Showing papers on "Missile published in 1981"

Guidance Laws for Short-Range Tactical Missiles

Abstract: Introduction G laws for short-range tactical missiles have become a well-researched topic over the past 35 years with publications of analytical treatment and implementation of missile guidance going back to the 1940's Thus, much of the guidance development available in the literature predates that which is known as modern control theory These early concepts, now commonly referred to as classical guidance, have been used from that time to the present to command missiles during their homing phases of flight to target impact To the extent that assumptions of comparable relative velocity and certain conditions on relative bearing between the pursuer and target were valid, the classical guidance techniques remained adequate However, evidence is evolving which suggests that the performance of present weapon systems may be seriously degraded in engagements against targets with predicted characteristics of the 1990's and beyond and in the battlefield environments of that time frame It has been established that the guidance laws currently in wide use may not be adequate in defeating those threats Thus, it is projected that fundamental advances in the application of control systems theory is required to enhance the guidance effectiveness of future missile weapon systems Additionally, missile air frame and propulsion systems also may require advances appropriate to defeat predicted targets In particular, air defense and air-to-air weapons currently undergoing research and development utilizing classical guidance technology may be seriously hampered in the combat scenarios envisioned In evaluating the extensive literature on guidance laws applicable to short-range missiles, the lack of a suitable survey became apparent Although excellent reviews of related topics such as optimal control' and sensitivity methods had appeared while those fields were relatively young, the missile guidance literature was found to be highly decentralized and fragmented This may be attributed, in part, to the fact that literature for guidance laws was usually classified for security purposes These works were rarely published beyond internal industrial reports, and though not made public they became reference documentation for missile designers spanning a period of over 35 years With classical techniques implemented even in today's highly sophisticated systems, the literature gave credence to a widely accepted definition of classical terminal homing and defined its extensions into the modern era It was observed that guidance laws typically fit within the following five categories, the first three of which are the well-known classical techniques: lineof-sight (LOS), pursuit, proportional navigation guidance

Comparison of Optimal Control and Differential Game Intercept Missile Guidance Laws

Abstract: Air-to-air missile guidance laws are derived using optimal control and differential game theory with final miss distance as the optimization criterion. A perfect target airframe/autopilot response is assumed, while both perfect and first-order missile responses are considered. With a first-order missile response the target is always able to force a nonzero final miss distance in the differential game formulation. For all other formulations considered there are states from which the missile can force zero terminal miss. In these cases, an auxiliary performance index (e.g., control energy) can be used to specify unique controls. Two simulation scenarios were used to evaluate the guidance laws: one with missile launch near the inner launch boundary and the other near the outer launch boundary. The differential game guidance laws are less sensitive to errors in estimates of current target acceleration than the optimal control laws. The laws based on a perfect missile response performed better for the outer launch boundary scenario; whereas for the inner launch boundary scenario the laws based on a first-order missile response achieved smaller miss distances.

Impact of Solid Missiles on Concrete Barriers

Abstract: Semianalytical formulas are developed to predict scabbing and perforation thicknesses for reinforced concrete panels subjected to impacts by solid steel missiles. The scabbing thickness is defined as the thickness that is just enough to prevent the peeling off of the back face of the panel opposite to the face of impact; perforation thickness is defined as the thickness that is just enough to allow a missile to pass through the panel without exit velocity. In the development of these formulas, simplified models for scabbing and for perforation were assumed; engineering mechanics principles were applied in the formulation, and the Bayesian statistics were utilized to determine coefficients in these formulas. The Bayesian approach was used because it can handle the estimation of parameters better than the classicial statistical method when suitable data are limited, as is presently the case in low velocity missile impact on concrete panels.

Symmetric Missile Dynamic Instabilities

Abstract: _ / Magnus moment \ V */2PSlVpd / = axial and transverse moments of inertia = amplitudes of the two yaw model arms for a symmetric missile = trim angle magnification factor = reference length = mass -XYZ components of the missile's angular velocity = reference area = dynamic stability factor = 2c0/d0o gyroscopic stability factor = (op) /4C^ = time = magnitude of the missile velocity = missile-fixed axes, the X axis along the longitudinal axis of the missile, positive forward = nonspinning aeroballistic axes = angles of attack and sideslip in the missilefixed system = circular limit motion radius = polar angle of £ = K j / K j ( j = l , 2 ) = value of \j for a linear Magnus moment = the complex angle of attack in the missile-fixed system = 0 4ict = be i9

Missile deployment apparatus

Abstract: Apparatus for deploying one or more submissiles (15) from a carrier missile (25) whereby each submissile (15) is deployed into a flight path which is initially parallel to a streamline (20) of the fluid flow contiguous to the carrier missile (25). An ejection mechanism (45) has a submissile support member (105) oriented substantially parallel to the streamline (20) at the point where the submissile (15) is separated from the support member (105). The ejection mechanism (45) also provides a minimum side force to the submissile (15) which is proportional to a speed of the carrier vehicle (25). Provisions are also made to reduce or minimize any change in the aerodynamic characteristics of the carrier missile (25) after a submissile (15) has been deployed.

Combined Optimal/Classical Approach to Robust Missile Autopilot Design

Abstract: The direct application of optimal control techniques to a complete autopilot design leads to a control system which requires excessive instrumentation and is sensitive to variations in the high frequency model A better approach is presented which utilizes classical control theory to bound the high frequency design and modern control theory to obtain optimal low frequency performance Results are presented for a separation roll autopilot demonstrating the appropriate tradeoffs and benefits associated w i t h the new design procedure Air launched missiles require active autopilot control for safe separation from modern launch aircraft because the f low field in the vicinity of the aircraft causes large torque disturbances on the missile and because the aircraft may be m=euvering when it releases its missile The effect of these disturbances and initial conditions are typically sensed by rate gyros and accelerometers whose out puts are connected through autopilot control circuitry to f in actuators Initially autopilot design is carried out b 1 decoupling the pitch, yaw and roll channels ( When this is done,classicd control theory has proven itself to be a valuable and efficient tool for autopilot design However aerodynamic crosscouplin g exists because the surface features of the missile create asymmetric flow fields over the control surfaces at c??fferent orientations of wind angle and angle of attack A simplified block diagram showing the cross-coupling appears in Fig I Here, if the roll rate response time is close enough to the pitchfyaw response time and the cross-coupling aerodynamic gain is high enough, instability can result Therefore successful autopilot design must take into consideration aerodynamic cross-couph g Althou h classical design techniques are well established fi 9 345) and relatively straight forward for planar autopilot design, trial and error must b? A I ROLL AUTOPILOT 1 ACTUATOR AND a L SENSOR -

Numerical Computation of Optimal Atmospheric Trajectories

Abstract: A second-order direct trajectory optimization method in which the state time history is described by Chebychev polynomials and the dynamical equations are satisfied by penalty functions is described. The convergence and fidelity of the method are demonstrated with solutions to the following problems: brachistochrone, subsonic transport minimum-time climb, supersonic interceptor minimum-time climb, Goddard rocket problem with a singular arc, subsonic transport minimum-fuel for a fixed-range mission including climb, cruise and descent, and optimal evasive maneuvers for an airplane pursued by a missile with proportional guidance. The results demonstrate that the method provides an efficient and reliable procedure for solving a wide variety of realistic trajectory optimization problems.

A method for combatting of targets and projectile or missile for carrying out the method

Abstract: The invention relates to combatting of hostile targets (M) by firing of controllable explosive projectiles or missiles (P, PO) towards the target, which projectiles or missiles are provided with target tracking devices for automatic guidance of the projectile or missile by reception and detection of electromagnetic radiation originating from the target. In order to improve the accuracy of fire at least one projectile or missile fired in a burst is provided with transmitter means (T, A1) which are activated after detection of a target (M) for transmission of a signal indicating the position of the target relative to the projectile to following projectiles in the burst. In these following projectiles (P) a correction of the projectile trajectory in direction to a trajectory passing through the target is effected by means of the position indicating signal from the preceeding projectile (PO). Suitably all projectiles in a burst can be provided with such transmitter means (T, A1). Hereby each projectile in the burst will get a more correct trajectory towards the target as compared the closest foregoing projectile and reliable hit will be ensured after a relatively small number of projectiles. The target tracking device may be of any known type, as devices of radiometric type, radar or IR-type, electro-optical tracking device operating with visible light or laser light (Figure 1a).

Discrete-time disturbance-accommodating control theory with applications to missile digital control

Abstract: This paper describes an extension of the theory of (analog) disturbance-accommodating control to include a general class of control problems involving sampled-data and digital controllers. Digital control systems designed by the methods described herein will maintain performance specifications in the face of a wide range of disturbances encountered in practical applications. Design algorithms are derived for stabilization, set-point regulation, and servo-tracking digital control problems. Application of these results to the design of a digital control system for a missile is illustrated by an example.

Cavity Oscillation in Cruise Missile Carrier Aircraft

Abstract: : This report discusses cavity oscillation in general, and particularly the problem of cavity oscillation in the missile bays of cruise missile carrier aircraft during missile launch. The missile bay configurations analyzed ranged from the complete interior volume of a large transport aircraft, to the bomb bay of a conventional bomber. All of the carrier aircraft cases evaluated were conceptual; no specific airframe models or manufacturers are identified. The principles and technology presented are not limited to missile bays; they are applicable to general cavities having free-stream flow velocities above Mach 0. 4. It is observed that above Mach 0.4 the pressure fluctuations in an oscillating cavity may arise from: (a) sustained periodic pressure fluctuations in the aperture shear layer that radiate noise into the cavity; and (b) sustained periodic pressure fluctuations in the aperture shear layer that couple with the cavity volume acoustic modes (this generally produces by far the most intense cavity oscillation). Theoretical/empirical techniques are presented for predicting oscillatory frequency, pressure level, pressure spatial distribution in the cavity, and the degree of alleviation achievable with suppressors. The information is based on extensive experimentation with subscale models having apertures of 2 to 6 in. in a cold air wall-jet flow facility. A bibliography is included containing 145 listings.

Active millimeter wave simulator for missile seeker evaluations

Abstract: An active millimeter wave simulator for missile seeker evaluations wherein a missile seeker generates seeker signals and transmits them in the direction of an array of active antenna elements. Range timing signals are delayed in a time delay circuit to simulate a range between the missile seeker and a target. The seeker signals as received by the active antenna elements are supplied to a millimeter wave spectrum analyzer for determination of their frequency. A computer receives the determined frequency and controls a millimeter wave source to generate simulated target response signals with that same frequency but delayed in accordance with the time delay signal. The computer controls a master target control circuit to select a triad of antennas in the antenna array and to generate a phase center in the triad generating the target response signals. The millimeter wave spectrum analyzer further determines the frequency of the target response signals. The computer compares the frequencies of the target response signals and the missile seeker signals and controls the millimeter wave source to ensure correspondence between those frequencies.

Subsonic Free-Flight Data for a Complex Asymmetric Missile

Abstract: A systematic technique used to extract the asymmetric aerodynamics from the measured motion patterns of complex missile configurations has been demonstrated. This paper discusses this technique which utilizes the maximum likelihood method, the equations of motion used in the reduction routines, and presents asymmetric aerodynamic derivatives and coefficients obtained from ballistic range tests of a typical complex missile configuration. These data show that the current state-of-the-art in free-flight testing is such that neither mathematical complexity nor computational difficulties represent serious limitations upon what can be successfully tested and analyzed within the ballistic range.

Transom missile launcher module

Abstract: A transom missile launching system is configured to mount rigidly above the water line on the stern of ships designated to carry missile type ordnance. The missile launcher consists of two symmetrical modules containing eight missile cells each. Missiles are launched in the normal mode from a "all up round" canister at a fixed angle of about 60° from a line athwartship both to port and to starboard. At this angle the probability of launch into a wave in heavy seas due to ship roll is eliminated. The missiles propulsion motor exhaust gases are vented directly overboard at launch without being directed either within the ship or across the weather deck. At ignition a water tight cover at the base of the launching chamber is blown directly overboard into the water by the exhaust gas pressure and a path is therefore provided for the exhaust gas to be discharged directly into the sea.

Double fabric retractable wing construction

Abstract: A simple, retractable, self-erecting wing for a low speed missile having a fabric wing cover affixed to a leading edge structure that is the only erected structural member in the wing operative position. The wing cover forms a pocket that contains air. The leading edge structure is hinged and folds, along with the wing cover, into a compact slotted space adjacent the outer wall of a missile body. In the folded position the leading edge structure forms a cover for the slot and the cover coincides with the outer shape of the missile body. A large fabric wing can be completely stored within the missile body for minimum drag during any high speed portion of the missile flight, the wing being released to the operative position by a simple mechanism.

Target apparatus for weapon fire training

Abstract: Target apparatus for use in the training of weapon direct fire, including a structure (1) in which a weapon can be placed and which forms a screen (3) of concave truncated spherical shape, at least one target image projector (4 ) located within the structure (1) for projecting a target image (T) onto the screen (3), with the projector (4) being mounted for universal movement so as to be capable of moving the projected target image (T) over the screen (3), and a visible laser projector (8) located on or adjacent the weapon to produce a visual indication (P) on the screen (3) by a projected beam of visible light, of at least a final portion of the flight path of the simulated fired projectile or missile, corresponding to the position at which the weapon was aimed when fired, for a projectile or missile whose trajectory or flight path cannot be controllably varied after firing, or corresponding to the position at which the weapon was aimed when fired and as subsequently controllably varied, for a projectile or missile whose trajectory or flight path can be controllably varied after firing. The target image projector (4) is located in the structure at the center of curvature of the concave truncated spherical shaped screen (3). An infra-red projector (9) may be included to project a beam of radiation along the line of sight of the weapon together with a detector (10) for this beam. The projector (8) may be operable to indicate visually on the screen (3) the impact of a missile or sequence of projectiles on the target image (T) and/or the whole of the flight path of the missile or projectile.

Aiming rocket launchers

Abstract: An autonomous weapon system comprises a rocket launcher 10 of rockets 11 which may be aimed towards a target, prior to firing, by movement of the launcher by drive 14. Control of the weapon is by a passive i.e. non-emitting primary detection means 15 such as formed by an array of microphones which detects a potential target by electronic scanning of the directional beam without movement of the weapon. When a target is detected the weapon moves to aim in that approximate direction of detection and an optical or thermal imaging system 16 is used to compare the target image with stored suitable targets. If verified as suitable, and within range (by size of image) the aim is centred on the target and a missile launched. The control 15, 16 and 17 maybe wholly or partially remote from the launcher or the optical imaging means 16 may be carried as part of a target seeking/homing device in the rockets.

Calculation of Visible Radiation from Missile Plumes

Abstract: A survey is presented of the present capability for prediction of low-altitude missile exhaust radiation in the visible and near-ultraviolet region of the spectrum. Example systems are selected for evaluation from the major categories of emission processes: thermal radiation from particles, atoms, and molecules, and emission from chemiluminescent molecules. These radiation models are then applied to the prediction of the visible spectrum from a typical aluminized composite propellant missile exhaust flame.

Real‐Time Missile Tracking with GPS

Abstract: This paper describes a system for real-time tracking of long-range missiles based on use of the Global Positioning System (GPS). When GPS is fully operational, an in-place reference system will exist for use in tracking moving vehicles such a missiles, aircraft, and ground vehicles. In order to obtain the maximum benefit of this capability, an economical means of tracking the test vehicles is necessary. This is particularly true in tracking expendable test vehicles such as missiles. The techniques presented in this paper represent an approach to economical tracking of expendable test missiles. In this concept, the tracked missile receives the GPS signals, translates a composite signal spectrum to a new S-band frequency, and then transmits the composite S-band spectrum to a ground-station receiver. The ground station receives and processes the translated GPS signals into normal pseudorange and range-rate measurements of the missile. A Kalman filter is used to obtain a position and velocity solution. In addition to its capability for standalone performance, the described system could be incorporated into existing tracking systems, resulting in improved tracking accuracy.

Remote Control Canard Missile with a Free-Rolling Tail Brake Torque System

Abstract: An experimental wind-tunnel investigation has been conducted at supersonic Mach numbers to determine the static aerodynamic characteristics of a cruciform canard-controlled missile with fixed and free-rolling tail-fin afterbodies. Mechanical coupling effects of the free-rolling tail afterbody were investigated using an electronic/electromagnetic brake system that provides arbitrary tail-fin brake torques with continuous measurements of tail-to-mainframe torque and tail-roll rate. Results are summarized to show the effects of fixed and free-rolling tail-fin afterbodies that include simulated measured bearing friction torques on the longitudinal and lateral-directional aerodynamic characteristics.

Viscous Effects on Missile Aerodynamics at Low Angles of Attack

Abstract: Analytic results obtained through a recently developed preliminary design code are compared with experimental results. It is found that, especially at transonic speeds, viscous flow effects can severely distort the inviscid unsteady aerodynamic characteristics of typical tactical missile geometries. The different sources for these "anomalous" viscous effects are described, and the potential danger of using subscale experimental data as the basis for a design code is illustrated by a few well-documented examples.

Infrared proximity detector device for flying missile and detector assembly for autorotating missile including such device

Abstract: A proximity detector device comprises a lens placed at the front of the missile, two circular infrared detectors of different radii centered on the optical axis of the lens and disposed in its focal plane. An electronic circuit is connected to the detectors for delivering a proximity signal when the time slot separating two pulses emitted by the two detectors is less than a predetermined threshold. The explosion of the missile is controlled by the proximity pulse.

Arrangement for the contactless transmission of electric energy to missiles during firing thereof

Abstract: An arrangement for the contactless transmission of electrical energy to a missile during the firing thereof from a firing device including a transformer-like coil system having a primary coil system connected to the firing device and a secondary coil system connected to the missile. The primary coil system is supplied with electric energy and the secondary coil system is responsive to the electric energy developed in the primary coil system for developing electrical energy therein. A partition is arranged between the primary coil system and the secondary coil system and is formed of a nonmagnetic material capable of withstanding thermal and mechanical stresses of repeated firings by the firing device. The partition is fixedly connected with the firing device and disposed for sealing the primary coil system with respect to the missile at least during the firing of the missile from the firing device.

Tracking and guidance system with modulated missile-mounted laser beacon

Abstract: An improved tracking and guidance system is provided for line-of sight commanded missiles. The system includes a missile mounted laser beacon which is modulated at a predetermined frequency. An infrared sensor mounted on a tracking unit receives the incoming optical energy and provides a corresponding electrical output. The output signals are filtered to eliminate clutter and those signals outside the range of frequencies within which the laser is modulated. The filtered signals are then peak detected to determine missile azimuth and elevation within a predetermined window. Azimuth and elevation error detector circuits compare the missile azimuth and elevation to predetermined signals to generate error signals. The error signals are utilized by the missile guidance system to provide updated guidance commands.

System for guiding a missile by light beam

Abstract: System for guiding a missile, comprising a source emitting a light beam of which the axis defines the direction of sight, at least one modulation sight placed in the path of the beam, means for producing a relative movement of rotation between the sight and the beam, and on the missile, at least one detector and a calculating circuit for determining, from the output signal from the detector, the coordinates of the detector with respect to the direction of sight. The control surfaces of the missile are actuated as a function of said coordinates with a view to controlling the path of the missile on the direction of sight. The modulation sight comprises transparent and opaque, and possibly semi-transparent sectors, defined by curves symmetrical with respect to the center of the sight, at least certain of these curves having for equation f (ρ, θ modulo π)=O, where ρvaries monotonically as a function of θ, and defining 2n angles at the center which are equal whatever the radius in question, so that the duration of relative illumination of the detector remains equal to 50%, whatever its positio

Beamrider guidance system using digital phase modulation encoding

Abstract: A beam of electromagnetic radiation is spatially encoded using a digital phase modulation technique. The spatial encoding defines the beam cross section into a series of resolution elements each identified by a different digital code. The codes defining resolution elements are detectable by a missile located in the radiation beam and can be used to define the location of the missile in this beam. In the preferred embodiment, an encoding mask, moved through the beam at its source, provides the digital phase modulation. The mask is provided with a series of bit areas, each of which bears at least two sets of cyclically recurring bands effective to modulate a detectable parameter of the radiation, such as intensity. The spacing between adjacent bands of a set, termed a bit cycle, is proportional to a predetermined phase of the modulation of the beam parameter. The novel arrangement enables the missile to identify its position within the beam under conditions of severe atmospheric turbulence and object induced perturbations to provide corrective maneuvers for maintaining the missile velocity vector aligned with the beam.