[551] The NACA produced six series of reports that were "published" in the commonly accepted sense of that term: i.e., issued to the public. Very often the public to which the reports were issued was a limited one-selected members of the military services or the American aircraft industry-but the reports were nevertheless public in the sense of being available to anyone with a demonstrable need to know the information they contained.

Heading, the hierarchy was the Technical Report (TR), later called simply the NACA Report. TRs were the most prestigious, the most polished, the most important, and the most widely distributed of all NACA reports. Printed by the Government Printing Office, bound each year with the Committee's Annual Report to Congress, and distributed by subscription to a mailing list of laboratories, libraries, factories, and military installations around the world, the TR was the rock to which the NACA anchored its reputation.

Considered by the Committee to be "lasting contributions to the body of aeronautical knowledge,"¹ the NACA Reports generally announced the final results of a research project. Thus they were usually the last of a series of reports, consolidating and summarizing information disseminated in earlier interim reports. The distinguishing mark of the TRs was the thoroughness with which they treated the entire topic, and with which they were edited and checked for content and style. The rarity of mistakes in an NACA report was a quality that aeronautical engineers around the world came to rely upon and value.

Recognizing a need to publicize research that might be incomplete or of insufficient significance to warrant a Technical Report, the NACA instituted in 1920 a second series called Technical Notes (TN). Reproduced within the NACA and distributed to addressees in the aeronautical and related industries, contractors, leading universities, and the larger public libraries, these documents reported on significant portions of NACA research projects, on research sponsored by the NACA in colleges and universities, and on preliminary theoretical work done by the NACA. Often the information in one or more Technical Notes would be combined, analyzed, and refined, and then republished as a Technical Report.

Over the years, the TN came to replace the TR as the most used and most significant NACA report. After World War II, no TRs were actually prepared as Reports. Rather, each year's production of TNs was evaluated annually by a committee at headquarters and those considered most worthy were republished as TRs.

Less formal still than the TN was the Research Memorandum (RM), introduced in 1946 to meet the need for rapid dissemination of defense-related aeronautical information. Reproduced within the NACA and generally restricted by military-security classification, Research Memorandums normally dealt with fragments of research projects. They might advance unproven theories for discussion, or report on a specific piece of military hardware, or present data that had not yet been completely analyzed. Their main function was to disperse information quickly, so the editing, illustrating, and printing were greatly expedited. In the NACA's later years, a Technical Report might take a year or two between first draft and final publication, whereas the Research Memorandum would take only a matter of weeks.

[552] The Research Memorandum replaced six series of reports instituted by the NACA before and during World War II to meet the needs of the services and industry for aeronautical information related to the war effort. All these reports were classified and received only limited circulation. All were designed for rapid dissemination of information.

A fourth type, advance reports, presented results that before the war would have been issued as Technical Notes or Technical Reports. Advance Confidential Reports (ACR) dealt with guarded subjects such as low-drag wings, late-compressibility wings, and jet propulsion; with general investigations of specific military airplanes; or with projects designated confidential by the army or navy. They were sent by registered mail and had to be kept in locked files when not in use. Normally they were issued to the subcommittees concerned, the NACA's laboratories, and the army and navy, as well as representatives of the aeronautical industry who had signed secrecy agreements with the services and were known to have a need for the information.² Advance Restricted Reports (ARR) contained results of other investigations having general engineering applications. Distribution was determined in the same way as for ACRs, but secrecy requirements were less severe to permit wider usage among those having a legitimate interest in the information.

Bulletins were short progress reports (usually from one to six pages) on limited phases of long investigations or on results of very brief investigations. Confidential Bulletins (CB) and Restricted Bulletins (RB) dealt with subjects appropriate to ARRs. Bulletins were distributed in the same way as advance reports.

Memorandum Reports (MR), a sixth type, prepared chiefly for the information of one or both of the military services (or occasionally for one particular subcommittee), contained subject matter not of general application but of interest to a limited number of readers, generally on a specific airplane or engine design.³ Classified versions of these reports were called Confidential Memorandum Reports (CMR) or Restricted Memorandum Reports (RMR).

After World War II, the NACA reviewed its wartime papers and declassified for publication those of continuing interest and significance. Some few were upgraded to RMs, TNs, or even TRs; most were published in a unique series called Wartime Reports (WR) that appeared between 1946 and 1948 and made available to the NACA's clients all the wartime research not still classified.

The NACA published two other series of papers, neither of which reported original research sponsored or conducted by the Committee. Technical Memorandums (TM) reprinted reports and articles from other research laboratories which the Committee felt should have wider dissemination than they had received in their original form. These were often translations of foreign-language reports otherwise unavailable to the American aeronautical community. Finally, between 1926 and 1937, the NACA published a series called Aircraft Circulars (AC). These were reprints, mostly of published articles, containing descriptions and specifications of individual aircraft. These two were often from foreign sources, bringing to the attention of Americans the latest designs from Europe and elsewhere.

The only other significant series was the Contract Reports (CR). These were apparently intended for internal NACA use when work done under contract to the NACA by an outside organization or individual was not deemed suitable for wider publication.

The library at the Langley Research Center holds index cards on a handful of other NACA reports: RIs, CCRs, CIs, and MRRs. These appear negligible, as do the few miscellaneous letters and memoranda that served from time to time as reports.

Table G-1 explains the system used by the NACA to designate its reports.

Series	Symbol	Consecutive?	Based on Source?**	Based on year/ month/day of issue?	Example
.
Reports	None	Yes	No	No	Report 1004: 1004th Report Issued
Technical Notes	TN	Yes	No	No	TN-2432: 2432nd Technical Note issued
Technical Memorandums	TM	Yes	No	No	TM-1313: Technical Memorandum issued
Wartime Reports	WR	Yes	Yes	No	WR A-6: 6th Wartime Report based on Ames research; reported earlier to a limited audience and reprinted
Aircraft Circulars	AC	Yes	No	No	AC 150th: Aircraft Circular Issued
Research Memorandums	RM	No	Yes	Yes	RM-1.9K03a: Research Memorandum written by Langley personnel in 1949 and issued November 3, being the second
Advance Confidential Reports	ACR	No	Yes, after March1944	Yes, after April l943*	ACR-E4D19: Advance Confidential Report written by Lewis personnel in 1944 and issued April 19
Advance Restricted Reports	ARR	No	Yes, after March1944	Yes, after April, 1943*	ARR-L4K22b: Advance Restricted Report written by Langley personnel in 1944 and issued November 22, being the third ARR issued on that date
Confidential Bulletins	CB	No	Yes, after April, 1944*	Yes, after March1944*	CB-E5J11: Confidential Bulletin written by Lewis personnel in 1945 and issued October 11
Restricted Bulletins	RB	No	Yes, after March1944	Yes, after April, 1943*	RB-E6D22: Restricted Bulletin written by Lewis personnel in 1946 and issued April 22
Memorandum Reports	MR	No	Yes, after October, 1944*.	Yes, after October, 1944*.	MR-A4L12: Memorandum Report written by Ames per-sonnel in 1944 and issued December 12

*Symbol and date only, prior to date mentioned

**A, Ames; E, Lewis; L, Langley

#5: 1945; 50: 1950; 6: 1946; 51: 1951; 7: 1947; 52: 1952; 8: 1948; 53: 1953; 9: 1949; 54: 1959; 55: 1955; 56: 1956; 57: 1957; 58:1958.

##A, January; B, February; C, March; D, April; E, May; F, June; G, July; H, August; 1, September; J, October; K, November; L, December.

###0l; 02; 03 . . . etc. to 31. followed by a, 2nd document issued that date, b, 3rd document issued that date.

[555] In the NACA's early years before the Langley laboratory was in full operation, most of its reports were prepared outside the Committee, usually by academics under contract to the NACA. From the 1920s on, most NACA reports were prepared by the Committee's staff, the major exception being those prepared under contract for the Committee throughout its history by the National Bureau of Standards. Unsolicited reports contributed from outside the NACA received consideration for publication, but most were rejected as being incorrect, trivial, inappropriate for the NACA, or not new.⁴

Lee M. Griffith set out the criteria for an ideal NACA report in a 4 September 1918 letter to the Executive Committee (see Appendix H). He recommended that all NACA reports have clear applications, logical discussion, concise summation, a description of the research equipment employed, and a standard style. George Lewis objected to including the description of apparatus, and not until the Committee's last ten years did much information of this type appear in the reports. Griffith's other recommendations were followed more or less consistently throughout the NACA's history.

A characteristic feature of NACA reports is the thoroughness with which they were reviewed and edited, a process that made the final reports late and reliable. In 1922, reports forwarded to headquarters from Langley were reviewed by one or two critics, presented with comments to the Publications Committee, prepared for publication, presented to the appropriate technical subcommittee, and presented at last to the Executive Committee. Only when the report had been approved at each of these stages was it cleared for publication.⁵

Although the procedure was streamlined in later years, by then the review and editing by the staff at the laboratories and at headquarters had grown more complicated. An excerpt from the NACA "Style Manual for Engineering Authors" (as amended in 1932) shows how cautious and time-consuming the review process could be.

The decision concerning the type (technical report or technical note) of the final paper to be presented is usually made when the job order is authorized. The outline should carry this information. When the copies of the rough draft are forwarded to Washington the letter of transmittal carries the recommendation of the division chief about its form and only in exceptional cases is the recommendation not adopted.

Revision of outline:

The outline is then submitted to the section head and the division chief for approval.

Preparation of the rough draft:

From the revised outline the author prepares the first draft of the paper. If the draft is well arranged and carefully written, the final report should not differ essentially from it. The author should have the report in the exact form in which he desires to have it printed before he presents it to the section head.

Revision of the rough draft:

The section head reads the rough draft and returns it to the author with his comments. The paper is revised until it is satisfactory to both the section head and the author. Five copies of the paper are then typed.

Criticism by division chief:

The section head then forwards one copy of the typed report to the division chief, who may note his corrections directly on the paper (author's copy).

Editing for English:

The report is sent to the English critic for correction of grammatical and typographical errors, and for noting haziness of composition and faulty arrangement of topics.

Correction by the author:

The author, after conferring about debatable points, incorporates the changes proposed by the division chief and the English critic. He forwards to the stenographic section the final corrected copy of the text and five copies of all illustrative material.

[556] Typing:

The stenographic section corrects the remaining four copies by the author's copy, binds all copies with a set of illustrations, and forwards them to the division chief.

Editing for technical context:

The division chief appoints an editorial committee of five, including the author, from the technical staff and forwards to each member a copy of the report with Form L.F. 103. The group meets under the guidance of a chairman and suggests necessary changes in the interest of technical clarity and soundness.

Final revision:

The author corrects his copy lightly and legibly in pencil. He forwards it to the section head, the chairman of the editorial committee, and the division chief for approval. He then returns to the stenographic section the corrected copy, the four uncorrected copies, and the originals of the curves and sketches in their final form. From the corrected author's copy of a report a stencil is cut and twelve copies mimeographed. The stenographic section obtains from the photographic section any extra photographs and from the drafting room the extra blueprints. The copies are then bound.

Transmittal to Washington:

Two copies are retained at the laboratory, one for the section files and one for the office files. For a technical report, ten copies are sent to Washington; for a technical note, three copies. In Washington a technical report goes through the following stages:

 

a. It is read by one or more critics.

b. It is presented to the Publications Committee.

c. The drawings are prepared for the printer.

d. Its publication is authorized by the Executive Committee.

e. A copy is marked for the printer.

In later years, the review at headquarters could be even more severe. In 1950, for example, staff members at headquarters were "required to check all references and correct the citations before the report is approved for release."⁶

The accuracy and reliability of NACA reports were among their chief virtues, their tardiness in appearing their principal flaw. The tardiness was compounded by the Committee's policy of allowing no publication of research results before they appeared first in a NACA report. Among criticisms of NACA reports over the years included the Committee's reluctance to publish negative results, a tendency to report direct research results without adequate analysis or conclusions, and, oppositely, a tendency to publish faired curves without the data points on which they were based.⁷ These criticisms notwithstanding, NACA reports enjoyed a high reputation in aeronautical circles and were much sought after. Many are still being used.

During its 43 years, the NACA produced more than 16,000 reports, averaging slightly more than one a day. Tables G-2 and G-3 show the numbers of reports in each category.

The expected interest in, and clearance to see, each of the Committee's reports dictated how many copies were printed. Thousands of copies of Technical Reports were printed and distributed around the world. In contrast, the Committee made only 10 copies of each Confidential Memorandum Report and Restricted Memorandum Report and these were distributed only within the NACA and the armed services.

Like the Committee itself, the NACA reports were intended to advance American aeronautics. As George Lewis advised John J. Ide in 1929, "Technical Notes, Technical Memorandums, and Aircraft Circulars of the Committee [were] issued only for the information of American manufacturers and aeronautical engineers."⁸

Any automatic distribution overseas of these reports was intended as a courtesy extended to friends and allies in expectation of receiving similar information in return. For example, the Committee regularly sent its reports to the British Aeronautical Research Committee, whose reports were received by the NACA in return. Furthermore, Ide normally got a modest number of reports to distribute at his discretion where he thought they would elicit valuable information in return. None of this, of course, prevented foreign governments from seeing and copying these reports in aeronautical libraries across the United States and in select locations around the world. It merely denied them the free receipt of the reports enjoyed by American firms and engineers, either through automatic distribution or on request.

The total number of copies of reports distributed each year increased rapidly in the years before World War II. In 1923, for example, the NACA sent out 36,870 reports, whereas in 1930 it distributed 112,010. World War II, however, put the Committee's reports under two new restrictions which prevailed for the rest of its years. First, the NACA increased its stock of proprietary information as it did more and [558] more cleanup and refinement of prototype aircraft and engines. Publication of the results of this work would amount to giving away trade secrets. The NACA therefore had to limit distribution of such reports to the armed services and to the manufacturer of origin. After World War II, the NACA tried to return to fundamental research whose results would apply to all aeronautics, but it never entirely freed itself from involvement with proprietary information.

World War II also brought the NACA into increased contact with classified information. Here the Committee deferred almost entirely to the military services: NACA reports on military aircraft and equipment were classified and distributed according to military criteria. During the war, the services themselves distributed NACA Confidential Memorandum Reports and Restricted Memorandum Reports; all others were distributed by the NACA according to military guidelines. If anything, it appears that the Committee was even more restrictive than the services in classifying and distributing its reports. For example, until May of 1941, the Committee made all its advance reports confidential, when the less severe restricted classification would have sufficed for many. When industry complained, the NACA created the separate series Advance Confidential Reports and Advance Restricted Reports.⁹

After World War II, the NACA tried to declassify and publish the results of its wartime research in the Wartime Reports series. Some of this information, however, remained classified for many years after the war, and new research by the Committee was also classified or proprietary. Some TNs and RMs published after World War II were classified; some were not. Distribution depended on content and was determined case by case. The Committee began a regular program of declassifying and redistributing its reports.

Table G-4 shows distribution of NACA reports during the years for which information is available. (Figures for the blank years no doubt exist somewhere in the NACA files, but they did not appear in the course of research for this study and they defied repeated attempts to ferret them out.) Note the cutback brought on by the Depression, the great increase during World War II, the precipitous decline in the NACA's later years, and the shifting ratio of reports distributed automatically to those distributed by request.

[560] In 1950 the NACA published an Index of NACA Technical Publications, 1915-1949, which was supplemented in 1951, 1953, and annually thereafter through 1960. Each supplemental volume listed the unclassified NACA technical reports issued since the last index and any reports from previous years declassified during the interval. Taken together, the indexes constitute a guide to all NACA technical reports except for those not declassified until after 1960.

Table G-5 lists subject headings in the 1957 Index. Except for category "1.4 Internal Aerodynamics," it was identical to the classification system used for all the other indexes. Table G-6 provides the conversion scheme for correlating 1.4 in the 1915-1949 index with that category in subsequent volumes. Some other subjects were added in later years, but the numbering did not change.

All NACA reports were categorized under one or more of the subject headings. The multiple listing makes it difficult to get from these indexes a total count of NACA reports, which numbered approximately 16,000 over the years; the indexes contain more than 40,000 entries, meaning that each report was indexed under an average of 2.5 different headings.

In spite of this multiple listing, the indexes allow the researcher to draw a few conclusions. Some subjects, for example, have hardly any entries: only 3 for diameter as a design variable of the aerodynamics of propellers (1.5.2.10)-all of these in the late 1940s-and only 1 entry each for control of pulse-jet engines (3.2.5) and for standard atmosphere (6.1.1). In contrast, there are 346 entries for turbojet engines (3.1.3), 960 for mach-number effects (1.2.2.6), and 1009 for longitudinal static stability (1.8.1.1.1).¹⁰

Clearly there were great differences in the amount of work the NACA did in the various branches of aeronautics. Table G-5 suggests how numerous and complex those fields were. Table G-7 shows the distribution of the NACA's reports-and, by inference, of its research-among the twelve principal subject areas. The figures are percentages of the total number of entries in the indexes, both for the entire history of the Committee and for each year. Aerodynamics, which accounted for 59 percent of all entries in the indexes, accounted for 17 percent of the 1916 entries and 68 percent of the 1949 entries. Figures for individual years reflect the year in which a report was first published.

Number	Subject-Heading	Number	Subject-Heading
.
1	AERODYNAMICS	1.2.2.2.7	Dihedral
1.1	Fundamental Aerodynamics	1.2.2.3	High-Lift Devices
1.1.1	Incompressible Flow	1.2.2.3.1	Trailing-Edge Flaps
1.1.2	Compressible Flow	1.2.2.3.2	Slots and Slats
1.1.2.1	Subsonic Flow	1.2.2.3.3	Leading-Edge Flaps
1.1.2.2	Mixed Flow	1.2.2.4	Controls
1.1.2.3	Supersonic Flow	1.2.2.4.1	Flap Type
1.1.3	Viscous Flow	1.2.2.4.2	Spoilers
1.1.3.1	Laminar Flow	1.2.2.4.3	All-Movable
1.1.3.2	Turbulent Flow	1.2.2.5	Reynolds-Number Effects
1.1.3.3	Jet Mixing	1.2.2.6	Mach-Number Effects
1.1.4	Aerodynamics with Heat	1.2.2.7	Wake
1.1.4.1	Heating	1.2.2.8	Boundary Layer
1.1.4.2	Heat Transfer	1.2.2.8.1	Characteristics
1.1.4.3	Additions of Heat	1.2.2.8.2	Control
1.1.5	Flow of Rarefied Gases	1.3	Bodies
1.1.5.1	Slip Flow	1.3.1	Theory
1.1.5.2	Free Molecule Flow	1.3.2	Shape Variables
1.1.6	Time-Dependent Flow	1.3.2.1	Fineness Ratio
1.2	wings	1.3.2.2	Cross Section
1.2.1	Wing Sections	1.3.2.3	Thickness Distribution
1.2.1.1	Section Theory	1.3.2.4	Surface Conditions
1.2.1.2	Section Variables	1.3.2.5	Protuberances
1.2.1.2.1	Camber	1.3.3	Canopies
1.2.1.2.2	Thickness	1.3.4	Ducted Bodies
1.2.1.2.3	Thickness Distribution	1.3.4.1	Nose Shape
1.2.1.2.4	Inlets and Exits	1.3.4.2	Tail Shape
1.2.1.2.5	Surface Conditions	1.3.4.3	Side Inlets
1.2.1.3	Designated Profiles	1.3.4.4	Side Exits
1.2.1.4	High-Lift Devices	1.3.5	Hulls
1.2.1.4.1	Plain Flaps	1.4	Internal Aerodynamics
1.2.1.4.2	Split Flaps	1.4.1	Air Inlets
1.2.1.4.3	Slotted Flaps	1.4.1.1	Nose, Central
1.2.1.4.4	Leading-Edge Flaps	1.4.1.1.1	Propeller-Spinner-Cowl Combinations
1.2.1.4.5	Slots and Slats
1.2.1.5	Controls	1.4.1.1.2	Subsonic
1.2.1.5.1	Flap Type	1.4.1.1.3	Supersonic
1.2.1.5.2	Spoilers	1.4.1.2	Nose, Annular
1.2.1.6	Boundary Layer	1.4.1.3	Wing Leading Edge
1.2.1.6.1	Characteristics	1.4.1.4	Side
1.2.1.6.2	Control	1.4.1.4.1	Scoops
1.2.1.7	Reynolds-Number Effects	1.4.1.4.2	Submerged
1.2.1.8	Mach-Number Effects	1.4.2	Ducts
1.2.1.9	Wake	1.4.2.1	Diffusers
1.2.2	Complete Wings	1.4.2.1.1	Subsonic
1.2.2.1	Wing Theory	1.4.2.1.2	Supersonic
1.2.2.2	Wing Variables	1.4.2.2	Nozzles
1.2.2.2.1	Profiles	1.4.2.3	Pipes

1.2.2.2.2	Aspect Ratio	1.4.2.4	Bends
1.2.2.2.3	Sweep	1.4.3	Exits
1.2.2.2.4	Taper and Twist	1.4.4	Jet Pumps and Thrust Augmentors
1.2.2.2.5	Inlets and Exits
1.2.2.2.6	Surface Conditions	1.4.5	Cascades
1.4.5.1	Theory	1.7.5	Airships
1.4.5.2	Experiment	1.7.6	Biplanes and Triplanes
1.4.6	Fans	1.8	Stability and Control
1.4.7	Boundary Layer	1.8.1	Stability
1.4.7.1	Characteristics	1.8.1.1	Static
1.4.7.2	Control	1.8.1.1.1	Longitudinal
1.5	Propellers	1.8.1.1.2	Lateral
1.5.1	Theory	1.8.1.1.3	Directional
1.5.2	Design Variables	1.8.1.2	Dynamic
1.5.2.1	Blade Sections	1.8.1.2.1	Longitudinal
1.5.2.2	Solidity	1.8.1.2.2	Lateral and Directional
1.5.2.3	Pitch Distribution	1.8.1.2.3	Damping Derivatives
1.5.2.4	Blade Plan Forms	1.8.2	Control
1.5.2.5	Mach-Number Effects	1.8.2.1	Longitudinal
1.5.2.6	Pusher	1.8.2.2	Lateral
1.5.2.7	Dual Rotation	1.8.2.3	Directional
1.5.2.8	Interference of Bodies	1.8.2.4	Air Brakes
1.5.2.9	Pitch and Yaw	1.8.2.5	Hinge Moments
1.5.2.10	Diameter	1.8.2.6	Automatic
1.5.3	Designated Types	1.8.2.7	Jet Reaction
1.5.4	Slipstream	1.8.3	Spinning
1.5.5	Selection Charts	1.8.4	Stalling
1.5.6	Operating Conditions	1.8.5	Flying Qualities
1.5.7	Propeller-Spinner-Cowl Combinations	1.8.6	Mass and Gyroscopic Problems
		1.8.7	Tumbling
1.6	Rotating Wings	1.8.8	Automatic Stabilization
1.6.1	Theory	1.8.9	Tracking
1.6.2	Experimental Studies	1.9	Aeroelasticity
1.6.2.1	Power-Driven	1.10	Parachutes
1.6.2.2	Autorotating	2	HYDRODYNAMICS
1.7	Aircraft	2.1	Theory
1.7.1	Airplanes	2.2	General Arrangement Studies
1.7.1.1	Components in Combination	2.3	Seaplane Hull Variables
		2.3.1	Length-Beam Ratio
1.7.1.1.1	Wing-Fuselage	2.3.2	Dead Rise
1.7.1.1.2	Wing-Nacelle	2.3.3	Steps
1.7.1.1.3	Tail-Wing and Fuselage	2.3.4	Afterbody Shape
1.7.1.1.4	Propeller and jet Interference	2.3.5	Forebody Shape
		2.3.6	Chines
1.7.1.1.5	Stores	2.4	Specific Seaplanes and Hulls
1.7.1.1.6	Jet Interference	2.5	Lateral Stabilizers
1.7.1.2	Specific Airplanes	2.5.1	Wing-Tip Float
1.7.1.3	Performance	2.6	Planing Surfaces
1.7.2	Missiles	2.7	Hydrofoils
1.7.2.1	Components in Combination	2.8	Surface Craft

		2.9	Ditching Characteristics
1.7.2.1.1	Wing-Body	2.10	Stability and Control
1.7.2.1.2	Tail-Body	2.10.1	Longitudinal
1.7.2.1.3	Jet Interference	2.10.2	Lateral
1.7.2.1.4	Wing-Tail-Body	2.10.3	Directional
1.7.2.2	Specific Missiles
1.7.3	Rotating-Wing Aircraft	3	PROPULSION
1.7.3.1	Autogiros	3.1	Complete Systems
1.7.3.2	Helicopters	3.1.1	Reciprocating Engines
1.7.4	Seaplanes	3.1.1.1	Spark-Ignition Engines
1.7.4.1	General Studies	3.1.1.2	Compression-Ignition (Diesel) Engines
1.7.4.2	Specific Types,
3.1.2	Reciprocating Engines Turbines	3.5.1.2	Turbulent-Flow Combustion
		3.5.1.3	Detonation
3.1.2.1	Turbosupercharged Engines	3.5.1.4	Effects of Fuel Atomization
3.1.2.2	Compound Engines	3.5.1.5	Reaction Mechanisms
3.1.2.3	Gas Generator-Turbine Engines	3.5.1.6	Ignition of Gases
		3.5.2	Effect of Engine Operating Conditions and Combustion Chamber Geometry
3.1.3	Turbojet Engines
3.1.4	Turbo-Propeller Engines
3.1.5	Ducted Propeller Engines
3.1.6	Pulse-Jet Engines	3.5.2.1	Reciprocating Engines
3.1.7	Ram-Jet Engines	3.5.2.1.1	Spark-Ignition Engines
3.1.8	Rocket Engines	3.5.2.1.2	Compression-Ignition (Diesel) Engines
3.1.9	Jet-Driven Rotors
3.1.10	Nuclear Energy Systems	3.5.2.2	Turbine Engines
3.1.11	Miscellaneous Engines	3.5.2.3	Ram-Jet Engines
3.1.12	Comparison of Engine Types	3.5.2.4	Pulse-Jet Engines
3.2	Control of Engines	3.5.2.5	Rocket Engines
3.2.1	Charging and Control of Reciprocating Engines	3.6	Compression and Compressors
		3.6.1	Flow Theory and Experiment
3.2.1.1	Spark-Ignition Engines	3.6.1.1	Axial Flow
3.2.1.2	Compression-Ignition Engines	3.6.1.2	Radial Flow
		3.6.1.3	Mixed Flow
3.2.1.3	Compound Engines	3.6.1.4	Positive Displacement
3.2.2	Control of Turbojet Engines	3.6.2	Stress and Vibration
3.2.3	Control of Turbine-Ram-Jet Engines	3.6.3	Matching
		3.7	Turbines
3.2.4	Control of Turbine Propeller Engines	3.7.1	Flow Theory and Experiment
		3.7.1.1	Axial Flow
3.2.5	Control of Pulse-Jet Engines	3.7.1.2	Radial Flow
3.2.6	Control of Ram-Jet Engines	3.7.1.3	Mixed Flow
3.2.7	Control of Rocket Engines	3.7.2	Cooling
3.2.8	Control of Gas Generator Engines	3.7.3	Stress and Vibration
		3.7.4	Matching
3.3	Auxiliary Booster Systems	3.8	Friction and Lubrication
3.3.1	Reciprocating Engines	3.8.1	Theory and Experiment
3.3.2	Gas Turbines	3.8.1.1	Hydrodynamic Theory
3.3.2.1	Liquid Injection	3.8.1.2	Chemistry of Lubrication
3.3.2.2	Afterburning	3.8.1.3	Surface Conditions

3.3.2.3	Bleedoff	3.8.2	Sliding Contact Surfaces
3.3.3	Rocket Assist	3.8.2.1	Sleeve Bearings
3.4	Fuels	3.8.2.2	Cylinder and Piston Mechanisms
3.4.1	Preparation
3.4.2	Physical and Chemical Properties	3.8.2.3	Slipper Plate
		3.8.2.4	Kingsbury and Mitchell Bearings
3.4.3	Relation to Engine Performance	3.8.3	Rolling Contact Surfaces
3.4.3.1	Reciprocating Engines	3.8.3.1	Antifriction Bearings
3.4.3.1.1	Spark-Ignition	3.8.4	Sliding and Rolling Contact Surfaces
3.4.3.1.2	Compression-Ignition (Diesel)	3.8.4.1	Gears
3.4.3.2	Turbine Engines, Ram Jets, Pulse jets	3.8.5	Lubricants
		3.9	Heat Transfer
3.4.3.3	Rockets (Includes Fuel and Oxidant)	3.9.1	Theory and Experiment
		3.9.1.1	Cascades
3.5	Combustion and Combustors	3.9.2	Heat Exchangers
3.5.1	General Combustion Research	3.9.2.1	Radiators
3.5.1.1	Laminar-Flow Combustion	3.9.2.2	Intercoolers
3.9.2.3	Aftercoolers	4.2.1	Wings and Ailerons
3.9.2.4	Regenerators	4.2.2	Tails
3.9.2.5	Oil Coolers	4.2.2.1	Elevators and Rudders
3.10	Cooling of Engines	4.2.2.2	Tabs
3.10.1	Reciprocating Engines	4.2.3	Bodies
3.10.1.1	Liquid-Cooled	4.2.4	Propeller, Fans, and Compressors
3.10.1.2	Air-Cooled
3.10.2	Gas-Turbine Systems	4.2.5	Rotating-Wing Aircraft
3.10.3	Ram jets	4.2.6	Panels and Surface Coverings
3.10.4	Pulse Jets	4.3	Structures
3.10.5	Rockets	4.3.1	Columns
3.11	Properties of Gases	4.3.1.1	Tubular
3.11.1	Kinetic	4.3.1.2	Beams
3.11.2	Thermodynamic	4.3.1.3	Sections
3.12	Accessories and Accessory Functions	4.3.2	Frames, Gridworks, and Trusses
		4.3.3	Plates
3.12.1	Fuel Systems	4.3.3.1	Flat
3.12.1.1	Spark-Ignition Engines	4.3.3.1.1	Unstiffened
3.12.1.2	Compression-Ignition Engines	4.3.3.1.2	Stiffened
		4.3.3.2	Curved
3.12.1.3	Compound Engines	4.3.3.2.1	Unstiffened
3.12.1.4	Turbojet Engines	4.3.3.2.2	Stiffened
3.12.1.5	Turbine-Propeller Engine	4.3.4	Beams
3.12.1.6	Pulse-Jet Engines	4.3.4.1	Box
3.12.1.7	Ram-Jet Engines	4.3.4.2	Diagonal Tension
3.12.1.8	Rocket Engines	4.3.5	Shells
3.12.1.8.1	Turbopump	4.3.5.1	Cylinders
3.12.2	Ignition Systems	4.3.5.1.1	Circular
3.12.3	Starting Systems	4.3.5.1.2	Elliptical
3.12.4	Lubrication Systems	4.3.5.2	Boxes
3.12.5	Cooling Systems	4.3.6	Connections
3.13	Vibration and Flutter	4.3.6.1	Bolted
4	AIRCRAFT LOADS AND CONSTRUCTION	4.3.6.2	Riveted

.		4.3.6.3	Welded
4.1	Loads	4.3.6.4	Bonded
4.1.1	Aerodynamic	4.3.7	Loads and Stresses
4.1.1.1	Wings	4.3.7.1	Tension
4.1.1.1.1	Steady Loads	4.3.7.2	Compression
4.1.1.1.2	Maneuvering	4.3.7.3	Bending
4.1.1.1.3	Gust Loads	4.3.7.4	Torsion
4.1.1.1.4	Buffeting Loads	4.3.7.5	Shear
4.1.1.2	Tail	4.3.7.6	Concentrated
4.1.1.2.1	Steady Loads	4.3.7.7	Dynamic
4.1.1.2.2	Maneuvering	4.3.7.7.1	Repeated
4.1.1.2.3	Buffeting and Gust	4.3.7.7.2	Transient
4.1.1.3	Bodies	4.3.7.8	Normal Pressures
4.1.1.4	Rotating Wings	4.3.8	Weight Analysis
4.1.1.5	Aeroelasticity	5	MATERIALS
4.1.2	Landing	5.1	Types
4.1.2.1	Impact	5.1.1	Aluminum
4.1.2.1.1	Land	5.1.2	Magnesium
4.1.2.1.2	Water	5.1.3	Steels
4.1.2.2	Round-Run	5.1.4	Heat-Resisting Alloys
4.1.2.2.1	Land	5.1.5	Ceramics
4.1.2.2.2	Water	5.1.6	Plastics
4.1.2.3	Prelanding Conditions	5.1.7	Woods
4.2	Vibration and Flutter	5.1.8	Adhesives
5.1.9	Protective Coatings	7.3.3	Wings and Tails
5.1.10	Fabrics	7.3.4	Windshields
5.1.11	Sandwich and Laminates	7.3.5	Miscellaneous Accessories
5.1.12	Ceramals	7.3.6	Propulsion Systems
5.1.13	Titanium	7.4	Noise
5.2	Properties	7.5	Heating and Ventilating
5.2.1	Tensile	7.6	Lightning Hazards
5.2.2	Compressive	7.7	Piloting Techniques
5.2.3	Creep	7.8	Physiological
5.2.4	Stress-Rupture	7.9	Fire Hazards
5.2.5	Fatigue	7.10	General
5.2.6	Shear
5.2.7	Flexural	8	INSTRUMENTS
5.2.8	Corrosion Resistance	8.1	Flight
5.2.9	Structure	8.2	Laboratory
5.2.10	Effects of Nuclear Radiation	8.3	Meteorological
5.2.11	Thermal	9	RESEARCH EQUIPMENT AND TECHNIQUES
5.2.12	Multiaxial Stress
5.2.13	Plasticity
5.3	Operating Stresses and Conditions	9.1	Equipment
		9.1.1	Wind/Tunnels
5.3.1	Airframe	9.1.2	Free-Flight
5.3.2	Propulsion System	9.1.3	Towing Tanks and Impacts Basins
6	METEOROLOGY	9.1.4	Propulsion Research Equipment
6.1	Atmosphere	9.1.5	Propeller
6.1.1	Standard Atmosphere	9.1.6	Materials

6.1.2	Gusts	9.1.7	Structures
6.1.2.1	Structure	9.2	Technique
6.1.2.2	Frequency	9.2.1	Corrections
6.1.2.3	Turbulence	9.2.2	Aerodynamics
6.1.2.4	Alleviation	9.2.3	Hydrodynamics
6.1.3	Electncity	9.2.4	Loads and Construction
6.2	Ice Formation	9.2.5	Propulsion
7	OPERATING PROBLEMS	9.2.6	Operating Problems
7.1	Safety	9.2.7	Mathematics
7.1.1	Pilot-Escape Techniques
7.2	Navigation	10	NOMENCLATURE
7.3	Ice Prevention and Removal	11	BIBLIOGRAPHIES
7.3.1	Engine Induction Systems
7.3.2	Propellers	12	TECHNICAL SUMMARIES

Subject Heading	Total	.
.
By year (19)-	.	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30	31	32	33	34	35
.
Aerodynamics	59.0	25	17	63	50	23	30	49	41	46	50	46	48	59	56	50	48	50	58	60	56	47
Hydrodynamics	2.2	-	-	-	-	-	-	1	1	-	1	4	3	3	4	2	1	3	3	5	10	11
Propulsion	14.7	8	25	6	50	29	23	18	6	16	8	16	18	16	11	14	15	16	17	12	11	10
Structures	9.3	17	-	13	-	6	4	4	4	7	8	6	7	2	6	17	12	12	6	9	6	17
Materials	5.4	17	-	13	-	16	15	3	5	5	12	2	6	8	7	6	11	4	4	2	4	1
Meteorology	1.0	8	-	-	-	-	1	1	1	1	-	-	1	-	1	1	-	1	1	1	1	-
Operating Problems	2.5	-	8	-	-	3	2	5	21	8	7	6	4	2	6	2	3	4	3	2	3	4
Instruments	1.5	25	17	-	-	3	6	7	11	7	4	8	5	2	2	4	3	4	4	1	3	4
Research Equipment Techniques	4.3	-	25	-	-	16	18	11	10	8	9	10	8	7	6	4	6	7	4	7	5	4
Nomenclature	0	-
Bibliographies and Indexes	0.2	-
Technical Summaries	0	-

.	36	37	38	39	40	41	42	43	44	45	46	47	48	49	50	51	52	53	54	55	56	57	58
.
Aerodynamics	51	55	54	53	52	61	52	47	48	45	51	63	65	68	67	63	62	62	62	60	61	57	57
Hydrodynamics	9	1	11	2	3	-	2	7	3	4	3	2	2	4	1	1	2	1	1	1	1	2	2
Propulsion	15	12	9	14	16	10	12	13	17	32	16	15	14	11	15	14	16	16	16	16	14	15	14
Structures	12	13	13	13	10	8	15	14	13	10	10	8	7	7	7	9	8	9	10	10	10	11	11
Materials	2	4	4	7	5	8	7	7	7	8	8	4	5	5	3	6	5	4	5	4	5	7	8
Meteorology	-	-	-	1	1	1	2	1	1	1	2	1	1	1	1	1	1	1	1	1	1	1	1
Operating Problems	3	2	2	2	3	4	4	3	3	2	3	2	2	2	1	1	1	2	2	2	2	3	3
Instruments	2	2	2	2	4	3	2	3	2	2	2	1	1	1	1	1	1	1	1	1	1	1	1
Research Equipment Techniques	5	9	6	6	5	6	4	3	5	5	5	3	3	2	3	4	5	4	4	4	4	4	3
Nomenclature
Bibliographies and Indexes
Technical Summaries

1. Eugene B. Jackson, chief, NACA Div. of Research Information, to Cyril W. Cleverdon, 29 Dec. 1953.

2. This, like other information presented here on advanced reports and on bulletins, is derived from George W. Lewis to Ames Aeronautical Laboratory, 22 June 1943.

3. George W. Lewis to Ames Aeronautical Laboratory, 6 Mar. 1943. As Lewis made clear in this memorandum, distinctions among the kinds of World War II reports were fuzzy even within the NACA. The terms confidential, restricted, memorandum, bulletin, and report were used loosely, and the descriptions of the various documents should not be taken too rigidly. Lines between confidential and restricted, and between bulletins and reports, were fine and shifting.

4. 57 A 415 (73), 53-2A, rejected reports.

5. F.H. Norton to George W. Lewis, 31 March 1922, and Lewis to Norton, 4 April 1922, both in 57 A 415 (2), 1-5A, 1919-1925.

6. John W. Crowley to NACA laboratories, 16 Oct. 1950, in 62 A 35 (73), 376, 8-12/1950.

7. See, for example, John F. Victory to George W. Lewis, 10 Jan. 1922, in 57 A 415 (66), 51-6G, 1921-1923; Lewis to John J. Ide, 3 Oct. 1929, ibid., 1927-1929; Langley laboratory to NACA, 30 March 1932, in 55 A 291 (4), RA 138; 57 A 415 (2), 1-5A, 1933-; and J.M. Shoemaker to Lewis, 10 Oct. 1927 (copy), in 55 A 344 (R4OZ), TN-284.

8. Lewis to Ide, 23 March 1929.

9. See R.J. Minshall to George W. Lewis, 7 May 1941, and Lewis to Minshall, 10 May 1941.

10. These figures, and those in the remainder of this appendix, were compiled by the author from the NACA indexes, 1949-1960. Year-by-year counts of all the Committee's technical reports in each subject area are available in the archives of this project (see bibliographic essay).

 

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