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HUGH LATIMER DRYDEN
1898-1965
BY JEROME C. HUNSAKER AND
ROBERT C. SEAMANS, OR.
H UGH LATIMER DRYDEN was born in Pocomoke City, Maryland,
on July 2, 189S, and died on December 2, 1965, after a lengthy
illness.
Hugh Dryden's father taught school and later kept a general
store. This business failed in the panic of 1907 and the family
moved to Baltimore, where the father became a street car con-
ductor, following this occupation for the rest of his life. Young
Hugh attended public schools and a high school, then called
Baltimore College, graduating in 1913 just short of age fifteen.
Entering Johns Hopkins University with advanced standing, he
completed a regular Bachelor of Arts curriculum in three years,
receiving his degree with honors in 1916 and his Master of
Arts degree in 1918.
It is of interest to observe that Dryden did not come from a
scholarly family. But he was endowed with the highest order of
intelligence; brought this gift to the realms of physics, engineering,
and Government service; and developed a vigorous philosophy
supported by strong Christian principles.
He married Mary Libbie Travers, on January 29, 1920, and their
three children were highly educated. The son, Hugh, fir., an
organic chemist, graduated from Johns Hopkins and the Mas-
sachusetts Institute of Technology. The elder daughter, Mary Ruth
Van Tuyl, graduated from Goucher College and is married to a
mathematician at the Naval Ordnance Laboratory. Daughter
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Nancy Travers graduated from American University and teaches
school in Montgomery County, Maryland. There are five grand-
children.
In June 1918, Hugh Dryden joined the staff of the National
Bureau of Standards as an inspector of munitions gauges, intend-
ing to return to graduate school on a fellowship in the fall.
However, because of World War I and with the encouragement of
Dr. Joseph S. Ames, Head of the Johns Hopkins Physics Depart-
ment and Chairman of the National Advisory Committee for
Aeronautics, his plans were changed. He obtained a transfer into
the Bureau's newly formed Wind Tunnel Section. After Dr. Ames
arranged to give courses to a number of Hopkins graduate stu-
dents at the Bureau, Dryden was able to complete his thesis work
on experiments carried on after hours in the wind tunnel. He was
granted the Ph.D. in physics in 1919, when he was just under
twenty-one, the youngest student ever to obtain a Ph.D. at Johns
Hopkins. His thesis, entitled "Air Forces on Circular Cylinders,"
addressed itself to the fundamental problem of scale effects on the
flow over circular cylinders normal to the wind. His results stimu-
lated some of the more sophisticated inquiries into the same subject
in the decade which followed.
In 1920, Dr. Dryden was placed in charge of the wind tunnels.
Here his research on the problems of wind tunnel turbulence and
boundary-layer flow brought him international recognition. He
and his colleagues were first interested in accurately measuring
turbulence in wind tunnels and in understanding its effects on
force measurements. They devised an electrical network that re-
stored the loss in amplitude and compensated for the lag. Extensive
tests were made of the intensity and scale of turbulence produced
by the wire screens at various distances from the working station.
Having means for varying the intensity and scale of the turbulence,
and for measuring these quantities with a compensated hot wire
anemometer, Dr. Dryden built wind tunnels of very low turbulence
and measured on models the effect of turbulence on aerodynamic
forces. The theoretical equations of laminar flow within a bound-
ary layer had been previously announced by Prandtl in 1907. Dr.
Dryden and his collaborators were able experimentally to verify
Prandtl's theories.
-
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In collaboration with Dr. Lyman J. Briggs, Dr. Dryden made
some of the earliest experimental measurements of the
aerodynamic characteristics of airfoils at high speeds. The early
motivation for this work had its origin in the effects of the high
propeller tip velocities that were being encountered with high-
powered engines. Dryden and Briggs carried out these investiga-
tions at a large compressor plant at the Edgewood Arsenal.
Through this work, they furnished the propeller designer with
airfoil data at high speeds and developed early insight into the
effects of compressibility on lift coefficient and pressure distribu-
tion. They were among the first to observe experimentally the
so-called transonic drag rise. Interest generated by this work led to
the construction of many high-speed wind tunnels and was of
pioneering significance when jet and rocket propulsion made
supersonic and hypersonic flight feasible.
Although Dr. Dryden's career at the Bureau of Standards is
characterized largely by his work in turbulence and boundary-
layer research, his inquiring mind led him to arable with other
. . i, . . . ~ ·, ,- .
~ 1 1 - - -
englneerlng problems wltn many ctliterent collaborators. His in-
vestigations of wind pressures on chimneys, mill buildings, and
skyscrapers laid the basis for rational design of structures sub-
jected to wind loads. His principal collaborator in this field was
G. C. Hill. The motivation for this work was undoubtedly the
strong concern during the early 1930's for the structural integrity
of propeller blades under increasing speeds and disc loadings.
A summary of Dr. Dryden's scientific and engineering research
would be incomplete without mention of his interest in the mea-
surement of the acceleration due to gravity. This work took place
during 1942 and 1943. This investigation, done in collaboration
with E. A. Eckhardt, W. D. Lambert, and A. H. Miller, undertook
to study the various determinations of the absolute value of the
acceleration due to gravity and to recommend a "best value." The
results indicated that only three determinations had been made
with sufficient attention to the elimination of systematic error to
. . . .
merit conslderatlon.
Dr. Dryden was responsible for extensive studies of the
aerodynamics of aircraft bombs and for the development of a
practical method of designing the tail fins to ensure aerodynamic
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stability. With E. I. Lorin, he standardized a form of bomb
geometry that remained in use for many years. His less-known
contributions ranged over aircraft noise, ventilating fans,
aerodynamic design of' aircraft control surfaces, automobile
streamlining, and aerodynamic cooling.
As time passed, Hugh Dryden's management responsibilities at
the Bureau ol' Standards grew, and he I'ound less time for his own
research. In 1934 he became Chief of' the Mechanics and Sound
Division. With the establishment of' the National Defense Research
Committee and later the O['l'ice ol' Scientific Research and De-
velopment in the early 1 940's, he became Chief' of a section
developing a guided glide bomb. This section, located at the
Bureau of Standards, was later expanded into the Navy Bureau ol'
Ordnance Experimental Unit, with a stalk of civilians from the
Bureau ol' Standards and the Massachusetts Institute ol'Technol-
ogy, as well as ot'l'icers and men of' the U.S. Navy. The radar
homing missile, BAT, which saw service in combat in the Pacific, was
designed by this team. The BAT missile destroyed many tons of'
Japanese shipping during the last year ol' the war. Fleet Air Wing
One, under Rear Admiral John D. Price, used the BAT el'l'ectively
against both ships and land targets. This was Dr. Dryden's first
taste ol' the management of' large orolects with which he would
have so much to do later.
(J 1 a
Hugh Dryden once described his wartime service:
I headed an r~nus~al group at the Bread <~t Ordnance Experimental Unit
which developecl the radar h`'ming missile, BAT. ~ also served as Deputy
Director `~l the Army Air F`'rce's Scientific Advisory Grip headed by v<'n
Karman The grip ``as appointed by General H H Arnold and many `~l
·~s revere in Europe fin V-E clay in ~~nit`'rm with simulated rank t<'st~dy the
rise `~f science by the diaries E~r`'pean Pantries T()~'ards Ned' Horizons,
the series `~! reports by the chin Karman grip pr`~`ecl invaluable in Ore
years
In September 1947, Dr. Dryden transferred from the National
Bureau of' Standards to become Director ol' Research of' the Na-
tional Advisory Committee I'or Aeronautics (NACA). In 1949, he
became Director Of NACA, its senior I'ull-time ol'l'icer. He directed
from Washington the activities of' the Langley, Lewis, and Ames
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laboratories and the flight research stations at Edwards Air Force
Base, California, and Wallops Island, Virginia. The magnitude of
this responsibility grew to embrace, during the last year of NACA'S
existence, 8,000 employees and an annual budget of about $100
million. Under his leadership, NACA produced a vast body of new
knowledge that made possible routine supersonic flight and laid
much of the technological groundwork for space flight that was to
come. We discern here, perhaps as much as in any other place, the
impact of Dryden's leadership. The development of high-speed
wind tunnels, flight testing, and a companion competence for
theoretical research within the NACA contributed substantially to
the leadership of the United States in supersonic flight.
In 1954, Dr. Dryden became the Chairman of the Air Force and
Navy and NACA Research Airplane Committee formed to guide the
development of an airplane to explore the problems of flight at the
highest speeds and altitudes then feasible. The series of experi-
mental aircraft, beginning with the X-1, X-2, X-3, D-558, and
culminating with the X-15, are well known. Some of these aircraft
were developed and tested prior to 1954; however, the hypersonic
research airplane, the X-15, drawing on the previous flight experi-
ence, was from its conception the concern of this Committee.
Before he died, Dr. Dryden saw the X-15 reach a maximum speed
in excess of 4,000 miles per hour and an altitude of nearly seventy
miles. It had been he who had carried the X-15 program through
the political labyrinth of Washington, where funds for basic re-
search and development were not plentiful. Much of this technol-
ogy of manned flight came to bear in Project Mercury.
It was during this period that Or. Dryden pressed for a solution
to the critical reentry heating problem. This solution, based on
knowledge accumulated in research, made it possible for the
United States to proceed with assurance in the development of its
ICBM program and manned satellites.
Hugh Oryden sustained a continuous interest in applied me-
chanics. He served as President of the International Union of
Theoretical and Applied Mechanics and as a Member of the
International Committee for the International Congress of
Applied Mechanics. He took an active role in the organization of
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the Sixth International Congress for Applied Mechanics in Paris in
1946 and again at the Seventh International Congress in Istanbul
in 1952. Together with von Karman, he was an editor of Applied
Mechanics Reviews.
The final period in Hugh Dryden's life commenced dramatically
in October 1957, with the launching of Sputnik I. The Executive
Branch and the Congress prepared immediately to establish a
civilian agency to conduct explorations of space for peaceful pur-
poses. With Dr. Dryden's help at critical moments, the NACA was
selected as the central building block of the new agency, and he
participated in the drafting of the legislation and its defense before
the Congress. On August 8, 1955, President Eisenhower appointed
Dr. Dryden as Deputy Administrator of the new agency, a position
he held under three Presidents until his death.
Project Mercury was conceived and organized with Hugh Dry-
den playing a major role. Later, he participated in the important
planning for Gemini and Apollo. His hand was prominent in the
studies and recommendations that led to the decision to mount a
lunar exploration mission. He was clearly committed to the Apollo
mission. This commitment was demonstrated in a notable letter
dated June 22, 1961, to the late Senator Robert S. Kerr, then
Chairman of the Senate Committee on Aeronautical and Space
Sciences. Dr. Dryden said in part:
The setting ol'the dit'l'icult goal of' landing a man on the moon and return
to Earth has the highly important role of' accelerating the development of'
space science and technology, motivating the scientists and engineers w ho
are engaged in this effort to move forward with urgency' and integrating
their el'l'orts in a way that cannot be accomplished by a disconnected series
of' research investigations in the several fields. It is important to realize,
however, that the real value and purposes are not in the mere ac-
complishment of' man setting foot on the moon, but rather in the great
cooperative national effort in the development of' science and technology
which is stimulated by this goal....
The national enterprise involved in the goal of' manned lunar landing
and return lecithin the decade is an activity with critical impact on the
future of' this nation as an industrial and military power, and as a leader of'
a free world.
Had Senator Kerr heard the Wilbur Wright Lecture of 1949, he
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would have perceived a remarkable thread of uniformity in Dr.
Dryden's approach to widely separated problems; a thread that
dominated his thinking and will most certainly dominate national
planning in science and technology for years to come.
A, ,
As Director of the National Advisory Committee for Aeronautics
for ten years, Dr. Dryden had great success in leading scientific and
engineering research into important technical applications. When
NACA was abolished in 1958 and the National Aeronautics and
Space Administration (NASA) was set up by the Congress in re-
sponse to Sputnik, Dr. Dryden was proposed by senior NACA
members to be the Administrator of the new agency. This recom-
mendation was seriously considered by the White House. How-
ever, his professional integrity may have antagonized members of
the House Select Space Committee when he objected to an un-
tested crash program to put a man on top of a missile in a sub-
orbital space flight for propaganda purposes. He said this would
have no more value "than shooting a woman out of a cannon at a
circus."
The first NASA Administrator, President T. Keith Glennan of
Case Institute, insisted that Dr. Dryden be Deputy Administrator
and overseer of all scientific and technical aspects of space re-
search.
Dr. Dryden felt a special responsibility for the 8,000 civil service
people of NACA who were to be taken over by NASA. These people
had been led, supported, chastised or promoted and, in many
instances, recruited by Dr. Dryden. Also he carried over to NASA a
most cordial and constructive relation with the military services,
Government regulating bodies, the universities, the air transport
and manufacturing industries, and professional societies and re-
search establishments. These were to prove invaluable to the U.S.
space program.
Dr. Dryden's public reputation permitted him to accept, in 1960,
the difficult task of providing for the United States an interim
"cover story" for the U-2 incident. The U-2 was a high-flying
airplane used for photographic weather observations but that
could be used for other reconnaissance. In providing the public
explanation that the U-2 shot down over the Soviet Union had been
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involved in scientific exploration, Dr. Dryden placed the impor-
tance of affording to the United States a short respite in which to
organize its policy response to this new development above the
opinions of his personal integrity that might later result from the
inevitable disclosure of the U-2's real mission.
Dr. Dryden's leadership capability itself was questioned in the
report to President-Elect John F. Kennedy, dated January 12,
1961, by an ad hoc Advisory Committee on Space headed by Dr.
Jerome Wiesner. This Committee found "a number of organiza-
tional and management deficiencies as well as problems of staffing
and direction which should receive prompt attention. These in-
clude serious problems within NASA, within the military establish-
ment, and at the executive and other policy-making levels of
government."
The Wiesner Committee recommended for NASA several "re-
quirements that must be met." These were, in fact, outstanding
features of Dr. Dryden's leadership. As Home Secretary, Dr. Dry-
den had close relations with the National Academy of Sciences and
in particular with the Space Science Board that was established
within the Academy to advise and assist NASA. "Exert the greatest
wisdom and foresight in the selection of scientific missions and of
the scientists assigned." This was one of Hugh Dryden's main
concerns within the policy and budget limitations of the President
and Congress as the new NASA program gained direction and
momentum.
The Wiesner Committee's report to President Kennedy, released
to the press, did Dr. Dryden no harm. Probably it helped clear the
air by requiring the new Administration to assess fully the space
effort under way. When lames E. Webb was asked by the White
House to be the second NASA Administrator, he accepted upon the
condition that Hugh Dryden remain as Deputy Administrator.
Dr. Dryden had a leading role in the sphere of international
cooperation. In 1959, he was appointed to assist Ambassador
Henry Cabot Lodge at the first meeting of the United Nations
Committee on the Peaceful Uses of Outer Space. His activities were
largely responsible for a proposal by NASA in December of that
year, for joint research with other nations to promote international
space cooperation.
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Working toward international cooperation and peace fitted with
Dr. Dryden's philosophy. A man of sincere religious faith, he was a
licensed preacher for the Calvary Methodist Church in Washington
during most of his adult life. He had found the bridge between
science and religion.
Hugh Dryden lived under a sentence of death after October
1961, when exploratory surgery had disclosed a serious malig-
nancy. Yet he continued on duty with frequent hospital treatments.
He conceded little to the illness that marked the last years of his
life.
In the last month of his life, he delivered the Thurston Lecture
before the American Society of Mechanical Engineers. He pointed
out that men were engineers for thousands of years before the
basic concepts of science were known. Engineers now follow the
scientists' step-by-step approach to develop the technology from
which real benefits arise. But Dryden had a keen sense of social
responsibility in planning engineering programs. He made the
difficult choice among the many possibilities available to change the
state of the art. In his Thurston Lecture he explained that the space
program was already having an impact on engineering from new
requirements in weight, size, performance, and reliability under
extreme environmental conditions.
President Lyndon B. Johnson expressed the esteem of the Na-
tion for Hugh Dryden when he said:
No soldier ever performed his duty with more bravery and no statesman
ever charted new courses with more dedication than Hugh Dryden.
Whenever the first American space man sets foot on the moon or finds a
new trail to a new star, he will know that Hugh Dryden was one of those
who gave him knowledge and illumination.
After Dr. Dryden's transfer to the NACA in 1947, he assumed
leadership in the fundamental research effort in the field in which
he had made basic contributions twenty-five years before. It is fair
to state that Dryden's 1920 work on supersonic aerodynamics led
consistently to operational supersonic airplanes, the famous
rocket-propelled X-15, and successful manned space flight. On
February 10, 1966, the President of the United States presented to
Mrs. Dryden the National Medal of Science awarded posthumously
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to Dr. Dryden: "For contributions, as an engineer, administrator,
and civil servant for ore-half' century, to aeronautics and astronau-
tics which have immeasurably supported the Nation's preeminence
in space."
Man's steps in the advance ot' the art ol' flight are marked by the
names ol' many researchers, designers, and flyers, but Hugh Dry-
den's name is rarely mentioned.
Hugh L. Dryden's life was given to helping good men get good
results.
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Representative terms from entire chapter:
applied mechanics
