Abstract
Observations on the method of determining the velocity of airships
Volterra, Vito,
NACA TM-24, June 1921, pp. 17.
Abstract
Large German airship stations
Sabatier, J,
NACA TM-36, August 1921, pp. 13.
Abstract
The employment of airships for the transport of passengers
Umberto Nobile,
NACA TN 63, Aug 1921, pp. 42.
Abstract
The R-38 catastrophe and the mechanics of rigid airship construction
Herrera, Emilio,
NACA TM-105, June 1922, pp. 16.
Abstract
The future of the airship
Warner, Edward P (Massachusetts Inst. of Tech),
NACA TM-121, July 1922, pp. 6.
Abstract
Principle of the Boerner airship
Kapteyn, A,
NACA TM-154, November 1922, pp. 8.
Abstract
Comparison of nonrigid and semirigid airships
Stapfer,
NACA TM-163, November 1922, pp. 4.
Abstract
Causes of failure of airship sheds
Sonntag, R; Hoff, W,
NACA TM-171, November 1922, pp. 13.
Abstract
Balloon fabrics made of goldbeater's skins
Chollet, L (Technical Section of Aeronautics (S.T.Ae.)),
NACA TM-172, December 1922, pp. 14.
Abstract
Stresses produced on an airship flying through gusty air
Max M. Munk,
NACA TN-111, September, 1922, pp. 6.
Abstract
The dead weight of the airship and the number of passengers that can be
carried
Colonel Crocco, Aeronautical Experimental Institute (September,
1920: Rome, Italy).
NACA TN-80, January, 1922, pp. 24,
Abstract
Surface area coefficients for airship envelopes
W. S. Diehl, Originally prepared as Aircraft Technical Note No.
199,
Bureau of Construction and Repair, Navy Dept.
NACA TN-86, February, 1922, pp. 8
Abstract
Hydrostatic tests of an airship model
Slightly revised form of the unpublished report #22, Construction
Department, Navy Yard, Washington, D.C.
Aeronautics Staff, Construction Department, Navy Yard,
Washington, D. C.,
NACA TN-87, March, 1922, pp. 20
Abstract
The choice of the speed of an airship
Max M. Munk,
NACA TN-89, March, 1922,pp. 10.
Abstract
Bending moments, envelope, and cable stresses in non-rigid airships
Burgess, C P,
NACA Report 115, 1923, pp. 13.
Abstract
The drag of Zeppelin airships
Munk, Max M,
NACA Report 117, 1923, pp. 11.
Abstract
The drag of C class airship hull with varying length of cylindric midships
Zahm, A F; Smith, R H; Hill, G C,
NACA Report 138, 1923, pp. 9.
Abstract
The drag of C class airship hull with varying length of cylindric midships
Zahm, A F; Smith, R H; Hill, G C,
NACA Report 138, 1923, pp. 9.
Abstract
Notes on aerodynamic forces on airship hulls
L. B. Tuckerman,
NACA TN-129, March, 1923, pp. 34.
Abstract
General theory of stresses in rigid airship, ZR-1
W. Watters Pagon,
NACA TN-140, May, 1923, pp. 47.
Abstract
An airship slide rule
Weaver, E R; Pickering, S F,
NACA Report 160, 1924, pp. 11.
Abstract
The inertial coefficients of an airship in a frictionless fluid
Bateman, H,
NACA Report 164, 1924, pp. 16.
Abstract
The aerodynamic forces on airship hulls
Munk, Max M,
NACA Report 184, 1924, pp. 18.
Abstract
Note on the pressure distribution over the hull of elongated airships with
circular cross section
Max M. Munk,
NACA TN-192, May, 1924, pp. 5.
Abstract
A method of determining the dimensions and horsepower of an airship for any
given performance
C. P. Burgess,
NACA TN-194, May, 1924, pp. 18.
Abstract
A study of static stability of airships
Frank Rizzo,
NACA TN 204, Sep 1924, pp. 77.
Abstract
Forces on airships in gusts
Burgess, C P,
NACA Report 204, 1925, pp. 8.
Abstract
Determination of turning characteristics of an airship by means of a camera
obscura
Crowley, J W; Jr Freeman, R G,
NACA Report 208, 1925, pp. 8.
Abstract
Pressure distribution on the nose of an airship in circling flight
Fairbanks, Karl J,
NACA TN-224, August 1925, pp. 6.
Abstract
Inertia factors of ellipsoids for use in airship design
Tuckerman, L B,
NACA Report 210, 1926, pp. 7.
Abstract
Water model tests for semirigid airships
Tuckerman, L B,
NACA Report 211, 1926, pp. 14.
Abstract
Stability equations for airship hulls
Zahm, A F,
NACA Report 212, 1926, pp. 4.
Abstract
Air forces, moments and damping on model of fleet airship Shenandoah
Zahm, A F; Smith, R H; Louden, F A,
NACA Report 215, 1926, pp. 32.
Abstract
Pressure distribution on the C-7 airship
Crowley, J W Jr; Defrance, S J,
NACA Report 223, 1926, pp. 41.
Abstract
The drag of airships
C. H. Havill,
NACA TN 247, Jan 1926, pp. 28.
Abstract
The drag of airships: drag of bare hulls II
Clinton H. Havill,
NACA TN 248, Oct 1926, pp. 35.
Abstract
Tests of the N.P.L. airship models in the variable density wind tunnel
George J. Higgins,
NACA TN 264, Sep 1927, pp. 12.
Abstract
Helium tables
Clinton H. Havill,
NACA TN 276, Jan 1928, pp. 20.
Abstract
Drag of C-class airship hulls of various fineness ratios
Zahm, A F; Smith, R H; Louden, F A,
NACA Report 291, 1929, pp. 16.
Abstract
Speed and deceleration trials of U.S.S. Los Angeles
De France, S J (Bureau Of Aeronautics (Navy), Washington, DC);
Burgess, C P,
NACA Report 318, 1930, pp. 20.
Abstract
Flight tests on U.S.S. Los Angeles. Part I: full scale pressure distribution
investigation
De France, S J,
NACA Report 324, 1930, pp. 33.
Abstract
Flight tests on U.S.S. Los Angeles. Part II: stress and strength
determination
Burgess, C P,
NACA Report 325, 1930, pp. 16.
Abstract
Full-scale turning characteristics of the U.S.S. Los Angeles
Thompson, F L,
NACA Report 333, 1930, pp. 14.
Abstract
Airship model tests in the variable density wind tunnel
Abbott, Ira H,
NACA Report 394, 1932, pp. 25.
Abstract
The drag characteristics of several airships determined by deceleration tests
Thompson, F L; Kirschbaum, H W,
NACA Report 397, 1932, pp. 13.
Abstract
Application of practical hydrodynamics to airship design
Upson, Ralph H; Klikoff, W A,
NACA Report 405, 1933, pp. 18.
Abstract
Measurements of flow in the boundary layer of a 1/40-scale model of the U. S.
Airship "Akron."
Freeman, Hugh B,
NACA Report 430, 1933, pp. 13.
Abstract
Force measurements on a 1/40-scale model of the U. S. Airship "Akron."
Freeman, Hugh B,
NACA Report 432, 1933, pp. 16.
Abstract
Pressure-distribution measurements on the hull and fins of scale model of the
U. S. Airship "Akron."
Freeman, Hugh B,
NACA Report 443, 1934, pp. 13.
Abstract
Procedure for determining speed and climbing performance of airships
Thompson, F L,
NACA TN-564, April 1936
Abstract
Ground-handling forces on a 1/40-scale model of the U. S. Airship "Akron."
Silverstein, Abe Gulick, B G,
NACA Report 566, 1937, pp. 11.
Abstract
Pressure-distribution measurements at large angles of pitch on fins of
different span-chord ratio on a 1/40-scale model of the U. S. Airship "Akron."
Mchugh, James G,
NACA Report 604, 1937
To obtain the absolute velocity of an airship by knowing the speed at which two routes are covered, we have only to determine the geographical direction of the routes which we locate from a map, and the angles of routes as given by the compass, after correcting for the variation (the algebraical sum of the local magnetic declination and the deviation).
A .PDF file of this report (449995 bytes): naca-tm-24.pdf
No Abstract Available
A .PDF file of this report (705454 bytes): naca-tm-36.pdf
It was a conclusion of this detailed study of the practicality of using airships for carrying passengers that, although slow, airships are capable of carrying useful loads over long distances. However, it is noted that there is a certain limit to the advantages of large cubature. Beyond a certain point, the maximum altitude of the airship goes on decreasing, in spite of the fact that the range of action in the horizontal plane and the useful load go on increasing. The possibility of rapid climb is an essential factor of security in aerial navigation in the case of storms, as is velocity. To rise above and run ahead of storms are ways of avoiding them. However, high altitude and high speed are antithetical. This investigation concluded that a maximum velocity of 120 km/h is as far as we ought to go. This figure can only be exceeded by excessive reduction of the altitude of ceiling, range of flight, and useful load. The essential requisites of a public transport service are discussed, as are flight security, regularity of service, competition with other forms of passenger transportation, and the choice between rigid and semi-rigid airships.
A .PDF file of this report (4913413 bytes): naca-tn-63.pdf
An airship frame may be regarded as a rigid girder subjected to a number of forces which, according to their nature, may be classified as follows: weight or loads (force of gravity); lifting forces (aero-static); accelerations (dynamic). These forces must be in equilibrium in the three most important cases during flight: 1) when the airship is floating (aerostatic problem); 2) when flying without acceleration (aerodynamic problem). 3) When under the influence of any accelerating force (dynamic problem). This report will briefly discuss each of these cases in regard to the R-38 airship accident.
A .PDF file of this report (602414 bytes): naca-tm-105.pdf
The author discusses the safety record of airships in light of the accidents with the Roma and the ZR2.
A .PDF file of this report (258386 bytes): naca-tm-121.pdf
The Boerner airship is built on entirely different principles from ordinary airships, of which the Zeppelin is the best known type. Mr. Boerner has abandoned the rigid body of the Zeppelin and has adopted a body with a double keel forming a rigid platform for attaching the gas ballonets, which must support the whole in the air.
A .PDF file of this report (262544 bytes): naca-tm-154.pdf
One of the main subjects of airship science consists in establishing cooperation between two vertical forces, the buoyancy of the air and the attraction of gravity. The mechanism for establishing this cooperation must have the minimum weight and offer the minimum head resistance. Starting with this principle, let us consider what improvements can be made in the present type of non-rigid airships.
A .PDF file of this report (97975 bytes): naca-tm-163.pdf
Different causes of airship shed collapse are discussed, with suction and human carelessness being the prime causes.
A .PDF file of this report (615690 bytes): naca-tm-171.pdf
Goldbeater's skin, which is the prepared outside membrane of the large intestine of an ox, is examined as a balloon fabric and details of how goldbeater's skin is prepared for use are provided. The construction techniques employed by Germany, France, and England are all discussed.
A .PDF file of this report (483557 bytes): naca-tm-172.pdf
The stresses produced by gusts are proportional to the speed of the airship. At highest speed they are of the same range of magnitude as the stresses during the creation of a large dynamic lift.
A .PDF file of this report (287340 bytes): naca-tn-111.pdf
In order to determine an approximate formula giving the weight of a dead load as a function of the volume (V) of the envelope and of the maximum velocity (v), we will take the relative weight of the various parts of the airship (P(sub v), M, V, A, T(sup 34)), adopting a mean value of the coefficients determined. This formula may be adopted both for semi-rigid airships with suspended nacelle and non-rigid envelope, with or without internal suspensions. It may also be adapted to airships with rigid longitudinal beam, with power units on external supports or in nacelles, and with non-rigid envelopes, with or without internal bracing cables.
A .PDF file of this report (1009310 bytes): naca-tn-80.pdf
In naval architecture, it is customary to determine the wetted surface of a ship by means of some formula which involves the principal dimensions of the design and suitable constants. These formulas of naval architecture may be extended and applied to the calculation of the surface area of airship envelopes by the use of new values of the constants determined for this purpose. Surface area coefficients were calculated from the actual dimensions, surfaces, and volumes of 52 streamline bodies, which form a series covering the entire range of shapes used in the present aeronautical practice.
A .PDF file of this report (259011 bytes): naca-tn-86.pdf
An airship model made by the Goodyear Rubber Company was filled with water and suspended from a beam. The deformations of the envelope were studied under the following conditions: 1) both ballonets empty; 2) forward ballonets filled with air; 3) rear ballonets filled with air; and 4) both ballonets filled with air. Photographs were taken to record the deflections under each of these conditions, and a study was made to determine the minimum head of water necessary to maintain the longitudinal axis of the envelope under these conditions. It was concluded that any pressure sufficient to keep the airship full may be used. It appears that a pressure of one inch of water would provide a suitable factor of safety, and therefore it is the pressure that is recommended.
A .PDF file of this report (962395 bytes): naca-tn-87.pdf
The favorable speed of an airship is chiefly determined by the condition of the consumption of the least amount of fuel per unit of traveled distance, although other conditions come into play. The resulting rules depend on the character of the wind and on the variability of the efficiency of the engine propeller units. This investigation resulted in the following rules. 1) Always keep the absolute course and steer at such an angle with reference to it as to neutralize the side wind. 2) In a strong contrary wind, take a speed one and one half times the velocity of the wind. 3) As a general rule, take the velocity of the wind and the velocity of the course component of the wind. Add them together if the wind has a contrary component, but subtract them from each other if the wind has a favorable component.
A .PDF file of this report (344732 bytes): naca-tn-89.pdf
This report describes the theory of calculating the principal stresses in the envelope of a nonrigid airship used by the Bureau of Aeronautics, United States Navy. The principal stresses are due to the gas pressure and the unequal distribution of weight and buoyancy, and the concentrated loads from the car suspension cables. The second part of the report deals with the variations of tensions in the car suspension cables of any type of airship, with special reference to the rigid type, due to the propeller thrust or the inclination of the airship longitudinally.
A .PDF file of this report (743638 bytes): naca-report-115.pdf
This report is a discussion of the results of tests with Zeppelin airships, in which the propellers were stopped as quickly as possible while the airship was in full flight. In this paper the author refers to the theory involved in these tests and calls attention to one scientifically interesting fact which can be derived from the tests and which has not yet been noted. The most important question concerning the tests is, of course: does the negative acceleration of an airship with stopped propellers supply proper data for determining the drag of the airship when in uniform flight? This can not be absolutely answered, however, except that in this particular case the agreement is sufficient and that the data obtained from the test are the true quantities, or, at least, the approximate quantities wanted.
A .PDF file of this report (542957 bytes): naca-report-117.pdf
A model of the C class airship hull, when severed at its major section and provided with a cylindric mid-body of variable length, had its air resistance increased about in proportion to the length of the mid-body up to 3 diameters, and in about the manner to be expected from the increase of skin friction on this variable length. For greater length the drag increased less and less rapidly.
A .PDF file of this report (344647 bytes): naca-report-138.pdf
For a first approximation the air flow around the airship hull is assumed to obey the laws of perfect (i.e. free from viscosity) incompressible fluid. The flow is further assumed to be free from vortices (or rotational motion of the fluid). These assumptions lead to very great simplifications of the formulae used but necessarily imply an imperfect picture of the actual conditions. The value of the results depends therefore upon the magnitude of the forces produced by the disturbances in the flow caused by viscosity with the consequent production of vortices in the fluid. If these are small in comparison with the forces due to the assumed irrotational perfect fluid flow the results will give a good picture of the actual conditions of an airship in flight.
A .PDF file of this report (1306407 bytes): naca-tn-129.pdf
(no abstract available)
A .PDF file of this report (2255161 bytes): naca-tn-140.pdf
This report prepared for the National Advisory Committee for Aeronautics, describes an airship slide rule developed by the Gas-Chemistry Section of the Bureau of Standards, at the request of the Bureau of Engineering of the Navy Department. It is intended primarily to give rapid solutions of a few problems of frequent occurrence in airship navigation, but it can be used to advantage in solving a great variety of problems, involving volumes, lifting powers, temperatures, pressures, altitudes and the purity of the balloon gas. The rule is graduated to read directly in the units actually used in making observations, constants and conversion factors being taken care of by the length and location of the scales. It is thought that with this rule practically any problem likely to arise in this class of work can be readily solved after the user has become familiar with the operation of the rule; and that the solution will, in most cases, be as accurate as the data warrant.
A .PDF file of this report (599990 bytes): naca-report-160.pdf
This report deals with the investigation of the apparent inertia of an airship hull. The exact solution of the aerodynamical problem has been studied for hulls of various shapes and special attention has been given to the case of an ellipsoidal hull. In order that the results for this last case may be readily adapted to other cases, they are expressed in terms of the area and perimeter of the largest cross section perpendicular to the direction motion by means of a formula involving a coefficient K which varies only slowly when the shape of the hull is changed, being 0.637 for a circular or elliptic disk, 0.5 for a sphere, and about 0.25 for a spheroid of fineness ratio 7. For rough purposes it is sufficient to employ the coefficients, originally found for ellipsoids, for hulls otherwise shaped. When more exact values of the inertia are needed, estimates may be based on a study of the way in which K varies with different characteristics and for such a study the new coefficient possesses some advantage over one which is defined with reference to the volume of fluid displaced. The case of rotation of an airship hull has been investigated also and a coefficient has been defined with the same advantages as the corresponding coefficient for rectilinear motion.
A .PDF file of this report (691771 bytes): naca-report-164.pdf
This report describes the new method for making computations in connection with the study of rigid airship, which was used in the investigation of the navy's ZR-1 by the special subcommittee of the National Advisory Committee for Aeronautics appointed for this purpose. It presents the general theory of the air forces on airship hulls of the type mentioned, and an attempt has been made to develop the results from the very fundamentals of mechanics without reference to some of the modern highly developed conceptions, which may not yet be thoroughly known to readers uninitiated into modern aerodynamics, and which may, perhaps, for all time remain restricted to a small number of specialists. (author)
A .PDF file of this report (1254479 bytes): naca-report-184.pdf
This note, prepared for the National Advisory Committee for Aeronautics, contains the demonstration that the pressure around the circular cross section of an elongated airship, plotted against the diameter of symmetry, can be expected to be represented by a straight line.
A .PDF file of this report (164947 bytes): naca-tn-192.pdf
A simple and easily applied method of calculating the dimensions and horsepower necessary for an airship to have any given performance is described and illustrated by examples. The method includes means for estimating the changes in performance or in size when modifications or new features are introduced into a design, involving increase or saving in weights, or changes in resistance or propulsive efficiency.
A .PDF file of this report (721035 bytes): naca-tn-194.pdf
The first section deals with the theoretical side of statical stability of airships in general. The second section deals with preliminary tests of the model and experiments for the determination of effects due to change of tail area, aspect ratio, tail form, and tail thickness.
A .PDF file of this report (2348251 bytes): naca-tn-204.pdf
In this report it is shown that determining the instantaneous angle of pitch, the acceleration of the gust is as important as its maximum velocity or yaw. Hitherto it has been assumed that the conditions encountered in gusts could be approximately represented by considering the airship to be at an instantaneous angle of yaw or pitch (according to whether the gust is horizontal or vertical), the instantaneous angle being tan to the (-1) power (v/v), where v is the component of the velocity of the gust at right angles to the longitudinal axis of the ship, and v is the speed of the ship. An expression is derived for this instantaneous angle in terms of the speed and certain aerodynamic characteristics of the airship, and of the maximum velocity and the acceleration of the gust, and the application of the expression to the determination of the forces on the ship is illustrated by numerical examples.
A .PDF file of this report (311456 bytes): naca-report-204.pdf
This investigation was carried out by the National Advisory Committee at Langley Field for the purpose of determining the adaptability of the camera obscura to the securing of turning characteristics of airships, and also of obtaining some of those characteristics of the C-7 airship. The method consisted in flying the airship in circling flight over a camera obscura and photographing it at known time intervals. The results show that the method used is highly satisfactory and that for the particular maneuver employed the turning diameter is 1,240 feet, corresponding to a turning coefficient of 6.4, and that the position of zero angle of yaw is at the nose of the airship.
A .PDF file of this report (417678 bytes): naca-report-208.pdf
In recent tests on the pressures occurring on the envelope and control surfaces of the naval airship C-7, it was noted that the pressures on the nose of the airship, while flying in level circling flight, were symmetrically distributed. Such a condition can only occur when the nose of the airship is pointed directly into the wind, and to accomplish this in circling flight, the axis of the airship must then be parallel to the direction of the motion of the nose. The question was raised as to whether the same conditions occur generally on all airships in circling flight. It appears that airships flying in a constant, level, circling flight path will generally head very closely into the wind, and any deviation will be so slight that the distribution of pressure over the nose will be but slightly, if at all, changed from a symmetrical distribution.
A .PDF file of this report (154490 bytes): naca-tn-224.pdf
This report is based on a study made by the writer as a member of the Special Committee on Design of Army Semirigid Airship RS-1 appointed by the National Advisory Committee for Aeronautics. The increasing interest in airships has made the problem of the potential flow of a fluid about an ellipsoid of considerable practical importance. In 1833 George Green, in discussing the effect of the surrounding medium upon the period of a pendulum, derived three elliptic integrals, in terms of which practically all the characteristics of this type of motion can be expressed. The theory of this type of motion is very fully given by Horace Lamb in his "Hydrodynamics," and applications to the theory of airships by many other writers. Tables of the inertia coefficients derived from these integrals are available for the most important special cases. These tables are adequate for most purposes, but occasionally it is desirable to know the values of these integrals in other cases where tabulated values are not available. For this reason it seems worth while to assemble a collection of formulae which would enable them to be computed directly from standard tables of elliptic integrals, circular and hyperbolic functions and logarithms without the need of intermediate transformations. Some of the formulae for special cases (elliptic cylinder, prolate spheroid, oblate spheroid, etc.) have been published before, but the general forms and some special cases have not been found in previous publications. (author)
A .PDF file of this report (167710 bytes): naca-report-210.pdf
The design of complicated structures often presents problems of extreme difficulty which are frequently insoluble. In many cases, however, the solution can be obtained by tests on suitable models. These model tests are becoming so important a part of the design of new engineering structures that their theory has become a necessary part of an engineer's knowledge. For balloons and airships water models are used. These are models about 1/30 the size of the airship hung upside down and filled with water under pressure. The theory shows that the stresses in such a model are the same as in the actual airship. In the design of the Army Semirigid Airship RS-1 no satisfactory way was found to calculate the stresses in the keel due to the changing shape of the bag. For this purpose a water model with a flexible keel was built and tested. This report gives the theory of the design, construction, and testing of such a water model.
A .PDF file of this report (778720 bytes): naca-report-211.pdf
In the text are derived simple formulae for determining, directly from the data of wind tunnel tests of a model of an airship hull, what shall be the approximate character of oscillation, in pitch or yaw, of the full- scale airship when slightly disturbed from steady forward motion. (author)
A .PDF file of this report (171955 bytes): naca-report-212.pdf
To furnish data for the design of the fleet airship Shenandoah, a model was made and tested in the 8 by 8 foot wind tunnel for wind forces, moments, and damping, under conditions described in this report. The results are given for air of standard density. P=0.00237 slugs per cubic foot with vl/v correction, and with but a brief discussion of the aerodynamic design features of the airship.
A .PDF file of this report (1536794 bytes): naca-report-215.pdf
This investigation was made for the purpose of determining the aerodynamic pressure distribution encountered on a "C" class airship in flight. It was conducted in two parts: (a) tests on the tail surfaces in which the pressures at 201 points were measured and (b) tests on the envelope in which 190 points were used, both tests being made under as nearly identical flight conditions as possible, so that the results could be combined and the pressure distribution over the entire airship obtained.
A .PDF file of this report (2086504 bytes): naca-report-223.pdf
In order to begin research on the drag of airships it was first necessary to make a logical digest of the reported past performances and data given on deceleration tests for a large number of airships.
A .PDF file of this report (1712250 bytes): naca-tn-247.pdf
The extension of wind tunnel tests of models of airship hulls to full scale requires an extension from a VL of the order of less than 500 sq.ft./sec., to that of 80000 sq.ft./sec., where V = air speed, feet per second, L = length in feel of the particular form of hull. The reason for this research was to furnish the airship designer with a method for finding the VL curve of any conventional type of hull, using data obtained from actual performance of airships flown prior to 1926.
A .PDF file of this report (3216948 bytes): naca-tn-248.pdf
During the years of 1922 and 1923, comparative tests were made on two N.P.L. airship models in six American atmospheric wind tunnels to determine their resistance with particular reference to scale effects. These tests were made for the purpose of determining some idea of the, standardization of wind tunnels.
A .PDF file of this report (369919 bytes): naca-tn-264.pdf
These tables are intended to provide a standard method and to facilitate the calculation of the quantity of, Standard Helium, in high pressure containers. The research data and the formulas used in the preparation of the tables were furnished by the Research Laboratory of Physical Chemistry, of the Massachusetts Institute of Technology.
A .PDF file of this report (1255836 bytes): naca-tn-276.pdf
This report presents the results of wind-tunnel tests on eight C- class airship hulls with various fineness ratios, conducted in the Navy Aerodynamic Laboratory, Washington. The purpose of the tests was to determine the variation of resistance with fineness ratio, and also to find the pressure and friction elements of the total drag for the model having the least shape coefficient. Seven C-class airship hulls with fineness ratios of 1.0, 1.5, 2.0, 3.0, 6.0, 8.0, and 10.0 were made and verified. These models and also the previously constructed original C-class hull, whose fineness ratio is 4.62, were then tested in the 8 by 8 foot tunnel for drag of 0 degree pitch and yaw, at various wind speeds. The original hull, which was found to have the least shape coefficient, was then tested for pressure distribution over the surface at various wind speeds. (author)
A .PDF file of this report (951829 bytes): naca-report-291.pdf
The trials reported in this report were instigated by the Bureau of Aeronautics of the Navy Department for the purpose of determining accurately the speed and resistance of the U. S. S. "Los Angeles" with and without water recovery apparatus, and to clear up the apparent discrepancies between the speed attained in service and in the original trials in Germany. The trials proved very conclusively that the water recovery apparatus increases the resistance about 20 per cent, which is serious, and shows the importance of developing a type of recovery having less resistance. Between the American and the German speed trials without water recovery there remains an unexplained discrepancy of nearly 6 per cent in speed at a given rate of engine revolutions. Warping of the propeller blades and small cumulative errors of observation seem the most probable causes of the discrepancy. It was found that the customary resistance coefficients C, are 0.0242 and 0.0293 without and with the water recovery apparatus, respectively. The corresponding values of the propulsive coefficient K, are 56.7 and 44.6. If there is an error in these figures, it is probably in a slight overestimate of C, and an underestimate of K. The maximum errors are almost certainly less than 5 per cent. No scale effect was detected indicating variation of C with respect to velocity (author)
A .PDF file of this report (891386 bytes): naca-report-318.pdf
The primary purpose of this investigation was to obtain simultaneous data on the loads and stress experience in flight by the U. S. S. Los Angeles which could be used in rigid airship structure design. A secondary object of the investigation was to determine the turning and drag characteristics of the airship. The aerodynamic loading was obtained by measuring the pressure at 95 locations on the tail surfaces, 54 on the hull, and 5 on the passenger car. These measurements were made during a series of maneuvers consisting of turns and reversals in smooth air and during a cruise in rough air which was just short of squall proportions. The results of the pressure measurements on the hull indicate that the forces on the forebody of an airship are relatively small. The tail surface measurements show conclusively that the forces caused by gusts are much greater than those caused by horizontal maneuvers. In this investigation the tail surface loadings caused by gusts closely approached the designed loads of the tail structure. The turning and drag characteristics will be reported in separate reports.
A .PDF file of this report (1507711 bytes): naca-report-324.pdf
The tests described in this report furnished data on the actual aerodynamic forces, and the resulting stresses and bending moments in the hull of the U. S. S. "Los Angeles" during as severe still-air maneuvers as the airship would normally be subjected to, and in straight flight during as rough air as is likely to occur in service, short of squall or storm conditions. The maximum stresses were found to be within the limits provided for in accepted practice in airship design. Normal flight in rough air was shown to produce forces and stresses about twice as great as the most severe still-air maneuvers. No light was thrown upon the forces which might occur in extreme or exceptional conditions, such as the storm which destroyed the "Shenandoah". The transverse aerodynamic forces on the hull proper were found to be small and irregular. Owing to the necessity of conserving helium, it was impossible to fly the airship in a condition of large excess of buoyancy or weight in order to determine the air pressure distribution at a fixed angle of pitch. However, there is every reason to believe that in that condition the forces on the actual airship are as close to the wind-tunnel results as can be determined by present type of pressure measuring apparatus. It is considered that most important data obtained are the coefficients of tail-surface forces and hull-bending moments. These are tabulated in this report.
A .PDF file of this report (776568 bytes): naca-report-325.pdf
This paper present a description of the method employed and results obtained in full-scale turning trials on the rigid airship U. S. S. "Los Angeles". The results of this investigation are not sufficiently comprehensive to permit definite conclusions as to the variation of turning characteristics with changes in speed and rudder angle. They indicate however, that the turning radius compares favorably with that for other large airships, that the radius is independent of the speed, that the position of the point of zero yaw is nearly independent of the rudder angle and air speed, and that a theoretical relation between radius and angle of yaw in a turn gives a close approximation to actuality.
A .PDF file of this report (755324 bytes): naca-report-333.pdf
This report presents the results of wind tunnel tests conducted to determine the aerodynamic characteristics of airship models. Eight Goodyear-Zeppelin airship models were tested in the original closed-throat tunnel. After the tunnel was rebuilt with an open throat a new model was tested, and one of the Goodyear-Zeppelin models was retested. The results indicate that much may be done to determine the drag of airships from evaluations of the pressure and skin-frictional drags on models tested at large Reynolds number.
A .PDF file of this report (1537617 bytes): naca-report-394.pdf
This report presents the results of deceleration tests conducted for the purpose of determining the drag characteristics of six airships. The tests were made with airships of various shapes and sizes belonging to the Army, the Navy, and the Goodyear-Zeppelin Corporation. Drag coefficients for the following airships are shown: Army TC-6, TC-10, and TE-2; Navy Los Angeles and ZMC-2; Goodyear Puritan. The coefficients vary from about 0.045 for the small blunt airships to 0.023 for the relatively large slender Los Angeles. This variation may be due to a combination of effects, but the most important of these is probably the effect of length-diameter ratio.
A .PDF file of this report (954968 bytes): naca-report-397.pdf
The purpose of the first two parts of this report is to present in concise format all the formulas required for computation of the hydrodynamic forces, so that they can be easily computed for either straight or curvilinear flight. Improved approximations are also introduced having a high degree of accuracy throughout the entire range of practical proportions. The remaining two parts of the report are devoted respectively to stability and skin friction, as functions of the same hydrodynamic forces.
A .PDF file of this report (1306753 bytes): naca-report-405.pdf
This report presents the results of measurements of flow in the boundary layer of a 1/40-scale model of the U. S. Airship "Akron" (ZRS-4) made with the object of determining the boundary-layer thickness, the point of transition from laminar to the turbulent flow, and the velocity distribution in the boundary layer.
A .PDF file of this report (1016067 bytes): naca-report-430.pdf
This report describes a series of tests made on a 1/40-scale model of the U. S. Airship "Akron" (ZRS-4) for the purpose of determining the drag, lift, and pitching moments of the bare hull and of the hull equipped with two different sets of fins. Measurements were also made of the elevator forces and hinge moments.
A .PDF file of this report (1027838 bytes): naca-report-432.pdf
This report presents the results of measurements of pressure distribution conducted in the propeller-research wind tunnel of the National Advisory Committee for Aeronautics on a 1/40-scale model of the U. S. Airship "Akron" (ZRS-4). The pressures, which were measured simultaneously at nearly 400 orifices located at 26 stations along one side of the hull, were recorded by two photographic multiple manometers placed inside the model. The hull pressures were measured both with and without the tail surfaces and the control car for eight angles of pitch varying from 0 degree to 20 degrees and at air speeds of approximately 70 and 100 miles per hour. The pressures were also measured at approximately 160 orifices on one horizontal fin for the above speeds and pitch angles and for nine elevator angles.
A .PDF file of this report (1122814 bytes): naca-report-443.pdf
The procedure for obtaining air-speed and rate-of-climb measurements in performance tests of airships is described. Two methods of obtaining speed measurements, one by means of instruments in the airship and the other by flight over a measured ground course, are explained. Instruments, their calibrations, necessary correction factors, observations, and calculations are detailed for each method, and also for the rate-of-climb tests. A method of correction for the effect on density of moist air and a description of other methods of speed course testing are appended.
A .PDF file of this report (1390950 bytes): naca-tn-564.pdf
This report presents the results of full-scale wind tunnel tests conducted to determine the ground-handling forces on a 1/40-scale model of the U. S. Airship "Akron." Ground-handling conditions were simulated by establishing a velocity gradient above a special ground board in the tunnel comparable with that encountered over a landing field. The tests were conducted at Reynolds numbers ranging from 5,000,000 to 19,000,000 at each of six angles of yaw between 0 degree and 180 degrees and at four heights of the model above the ground board. The ground-handling forces vary greatly with the angle of yaw and reach large values at appreciable angles of yaw. Small changes in height, pitch, or roll did not critically affect the forces on the model. In the range of Reynolds numbers tested, no significant variation of the forces with the scale was disclosed.
A .PDF file of this report (1052985 bytes): naca-report-566.pdf
Report presents the results of pressure-distribution measurements on a 1/40-scale model of the U. S. Airship "Akron" conducted in the NACA 20- foot wind tunnel. The measurements were made on the starboard fin of each of four sets of horizontal tail surfaces, all of approximately the same area but differing in span-chord ratio, for five angles of pitch varying from 11.6 degrees to 34 degrees, for four elevator angles, and at air speeds ranging from 56 to 77 miles per hour. Pressures were also measured at 13 stations along the rear half of the port side of the hull at one elevator setting for the same five angles of pitch and at an air speed of approximately 91 miles per hour. The normal force on the fin and the moment of forces about the fin root were determined. The results indicate that, ignoring the effect on drag, it would be advantageous from structural considerations to use a fin of lower span-chord ratio than that used on the "Akron."
A .PDF file of this report (1331229 bytes): naca-report-604.pdf
A series of test flights was conducted by the U. S. Navy over a 3-year period to evaluate the effects of icing on the operation of the ZPG-2 airship.
A .PDF file of this report (2,421,556 bytes): naca-tn-4220.pdf