Ludwig Prandtl: A Life for Fluid Mechanics and Aeronautical Research

368 Pages·2019·8.52 MB·English

by  Michael Eckert

Springer Biographies
Ludwig Prandtl
A Life for Fluid Mechanics
and Aeronautical Research
MICHAEL ECKERT
Springer Biographies
More information about this series at http://www.springer.com/series/13617
Michael Eckert
Ludwig Prandtl
A Life for Fluid Mechanics and Aeronautical
Research
Translated by David A. Tigwell
123
Michael Eckert
Deutsches Museum
Munich,Bayern, Germany
ISSN 2365-0613 ISSN 2365-0621 (electronic)
SpringerBiographies
ISBN978-3-030-05662-9 ISBN978-3-030-05663-6 (eBook)
https://doi.org/10.1007/978-3-030-05663-6
LibraryofCongressControlNumber:2018966436
TranslationfromtheGermanlanguageedition:LudwigPrandtl:StrömungsforscherundWessenschafts-
managerbyMichaelEckert,©Springer-VerlagBerlin,Heidelberg2017.AllRightsReserved.
©SpringerNatureSwitzerlandAG2019
Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart
of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,
recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission
orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar
methodologynowknownorhereafterdeveloped.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this
publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom
therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse.
The publisher, the authors and the editors are safe to assume that the advice and information in this
book are believed to be true and accurate at the date of publication. Neither the publisher nor the
authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor
for any errors or omissions that may have been made. The publisher remains neutral with regard to
jurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations.
ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG
Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland
Preface to the English Edition
Forthecommunityofaeronauticalengineersandfluiddynamicists,LudwigPrandtl
is a celebrity—not only in Germany. Yet the story of his life has found little
attentionasthesubjectofscientificbiography.TheresponsetotheGermanedition
shows that this neglect was undeserved.
PartofthedelayedinterestinPrandtl’slifeisrelatedtowhathasbeennamedin
German “Vergangenheitsbewältigung”, mastering the past. In earlier accounts,
Prandtl’sscientificmeritsoutshonehisperformanceinthepoliticalarena.Exposing
his less laudable activities as an advisor for Göring’s Air Ministry still evokes
mixedfeelingsamongstsomeofhisGermanadmirers.Similarsensitivitiesmaybe
observed in the case of other German scientists whose Nazi past prevents their
unobstructed reverence. Prandtl’s political performance is all the more noteworthy
because he described himself as “non-political”. To unearth evidence for this
apparent contradiction has been one of the major challenges for Prandtl’s
biography.
Ofcourse,theportrayalofpoliticalactivitiesisnotmeanttodetractfrommerits
in other areas. Prandtl’s international reputation as a pioneer of aeronautical
research and fluid mechanics is beyond dispute. In this regard, it is of particular
interest to observe the juxtaposition of science and technology which pervades
Prandtl’s professional life—from his affiliation with aeronautics to his nomination
for the Nobel Prize. As this dichotomy is shaped by national traditions and con-
ventionsindifferentways,Prandtl’scharacterisationas“scientificengineer”should
be interpreted by readers of this English edition as a peculiar German feature.
Finally,IwouldliketoextendmythanksfromtheprefacetotheGermanedition
to the translator, David Alan Tigwell, and Andreas Dillmann from the DLR for
providingthefinancialsupport.Itisapleasuretoacknowledgethecloseinterestof
Prandtl’s scientific heirs at Göttingen in this biography.
Munich, Germany Michael Eckert
November 2018
v
Preface to the German Edition
LudwigPrandtl(1875–1953),asthe“fatherofmodernaerodynamics”,isrespected
by a worldwide community of aeronautical engineers. His scientific achievements
arenotsimplylimitedtothefieldofaircraftaerodynamics,butalsoencompassthe
entire spectrum of fluid mechanics. Ludwig Prandtl, ein Führer in der
Strömungslehrewasthetitleofabookpublishedtocelebratehis125thbirthday,in
whichleadingresearchersinthefieldoffluidmechanicshonouredtheworkoftheir
master.1 The title made reference to Prandtl’s legendary “Führer durch die
Strömungslehre” (Essentials of Fluid Mechanics), which has been repeatedly
published, in many editions, and which, even today, still counts amongst the
standard works on fluid mechanics.2
Prandtl was highly respected by his contemporaries. It was his model student
Theodore von Kármán who gave him the name of “father of aerodynamics“.3
Nomenclaturesuchasthe“Prandtlnumber”,“Prandtl’sboundarylayer”,“Prandtl’s
mixing length” and other specialist terms associated with his name serve as a
reminder,eventoday,ofhow,throughhisscientificendeavours,hehasleftalasting
mark on various branches of science. However, until now, there has not been a
biography that has fulfilled the requirements of a modern history of science and
technology, but also provided a summary of Prandtl’s life and work which is
accessible to non-experts, as well.
ThisdoesnotmeanthatPrandtl’sachievementshavedisappearedintoobscurity.
His daughter has written a “Lebensbild” (biographical sketch) which provides a
portrait ofPrandtlasaprivateperson andfather,drawing on numerous documents
passeddownfromthefamily.4Therearealsohistoricalaccountsavailablefromthe
Aerodynamische Versuchsanstalt (Aerodynamic Research Establishment) and the
Kaiser-Wilhelm-Institut für Strömungsforschung (Kaiser Wilheim Institute for
1Meier(2000).
2Oertel(2008),Oertel(2010).
3vonKármánandEdson(1968,p.97).
4Vogel-Prandtl(2005).
vii
viii PrefacetotheGermanEdition
FluidMechanics),inwhichPrandtlservedasdirectorduringhistimeinGöttingen.5
Prandtl acted locally as the founder of the Göttingen Aeronautical and Fluid
Mechanics Research Facilities and nationally as an advisor to government min-
istries and internationally as a representative of German research. For this reason,
therefore, this biography is not concerned so much with a “forgotten pioneer” of
fluid dynamics, but instead offers an account of the life of a researcher and rep-
resentative of science who, at many levels, has had an ever-unfolding influence,
right through to today.
There is no ideal biographical approach to individuals such as Prandtl, who
made technology and science their purpose in life butwho, beyond that, have also
played a decisive role as experts in politics and industry. Their careers and pro-
fessionalassociationsaretoodifferent.Soalsoaretheirpersonalidiosyncrasiesand
their relationships within their families, to society and to politics which, in the
course of time, give an orientation to the life of an individual and allow the
biographer to subordinate the totality to a rigid schema. Despite the number of
comprehensive biographies that are available and a wide discussion about the role
of biography in science and technology,6 no methodology has been identified for
best bridging the divide between “life” and “work”. All too easily, biographies of
scientists split into chapters with generally understandable descriptions of the cir-
cumstances surrounding the scientist’s life and those with technical scientific
accounts that are difficult to follow. Finding a continuous account that integrates
both the subject’s life and work is one of the most challenging tasks of scientific
biography. Fortunately, in the case of Prandtl, there is a very extensive legacy of
letters,manuscriptsandotherhistoricaldocumentation,sothatthebiographycould
becreated,toalargeextent,fromauthenticsourcesthatoftenintegratehislifeand
workinanaturalway.Therefore,aboveall,thematerialgleanedfromlettershasa
great value from the methodological perspective. In his correspondence with
politicalauthorities, it isapparentthat Prandtl’s science—fluidmechanics—played
suchanimportantroleinrelationtowarandpeacethatpoliticaldevelopmentsmust
also be an integral part of this biography.
Figures such as Prandtl are always an inspiration for the close interdependence
of science and politics. When considering the role of experts who offered their
knowledge and expertise to the Nazi regime, “self-enforced conformity”,
“self-mobilisation” and “collaborative relationships” are expressions which are
frequently employed.7 Across disconnects in the political system—from the
GermanEmpireviatheWeimarRepublicthroughtotheNSstate—therehasbeen,
inthecourseofthetwentiethcentury“adeepandfar-reachingchangetakingplace
regarding what politics and science are or could be”. This was the way in which a
new social–historical study of science and politics addressed the interaction of the
two spheres. “Even when one speaks of two fundamentally separate spheres and,
forvariousreasons,acertainpracticalvaluecanbeclaimed,inthemeantime,they
5Rotta(1990a),Tollmien(1998).
6ShortlandandYeo(1996),FüsslandIttner(1998),Klein(2009).
7Mehrtens(1986),Mehrtens(1994),Trischler(1994).
PrefacetotheGermanEdition ix
havebecomesostronglyintertwinedthatonecannotgetbywithouttheother”.8At
thesametime,scienceandpoliticsappearas“resourcesforoneanother”,9whereby
the term “resources” must be understood not only in the economic sense. “The
resources referred to here can be cognitive-conceptual, instrument-based-
institutional, financial or also of a rhetorical nature”.10 This is readily apparent
taking Prandtl as an example. Included in the category cognitive–conceptual
resources are “epistemic techniques”,11 such as the boundary layer theory or the
airfoiltheory,withwhichPrandtl’ssciencegainedaparticularinterestforpractical
application and consequently for politics. The instrument-based institutional
resources came to be used in the form of wind tunnels and other experimental
facilities.ResourcesofarhetoricalnaturearerepresentedbyPrandtl’ssubmissions
andmemorandatospecificallytargetedpoliticians.Nonetheless,throughouthislife,
Prandtl considered himself to be non-political. In 1946, he addressed a memoran-
dumtotheBritishMilitaryAuthoritywiththeheading“Thoughtsofanon-political
German on denazification”. This self-assessment was in line with that of a Nazi
henchman who described Prandtl as being “completely uninterested” in politics.
But, Prandtl’s contact with politics, from the “Deutsche Forschungsrat für
Luftfahrt”(GermanResearchCouncilforAeronautics)inthelate1920sthroughto
the“Forschungsführung”(ResearchExecutiveCommittee)underHermannGöring,
duringtheSecondWorldWar,givesadifferentpicture.Theresourcesconcept,with
which the diverse relationships with politics show up, reveals the incongruity
between the self-assessment made by Prandtl as being a “non-political German”
and his actual political role.
However,Prandtlwasfirstandforemostascientistandengineer.Therefore,the
biography must—if it is to remain generally understood—dispense with some
things that experts would consider to be of value. Dispensing with mathematical
deliberations is, in the case of applied mathematics and mechanics, as Prandtl’s
scientific discipline was known from the 1920s, particularly agonising. In order to
provide readers with a preparatory mathematical background (but not, however,
necessarily expert knowledge in specific sub-specialities), whilst giving a better
insight intoPrandtl’swayofthinking, atappropriate pointsinthetext,boxes have
been inserted that contain background information which elucidate the subject
matter discussed in the main text. In these boxes, the core of the relevant research
work(e.g.thederivationofthelawofthewall,inthecaseofturbulentpipefriction)
is exemplified. More comprehensive accounts can be found in the specialist
literature.
Withoutthehelpandassistanceofmanyindividualsandinstitutes,itwouldnot
havebeenpossibletogainanoverviewandadequatelyrepresentPrandtl’slifeand
work with all the diverse connections with science, technology and politics during
8Ash(2010,p.11).
9Ash(2002).
10Ash(2010,p.16).
11Pleaserefer toMoritz Epple’sexpansionoftheRheinbergerterm“epistemicthings”inEpple
(2002b).
x PrefacetotheGermanEdition
theturbulent times inwhich helived.First and foremost,Iwouldlike tothank the
DeutscheForschungsgemeinschaft(GermanResearchFoundation)forthefinancial
support they have provided over the years and the Research Institute of the
Deutsches Museum in Munich, which provided an ideal environment for research
in the history of science and technology and which also made available the
infrastructureoftheDeutschesMuseum—fromarchivesthroughtolibraryfacilities
and departmental collections (in particular, those related to aviation). I would also
like to thank, at this juncture, the numerous archives that allowed me to access
relevant source material, above all, the archive of the Deutsche Zentrum für Luft-
und Raumfahrt (German Aerospace Centre) in Göttingen and the Archiv zur
Geschichte der Max-Planck-Gesellschaft (Historical Archive of the Max Planck
Society) in Berlin. I would certainly not have been able to have written this
biography if I had not had access to the letters exchanged with Prandtl. I owe a
specialwordofthankstotheVogelfamily,whogavemeaccesstoPrandtl’sprivate
collectionofmanuscripts,notesandmemorandaleftbehindafterhisdeath.Florian
Schmaltz gave me access to several chapters of the rough version of his unpub-
lished monograph about the Aerodynamische Versuchsanstalt (Aerodynamics
Research Institute), in which he shed much light on the institutional context of
Prandtl’s working. I also owe him a special word of thanks for his critical com-
ments on the preliminary version of this biography. I would like to thank Cordula
Tollmien for providing access to the collection of material she assembled in the
1980s for her article on the history of the Kaiser-Wilhelm-Institut für Strömungs-
forschung during the time of National Socialism,12 also for the information about
herfather,thepupilofPrandtl,WalterTollmien.Last,butnotleast,Iwouldliketo
express my thanks to my colleagues at the Deutsches Museum, especially Silke
Berdux, Ulf Hashagen, Jürgen Teichmann, Helmuth Trischler and Stefan Wolff
who, for many years now, have accompanied my research about Ludwig Prandtl.
Munich, Germany Michael Eckert
December 2015
12Tollmien(1998).