German Rocket Society - Verein für Raumschiffahrt by Frank H. Winter - Part 1

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The following paper is ©2015 Frank H. Winter.


The Founding of the VfR and the Die Rakete Years (1927-1929)

Definition of the VfR

Verein für Raumschiffahrt, or VfR – Translates into English literally as the “Society for Spaceship Travel” but more generally known as the “Society for Space Travel,” or more rarely, “the German Interplanetary Society,” although afterward more popularly (but incorrectly called) the “German Rocket Society” in English-speaking countries. (It was never called this in German during its existence.) The VfR lasted for only seven years in Germany from 1927 to 1934. Yet, its role was of great importance in the history of the development of the concept of space flight as well as in the development of liquid-propellant rocket technology.

The Background and Founding of the VfR

The VfR was founded on 5 July 1927 by nine men and one woman who met at 6:30 p.m. in the back room (according to Ley), or parlor, of the Goldnen Zepter (the Golden Scepter) tavern on Schmiedebrücke 22 (literally, Wrought (Iron) Bridge, or Blacksmith Bridge 22) in the German industrial town of Breslau (now, Wrocław, Poland) but then the capital of the province of Silesia. (Interestingly, the Goldnen Zepter was already an historic inn and hotel. The building was erected in the 14th or 15th century and since 1507 was used as both an inn and hotel, one of the most popular of the latter in Breslau. Then, early in the 19th century, the Prussian officer Major (later, Lt. General) Ludwig Wilhelm von Lützow lived there and used it as a recruitment site during 1813 for volunteers in the war of liberation against Napoleon and the French occupation. Among famous guests at the inn were Józef Wybickim author of the lyrics of the Polish national anthem and co-originator of the Polish Constitution of 3 May 1791. However, the building no longer exists. It was destroyed during the war, in 1945, although was reconstructed in the 1980s from the ruins and the ground floor and cellars were adapted for a mineral museum, while the upper floors, together with adjacent buildings of what is now called Kuźnicka ul. or Street, form the Institute of English Studies of the University of Wrocław.)

The Goldnen Zepter in Breslau, location of the founding of the VfR (ca. 1927)
The Goldnen Zepter in Breslau, location of the founding of the VfR (ca. 1927)

For a thorough account of the rocketry and spaceflight “fad” of the 1920s-30s, particularly in Weimar Germany, that led to the forming of the VfR, consult Michael J. Neufeld, “Weimar Culture and Futuristic Technology: The Rocketry and Spaceflight Fad in Germany, 1923-1933,” in Technology and Culture, Vol. 31, No. 4, October 1990, pp. 725-752. But what is most important is what precipitated the “rocket fad” in the first place: the appearance of the book by Hermann Oberth, Die Rakete zu den Planetenräumen (By Rocket into Interplanetary Space) in 1923.

The Russian Konstantin Eduardovich Tsiolkovsky had preceded Oberth by more than 20 years; he had begun to theorize earlier on the possibilities of spaceflight by the 1890s but produced his first seminal article on this subject in 1903, “Isseldovanie mirovykh prostranstv reaktivnym priborami” (The Exploration of Space with Reaction-Propelled Devices”(i.e. the rocket)), in the journal Nauchnoe Oborozrenie (The Science Review) of Moscow in 1903. However, this journal was almost unknown in the West; there was also a language problem. Consequently, Tsiolkovsky's contribution remained virtually hidden outside of his own country for many years. Even so, according to Willy Ley, even after Tsiolkovsky's work was republished (out of pocket) in his provincial home town of Kaluga in 1924 and also in 1926, “...still nobody (or hardly anybody) outside of Russia ever saw them. I was one of three people in Germany, plus two libraries who had them).”

The treatise by the American physicist Dr. Robert H. Goddard, A Method of Reaching Extreme Altitudes, was published in 1919 by the Smithsonian Institution in its Miscellaneous Collections series but mainly stressed the application of the rocket for upper atmospheric research (i.e. or what we term today an upper atmospheric “sounding rocket”). Goddard's true goal was to ultimately develop the rocket for the potential application for space flight. But he was always very secretive in nature although did dare to postulate, in his A Method of Reaching Extreme Altitudes, coverage of a hypothetical multi-stage unmanned solid-propellant rocket that could announce its impact upon the surface of the Moon with the explosion of flash powder that could be seen on Earth. However, this so-called “Moon rocket,” that had meant to be a largely mathematical demonstration of the potential of the rocket, created a sensation in the popular press, not only in the U.S. but in many other countries, since the notion of a rocket for achieving space flight was then wholly novel, despite the earlier work of Tsiolkovsky. (Goddard well knew that theoretically, liquid-propellants had far greater energy potential than solid-propellants but he was so cautious that he barely mentioned the possibility of liquids in his treatise.

Ley, in his “The End of the Rocket Society,” also says that “the germ of the idea” of space flight itself, probably dates to Johannes Kepler's novel Somnium (The Dream), written in 1608 but not published until 1634. It is an imaginative description of how the Earth might look when viewed from the Moon, and is considered the first serious scientific treatise on lunar astronomy. The means of transport to the Moon is also fanciful; it is accomplished by “daemons” having the power to move Earthlings anywhere on Earth in an instant, and also the Moon, but the whole story is a dream. But the history of science fiction and/or mythological aspect of concepts of “space flight,” to the Moon or planets probably considerably pre-date that of Kepler. But this phase of the earliest history of concept of space flight is beyond the scope of this article, but we know for certain that Goddard's hypothetical “Moon rocket” in his 1919 treatise was the first serious treatment of this idea, at least in the West (i.e. outside Russia) since Tsiolkovsky wrote the novel На Луне (On the Moon) in 1887, afterward published in 1893, that described, in fictional format as a novel, many of his ideas on space flight, including rocket propulsion but in this period the work was only available in Russia, and even then not widely circulated.

In any case, the idea of the “space rocket” quieted down for a few years after the world-wide, almost sensationalist publicity of Goddard's so-called “Moon rocket” until the appearance of Oberth's book in 1923. By stark contrast to the overly-cautious Goddard, Oberth's book boldly presented his scientific concepts for a type of liquid-propellant (liquid oxygen/alcohol) manned rocket for space flight (he described a Model A and B), and stated at the outset of his work that this development was technically feasible within “...the present state of science and technology...” Moreover, Oberth went further and included discussions of hypothetical physical and psychological effects of man in space, as well as the design of a spacesuit, dangers in spaceflight, but also possible spaceflight missions such as the establishment of a space station for astronomical observations and an orbiting space telescope.[1]

But despite these truly revolutionary concepts, Oberth's 80 + page work was replete with mathematics and technical discussions and it took the work of the Austrian Max Valier to begin to popularize Oberth's many ideas in his own books, articles, and lectures that surely set the stage for the rocket (and spaceflight) fad, which soon included the initiation of the VfR.

The founding members of the VfR were: Max Valier, the Austrian writer and popularizer of spaceflight, notably his book Der Vorstoss in den Weltraum - eine technische Möglischkeit (Advance into Interplanetary Space - A Technical Possibility) (1924) that was to go through four editions; Johannes Winkler, a Breslau engineer then working as a church administrator; Georg Lau, a member of the District Board of Works of Breslau; Theodor Fuhrmann, a clergyman from Breslau; Alfons Jakubowicz, from the same city and a candidate for a chemical engineering degree; Miss Hedwig Bernhard of Breslau; Gerhard Guckel of Breslau; Herbert Fuchs, a pastor from the nearby town of Nestau bei Suhlendorf; Walter Neubert of Munich, probably a friend of Valier since the latter then lived there as a free-lance writer; and H. Sauer, a Dipl. Ing. (Diploma Engineer) from Berlin.

Johannes Winkler, first president of the VfR and editor of their journal, Die Rakete.
Johannes Winkler, first president of the VfR and editor of their journal, Die Rakete.

Ley, the German-born historian of rocketry and spaceflight, later indicated he had also been a founding member although there is no documentation to support this assertion. In a semi-autobiographical article in Space World for June 1961, he recalled: “In 1927 (just before our meeting), I received a letter from Max Valier, who was lecturing a great deal (on the subject). He suggested that a club be organized to raise money and finance experiments for (Hermann) Oberth. Such a club would need a legal charter and Valier asked that I contact a man in Breslau by the name of Johannes Winkler who would make the necessary court applications. Winkler complied...I was not personally at the first meeting...”[2].

Ley, who had become fascinated in spaceflight after reading Oberth's landmark book Die Rakete zu den Planetenräumen (By Rocket into Interplanetary Space) of 1923, thereafter became a popularizer of the subject. His first work on the topic, Die Fahrt ins Weltall (Travel in Outer Space) appeared in 1926. However, Ley never mentioned being a co-founder of the VfR in any of the editions of his highly popular Rockets, Missiles, & Space Travel, published between 1944 and 1968. In addition, Oberth is not known to have undertaken any rocketry experiments until 1929, when (as described by Ley himself), he was requested to do so by the Ufa Film Company for publicity for the Ufa film “Frau im Mond” (“Woman on the Moon”), released in October of that year. But Ley's version of the beginning of the Society, in the first part of his two-part article, “The End of the Rocket Society,” published in Astounding Science Fiction for August 1943, appears to be the more accurate version of his connection with the VfR, particularly since it is his earliest known account of the founding of the VfR. Soon after the Society had been formed, he explained, “...Valier wrote me a letter asking me to join. Winkler (also) wrote to Professor Oberth and to many others. And they all joined.” This was also in 1927.[3].

Valier had chosen not to take the position as President of the new group since he was fully occupied with his continuous lecture tours, although at the first meeting he was designated as one of the Board of Directors that also included Winkler, Furhmann, Jakubowicz, Sauer, and Neubert.[4].

Winkler was made the first President. Born in 1897 in the village of Bad Carlsruhe, Upper Silesia, the son of a master cabinet-maker and apparently a part-time pastor, Winkler was technically-inclined and often in his youth used his father's shop to work out inventions and other constructions. The apparition of Halley's Comet early in 1910, led young Winkler to acquire a life-long interest in astronomy. He later studied at the technical universities of Breslau and Leipzig; in addition, he attended lectures in astronomy, thermodynamics, and aircraft design. (Due his father's church duties, Winkler studied theology as well but his chief passions were technology and astronomy; besides Winkler working as a church administrator, two other fellow-founders of the VfR, Fuhrman and Fuchs, were clergymen and it is likely they were ecclesiastical colleagues of Winkler.)

Winkler was also greatly influenced by reading several fictional works on spaceflight, including Jules Verne's novel, From the Earth to the Moon (1865), Kurd Lasswitz's Auf zwei Planeten (On Two Planets) (1897) that postulated intelligent life on Mars, and Otto Willi Gail's Der Stein vom Mond (The Stone From the Moon) (1926). The latter work in particular, besides other stories by Gail, featured realistic descriptions of spaceflight by rocket ship since Gail was inspired by Oberth's Die Rakete zu den Planetenräumen. Winkler himself was thus compelled to read Die Rakete, as well as A Method of Reaching Extreme Altitudes (1919) by Robert H. Goddard, and he soon began communicating with the chemist Dr. Franz Oskar Leo Elder von Hoefft of Austria one of the early devotees of Oberth's ideas on spaceflight. In 1926, with fellow Austrian Guido von Pirquet, von Hoefft had founded the Wissenschaftliche Gesellschaft für Höhenforschung (the Scientific Society for High Altitude Research), the first space-related society in western Europe. Von Hoefft was its first president and formed a “Rocket Committee” besides communicating with Hermann Oberth.[5]

By 1926, even before the founding of the VfR, Winkler had already started theoretical studies on possible rocket fuels (perhaps the main reason he initiated communication with the chemist von Hoefft) and he was especially interested from this time with the propellant combination of liquid methane and liquid oxygen (LOX). He also began to write drafts of his own concepts of achieving spaceflight. For example, there is a typed manuscript in the Winkler papers titled “Wege zum Raumschiff” (“Way to the Spaceship”) dated ca. 1926. In addition, by October of that year he opened correspondence with Oberth and his extant notes from this time reflect that he was then concerned that there were several people of like-minded interest in spaceflight yet there was then no proper organization to bring them together. [6].

Earlier Spaceflight Groups, USSR

Hence, the earlier Austrian group had already set a precedent for the VfR but it remained a small and ineffectual organization although rudimentary rocketry experiments may have been carried out with solid-propellant (i.e. gunpowder) rockets; little else is known of this group. There had been even earlier space-flight advocate organizations, starting in the former Soviet Union through the efforts of Fridrikh Arturovich Tsander in April 1924 with the “Interplanetary Communications Section” of the N.E. Zhukovsky Air Force Academy in Moscow and later known as “Obschestvo po Izutcheniyu Mezhplanetnykh Soobschenii” (OIMS, or Society for the Study of Interplanetary Communication); however, it only lasted a year. Far smaller similar groups also appeared in the USSR by the mid-20s. These included the “Space Studies Society” of Kiev and the “Ukrainian Astronautical Society” and perhaps other similarly named groups.

Evidently, the intense interest in spaceflight in the USSR during these years was initially due more to publicity filtering in the popular scientific press about Oberth and the American rocket pioneer Robert H. Goddard than about the work of Russia's own pioneer of the theory of spaceflight by rocket propulsion, Konstantin Eduardovich Tsiolkovsky whose own written works were paid out of pocket and not widely distributed in his country; but by the late 1920s, he did become more recognized. The level of interest was such that between April and June 1927 the “Interplanetary Section of the Association of Inventors” presented the “First World Exhibition of Interplanetary Machines and Mechanisms” at the Association of Inventors Building at 68 Tverskaya Street, Moscow. The “machines and mechanisms” were models; also exhibited were photos, busts, drawings, and articles and other publications that were provided by spaceflight and rocketry pioneers from “different countries.” Yet due to the isolated and closed nature of the Soviet Union at the time, practically no knowledge of the early Russian spaceflight groups, or of the historic exhibit, reached Western Europe and these efforts only became known very many years later.[7]

Upon the founding of the VfR in early June 1927, Winkler took on the responsibility of registering it. “This was required for business reasons,” according to Ley and it was done in the courts of Breslau. German law at the time, he continues, stipulated that the minimum number of people who could legally found a society was seven so that they made that number with two individuals to spare. The registration was indicated by not only recording the act in court records, but adding the letters e.V. (eingetragener Verein, or “registered society” that was comparable to adding “Inc.,” or “Incorporated” after a company name” in the U.S. However, Ley continues, the word “Raumschiffahrt” (spaceship travel or, simply “space travel,” was then “not defined in any (German) dictionary,” but after some deliberations “the court relented and, since new inventions require new words, it accepted the registration...under the condition that the document of registration itself define the name in an unmistakable manner.”

But as contrasted with the small and unsuccessful Austrian Wissenschaftliche Gesellschaft für Höhenforschung as well as the then, largely unknown groups in the USSR, the Verein für Raumschiffahrt e.V. (but usually shortened to VfR) flourished and within six months already claimed a world-wide membership of 500 (in his “The End of the Rocket Society,” Ley said that as early as two months after its founding, the VfR had already reached 400 members.); by September 1929 the number had risen to 870 then reached the 1,000 mark soon after. Among this membership were the foremost names in the fledgling science of what later became known as astronautics. It included, besides Valier, Oberth, von Hoefft; fellow Austrian Baron Guido von Pirquet; Walter Hohmann the city architect of Essen-on-the-Ruhr who wrote the very important book Die Erreichbarkeit der Himmelskörper (The Attainability of Celestial Bodies) (1925) about trajectories to the planets; and Robert Esnault-Pelterie of France. Another highly distinguished member was Professor Nikolai Alekseevich Rynin of the USSR, later to compile what is claimed as the world's first “encyclopedia” of space flight, the nine volume Mezhplanetnye Soobschniya (Interplanetary Communications) (1928-1932), which, however, was not a true encyclopedia with alphabetically arranged articles, but was enormously comprehensive nonetheless.

This huge success of the VfR was largely due to Winkler's wise decision to publish the Society's journal he titled Die Rakete (The Rocket), of which he served as the editor. This was the world's first magazine devoted entirely to rocket technology and spaceflight. However, Die Rakete already had a complicated pre-history and technically did not originate upon the founding of the Society.[8].

Die Rakete - Its Founding

In January 1927 - a full six months before the VfR was founded - Winkler had launched the Deutsche Jugend-Zeitung (German Youth Journal). The lead article was “Der Flug zum Monde, seine astronomischen und technischen Grundlagen” (“Flight to the Moon, its Astronomical and Technical Foundation"). However, issue No. 2 of April 1927 appeared almost identical in format but the most noticeable difference was its title: Die Rakete. Directly underneath the title he added a sub-title: Zeitshrift für Raumschiffahrt vereinigt mit “Deutsche Jugend-Zeitung” (Magazine for Spaceship Travel <or Spaceflight> associated with the "German Youth Journal").

Cover,  Die Rakete, for January-June 1927.
Cover, Die Rakete, for January-June 1927.

To make matters more confusing, the original Deutsche Jugend-Zeitung ran to 32 pages whereas the second issue, now titled Die Rakete, started with page 33. Soon after the establishment of the VfR, the membership wanted to acquire copies of the Deutsche Jugend-Zeitung/Die Rakete issues of the previous months but supplies had become exhausted. This explains why Winkler issued a special 28-page January-July 1927 “Ergängsheft” (“Supplement”) to Die Rakete of the VfR.

In other words, there were really two magazines called Die Rakete. To help set matters straight, the sub-title for the Die Rakete Supplement was sub-titled, Zeitschrift für Raumschiffahrt (Journal for Spaceflight) while the main journal itself, starting with the issue of 15 July 1927, was fully titled Die Rakete - Zeitschrift des Vereins für Raumschiffahrt E.V., Breslau (The Rocket - Journal of the Society for Space Travel Registered Society, Breslau). Fittingly, the lead article in the Supplement was “Der Flug zum Mond...” But the most important changes were that both the Supplement and the main journal were now devoted exclusively to the subject of spaceflight.[9]

Highlights of Issues of the First Year of Die Rakete, 1927

As may be expected, the field was almost brand new and not much literature existed on the possibilities of spaceflight at the time; not much real “news” could thus be reported in the opening issues. (Moreover, no experimentation had started - other than by Goddard in America, but he was altogether secretive and nothing was openly known of his activities, even in the U.S.) Consequently, the first issues of Die Rakete ran primarily theoretical pieces. These included possible trajectories (and most favorable launch times) for trips to the Moon, Mars, and other planets. There was also an article postulating on mathematical and other means of a spaceship crew communicating with inhabitants of Mars. Another, rather long article, discussed Einstein's theory of relativity - evidently to help better define the nature of space (and time).

In all likelihood, Winkler himself authored these pieces, particularly the latter topic, since his extant papers (now in the Deutsches Museum in Munich) contain numerous notes, lecture drafts, and articles on relativity besides the potential application of nuclear energy in spaceflight. (Winkler's papers show clear evidence that he maintained a deep interest in these topics throughout his life and in his final years he was still presenting glass-plate slide lectures on the possibilities of atomic (nuclear) rocket propulsion.)[10]

It is also clear that Winkler's own house at Breslau 13, Honehzollernstrasse Nr. 63/65, was the first headquarters of the VfR besides the editorial office of Die Rakete. The printer of Die Rakete was the firm of Otto Gutsmann, Breslau, Schubrücke 32. The subscription price was 60 Pfennigs plus postage for the “quarterly” (actually, monthly) journal and appeared on the 15th of each month and was available to all members gratis. The annual membership fee was five RM (Reichmarks).[11]

The cover of the first issue of the VfR's Die Rakete, issue of 15 July 1927, features a stylized picture of a huge, multi-engine liquid-propellant rocket ascending into space. It was probably drawn by Hans von Römer, one of the von Römer twins who beautifully illustrated all the popular works on spaceflight by Valier besides his lecture posters. (Botho von Römer, the brother of Hans, was a mechanical and aircraft construction engineer who provided technical advice for the art work.) Valier's biographer, Ilse Essers, credits the von Römer brothers as “the creators of the first (space) rocket poster.” The von Römers continued providing covers for Die Rakete and were thus among the first “space artists” and helped spread the spaceflight “idea” in these formative years of the pre-Space Age.

Also found in this issue is the anonymously-written brief article, “Die experimentelle Feststellung der Leistungsfähigkeit” (“The Experimental Assessment of the Performance of Rockets”) and presents the fundamental mathematical formula and drawing of a device to work out altitudes attained by rockets. However, it is merely the description of a simple quadrant on a stand (a tripod) for determining the altitude of a rocket, with the help of the triangulation method. It is not recorded if this device was built but the article does represent the earliest known suggestion of rocket-related “hardware” proposed by the VfR.[12].

The opening issue additionally featured the first part of a six part “cosmic fantasy” story by Valier, “Die Fahrt ins All” (“The Journey into Space”). The remaining parts appeared in subsequent issues up to December and was then published in book form as Auf Kühner Fahrt zum Mars - Eine Kosmische Phantasie (On a Daring Voyage to Mars -- A Cosmic Fantasy) (1928). Valier had another objective for writing the story: “The following tale introduces the very interesting problems of spaceflight in an entertaining way,” he wrote in his introduction. “It will be particularly welcome to the reader who has not received a technical education. The numerical data referred to are based on accurate calculations. Of course, it will be a long time before we have such well-constructed rocket machines...”[13].

It is important to note that, as was true in the earliest years of the later American Interplanetary Society, founded in 1930 and afterward known as the American Rocket Society, science fiction literature (more specifically, “interplanetary stories”) played a stronger role in attracting new members and circulating ideas on spaceflight in the earliest years of the VfR than is generally realized.

(It is likewise often overlooked that the spaceflight movement in Germany was stimulated not only by Oberth's Die Rakete, but also by Kurt Lasswitz' novel, Auf Zwei Planeten (On Two Planets) of 1897, as well as German translated versions of Verne's From the Earth to the Moon of 1865 that were both avidly read as youngsters by some of the leading members, Oberth included. Indeed, Ley credits Auf Zwei Planeten as one of the earliest works suggesting the space station - and living and moving in space, for that matter. Another very influential German author of interplanetary stories was Hans Dominik whose works included the short story Die Reise zum Mars (The Flight to Mars) as early as 1908; although he also produced larger, later works in this vein as Das Erbe der Uraniden (The Legacy of Uraniden) in 1928.[14].

Continue to Part 2


  1. ^ “Verein für Raumschiffahrt E.V.,” Die Rakete (Breslau), 15 July 1927, p. 84. The founding is also documented in the German aviation journal Der Luftweg, Heft 15, 10 August 1927, p. 205; Willy Ley, „The End of the Rocket Society,“ Astounding Science Fiction, Vol. 31, August 1943, p. 64; e-mail, Dorota Trąbka, Scientific Information Department, University of Wrocław, Poland, to Frank H. Winter, 24 May 2014, using the following works: Atlas Architektury Wrocław (Wydawnictwo Dolnoślaskie: Wrocław, 1997, pp. 159, 209, 281; and, Janusz Czerwiński, Wrocław Przewodnik (Wydawnictwo Eko-Graf: Wrocław, 2002), pp. 69, 264; Hermann Oberth, Die Rakete zu den Planetenräumen (Verlag R. Oldenbourg: Munich, 1923), (Reproduction by Uni-Verlag, Nürnberg, 1960), p. 7. Despite Goddard's shortcomings, he did play important roles in the development of spaceflight. For a detailed analysis of the initial impact of Goddard's A Method of Reaching Extreme Altitudes as well as his overall impact, see Frank H. Winter, “The Silent Revolution: How R.H. Goddard Helped Start the Space Age,” in Å. Ingemar Skoog, ed., History of Rocketry and Astronautics – Proceedings of the Thirty-Eighth History Symposium of the International Academy of Astronautics – Vancouver, British Columbia, Canada, 2004 (Univelt, Inc.: San Diego, 2011), pp. 3-54.
  2. ^  Willy Ley, “How It All Began,” Space World, Vol. 1, June 1961, p. 23. (A very brief biographical sketch of Ley is given in the later journal of the VfR, Die Rakete for 15 Aug. 1928, but says nothing about his being one of the founders; nor is there any mention of this in any issues of Die Rakete.) “Willy Ley,” Die Rakete, 2 Jahr., 15 August 1928, p. 126.
  3. ^ . Willy Ley, Rockets, Missiles & Space Travel (The Viking Press; New York, 1954), pp. 117, 124-126; Ley, “The End of the Rocket Society,” p. 65.
  4. ^  “Verein für Raumschiffahrt,” op. cit.; Ley, op. cit., p. 66.
  5. ^  Werner Brügel, Männer der Rakete (Hachmeister & Thal: Leipzig, (1933), pp. 100-113; Letter from Johannes Winkler to “the American Garrison,” 22 May 1945, Johannes Winkler Papers, now housed in the Deutsches Museum, Munich; Harns Barth, Hermann Oberth Briefwechsel (Kriterion Verlag: Bucharest, 1979), Vol. I, pp. 94, 96, 103, 105, 107, 109, 113, 116.
  6. ^  Headquarters, United States Strategic Air Forces in Europe, Office of Assistant Chief of Staff A-2, Technical Intelligence Report No. I-46, “Interview of Johannes Winkler Regarding Liquid Propellant Rocket Units,” by Dr. F.J. Ewing, H.R. Norris, and M.M. Mills, 26 May 1945, p. 1, copy in “Johannes Winkler” biographical file, National Air and Space Museum (hereafter, NASM), Smithsonian Institution, Washington, D.C.; Frank H. Winter, “Inventory of Johannes Winkler Papers,” 7 January 1983, p. 10, copy in “Johannes Winkler” biographical file, NASM (noting Winkler-Oberth correspondence of 6 October and 11 December 1926, besides later correspondence); “Winkler – Archiv,” p. 2, courtesy, Deutsches Museum, copy in the “Johannes Winkler” biographical file, NASM.
  7. ^  Frank H. Winter, Prelude to the Space Age – The Rocket Societies: 1924-1940 (Smithsonian Institution Press; Washington, D.C., 1983), pp. 27-33.
  8. ^  Ley, Rockets, Missiles, p. 117.
  9. ^  Mitchell Sharpe, “Johannes Winkler: Early Investigator in Liquid Propellants (1897-1947),” in Dr. Ernst A. Steinhoff, The Eagle Has Returned – Second Part – Vol. 45, Science and Technology – A Supplement to Advances in the Astronautical Sciences (Univelt, Inc.: San Diego, CA, 1976), p. 255; Ley, “The End of the Rocket Society,” pp. 64-65; Winter, Prelude, p. 36.
  10. ^  “On the VfR and `Die Rakete,'” Letter, Frederick I. Ordway, Spaceflight (London), Vol. 20, February 1978, pp. 78-79.
  11. ^  (Probably Johannes Winkler), “Der Flug zum Monde...,” Die Rakete - Ergängsheft, January-June 1927, pp. 2-7; “Nomographische Tafelen zur Raumschiffahrt,” Die Rakete - Ergängsheft, January-June 1927, pp. 9-13; “Ein Brief an die Marsbewhoner,” Die Rakete - Ergängsheft, January-June 1927, pp. 13-15; (Probably Johannes Winkler), “Die Einstsche Relativitätstheorie,” Die Rakete - Ergängsheft, January-June 1927, pp. 15-26.
  12. ^  Die Rakete - Ergängsheft, January-June 1927, p. 28.
  13. ^  I. Essers, Max Valier - A Pioneer of Space Travel (English translation of Max Valier - Ein Vorkampfer der Weltraumfahrt (1895-1930) (VDI-Verlag GmbH: Dusseldorf, 1968) (National Aeronautics and Space Administration: Washington, D.C., November 1976), NASA Technical Translation NASA TT F-664, p. 127; “Die experimentelle Feststellung der Leistungsfähigkeit,“Die Rakete, 15 July 1927, pp. 86-87.
  14. ^  Max Valier, “Die Fahrt ins All,” Die Rakete, 15 July 1927, pp. 87-92, et. seq.
  15. ^  Ley, Rockets, Missiles, pp. 45-48, 114, 148, 366n.; Robert Godwin, Hans Dominik and Hermann Oberth by Robert Godwin, The Space Library July 2014.