Missile Design Research Articles

A novel technique for obtaining aerodynamic data using simple, free flight trajectory measurements

Free flight testing of missile designs is generally necessary to confirm that accurate estimates have been made of effects due to the change in size from wind tunnel model to full scale missile and of effects arising from the flight dynamic behaviour of the missile. The amount of such testing is generally limited by the high costs involved and so every effort is made to obtain the maximum information from each flight trial. During recent years parameter estimation techniques have been developed to provide superior methods for analysis of free flight tests. They enable the analyst to extract the required data with greater accuracy from fewer tests than has previously been possible. The old equation error methods relied on measuring all the variables characterising the projectile motion and using the equations of motion to obtain a relationship between aerodynamic forces and moments and translational and angular velocities of the vehicle.

Performance optimization of an air-to-air missile design

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Aerodynamic methods for high incidence missile design

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Engineering applications of ADI methods to piecewise linear multidimensional heat transfer

Transient multidimensional forms of the heat equation are developed with alternating-direction-implicit (ADI) methods. Nonlinearities which stem from boundary conditions and variable properties are approximated in a piecewise linear manner. The resulting ADI forms of the heat equation are successfully demonstrated on a diverse pair of applications consisting of an air-to-ground missile design and an orbiting hollow cube exposed to short-duration radiation. In both applications, the ADI equations prove to be an order of magnitude more economical of computer time than the traditional Crank-Nicolson method. Moreover, the ADI equations prove to be less sensitive to approximation of nonlinearities than the DuFort-Frankel explicit method.

Using N-C Component Inserters in Manufacturing Missile Modules

This paper discusses the component insertion investigation work of a manufacturing methods study contract performed by the Martin Marietta Corporation for the U.S. Army Missile Command, and covers the results of a produceruser survey defining present and predicted future missile electronic module designs with an analysis on the use of numerical control component insertion. Survey data is tabulated for module designs, component usage .and application of component insertion equipment. Description and photographs of modules and available component insertion equipment are provided. Criteria influencing numerical control insertion decisions and capabilities of component inserters are discussed, and advantages and disadvantages of component insertion application are tabulated.

Piercing the Silent Curtain

Scientists predicted it, missile designers were plagued by it, astronauts have had to live with it, and it is likely to continue making trouble for years to come. But space researchers are fighting back, looking for a way to puncture the wall of silence that temporarily cuts off communications to and from spacecraft and missiles reentering earth's atmosphere at high speed. The blackout was anticipated as long ago as the early 1950's in research that was to lead to the intercontinental ballistic missile program. When an object plunges through earth's atmosphere at speeds greater than about 10 times the speed of sound, the investigators theorized, the heat of friction should produce a layer of ionized gas or plasma surrounding the forward parts of the object's skin. This curtain could completely block off radio transmissions in both directions, leaving the object cut off from the ground for a possibly critical few moments. Early ICBM tests and sounding rocket flights proved the theory rightand turned up another problem. When a rocket has been launched, as the surrounding atmospheric pressure decreases with altitude, the hot plume of the rocket's exhaust expands to many times its original size. As with the reentry sheath, the ionized exhaust gases can block off signals to and from the ground below. The rocket exhaust blackout problem has since been circumvented by stuch methods as relaying ground communications up from a point well away from the launch site, to enable transmissions to reach around the plume. But it was during just such a blackout that a phenomenon occurred which has since become the basis for much of the research into remedying the more troublesome reentry blackout. On July 1, 1960, the National Aeronautics and Space Administration launched the first of its Scout rockets, which have since become the agency's most popular workhorse boosters. As usual, the exhaust plume soon began to blank out the telemetry signals from the vehicle. Then several observers noticed that whenever the rocket's hydrogen peroxide control jets fired into the plume, the strength of the signal was partially restored. Some of them thought their equipment was wrong, says Theo E. Sims, who was one of the original observers

On Fitting Man into the Control System of Certain Guided Weapons

Substantial cut-backs in the national defence budget over the past five years have forced upon the Defence Ministry and missile designers alike a growing awareness of the importance of weapon costs. As a result, the ideal technical solution to a particular defence problem sometimes has to give way to the realism of what the country can afford to develop and procure—and, most important, what it could afford to sustain, if need be, in anger. A further factor has been the growing importance of exports to the country's economic position, to which arms make an important contribution. Weapon designs, therefore, have to be such that overseas customers can afford not only to purchase them but can also maintain and use them. This is particularly important in the case of developing countries.

Analysis and design of missile and aircraft control systems.

Analysis and design of missile and aircraft control systems.

A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - Practical aspects of rain erosion of aircraft and missiles

All-weather operational requirements have added considerably to aircraft and missile design problems as the effects of various meteorological hazards, predominantly rain, are aggravated by high speed flight. Typical damage patterns are reproduced and discussed. The problem of rain erosion is reviewed with regard to the functional requirements of the components, the flight plan of the vehicle and the occurrence of rain over the geographical terrain of operation. The factors affecting rain erosion characteristics such as type of material, surface finish, shape of component, speed and rainfall intensity are discussed and empirical data derived. The translation of significant results into practical applications is described with particular reference to supersonic transport aircraft. Details given of equipment for the simulation of rain erosion are concerned principally with the R. A. E. ‘whirling arm’ and rocket runway high speed sled techniques. Correlation of test results from these facilities with those from flight tests are briefly discussed. Degree of erosion of a material is defined in relation to the particular application of the material and details are given of the characteristics of numerous materials, both metals and non-metals. The utilization of these materials for such applications as radomes, transparencies, high temperature materials, de-icing systems are briefly discussed together with methods of extending the rain erosion ‘life’ of materials by design or by use of protective coatings.

An integrated software system for hybrid flight simulation: The boeing hybrid simulator

The Boeing Hybrid Simulator is a general-purpose hybrid computer designed to provide a laboratory for the development of hybrid methods of solving a variety of aero-space problems as well as to support large-scale simulations. The first such simulation is a Flight Simulation Program which provides both a three-degrees-of-freedom missile performance analysis tool and a six-degrees-of-freedom missile subsystem design analysis tool. The 3D simulation was implemented by placing the integrations of the translational equations on the analog, utilizing the digital for function generation, some algebraic manipulations, and basic bookkeeping. The 6D was implemented by placing the integrations of the rotational equations on the analog and the integrations of the translational equations on the digital. Phase control was supplied on the analog in both cases. A hybrid oriented execute-time monitor system supported the simulations by 1) providing a flexibile man-machine relationship, 2) providing an automatic and manual control capability, and 3) reducing digital and analog setup time. It enabled the man at the console to bring system packages into computer memory either to temporarily displace the simulations or to tie in with them in such a way that activities closely related to the execution of the simulations occur at the end of frame calculations.

Space vehicle electronics, principles of guided missile design

Space vehicle electronics, principles of guided missile design

Rain Erosion Aspects of Aircraft and Guided Missiles

Summary“All-weather” operational requirements have added considerably to aircraft and missile design problems as the effects of various meteorological hazards, predominantly rain, are aggravated by high speed flight. The problem of rain erosion is reviewed with regard to the functional requirements of the components, the flight plan of the vehicle and the occurrence of rain over the geographical terrain of operation. The factors affecting rain erosion characteristics such as type of material, surface finish, shape of component, speed and rainfall intensity are discussed and empirical data derived. The influences on the problem of radar limitation in rain, the probability of rain occurrence and the effect of wind and wind-shear are mentioned. Details given of equipment for the simulation of rain erosion are concerned principally with the R.A.E. “whirling arm” and rocket runway high speed sled techniques. Correlation of test results from these facilities and flight tests are briefly discussed.Degree of erosion of a material is defined in relation to the particular application of the material and details are given of the characteristics of numerous materials, both metals and non-metals. The utilisation of these materials for such applications as radomes, transparencies, high temperature materials, de-icing systems are briefly discussed together with methods of extending the rain erosion “life” of materials by design or by use of protective coatings.

Can electric actuators meet missile requirements?

ONE OF THE vital components of a missile is the device used to position the thrust directors or control surfaces. In addition to satisfying rather stringent dynamic performance requirements, this device must be highly reliable. Missile designers favor hydraulically operated actuators because of their high dynamic performance capabilities, relatively low weight, and small size.1 However, the hydraulic actuators have still not reached the desired reliability because of sensitivity to dirt particles and other factors.

Stability of Orthotropic Cylindrical Shells Under Combined Loading

N THE design of modern missiles and space vehicles, in­ creasing use is made of the newer materials, such as rein­ forced plastics, whisker materials and fiber reinforced metals. Materials of this sort are elastically orthotropic; that is, they have three mutually perpendicular planes of elastic symmetry. This means that the material composing the wall of a shell has a modulus of elasticity and Poisson's ratio different in the axial than in the circumferential direction, and a shear modulus which is completely independent of these. The critical item in the design of structures utilizing these materials may be stability, depending on the strength, duc­ tility and stiffness of the material. If such is the case, a method of predicting the buckling load is required. One possibility is to use an isotropic analysis such as given in (l), 2 assuming some average material properties. However, this approach could lead to results that would be unduly conserva­ tive in some cases, and disastrously nonconservative in other cases. Therefore, the purpose of this report is to present a method of determining the buckling loads on shells composed of an orthotropic material. In this report the small deflection differential equations describing the action of an orthotropic cylindrical shell under arbitrary loading are derived. These equations are then transformed into the large deflection equations effectively, describing the stability of the shell under the action of ex­ ternal pressure and axial compression (2). The solution of the latter equations yields an expression for the critical loads in terms of shell geometry, material properties and buckling modes. There is an infinite number of possible buckling modes but the only one of practical interest is the one cor­ responding to minimum load. A family of curves is plotted giving the critical axial load and critical external pressure for an orthotropic cylinder. For a conical shell of small vertex angle, the equivalent cylinder method developed by Bijlaard (7) and discussed in (1) is recommended.

Design of a Pressurized Missile Body

THE structural design of a long range ballistic missile or a space rocket vehicle is an intriguing problem. It is hardly necessary to stress the importance of achieving as light a structure as possible, since any unnecessary increase of structural weight can severely affect its performance or result in a profound increase of its total weight. There is a dearth of published information on this subject, presumably because of security restrictions. Among the papers available, only Sechler dwells on the structural design consideration in any detail. We have therefore very few specific facts to guide us, and can only relate the problem to our aircraft design experience with commonsense.

Optimum compensation of a position servo with a magnetic clutchactuator

In the past decade improvements have been made in the design of dry powder magnetic clutches which now make them competitive with hydraulic devices for missile servo actuator applications. Some of the inherent advantages of magnetic clutch actuators are: (a) increased control system reliability, (b) simplified equipment requirements, (c) properties remain constant with usage, (d) environmental requirements are quite compatible with an orbiting vehicle. The dynamic servo response of the magnetic clutch servo actuator is required in order to incorporate these advantages in missile and space control system design. This paper presents a synthesis procedure for the optimum design of a position servo based upon the closed-loop transient response to a step input. The transient response of the position servo is described by four independent parameters. These parameters are the rise time, damping ratio, undamped natural frequency, and the steady-state gain. The synthesis procedure is based upon a theoretical model of a dry powder magnetic clutch, which is an air-gap, iron-care transformer with a one-turn secondary. The air gap is filled with dry ferrite particles. To provide simple analytic functions, a definition for rise time is developed which corresponds to the first crossing of unity gain to a high order of accuracy. The theoretical model of the magnetic clutch has two, first-order time lags. These two time lags are derived from the properties of the theoretical clutch model. They arise from the inductive properties of the clutch excitation coil and the clutch rotor induced eddy current, which is the current in the equivalent transformer single-turn secondary. The compensation for the excitation coil time lag consists of excitation current feedback, which decreases the effective transfer function time constant. The induced rotor eddy current time lag is optimally compensated by the proper selection of feedback gains as outlined in the synthesis procedure. The position servo drives an undamped inertial load. This is characteristic of a control system for an outer space vehicle or a guided missile which utilizes swivel rocket nozzles for control. It is also a first-order approximation to an airframe control servo utilizing neutral aerodynamic surfaces with low damping. The position servo characteristics are provided by a position feedback branch, and the basic servo stability is provided by a tachometer feedback. The theoretical model results in a third-order system which cannot be unstable. Practical magnetic clutches differ from the theoretical model primarily because they have ferromagnetic hysteresis. At high frequencies, hysteresis appears as a constant time delay which makes servo instability possible. An additional constraint to the synthesis procedure is given which guarantees a stable, closed-loop position servo with the desired performance characteristics. The entire analysis in this paper is based upon the application of Root-Locus analytical methods to extract the theoretical roots of the third-order system describing the magnetic clutch actuator position servo.

Space Flight—Volume I—Environment and Celestial Mechanics

A number of books in a series entitled Principles of Guided Missile Design have already appeared. The subject of Space Flight is to be treated in three volumes of which the book under review is the first.

Application of Power Spectral Methods in Airplane and Missile Design

Application of Power Spectral Methods in Airplane and Missile Design

Thermal Buckling of Circular Cylindrical Shells Under Circumferential Temperature Gradients

The thermal buckling of thin-walled circular cylindrical shells due to axial stresses caused by variations in temperature around the circumference is analyzed. This problem is of considerable importance in the structural design of high-speed airplanes and missiles, since they are subjected to high rates of aerodynamic heating. The analysis is performed with the aid of Donnell's equations, which can be shown to be satisfactory for the problem under consideration. The variation of the thermal stress with the circumferential coordinate is represented by Fourier series; the stresses are assumed constant through the thickness and in the axial direction. The conclusion reached is that the axial buckling stress under variable thermal stress conditions is close to the critical stress of the cylinder when it is subjected to uniform axial compression, if the variation of the intensity of the thermal stress is not large within a half-wavelength of the buckling pattern.

Dictionary of guided missiles and space flight. Grayson Merrill (Editor). 5th volume in series Principles of Guided Missile Design. D. van Nostrand, Princeton. 688 pp. Illustrated. 131s. 6d. - Rocket encyclopedia.J. W. Herrick and E. Burgess (Editors). Aero Publishers, Los Angeles. 607 pp. Photolithogravure. Illustrated. 69s. - Rocketry and space exploration. A. G. Haley. D. van Nostrand, Princeton. 334 pp.

Dictionary of guided missiles and space flight. Grayson Merrill (Editor). 5th volume in series Principles of Guided Missile Design. D. van Nostrand, Princeton. 688 pp. Illustrated. 131s. 6d. - Rocket encyclopedia.J. W. Herrick and E. Burgess (Editors). Aero Publishers, Los Angeles. 607 pp. Photolithogravure. Illustrated. 69s. - Rocketry and space exploration. A. G. Haley. D. van Nostrand, Princeton. 334 pp.