Balloon Design Research Articles

Superpressure balloon design

As scientists continue to make use of stratospheric platforms to position their instruments for astrophysical and atmospheric measurements there is an increasing need to lift larger payloads for extended periods of time. A superpressure balloon capable of supporting one metric ton for a period of one month at altitudes above 40 Km is now considered feasible. This has been made possible by an improved understanding of the upper atmosphere and the impact of this information on the mechanics of a completely sealed membrane structure. In addition to a refined set of requirements, new materials are now available which permit the engineer to design a far more robust system capable of surviving most of the atmospheric anomalies now envisioned. This paper will review a variety of areas which influence the selection of various elements of a superpressure balloon design. (1) The mechanism by which the payload is attached to the balloon has resulted in a variety of operational problems which may be eliminated by the design process. (2) The sensitivity of the state of stress to the mass of lifting gas will be discussed in detail. Unlike zero pressure balloons which automatically vent excess gas, the free lift of a superpressure bailloon is the result of a detailed study of the actual flight conditions to determine the precise limits of the inflation. (3) Materials may now be “designed” rather than selected as in the past. However, balloon manufacturing techniques must be considered in order to join the many gores together to form a pressure vessel. Finally, a preliminary design will be presented which is capable of achieving the projected needs of the science community for long duration flight in the stratosphere.

The hostile environment of the aging human aorta and the smaller patient- their implications for the intra-aortic balloon

Intra-aortic balloon counterpulsation (IABC) has been a clinical modality since 1968. In the intervening years the patient population has become older, sicker and smaller. Modern balloon design permits the insertion of balloons into this evolving patient population and the balloon is increasingly threatened by the calcific plaque of the aging aorta and by the geometry of the shorter descending thoracic aorta in the smaller patient. Balloon sizing consideration and radiographic verification of balloon position within the aorta will reduce the incidence of balloon damage during IABC.

French contribution to new balloon designs and materials

Research and development are permanent concerns in the French Balloon activity. One of the most significant improvements took place in the mid 80's in the field of materials, where linear low density polyethylenes demonstrated outstanding qualities at very low temperature, and allowed balloons to renew with success after the gap of the years 1985–1986. Successfull flights have since then been achieved under very cold temperatures, either in tropical or artic zones, with very large and heavily loaded balloons. Significant steps have equally been achieved in balloon design, thanks to a new approach using the finite elements method. Because of its versality, this method allows a very precise design of any shaped enveloppe (spherical, cylindrical, natural or else) with any type of appendix (belt, polar load, sleeve or else).

Recent advances in the structural analysis of scientific balloons

The analysis of balloon envelopes by the finite element (FE) method is plagued by convergence problems. A practical FE analysis approach is based on the fact that in thin shells with non-zero Gaussian curvature the membrane solution component is essentially decoupled from the bending solution component. A proxy-problem is solved by using a small artificial bending stiffness that assures convergence without significantly affecting the membrane solution component. This approach has been previously validated on slightly overpressurized balloon envelopes. Extensions of this approach to more difficult problems in the structural analysis of balloon envelopes are presented. The convergence forcing modelling measures are discussed. Implications of the findings of the analysis results to future balloon designs are also discussed.

NASA balloon design and flight: Philosophy and criteria

The catastrophic balloon failures during the first half of the 1980's were devastating to the USA scientific ballooning community as well as balloon users from other countries. Confidence in the balloons reached an all time low with success rates of 50% or lower being experienced across all payload ranges. An intensive investigation by the USA National Aeronautics and Space Administration (NASA) was initiated in 1983 to identify the cause(s) of the failures. Findings from the investigation resulted with NASA implementing a new balloon design and flight philosophy for all NASA scientific balloons. The NASA Balloon Program philosophy and criteria for scientific balloon design and flight are presented.

The Moby Dick Project: Reconnaissance Balloons over Russia by Curtis Peebles

Technology and culture Book Reviews 833 other words, the book could have benefited from going substantially farther. Barton C. Hacker Dr. Hacker is historian at the Lawrence Livermore National Laboratory. The Moby Dick Project: Reconnaissance Balloons over Russia. By Curtis Peebles. Washington, D.C.: Smithsonian Institution Press, 1991. Pp. ix + 250; illustrations, notes. $40.00. Rapid demobilization in the wake of World War II left the United States intelligence community fragmented and diminished at a time when the threat posed by the Soviet Union was becoming increasingly apparent. The reorganization and expansion of intelligence in the late 1940s was largely a response to the pressing need to learn more about Soviet capabilities and intentions. It was soon realized that the creation of effective espionage networks within the Soviet Union would be a time-consuming task. The use of technical means of gathering information promised more immediate results, hence the development of such methods became characteristic of the burgeon­ ing U.S. intelligence effort. Curtis Peebles alludes to this background when he states, “In the early years of the Cold War, the Soviet Union was a blank threatening void,” and he goes on to describe his book as “a history of the first attempt to light that darkness: reconnaissance balloons” (p. 1). Actu­ ally, the balloons were not the first U.S. attempt to reconnoiter the Soviet Union. Airplanes had been used to obtain photographic and electronic intelligence by flying along the Soviet perimeter and brief flights over Soviet territory had been carried out. But these forays into Soviet airspace had revealed that the defenses were too formidable to allow conventional military airplanes to make the repetitive overflights ofareas deep within the Soviet Union that were needed by intelligence analysts. The balloon program represented the first deployment of a reconnaissance vehicle specifically designed to achieve this objective. The balloons were only marginally successful and were soon superseded by other vehicles—first by special airplanes and later by satellites. Nevertheless, the balloon program was significant because its qualified success validated the development of the more suitable vehicles that followed and because the advances in balloon design and construction achieved by the program greatly enhanced the utility of balloons as platforms for scientific research. This book, therefore, deals with an important and little-known aspect of the history of balloon technology. Moreover, the book delivers more than the title suggests. Peebles not only presents a thorough account of the MOBY DICK reconnais­ sance balloon project but, as background, devotes nearly as many 834 Book Reviews TECHNOLOGY AND CULTURE pages to a history of balloons both as reconnaissance and attack vehicles. The modern use of attack balloons is a facet of balloon history even less well known than the role of balloons in reconnoitering the Soviet Union. The public is generally unaware that the United States developed a balloon “bomber” in World War I; that the Japanese deployed transpacific balloons to bomb the United States in World War II (project FUGO); that the British used balloons to drop incendiary bombs on occupied Europe during much of World War II (OUTWARD); and that the United States developed an attack balloon in the 1950s to deliver chemical and biological weapons of mass destruction (FLYING CLOUD). Peebles describes these projects as well as those in which balloons were employed for reconnaissance and other tasks (e.g., bombing Venice in 1849, dropping propaganda leaflets in World War I, and monitoring Soviet atomic tests during the Cold War) as part of a history of the military uses of balloons from 1794 to 1958. He also briefly describes the political context in which advances in balloon technology occurred. The book thus forms a valuable addition to the literature on ballooning that, for the most part, deals with their nonmilitary applications. The book has a few shortcomings: Peebles has failed to provide an index, he relies too heavily on secondary sources, and his technical descriptions lack detail. These are relatively minor flaws, however, in a wide-ranging and well-written account of an underreported seg­ ment of technology. Charles A. Ziegler Dr. Ziegler, lecturer in cultural anthropology at Brandeis University, holds advanced degrees in anthropology and physics and has a special...

Efficacy of Percutaneous Mitral Balloon Valvuloplasty With the Inoue Balloon

Percutaneous mitral balloon valvuloplasty has become an accepted technique for use in selected patients with severe, symptomatic mitral stenosis. Recently, a new balloon catheter with an "hourglass" shape and specially designed guidewires and dilators has become available (Inoue balloon). The design of this balloon provides ease of manipulation and self-stabilization across the mitral valve during inflation. These features should decrease the incidence of complications associated with the procedure. Preliminary results in 12 consecutive patients who underwent percutaneous mitral balloon valvuloplasty with the Inoue balloon are presented. The mitral valve area increased from 0.92 +/- 0.21 cm2 before the procedure to 1.75 +/- 0.40 cm2 after the procedure. No complications occurred from the procedure, including no increase in severity of mitral regurgitation or creation of an atrial septal defect. Further follow-up is necessary to determine the long-term efficacy with this new balloon. Nonetheless, the preliminary results are encouraging.

Aortic valvuloplasty of calcific aortic stenosis with monofoil and trefoil balloon catheters: practical considerations

In order to evaluate the relation between balloon design (monofoil, trefoil) and valvular configuration, experimental aortic valvuloplasty was performed in four post-mortem hearts with calcific aortic stenosis of various morphology. The degree of obstruction of the aortic orifice was assessed by computed axial tomography during inflation of monofoil 15 and 19 mm and trefoil 3 x 12 mm balloon catheters. We also evaluated the hemodynamic repercussion of balloon inflation (fall in systolic aortic pressure) in four elderly patients with acquired aortic stenosis who underwent a percutaneous transluminal aortic balloon valvuloplasty, with stepwise increasing balloon sizes of 15 mm, 19 mm and 3 x 12 mm, as during our in vitro experiments, and who underwent aortic valve replacement later on. In these patients, we correlated the anatomy of the excised aortic valves with the retrospective analysis of aortic pressure curves recorded during previous valvuloplasty procedures. Our experimental and clinicopathological observations showed that the degree of obstruction of the aortic orifice in post-mortem specimens and the tolerance to balloon inflation in live patients are dependent of the valvular configuration. Although trefoil balloons have the theoretical advantage to avoid complete obstruction of the aortic orifice during inflation, we observed that in presence of a tricuspid configuration, they could be potentially more occlusive than monofoil balloons since each of the 3 individual components of the trefoil balloon occupied the intercommissural spaces while inflated. However, they offered more residual free space when inflated in aortic valves with a bicuspid configuration (i.e. congenitally bicuspid valves or tricuspid valves with one fused commissure). In our opinion, these observations are relevant, since degenerative disease of the aortic valve (i.e. tricuspid valve without commissural fusion) is now recognized as the most common etiology of aortic stenosis in the elderly.

Development of balloon technology in China

The first stage in the development of the Chinese scientific balloon facility, commenced in 1979, has been completed successfully. The targets of the second stage, started in 1985 are: increasing balloon volume up to 4×10 5M 3 and payload carrying capacity 1000–1500 kg.; long duration flights from Beijing to the Gobi region in North west China; developing a new telemetry and telecommand system. In this paper we present the recent progress in China on balloon materials, balloon design and manufacture procedures, launch and recovery techniques, telemetry and telecommand facilities etc.

An improved shape for zero-pressure balloons

Since the 1950s, efforts have been made to optimise the design of zero-pressure balloons. A possible method for improving on the classical natural-shape is discussed in this paper. It is shown by surface element analysis, that the meridional stress in the balloon film can be adjusted by changing the circumferential stress. It is probable that the stress concentration at the top of a natural-shape balloon can be reduced. A mixed-shape balloon, which has positive circumferential stress above the maximum diameter, has been derived and the results are presented in a form similar to Smalley's ‘sigma’ table. The stress distribution for balloons having different shapes, with or without load tapes, are also described.

A stress index model for balloon design

The modern day scientific research balloon has historically maintained an approximate 85% success rate as launched by the USA National Scientific Balloon Facility (NSBF). Failures were across all operational phases and modes. Balloons fabricated after 1980 have met with less favorable results with catastrophic failures on ascent becoming the principle failure mode. In 1983, the USA National Aeronautics and Space Administration (NASA) conducted an intensive investigation to identify the possible causes for these failures. Although the most probable cause was identified as the balloon material, additional contributing factors were identified. One of these factors, balloon stress, was calculated using a stress equation defining only the total required thickness for launch. No model existed to predict the stress distribution in an ascending balloon. Early in 1984, NASA began the development of a stress index model to establish the relative stress magnitudes at any altitude. Studies were conducted applying this model to several hundred balloon flights. The study indicated a strong correlation between stress levels, failure rates, and the point of maximum stress coinciding with observed failure locations. In January 1985, NASA instituted a stress index design and flight specification that all NASA balloons must meet. The details and results of this work are presented.

Buoyant station mission concepts for Titan exploration

An advanced mission to this unique satellite of Saturn appropriate to the turn-of-the-century time period is described. The mission concept evolves about one or more buoyant stations (balloons and/or airship) operating at varying altitudes in Titan's atmosphere. An orbiter of Titan provides communications link support and accomplishes remote sensing science objectives. Use of buoyant stations are favored over a fixed site lander for two reasons: (1) adaptable to several possible surface physical states and topographies; and (2) capable of exploring both the atmosphere and surface with regional and possibly global mobility. Auxiliary payload concepts investigated include tethered packages and sounding rockets deployed from the buoyant station, and haze probes and surface penetrators deployed from the orbiter. The paper describes science objectives and payloads, propulsion system/mass delivery trades, balloon design requirements and deployment/motion characteristics, and communications link geometry and data characteristics.

Balloon materials and designs

Improvements of materials can extend the performance of scientific balloon flights in altitude, suspended load and duration. The impact of new materials is considered in the design of superpressure balloons for long duration improvement, ultra light weight for sounding balloons, and a launch technique for minimizing relative wind problems.

The development of plastic, zero pressure balloon design since 1945

There have been four major thrusts in plastic, zero pressure balloon design in the U.S. since the late 1940's. First, the pioneer balloonists made designs according to geometric shapes. When these balloons began to fail, a study at the University of Minnesota produced the first mathematical model for determining the proper design for “natural shaped” balloons. With the advent of high speed digital computing came the “Sigma” tables of the 1960's. When computers became more widespread and inexpensive, direct or “full-sized” designs began to be used. Now, with the problems involved in flying heavy payloads (greater than 400 lbs) and super pressure balloons, a new tool has become available to the balloon designer. An inexpensive stress analysis code is available but is as yet unproven.

Zero-Pressure Balloon Design

In atmospheric balloon research it is very important to describe accurately the balance of forces applied to a film and to use this analytical description to produce a suitable manufactured balloon shape. This paper investigates several additions to the presently accepted method for free balloon design. This includes a study of the nonuniform stress state created by the inclusion of load tapes in the theoretical model. The effects of balloon material properties and deformations are also considered. These refinements result in a more accurate theoretical model and an improved design for atmospheric balloons.

Superpressure Balloon Flights in the Tropical Boundary Layer

Abstract Two series of quasi-constant-level pressurized balloons have been flown within the tropical planetary boundary layer, preliminary to a larger experiment for exploring the low-level flow over the Indian Ocean. The first flight series from a South Pacific island indicated a very short life expectancy of the equipment due to the high probability of the vehicle being overloaded by rain drops or dew and the catastrophic effect of immersion. A second series of flights from Ascension Island in the South Atlantic was performed to test a new and completely self-enclosed balloon design, as well as a metalized reflecting screen for radiative control of the envelope temperature. This new design demonstrated acceptable vertical stability, thus proving the feasibility of long-duration quasi-horizontal balloon flights at levels as low as 500 m above the sea surface.

Safety of Intraaortic balloon pumping. I. Biochemic and hematologic values influenced by use of balloon

Safety of mechanical circulatory assistance by intraaortic balloon pumping (IABP) for 3 days in 37 healthy calves was investigated using 3 balloon designs. A single-chambered device A in 10 animals and a triple-chambered device B in 12 animals were pumped without clinical complications. Eight of 15 animals with device C (dual-chamber) did not survive 3 days of IABP. Observations of a series of blood biochemical and hematological parameters during the prolonged IABP indicate significant changes common to all the experimental animals as follows: (1) the peripheral blood was invariably flooded with leukocytes, (2) changes in the serum albumin/globulin fraction ratios were due to increases in the beta and gamma globulin fractions, and (3) there was an appreciable increase in the total blood fibrinogen. These changes were presumably due to intravascular trauma produced by the prolonged pumping of the mechanical circulatory assists. The precise source of the intravascular damage was uncertain, however.

The Limitations of Wind Measurement Accuracy for Balloon Systems

The error in horizontal wind field measurements as computed from the trajectory of balloons with linear and quadratic rise rates (as functions of altitude) has been derived. Balloon trajectories through light, moderate, and severe wind fields have been considered. Figures are presented which show the wind error vs altitude for various rise rates in each wind field, assuming linear smoothing of the trajectory data. The rise rate profile of the Jimsphere is analyzed as a special case. The results and figures presented are useful in determining the ultimate capability of rising balloon systems in general and for the Jimsphere system in particular for measuring wind from the surface to 18 km. Using the figures presented, it is possible to estimate the wind accuracy that can be achieved by any type of rising balloon by knowing only its rise rate behavior vs altitude. In addition, the results can be used in balloon design to determine what rise rate function is needed to achieve specified wind accuracies. A table is presented which shows the balloon radius for smooth and roughened spheres needed to achieve 2 to 20 m/sec rise rates at 10 and 14 km altitudes.

A Stability Analysis for Tethered Aerodynamically Shaped Balloons

This work investigates the dynamic stability of tethered, aerodynamically shaped balloons by considering the system to pose essentially a cable problem, with the balloon's dynamics giving end and auxiliary conditions. This physical model gives a first-order problem in a sequence of partial differential wave equations with nonhomogeneous boundary conditions. Further, these equations uncouple to give a lateral problem and a longitudinal problem—as in first-order airplane dynamics. The solution of either problem takes the form of a transcendental characteristic equation for the stability roots, from which these roots are extracted by using an electronic computer and a roots locus plot. Further, this theory was applied toward the development of a highperformance tethered balloon design, and the results showed that good stability was attainable by the use of large and aerodynamically efficient fins.

Intra-aortic balloon experiments in a lumped-element hydraulic model of the circulation

A lumped-element hydraulic model of the arterial system was designed consistent with physiologic measurements of input impedance as seen from the heart. Experiments simulated trials of intra-aortic balloons in both humans and dogs, for both liquid and gas inflation. Both the conventional ‘limp’ intra-aortic balloon and a balloon design including longitudinal mechanical constraints were tested. The ‘beamed balloon’ was found in every case to overcome a serious problem of limp balloon operation, the ‘bubble-blowing phenomenon’.