SP-4302 Adventures in Research: A History of Ames Research Center 1940-1965

 

Part I : INITIATIONS : 1936-1945

 

13

 

The 40-by-80 Begins Operations

 

[103] RESEARCH in the 40- by 80-foot tunnel did not get under way until mid-1944. Harry Goett was put in charge of the facility and in September was replaced as head of the 7-by-10's by Charles Frick. In the years that followed Frick proved to be an aggressive, competent leader, a man continuously on the move, whose furious pipe-smoking practices, incidentally, threatened to burn the place down. Brilliant himself, Frick would exhibit sharp impatience when confronted with obtuseness, or laggardly action, on the part of any member of his staff-a group which therefore remained very alert.

Goett took with him to his new assignment in the 40-by-80 a number of men from his former staff in the 7-by-10's. Victor Stevens, William Harper, and Bradford Wick went with him, and to this group of former comrades were added J. S. W. (Sam) Davidsen, Gerald McCormack, and a number of others including Dean Chapman, a new man who had been doing graduate work at Caltech. Goett thus started out with a very able team and men who worked for him had a way of developing.

The 40- by 80-Foot Wind Tunnel and the Flight Research Sections comprised the Full-Scale and Flight Research Division, which was under the command of Parsons, who also headed up the Construction Division. The 40-by-80 operation and flight research proved to be an extremely compatible and significant combination of activities; indeed, they were complementary as well as compatible. The 40-by-80 had the unique ability to test a full-scale, actual airplane with engines running, even with a "pilot" in the cockpit, and thus the results obtained from it could easily be confirmed by flight tests of the same airplane. And yet while the forces and operation of the airplane could more easily be checked and measured in the wind tunnel, the dynamic handling qualities of the airplane, as appreciated by the pilot, could only be determined in flight.

In wind-tunnel work there were many advantages in testing actual airplanes rather than models. For one thing, it took time to build a model, whereas an airplane with a problem could be installed in the 40-by-80 and....

 


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104]

Charles W. Frick.

Charles W. Frick.

 

....checked out very quickly. Moreover, no model could be built which in external configuration represented the airplane as perfectly as the airplane represented itself. On the other hand, of course, the speed of a tunnel the size of the 40-by-80 was limited by practical considerations and was much lower than could be achieved in smaller tunnels. The conditions it could best simulate were thus the lower half of the speed range, including landing, takeoff, and climb. Problems in this speed range were becoming increasingly critical as airplane designers attempted to hold takeoff and landing speeds as low as possible while boosting the top speed ever higher. With these strengths and weaknesses the 40-by-80 was a natural and very effective partner of the other facilities at Ames. It was, nevertheless, better adapted to development work than to fundamental research.

The first research project undertaken in the 40-by-80 was a series of tests, begun about August 10, 1944, on an 8- by 48-foot wing having Clark Y sections. It was something of a calibration test.

The first airplane development test program to be undertaken in the 40-by-80 was a series of tests on the Douglas El Segundo XSB2D-1, later designated BTD-1, airplane. Models of this airplane, a rather ambitious design, had earlier been tested in the 7- by 10-foot and the 16-foot tunnels, and the prototype soon was to be tested by Flight Research. The Ames Laboratory probably spent more time on the BTD-1 than on any other single airplane. Soon afterward, the Navy lost interest in the BTD-1 and it was never put into quantity production. It was immediately followed, however, by a series of simple but very successful fighter-bomber naval aircraft which did much credit to Ed Heinemann and his design staff at Douglas El Segundo.

Following the BTD-1 program, which was organized and reported by Sam Davidsen and N. J. Martin, tests were undertaken in the 40-by-80 of a number of airplanes, including the Northrop N9M-2 flying-wing prototype, [105] the Grumman XF7F-1, the Ryan XFR-1, the General Motors P-75A, and the Douglas El Segundo A-26B. Also, under the supervision of Brad Wick and Adrian Anderson, the first 40-by-80 research programs on propellers were run.

The case of the XFR-1 illustrates the value of the wartime development activities in the 40-by-80. The XFR-1 was a promising new type of Navy fighter airplane which, as earlier described, had a composite powerplant consisting of a conventional Wright 1820 reciprocating engine and propeller in front and a General Electric I-16 jet engine enclosed in the fuselage behind the pilot. The jet engine inducted air through leading-edge inlets in the wing roots and its exhaust was ejected through the tail of the fuselage. The Navy's flight tests of the airplane at Patuxent River had shown it to be seriously lacking in certain stability and control characteristics, particularly in the carrier-approach condition. These deficiencies were so serious that the airplane, in its existing form, was unacceptable to the Navy. The assistance of NACA in correcting the faults of the airplane was requested.

First of all, the XFR-1 was flown by the Ames Flight Research Section to confirm and quantitatively evaluate its reported deficiencies. It was then put in the 40-by-80. Within a few weeks a 40-by-80 research team headed by Victor Stevens and Donald Jacoby had discovered a number of fairly simple modifications which largely eliminated the deficiencies and enabled the airplane to satisfy Navy flight requirements. The proposed modifications, though individually fairly simple, were quite extensive and involved a new rudder, new ailerons, revised elevator trim tab, revised wing flaps, revised elevator control system, and revised wing dihedral. Each change was later checked, and its usefulness evaluated, in flight by the Ames Flight Research Section. The Ryan management expressed its gratitude to DeFrance for the major contribution Ames made to the success of the airplane.1

The XFR-1 example illustrates not only the extraordinary usefulness of the 40-by-80 but also its rather unique complementarily with Ames Flight Research. Nor was the case of the XFR-1 unusual. There was also, for example, the case of the Douglas A-26B, the mission of which was changed, after the plane was built, to include low-level strafing. But low-level strafing required a lightness of controls which the airplane did not have. A 40-by-80 research team headed by Gerald McCormack investigated the problem and found a solution. Here again there was coordination of effort between the 40-by-80 and Flight Research.

The 40-by-80 had been in use only a year when the war ended, yet by that time the tunnel had demonstrated that NACA had made no mistake in building it.


1 Letter, T. Claude Ryan, President, Ryan Aeronautical Co., to Dr. G. W. Lewis, Director Aeronautical Research, NACA, June 29, 1944.


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