feedlines reduced Pogo to the lowest level ever in a Titan II flight, only one-ninth the force of gravity (±0.11g), and for the first time well below the ±0.25g that NASA insisted marked the upper limit for pilot safety.3

The Gemini Program Office had no way of forecasting that the next five months were to see the Titan II test flight program produce an unbroken string of successes. But, knowing that standpipe and accumulator had worked on Missile N-25, GPO inferred that the theory behind installing these devices had been confirmed and acted quickly, sure that the Pogo problem had been solved. On 6 November, GPO decided to procure several sets of the suppression devices for Gemini launch vehicles. The soundness of that action was soon confirmed. Titan II launches on 12 December 1963 and 15 January 1964 both carried the oscillation dampers and both met NASA standards. The 15 January flight, added at Aerospace urging, proved the devices effective even with reduced fuel-tank pressures. This was all the more heartening because raised tank pressures had lowered Pogo levels in some earlier missile flights.4

While Titan II was proving itself in flight, NASA and the Air Force completed their nearly year-long efforts under the aegis of the Gemini Program Planning Board to fix standards for the Gemini launch vehicle. NASA's final statement, on 15 November 1963, rehearsed its long-stated demands: longitudinal oscillations during powered flight must be no greater than ±0.25g, incipient combustion instability must be eliminated, and all known design shortcomings and anomalies revealed in Titan II ground and flight tests must be corrected. On the same day, BSD and SSD (Space Systems Division) of the Air Force Systems Command issued a plan to prove in flight their program to reduce Pogo and improve engines. These two documents, along with the earlier Air Force plan for cleaning up Titan II problems, answered the board's request of 11 October 1963 for data on [168] which to base a formal Memorandum of Understanding between NASA and the Air Force.5

What NASA required and how the Air Force planned to respond were discussed for the last time at the board meeting of 3 December. The board accepted the NASA specifications as reasonable, the Air Force plans to resolve the problems and verify the results as technically feasible. Then the co-chairmen of the board, Brockway McMillan for the Department of Defense and Robert Seamans for NASA, signed the formal "Memorandum of Understanding on Certain Design Requirements for the Gemini Launch Vehicle."6 No further managerial obstacles blocked the way to a man-rated Gemini launch vehicle.

The compound of jurisdictional disputes and technological problems that had made the launch vehicle the single biggest question mark in the Gemini program until late in 1963 vanished almost overnight. By mid-January 1964, Titan II no longer seemed a concern. After the missile's third success with Pogo suppression gear, on 15 January, Seamans was convinced "that the currently completed flight demonstrations of POGO fixes indicated a qualitative understanding of the problem and its solution and provided sufficient confidence to go ahead with the Gemini program." Another sign of the times was the end of the weekly Titan II status reports Seamans had been getting from Air Force Systems Command because, "based on the successful resolution and flight verification of the axial oscillation fix (Pogo) on missiles N-25, -29, and -31, the primary requirement, for which this weekly report was originated, has been satisfied."7

Pogo had not, of course, been the only problem, although it was the greatest. Still to be resolved was the potential instability of Titan II's second-stage engine, which Aerojet-General had begun to tackle in October 1963 with Gemsip, the Gemini Stability Improvement Program, focused on working out a new design for the propellant injectors. Gemsip ended 18 months later with complete success, having cost the Air Force about $13 million. NASA spent $1.45 million to install the changes in the last six Gemini launch vehicles. The first six flew with the old-style injectors, which NASA later defended on the somewhat specious grounds that no instability had shown up in a Titan II flight. That was essentially a statistical argument of the kind earlier rejected as a basis for man-rating. NASA found a better reason for going on with the flight program. Aerojet engineers knew that any number of techniques might be used to reduce starting shocks, the major trigger for unstable burning. Very early in Gemsip, they found that a certain minimum pressure in the cartridges that started the motor eased the problem. Temperature conditioning - keeping the start-cartridge temperature above a critical value - proved even more effective. This was the finding that chiefly convinced NASA that Titan II's second-stage engine was safe enough for manned missions, [169] although only Aerojet's redesigned injector finally provided a dynamically stable engine.8

NASA's third concern about Titan II had been just how reliable some engine parts were. This was less a matter of design than of the general standards of manufacturing and quality control observed by Aerojet-General. The Air Force, however, saw potentially dangerous weaknesses in design that demanded the development of new parts, an effort that got under way in September 1963 as the Augmented Engine Improvement Program. NASA deemed improved engines nice but not vital (as damped Pogo and stable second-stage engines were) for Gemini. This was just as well, because the engine improvement program produced small results for the $11 million it cost the Air Force: some minor design shortcomings corrected, welding techniques improved, and better assembly methods adopted. NASA did buy one product of the program for Gemini, redundant shutdown circuitry, at a cost of $1.5 million. But the rest of the hardware developed under the program looked more risky than what it was intended to replace. The Air Force canceled the program in November 1964.9

Looking back, NASA officials had nothing but praise for the hard work put in by the Air Force and its contractors to man-rate Titan II for Gemini even while they were trying to prove it as a missile. As George Mueller reported to NASA Administrator James Webb:

In the broad view of this booster program where a military vehicle, the Titan II, was selected prior to its development and a program of man-rating carried out actually in parallel with the flight test and acceptance of the military versions, we have, I believe, a unique situation. It is unique not only in technical complexity but also in management relations and control. . . . [T]his collaboration between two demanding users has produced an unusually reliable military launch vehicle . . . [and] a man-rated launch vehicle with a remarkable record of success. . Configuration management is not a new term but the detailed application of the Air Force to the GLV [Gemini launch vehicle] development is a model of its kind and a significant contribution toward improved management of all major programs, in DOD and in NASA. We have seen major improvements in electrical circuit design, in electrical soldering and welding techniques, in assembly procedures and in test specification.10
This picture of a smoothly meshed team moving from success to success, although true enough for the last six months of the program, slighted the obstinate technical and managerial problems that had to be surmounted before the happy outcome was reached.

Even in retrospect, the record of Titan II research and development flights was spotty, especially in view of the high promise that had induced NASA to choose it for Gemini in the first place. [170] Only 22 of the 32 flights that comprised the test program would have succeeded in launching a Gemini mission. Based on Titan II flight tests, in other words, every third or fourth Gemini mission would have been abortive; this does not include the Pogo that rattled missiles during first-stage flight without compromising Air Force test objectives. This picture was, nevertheless, far brighter than it had been in mid-1963 - half the 20 tests flown by 20 June would have been failures on Gemini. The concentration of all 10 unsuccessful flights in the earlier part of the program, however, may have held the greatest promise. The unbroken string of 12 nearly flawless flights that concluded the Titan II test program strongly implied that the missile's problems had, in fact, been solved. With Pogo reduced to tolerable levels by techniques that accorded with theoretical analysis, the threat of combustion instability eased by an operational expedient, and a series of successes to show that other troublesome areas had been cleared up, Titan II could be judged man-rated in the early spring of 1964. This judgment seemed amply confirmed by Gemini-Titan 1, launched 8 April 1964,* the day before the last flight in the missile's research and development test program and well before men were first scheduled to ride the Titan.11

The striking vindication of Titan II in the final months of 1963 had no parallel in the paraglider program. Paraglider's only chance to regain a place in Gemini hinged on the outcome of North American's new series of deployment flight tests with the full-scale vehicle. A full-scale wing was to be uncased and inflated in midair, to prove it could support the vehicle in stable gliding and maneuvering under radio control. Each of the planned 20 tests was to end with the wing cut loose at 3,000 meters and the test vehicle landing by parachute. The parachute system was qualified on 3 December 1963, clearing the way for flight testing of the full-scale vehicle to begin on 22 January 1964. The first test did nothing to dispel doubts about paraglider; the second test, on 18 February, was also a failure.12

That same day, George Mueller told the House Subcommittee on Manned Space Flight that the paraglider "is not presently scheduled on the . . . Gemini spacecraft."

"Will it be used at all in the Gemini program?" one of the Representatives wanted to know.

Mueller replied, "That will depend upon the development status of the paraglider which we will evaluate next spring. It will also depend upon the needs for a paraglider for precise landing of the Gemini spacecraft which we are developing now with the Air Force."

Further probing revealed that paraglider could be ready for the tenth Gemini mission, particularly if the Department of Defense lent [171] its support - this from George Low. But, he added, "we have no money included [in] 1965 or beyond for the paraglider under the assumption we will not go into production."13

NASA's public position was that, while land recovery appeared to be both desirable and feasible, it was riskier than water landing. Crew safety, the paramount concern, dictated the proven mode of safer landing for all 12 Gemini flights.14 The risks of land recovery were real enough, needless to say, but they had been just as real in 1961 when NASA decided to adopt land landing as a major Gemini objective. Toward the end of winter in early 1964, however, the means to that end, a paraglider landing system, had yet to achieve a level of performance great enough to rely on. After nearly three years of work, there was still no certain answer to the key paraglider problem - how to unship and inflate the wing from a two-tonne spacecraft plunging downward through the atmosphere. The risk that loomed so large early in 1964 was perhaps not so much land landing as paraglider landing.

Paraglider still had ardent defenders in NASA, and the decision to strike it from Gemini was not yet final.15 But NASA was ready to drop the paraglider, the more so since the system might still fly in another version of Gemini. In the spring of 1963, under the auspices of the Gemini Program Planning Board, the Air Force had begun laying the groundwork for its own Gemini program. Gemini B/Manned Orbital Laboratory (Gemini B/MOL). The Air Force X-20 orbital glider, still often called by its former name, Dyna-Soar, had been canceled in December 1963, a victim of low priorities and lagging development. Some X-20 funds were diverted to the new MOL program, which projected two men in a modified Gemini spacecraft launched by a Titan III. In orbit, the crew would transfer to a separately launched laboratory for two to four weeks, after which they would return in their spacecraft.16

Air Force planning had progressed far enough by January 1964 to require a formal agreement between NASA and the Air Force in the form of a memorandum signed by Seamans for NASA and Harold Brown for the Air Force.17 Although Gemini B/MOL would not be officially approved until August 1965 and design work was only beginning, NASA saw a chance to save paraglider. On 17 March 1964, George Mueller asked the Air Force for "an expression of the DOD interest in this capability," whether for Gemini B/MOL or any other program. Six weeks later, having concluded that paraglider development had too many problems to warrant putting it in the new program, the Air Force discounted any prospect of joining in paraglider development and threw the problem back to NASA: "Should the NASA qualify and demonstrate the paraglider in the NASA Gemini program, consideration would be given to its application to the Gemini B/MOL."18 By then, however, it was too late.

[172] North American's further efforts to fly the full-scale test vehicle produced a string of failures, each distinct in detail but united in a single root cause, "an inability to adequately predict the wing loads of flexible structure[s]." The fifth failure in a row, on 22 April, was the last straw. The next day, William Schneider, NASA Headquarters Gemini chief, informed George Mueller that he planned to transfer what was left of the paraglider program to Flight Research Center and to spend no more Gemini money. A week later, the program office in Houston began cutting back paraglider work and phasing the program out of Gemini. Early in May, GPO and North American agreed to run the rest of the flight-test program with the equipment and money already committed. Paraglider was dead as far as Gemini was concerned, although a public statement of its demise waited until 10 August.19

Ironically, North American achieved its first full-scale test vehicle success on 30 April, the day after phasing it out of Gemini began. In fact, the worst was over. Before the end of 1964, North American flew 19 more tests for a total of 25, 5 more than originally planned. By July, the deployment sequence was no longer giving much trouble, although a stable glide after the wing inflated was harder to manage. The last three flights, however, displayed the complete sequence without flaw.20

The last full-scale test vehicle flight was on 1 December 1964. Two days later, NASA told North American there would be no more money for flight testing, but equipment on hand might be used, if the company cared to spend its own money. North American seized the chance to complete the other major portion of the May 1963 program - working out landing techniques with a piloted tow-test vehicle. Tow-testing had begun during the summer. On 29 July, a helicopter had towed the vehicle up to a height of a few hundred meters, around the test area, and back to a safe landing. A free flight followed on 7 August, but the vehicle went into a series of uncontrolled turns, forcing the pilot to bail out. North American attacked the problem with dispatch and came up with an altered wing design. On 19 December, a pilot flew the tow-test vehicle through the complete test to a safe landing.21

NASA had long since decided to dispense with paraglider for Gemini, however, and that was irrevocable.** 22 [173] The system's shortcomings, or at least North American's slowness in coming up with answers, account chiefly for paraglider's failure to survive in Gemini. But the immediate reason for the abrupt action in the last week of April 1964 to kill what remained of the Gemini paraglider may have had more to do with money than with technology.

* This flight will be discussed in detail in Chapter IX.

** Paraglider's partisans in NASA had not lost faith, and the concept itself retained enough of its pristine attractiveness to justify a further effort. During the last half of 1965, North American conducted a research and development program under NASA contract to determine flight and landing characteristics in a series of 12 manned tests, plus a number of associated unmanned flights. More recently, both the Army and Air Force have been interested in developing the system as part of an unmanned cargo delivery system for combat situations.

3 MSC Weekly Activity Report for Office of the Dir., Manned Space Flight, 27 Oct. - 2 Nov. 1963, p. 2; memo, George E. Mueller to Adm., "Development of the Gemini Launch Vehicle," 6 Dec. 1965, with enclosure, "The Gemini Launch Vehicle Story," pp. 2-3; memo, David B. Pendley to Asst. Dir. for Flight Operations Dir. (FOD), "N-25 Titan II Piggyback Malfunction Detection System (MDS) flight," 7 Nov. 1963; memo, Pendley to Asst. Dir., FOD, "Titan II Malfunction Detection System (MDS) Piggyback Mission No. N-29," 19 Dec. 1963; TWX, Charles W. Mathews to NASA Hq. for Robert C. Seamans, Jr., GPO-52133-LV, 14 Nov. 1963; letters, Lt. Gen. Howell M. Estes, Jr., to Seamans, "Titan II/ Gemini Program Status Summary," 6 and 15 Nov. 1963; memo, Mathews to Carol Sweeney, "Questions submitted by House Committee Staff Members for Dec. 11 Visit to MSC," 17 Dec. 1963; letter, Bernhard A. Hohmann to James M. Grimwood, "Comments on the Draft of On the Shoulders of Titans[:] a History of Project Gemini," 30 May 1974, with enclosures; memo, Sheldon Rubin to Col. Richard C. Dineen, "Results of Analysis of N-25 Configuration on Aerospace Analog Model of POGO," Aerospace 63-1944- 51, 15 Oct.1963, and annotated pages of draft history.

4 Howard T. Harris, "Gemini Launch Vehicle Chronology, 1961-1966," AFSC Historical Publications Series 66-22-1, December 1966, p. 29; Weekly Activity Report, 8-14 Dec. 1963, p. 2; TWX, Mathews to NASA Hq., for Seamans, GPO-52187LV, 23 Dec. 1963; letters, Brig. Gen. W. E. Leonhard to Seamans, "Titan II/Gemini Program Status Summary," 19 Dec. 1963 and 27 Jan. 1964; Pendley memo, 19 Dec. 1963; Hohmann letter, 30 May 1974.

5 "Gemini Launch Vehicle Supplemental Specifications," NASA, Nov. 15, 1963; "Minutes of the Tenth Meeting, Gemini Program Planning Board [GPPB], Tuesday, December 3, 1963," p. 2; "Joint Titan II/Gemini Development Plan on Missile Oscillation Reduction and Engine Reliability and Improvement," [Air Force Systems Command], 5 April 1963 (revised 7 Aug. 1963); memo, Mueller to Assoc. Adm., "Memorandum of Understanding on Certain Design Requirements for the Gemini Launch Vehicle," M-C S 1370-860, 23 Nov. 1963; letter, Seamans to McMillan, M-C S 1370-821, 15 Nov. 1963.

6 "Minutes of the Tenth GPPB Meeting"; "Memorandum of Understanding on Certain Design Requirements for the Gemini Launch Vehicle," signed by Seamans and McMillan, 3 Dec. 1963.

7 "Minutes of the Eleventh Meeting, Gemini Program Planning Board, Monday, January 20, 1964"; Leonhard letter, 27 Jan. 1964.

8 Harris, "Launch Vehicle Chronology," p. 29; TWX, Mathews to SSD, Attn: Col. Richard C. Dineen, GP-54987, 24 Sept. 1964; TWX, Dineen to MSC, for Mathews, SSVLP 00009, 29 Sept. 1964; memo, Mueller to Assoc. Adm., "Status of Gemini Launch Vehicle Improvement Program," 4 March 1965; memo, Adm. W. Fred Boone to James E. Webb, "Manrating of Titan II - Applications to Titan III," 14 Oct. 1965, with enclosure, memo, Milton W. Rosen to Boone, "Gemini Launch Vehicle Man-rating," 8 Oct. 1965; letter, Mueller to Wernher von Braun, 29 Nov. 1963; Willis B. Mitchell, Jr., telephone interview, 1 Aug. 1974.

9 Letter, Lt. Col. John J. Anderson to Seamans, 21 Oct. 1963, with enclosure, "Statement of Work, Titan II Augmented Engine Improvement Program," 3 Oct. 1963; letter, Leonhard to NASA Hq. (Seamans), "Titan III Gemini Program Status Summary," 27 Sept. 1963; Harris, "Launch Vehicle Chronology," p. 30; Estes letter, 15 Nov. 1963; Mueller memo, 4 March 1965; Rosen memo, 8 Oct. 1965; "The Gemini Launch Vehicle Story," p. 3; Mathews TWX, GP-54987, 24 Sept.1964; Dineen TWX, SSVLP 00009, 29 Sept. 1964.

10 Mueller memo, 6 Dec. 1965.

11 Rosen memo, 8 Oct. 1965; "Titan II Flight Summary," MG 4-8015, in "Gemini Administrators Review, 1964" [November 1964].

12 Letter, George W. Jeffs to MSC, Attn: Robert L. Kline, "Contract NAS 9-1484, Paraglider Landing System Program, Monthly Progress Report No. 8 (December 1963)," 64MA632, 13 Jan. 1964, p. 2; letter, Harrison A. Storms, Jr., to MSC, Attn: Stephen D. Armstrong, "Contract NAS 9-1484, Paraglider Landing System Research and Development Program, Transmittal of the Final Fee Settlement Proposal," 65MA3479, 18 March 1965, with enclosure, "A Final Fee Settlement Proposal for Contract NAS 9-1484," 18 March 1965, p. V-113; "Final Report of Paraglider Research and Development Program, Contract NAS 9-1484," North American SID65-196, 19 Feb. 1965, p. 240.

13 1965 NASA Authorization, pp. 509-510; Heather David, "NASA Testifies That Rogallo Wing Is Probably Dead in Gemini Program," Missiles and Rockets, 24 Feb. 1964, p. 21.

14 Memo, John A. Edwards to Dep. Dir., Gemini Program, "Gemini Water Landings," 18 Feb. 1964; André J. Meyer, Jr., notes on GPO staff meeting, 20 Feb. 1964, p. 1; memo, Robert F. Freitag to dist., "MSF Position on Land Versus Water Landings - Apollo and Gemini," 5 March 1965.

15 Memo, Day to Dep. Dir., Gemini Program, "Future of the Paraglider," 3 March 1964, with enclosure, memo, Eldon W. Hall to Day, "Gemini Space Vehicle System Capability Using Paraglider Landing System," 27 Feb. 1964.

16 "Minutes of the Fourth Meeting, Gemini Program Planning Board, Tuesday, April 9, 1963," p. 2; Gen. Bernard A. Schriever and D. Brainerd Holmes, "Additional Guidance to Joint Ad Hoc Study Group, Air Force Participation in the Gemini Program," 12 April 1963; "DOD-NASA Ad Hoc Study Group, Air Force Participation in Gemini," Final Report, 6 May 1963, with errata; 1965 NASA Authorization, p. 508; U.S. Congress, Senate, Committee on Aeronautical and Space Sciences, NASA Authorization for Fiscal Year 1964: Hearings on S. 1245, 88th Cong., 1st sess., 1963, pp. 102729; Astronautics and Aeronautics, 1963: Chronology on Science, Technology, and Policy, NASA SP-4004 (Washington, 1964), pp. 473-74; John G. Norris, "Space Program Is Revised to Put Laboratory in Orbit," The Washington Post, 11 Dec. 1963; Jack Raymond, "Air Force to Loft Space Station in Place of Dyna- Soar Glider," The New York Times, 11 Dec. 1963.

17 Memo, Mueller to Assoc. Adm., "Discussion Paper for Meeting with Dr. H. Brown Regarding MOL," 13 Jan.1964; TWX, Seamans to MSC for Robert R. Gilruth, to Western Operations Office for Mueller, to Kennedy Space Center for Kurt H. Debus, 23 Jan. 1964; letter, Harold Brown to Seamans, 28 Jan. 1964, with enclosure, memo, Brown and Seamans for record, "Gemini and Gemini-B/MOL Program," 28 Jan. 1964; memo, Mueller to Adm., "NASA/Air Force discussions on Gemini B-MOL," 5 May 1964, with enclosure.

18 Letter, Mueller to Alexander H. Flax, 17 March 1964; letter, Maj. Gen. Ben I. Funk to Gilruth, "Evaluation of the Paraglider," 29 Nov. 1963; letter, Gilruth to Funk, GPO-01098-M, 26 Dec. 1963; letter, Flax to Mueller, 1 May 1964; letter, Schriever to Edward C. Welsh, "Gemini Paraglider for MOL," 13 July 1964; letter, Albert C. Hall to Welsh, 13 July 1964; John W. Finney, "Johnson Orders Building of Orbiting Laboratory for Defense Experiment," The New York Times, 26 Aug. 1965; Philip Dodd,"1 1/2 Billion Space Lab Okd," Chicago Tribune,26 Aug. 1965; "The Presidents News Conference of August 25, 1965," in Weekly Compilation of Presidential Documents, Monday, August 30, 1965, p. 142; Brown and Seamans memo, 28 Jan. 1964.

19 "Paraglider Final Report," pp. 240-57; memo, Schneider to Assoc. Adm., MSF, "Fifth Deployment Test of Gemini Paraglider," 23 April 1964; TWX, Mathews to North American, Attn: Jeffs, GP-54640, 26 March 1964; Meyer, notes on GPO staff meeting, 29 April 1964; "A Final Fee Settlement Proposal," Sect. III; Meyer, notes on GPO staff meeting, 7 May 1964; memo, Mathews to Armstrong, "Contract NAS 9-170, Paraglider Recovery System, CCP No. 5," GP-03697, 12 June 1964; letter, Schneider to Mathews, 26 June 1964; Jim Maloney, "Paraglider Is Dropped from Gemini Project," The Houston Post, 11 Aug. 1964.

20 "Paraglider Final Report," pp. 244-57.

21 MSC Consolidated Activity report for Office of the Assoc. Adm., 19 July - 22 Aug. 1964, p. 19; letter, Jeffs to MSC, Attn: Armstrong, "Contract NAS 9-1484, Paraglider Landing System Program, Monthly Progress Report No. 15 (July 1964)," 64MA10284, 7 Aug. 1964, p. 2; letter, Jeffs to MSC, Attn: Armstrong, "Contract NAS 9-1484, Paraglider Landing System Program, Monthly Progress Report No. 16 (August 1964)," 64MA11840, 16 Sept. 1964, p. 3; Harold Emigh, interview, Downey, Calif., 21 April 1966; "Paraglider Final Report," pp. 344, 349, 371-72; letter, Jeffs to MSC, Attn: Armstrong, "Contract NAS 9-1484, Paraglider Landing System Program, Monthly Progress Report No. 20 (December 1964)," 65MA853, 15 Jan. 1965.

22 TWX, Armstrong to North American, Attn: R. S. Maynard, MSC-1313, 2 Dec. 1964; letter, Ralph B. Oakley to James M. Grimwood, 14 June 1972, with enclosures, "Paraglider Landing System Test Program Final Report, Contract NAS 9-5206," North American, SID 65-1638, December 1965, and Richard B. Dimon, "Dry Land Recovery! Manned Test Flight of Space Divisions Paraglider System Proves Feasibility of New Technique," Skyline, XXIII, No. 2 (1965), pp. 43-47; Emigh interview; letter, Mathews to Maj. E. K. Hartenberger, "Use of Paraglider Wing in North American Aviation, Inc., Sponsored Development Program for Aerial Delivery of Cargo," GPO-03270-A, 28 Nov. 1963.

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