Papers by christian gelzer
The journal of transport history, Sep 1, 2005
The accuracy of the Content should not be relied upon and should be independently verified with p... more The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden.
Technology and Culture, 2004
Quest: The History of Spaceflight Quarterly, 2020
In 1973 engineers at Dryden began investigating ways to reduce aerodynamic drag on land vehicles.... more In 1973 engineers at Dryden began investigating ways to reduce aerodynamic drag on land vehicles. They began with a delivery van whose shape they changed dramatically, finally reducing its aerodynamic drag by more than 5 percent. They then turned their attention to tracator-trailers, modifying a cab-over and reducing its aerodynamic drag by nearly 25 percent. Further research identified additional areas worth attention, but in the intervening decades few of those changes have appeared.
For nearly a century Ludwig Prandtl's lifting-line theory remains a standard tool for underst... more For nearly a century Ludwig Prandtl's lifting-line theory remains a standard tool for understanding and analyzing aircraft wings. The tool, said Prandtl, initially points to the elliptical spanload as the most efficient wing choice, and it, too, has become the standard in aviation. Having no other model, avian researchers have used the elliptical spanload virtually since its introduction. Yet over the last half-century, research in bird flight has generated increasing data incongruous with the elliptical spanload. In 1933 Prandtl published a little-known paper presenting a superior spanload: any other solution produces greater drag. We argue that this second spanload is the correct model for bird flight data. Based on research we present a unifying theory for superior efficiency and coordinated control in a single solution. Specifically, Prandtl's second spanload offers the only solution to three aspects of bird flight: how birds are able to turn and maneuver without a verti...
This presentation and companion text describe the history of the development of Reaction Control ... more This presentation and companion text describe the history of the development of Reaction Control Systems.
The author examines early research regarding return flight from a Moon landing made prior to Pres... more The author examines early research regarding return flight from a Moon landing made prior to President Kennedy's 1961 challenge to put men on the Moon before the end of the decade. Organizations involved in early research include NACA, the Flight Research Center (now Dryden) Bell Aircraft Corporation. The discussion focuses on development of a flight simulator to model the Moon's reduced gravity and development of the Lunar Landing Research Vehicle.
Technology's Stories
In 1830 the Lancaster, Ohio school board observed with one voice that if God Gelzer-Speed is a Vi... more In 1830 the Lancaster, Ohio school board observed with one voice that if God Gelzer-Speed is a Virtue June 2015 transit, and its importance so assumed, that few think to explain why it is that haste in transit is so important to Americans' daily life. There was something distinct in the American desire for speed, a desire that knew few bounds and which became vested with a degree of nobility. This peculiarity stemmed from a number of influences: a Protestantism that, by the beginning of the nineteenth century, was already distinct from its European ancestry-and became more so as the years passed; the nation's geography and topography, a nation whose size dwarfed all of Western Europe; a social fluidity that fascinated and perturbed foreign visitors unaccustomed to loosely-defined classes; and the opportunities that came with the founding of a new government. With all this in mind, to Americans the quest for speed was not simply a convenience, a distraction, or a thrill: it was a virtue. There are several reasons for this development to consider. The immensity of the country is perhaps the most obvious. Travel time between Baltimore and Washington, D.C., in 1812, the year in which the first steamboat, the New Orleans , began plying the waters of the Mississippi, took a three-horse coach a day-and-a-half. 3 Riders traveling from Providence to Boston, a trip of fifty miles over long-established roads, had to settle for a journey of just under five hours. "If anyone wants to go faster," wrote one traveler to a friend in 1822, "he may send to Kentucky and charter a streak of lightning." 4 Nevertheless, we cannot account for this desire for a speedy voyage simply by nodding to the expansive territory Americans progressively occupied and the enormous distances they had to cross, however real those observations: that does not, by itself, account for a readiness to risk everything.
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Papers by christian gelzer