NASA / TM-1999-209127

A Digital Library for the National

Committee for Aeronautics

Advisory

Michael L. Nelson

Langley Research Center, Hampton, Virginia

April 1999
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NASA/TM-1999-209127

A Digital Library for the National

Committee for Aeronautics

Advisory

Michael L. Nelson

Langley Research Center, Hampton, Virginia

National Aeronautics and

Space Administration

Langley Research Center

Hampton, Virginia 23681-2199

April 1999
Available from:

NASA Center for AeroSpace Information (CASI)

7121 Standard Drive

Hanover, MD 21076-1320

(301) 621-0390

National Technical Information Service (NTIS)

5285 Port Royal Road

Springfield, VA 22161-2171

(703) 605-6000
A Digital Library for the

National Advisory Committee for Aeronautics

Michael L. Nelson

NASA Langley Research Center

MS 158, Hampton, VA 23681

m.l.nelson@larc.nasa.gov

April 1999

Abstract

We describe the digital library (DL) for the National Advisory Committee for Aeronautics

(NACA), the NACA Technical Report Server (NACATRS). The predecessor organization

for the National Aeronautics and Space Administration (NASA), NACA existed from 1915

until 1958. The primary manifestation of NACA's research was the NACA report series.

We describe the process of converting this collection of reports to digital format and

making it available on the Worm Wide Web (WWW) and is a node in the NASA Technical

Report Server (NTRS). We describe the current state of the project, the resulting DL

technology developed from the project, and the future plans for NACATRS.

1 Introduction

The National Aeronautics and Space Act of 1958 created the National Aeronautics and

Space Administration (NASA) from the National Advisory Committee for Aeronautics

(NACA). As NASA's predecessor organization, NACA was chartered in 1915 and was

operational from 1917 until 1958. NACA played an integral role in the development of

the United States' fledgling aeronautics industry as the main research body for a

collection of federal, commercial and university interests.

The main product of NACA's research was its multi-tiered report series. Although the

exact number of NACA reports published is unknown, most estimates place this number

between 20,000 and 30,000. This collection of work remains in high demand even today,

especially in the areas of general aviation and the basic fundamentals of flight [11].

Unfortunately, although significant collections of NACA documents exist at a handful of

NASA centers, universities and other government and industrial research laboratories, no

single library contains a complete collection. Even what constitutes a complete NACA

corpus is subject to debate. Furthermore, because of their age, high circulation, and acidbased paper, many of these reports are in poor condition and will cease being serviceable

in the near future. Conversion to digital format is necessary for preservation as well as

for wider dissemination.

This paper discusses the ongoing digital conversion of the NACA collection, begun in

1995, and the dissemination of this collection over the World Wide Web. We present the
structureandtechnologyof theNACA TechnicalReportServer(NACATRS), thedigital

library (DL) that servesthe NACA collection.We discusstheresultingtechnologyfrom

thisprojectandthefuturework for NASA andNACA DLs.

2 Contents and Access

The NACATRS can be accessed via the WWW at: http://naca.larc.nasa.gov/. The

NACATRS currently has over 1800 documents and an accession rate of about 30

documents a week. Figure 1 shows the NACATRS interface.

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Figure l: The NACA Technical Report Server

2
2.1 NACA Contents

NACA published in a variety of internal report series. Currently, the NACATRS holds

the following NACA publications series:

NACA Reports - NACA reports were considered to be the final and complete

documentation on a subject or project and they often superceded one or more other

NACA publication types. NACA Reports are sometimes (erroneously) referred to as

"NACA Technical Reports."

• NACA Technical Notes (TNs) - Technical Notes were the basic unit of the research

report series. Some early TNs were translations of foreign works.

• NACA Technical Memorandums (TMs) -TMs are translations of foreign works. The

TM series probably replaced translations in the TN series.

NACA "Wartime Reports" - Reports produced specifically for World War II

research, they were declassified after the conflict. Due to their urgent nature, they

frequently received little editing when written, and no editing was done after they

were declassified. The moniker "Wartime Reports" was added when they were

declassified; previously they were issued as Advance Confidential Reports (ACRs),

Advance Restricted Reports (ARRs), Restricted Bulletins (RBs) and Confidential

Bulletins (CBs).

NACA Research Memorandums (RMs) - RMs were initially restricted, and

represented initial or limited scope results, and thus received less editing and

preparation than other report series.

NACATRS currently does not include:

NACA Annual Reports - Annual Reports were simply the concatenation of a single

year's NACA Reports (i.e., excluding TNs, TMs, etc.). Inclusion of the NACA

Reports in NACATRS implicitly includes the Annual Reports.

• Aircraft Circulars - Reports published in the 1920s-1930s that reviewed the design

and performance of contemporary aircraft (one AC per vehicle).

Conference or Journal Preprints - We are unaware of how many items this would

include. However, their content would likely be covered in a Report or TN, so this

exclusion is probably negligible.

• Books - No books by NACA authors are included.
We canprovidesomegeneralizedobservationsjust from handlingthe collection. The

first NACA Reportswereissuedin 1917,but TNs andTMs did not appearuntil 1920.

Theearlypublicationswereofteneithertranslationsfrom Europeanaeronauticsworks or

authoredby universitiesor otherfederalor military researchlaboratories.This is because

NACA was initially truly a committeeof aeronauticallyinterestedorganizationsrather

thanafederalagencyin presentcontext. As NACA acquiredits own staff anddeveloped

its own researchfacilities, the numberof publicationsauthoredby non-full-time NACA

staffdecreased.

2.2 WWW Contents

The NACA publications are scanned, and TIFF images are the output of the process.

Optical Character Recognition (OCR) is not being applied for the NACATRS, primarily

because the format of the NACA publications are often pages of equations, tables, charts

and figures - none of which are well suited for OCR. Instead, the report is converted into

a combination of GIF and PDF files for easier WWW dissemination.

NACATRS offers browsing and keyword searching of its holdings. These DL functions

are provided using the TRSkit software package [7]. Although NACATRS is a "freestanding" DL, it is also a node in the NASA Technical Report Server (NTRS) [6], a DL

that offers keyword searching to over 20 different DLs hosted by various NASA centers,

institutes and projects. Although browsing and keyword searching is available, the

reports are also accessible via the following naming convention:

http://naca.larc.nasa.gov/reports/YEAR/naca-REPORTTYPE-NUMBER

So the popular NACA Report 1135 is available at:

http://naca.larc.nasa.gov/reports/1953/naca-report-l135/

2.3 Document Presentation in NACATRS

One reason previous attempts at NACA archives [1] received limited usage was due to

non- or limited-WWW interfaces, so we made every attempt to provide an intuitive,

attractive WWW interface to the DL and individual reports. Figure 2 shows the

presentation of a report. The thumbnail images are clickable, and will present a large

GIF image for easy on-line viewing. Should the user desire to download the entire report

for local storage or printing, the entire report in a single PDF file is available.

Currently, 10 thumbnails will be shown at a time with options such as "next", "previous",

"first" and "last" being available to paginate through large reports. When viewing single

pages (large GIFs), there are also similar pagination commands allowing you to step

through the report on-screen one page at a time (Figure 3).

4
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Figure 2: Initial Presentation of a Report

Figure 3: An Expanded View of a Single Page

5
We feelthis methodof presentationis superiorto servingjust PDF files. In NACATRS,

PDF files areavailable, but in addition the paginationof the thumbnail and full size

imagesallows for quick reviewandaccessto thedocumentwithout havingto download

theentirereport (whichis oftenmanymegabytes).

Additionally, this methodallows for the integration of the datafiles (PDF, GIFs,etc.)

with themetadatain a singlelocation. For example,althoughnotexplicitly advertisedto

theuser,thestructuredmetadatafor NACA Report1135is availableat:

http://naca.larc.nasa.gov/reports/1953/naca-report-l135/naca-report-l135.refer

This offers long term advantages in DL maintenance and operation because the metadata

and data collocated. This also allows for the reports in NACATRS to be indexed by

more than one DL, since the data and structured metadata are publicly available. Given

the root of the NACA collection, a WWW robot or gatherer could construct an index to

this collection.

3 Preparation

Though many nodes in NTRS are populated by capturing the electronic source files

involved in the publishing process, it is obvious given the age of the NACA reports that

electronic source is not an option. All the reports must be scanned. Given the poor

condition of the some of the reports, finding suitable candidates for scanning is nontrivial. Initially, the NACATRS was fed by reports that were hand scanned at 400 dots

per inch (dpi) by volunteers to help populate the prototype. Currently, the bulk of the

reports are scanned at 300 dpi under a contract with the Phillips Research Site of the

Airforce Research Laboratory. NASA Langley ships Phillips photocopies of the reports

to be scanned, and they ship back tapes of TIFF images.

3.1 DTRTWT

Although TIFF is the output of the report scanning process, TIFF is not a widely accepted

format for distribution on the WWW. We developed the DTRTWT (Does The Right

Thing With TIFF) software package to process the TIFF into a more WWW-friendly

presentation. Given the following input:

• 1 report = 1 directory

• 1 page = 1 TIFF file (all files residing in the report's directory)

DTRTWT produces the following output in the report directory:

• 1 PDF file for the entire report

• 1 large GIF image per page

• 1 thumbnail GIF image per page

• 1 Perl 5.0 index.cgi file to negotiate access and presentation to the report directory

6
DTRTWT expectsa metadatafile (in "refer" format [5]) to bepresentto extractvalues

for the title, authors,abstract,etc. into the index.cgifile. We currently generatethese

metadatafiles in a semi-automatedfashion. This greatly slows down the growth of

NACATRS,butallowsusto correctmanyerrorsandomissionspresentin currentNACA

bibliographicdatabases.

DTRTWT is a collection of Perl programsand shell scripts. For imageprocessing,it

usesboth the commercialpackage"Image Alchemy" [2] and the freeware package

"ImageMagick" [3]. DTRTWT runs underUnix, and the Sun Sparcstationsand IBM

RS/6000sweuseprocessaboutonepageperminute. Theprocessingloadcanbespread

acrossseveralmachinesin parallel.

Figure4 showsareportbeingconvertedusingDTRTWT. TheTIFF pagesarenumbered

sequentially,collectedin a directory. DTRTWT is invokedwith argumentsfor creating

thePDF files, convertingtheTIFFs to GIFs,resizetheGIFs to big andthumbnailsizes,

and creatingthe index.cgi to managethe collection. The refer metadatacanbe added

later. TheTIFFscanbestoredin thedirectoryorremovedto conservestorage.

% is naca-tn-3301

naca-tn-330iIOOOl.tif *

naca-tn-3301

naca-tn-3301

naca-tn-3301

naca-tn-3301

naca-tn-3301

naca-tn-3301

naca-tn-3301

lO002.tif*

lO003.tif*

lO004.tif*

lO005.tif*

10006.tif*

10007.tif*

10008.tif*

naca-tn-330i/OOO9.tif*

naca-tn-330i/OOlO.tif*

naca-tn-330i/OOll.tif*

naca-tn-330i/OO12.tif*

naca-tn-330i/OO13.tif*

naca-tn-330i/OO14.tif*

naca-tn-330i/OO15.tif*

naca-tn-330i/OO16.tif*

-resize -index naca-tn-3301

naca-tn-3301/O017

naca-tn-3301/O018

naca-tn-3301/O019

naca-tn-3301/0020

naca-tn-3301/0021

naca-tn-3301/0022

naca-tn-3301/0023

% dtrtwt -pdf -convert

% is naca-tn-3301

O001-t.gif O007-t.gif O013-t.gif O019-t.gif

0001.gif 0007.gif 0013.gif 0019.gif

0001.tif* 0007.tif* 0013.tif* 0019.tif*

0002-t.gif 0008-t.gif 0014-t.gif 0020-t.gif

0002.gif 0008.gif 0014.gif 0020.gif

0002.tif* 0008.tif* 0014.tif* 0020.tif*

0003-t.gif 0009-t.gif 0015-t.gif 0021-t.gif

0003.gif 0009.gif 0015.gif 0021.gif

0003.tif* 0009.tif* 0015.tif* 0021.tif*

0004-t.gif 0010-t.gif 0016-t.gif 0022-t.gif

0004.gif 0010.gif 0016.gif 0022.gif

0004.tif* 0010.tif* 0016.tif* 0022.tif*

0005-t.gif 0011-t.gif 0017-t.gif 0023-t.gif

0005.gif 0011.gif 0017.gif 0023.gif

0005.tif* 0011.tif* 0017.tif* 0023.tif*

tif*

tif*

tif*

tif*

tif*

tif*

tif*

Figure 4: Report Conversion with DTRTWT

7
3.2 Storage Requirements

Since the NACA collection is a fixed size, it allows us to make a number of simplifying

assumptions in implementation. The Unix file system is used to store the current reports,

and we expect that this will be sufficient to store the entire NACA collection. Scanned at

300 dpi, each page consumes roughly 15KB. After processing by DTRTWT, the total of

all the resulting pages is about 80KB per page.

If we assume the entire NACA collection is 30,000 reports, and each report has 20 pages,

then the NACA collection is equivalent to 600,000 pages. At 80KB per page, this

translates into about 48GB of storage required for the entire collection. This could be

stored comfortably on 6 9GB disk drives, which have a current retail price of less than

$1,000. The files are backed up to the Distributed Mass Storage System (DMSS) [10], so

if a drive fails the affected reports can be restored from DMSS.

4 Usage

Interest has been high in the NACATRS. On a monthly basis, NACATRS disseminates

over 5,000 PDF files. This does not count browsing the GIFs. There are over 3,000

searches per month issued from the NACATRS page, and approximately 10,000 searches

a month issued from NTRS. For comparison, NTRS handles over 30,000 searches per

month, so as much as 1/3 of the NTRS searches involve NACATRS.

Anecdotally, we frequently receive email from users world wide requesting specific

reports to be added and thanking us for making available a collection that to many

university and industry users is not ordinarily available.

5 Future Work

The most obvious area for improvement is increasing the number of reports available. At

just over 1200, NACATRS is large enough to be interesting, but with as many as 30,000

NACA reports, it is far from a canonical collection. However, there are opportunities to

expand the NACATRS holdings beyond simply reports, especially airfoil data.

5.1 NACA Information

We receive many emails requesting access to NACA airfoil ordinates. We currently do

not have this information. We also do not have any of the tabular data in non-scanned

form. There are programs to generate NACA airfoil data [4], and the NACATRS even

has links to Java programs written by non-NASA personnel to generate airfoil data.

There are also programs to generate and refine data in handbook-type NACA reports

[12]. However, there has been no concentrated effort to generate a database of numerical

data to complement the NACA collection.
5.2 Buckets

An anticipated infrastructure upgrade is the switch to buckets. Buckets are aggregative,

intelligent archival objects developed for DLs developed by the NASA Langley Research

Center / Old Dominion University DL Research Group for the NCSTRL+ project [8]. In

fact, the inspiration for buckets grew out of our work on the NACATRS, so we

frequently refer to the current implementation of reports in NACATRS as "protobuckets". Buckets allow storage of many different data objects as a single entity within a

DL. Buckets also negotiate access and presentation of their contents. This corresponds

to the index.cgi in a NACA report directory controlling the presentation of the PDF and

the GIFs. Additional features of buckets such as intelligence, object level terms and

conditions, and mobility are further described in [9]. Although the user is unlikely to

notice specific changes, we intend to upgrade the "proto-buckets" to fully implemented

buckets for smoother operation of the NACATRS and to continue refining our bucket

concepts and implementation.

6 Conclusions

We have created a digital library, the NACA Technical Report Server, to capture,

preserve and disseminate the in-demand, rare and decaying report collection of the

National Advisory Committee for Aeronautics. NACATRS currently provides WWW

access to over 1800 NACA publications. The publications are available in PDF for local

storage and printing, in thumbnail GIFs for quick review, or large GIFs for easy onscreen reading. These formats are generated from the original TIFF images using the

DTRTWT software package developed to create NACATRS. The NACATRS is

available as a standalone DL, or as a node in NTRS. NACATRS serves approximately

5000 PDF reports per month, and handles over 13,000 monthly keyword searches.

Future plans include providing access to the full NACA collection (approximately 30,000

documents), integrating numerical databases and software into the collection and the

conversion to "buckets," aggregative and intelligent agents for DLs that were inspired by

the original work on the NACATRS.

Acknowledgements

The NACATRS could not have proceeded without the assistance of many people. We

would like to thank: Nola Graves (NASA LaRC) and Jim Coon (formerly of NASA

LaRC) for metadata entry and population; Michael Nemeth (NASA LaRC) for lending a

large collection of hard copy NACA reports to be scanned; Sharon Jenkins (NASA

LaRC) , Zylphia Wilkins (NASA LaRC) and Donnell Lassiter (NASA LaRC) for their

work in scanning Nemeth's collection; William Kleb (NASA LaRC) for scanning the

reports he directly used in his research; Eloise Johnson (NASA LaRC), Henry Woolard

(retired aerospace engineer) and Yvonne Kellog (NASA DFRC) for assistance in helping

in our understanding the scope, purpose and terminology of the NACA collection; and

David Adams (formerly of NASA LaRC), George Roncaglia (NASA LaRC) the NASA

Langley Technical Library and the Code R Unilibrary Project for providing scanned

reports that form the bulk of NACATRS.

9
References

1. M. Y. Ambur, D. L. Adams, P. P. Trinidad, "Desktop Access to Full-Text NACA and NASA Reports:

Systems Developed by the NASA Langley Technical Library," AIAA 97-0467, Proceedings of the 35 th

Aerospace Sciences Meeting & Exhibit, Reno NV, January 6-10, 1997.

2. Image Alchemy, http://www.handmadesw.com/his/specs.html

3. ImageMagick, http://www.wizards.dupont.com/cristy/ImageMagick.html

4. C.L. Ladson, C. W. Brooks Jr., A. S. Hill and D. W. Sproles, "Computer Program to Obtain Ordinates

for NACA Airfoils," NASA TM-4741, December 1996.

5. M. E. Lesk, "Some Applications of Inverted Indexes on the UNIX System," Bell Laboratories

Computing Science Technical Report 69, 1978.

. M. L. Nelson, G. L. Gottlich, D. J. Bianco, S. S. Paulson, R. L. Binkley, Y. D. Kellogg, C. J.

Beaumont, R. B. Schmunk, M. J. Kurtz & A. Accomazzi, "The NASA Technical Report Server,"

Internet Research: Electronic Networking Applications and Policy, 5(2), 1995, pp. 25-36.

7. M. L. Nelson and S. L. Esler, "TRSkit: A Simple Digital Library Toolkit," Journal of Internet

Cataloging, 1(2), 1997, pp. 41-55.

. M. L. Nelson, K. Maly, S. N. T. Shen, & M. Zubair, "NCSTRL+: Adding Multi-Discipline and MultiGenre Support to the Dienst Protocol Using Clusters and Buckets," Proceedings of Advances in Digital

Libraries 98, Santa Barbara, CA, April 22-24, 1998, pp. 128-136.

9. M.L. Nelson, K. Maly, S. N. T. Shen & M. Zubair, "Buckets: Aggregative, Intelligent Agents for

Publishing," WebnetJournal, 1(1), 1999, pp. 58-66.

10. J. Z. Pao and D. C. Humes, "NASA Langley Research Center's Distributed Mass Storage System,"

Proceedings of the Third Goddard Space Flight Center Conference on Mass Storage Systems and

Technologies, College Park, Maryland, October 19-21 1993, pp. 207-216.

11. R. Smith, "The NACA Collection: When Old is New Again - A Status Report on the NACA

Documents Project," Sci-Tech News, 46(2), April 1992, pp. 15-20.

12. D. W. Witte and K. E. Tatum, "Computer Code for Determination of Thermally Perfect Gas

Properties," NASA TP-3447, September 1994.

10
REPORT DOCUMENTATION PAGE FormApprov_

QM[_ NR, ft7fH-ftlt:lt:l

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data

sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other

aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and

Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188),

Washington, DO 20,503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

April 1999 Technical Memorandum

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

A Digital Library for the National Advisory Committee for Aeronautics

6, AUTHOR(S)

Michael L. Nelson

7, PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Langley Research Center

Hampton, VA 23681-2199

9, SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

8. PERFORMING ORGANIZATION

REPORT NUMBER

L-17844

10, SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA/TM- 1999-209127

11,SUPPLEMENTARYNOTES

12a, DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified-Unlimited

Subject Category 82 Distribution: Standard

Availability: NASA CASI (301) 621-0390

12b, DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

We describe the digital library (DL) for the National Advisory Committee for Aeronautics (NACA), the NACA

Technical Report Server (NACATRS). The predecessor organization for the National Aeronautics and Space

Administration (NASA), NACA existed from 1915 until 1958. The primary manifestation of NACA's research

was the NACA report series. We describe the process of converting this collection of reports to digital format

and making it available on the World Wide Web (WWW) and is a node in the NASA Technical Report Server

(NTRS). We describe the current state of the project, the resulting DL technology developed from the project,

and the future plans for NACATRS.

14. SUI_IECT TERMS

Digital Libraries, NACA, WWW, Scanning

17, SECURITY CLASSIFICATION

OF REPORT

Unclassified

NSN 7540-01-28U-5500

18, SECURITY CLASSIFICATION

OF THIS PAGE

Unclassified

19, SECURITY CLASSIFICATION

OF ABSTRACT

Unclassified

15. NUMBER OF PAGES

15

16. PRICE CODE

A03

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OF ABSTRACT

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