摘要:
Transients and steady state error induced in maneuvering a satellite due to a disturbance torque caused by thrust mismatch or differential in the alignment of thrusters with respect to the center of mass are minimized by introducing a torque balancing bias at the input of a thrust modulator of the thrusters (18, 20) prior to sensing position or attitude error. The bias may instantly off-modulate the thruster control signal to cancel the effects of attitude transients before errors develop. Other axes thrusters (22, 24, 11, 18) may be on-modulated instantaneously to compensate for cross- axis torque. The bias may be introduced into the satellite control scheme by manual ground control or in automatic on-board compensation based on stored parameters obtained for example from calibration measurements. Specifically, the torque balancing bias may be developed by reference to thrust mismatch detected and stored during previous maneuvers, thus anticipating expected attitude error without actual detection thereof.
摘要:
A stable electromagnetic oscillator (30) comprises an amplifying element (3) in feedback association with a dual mode resonant cavity (12) that provides a double pole bandpass filter function. Two orthogonal modes (1 and 2) of electromagnetic energy resonate within the cavity (12). An output fromthe amplifying element (3) excitationally couples into the first mode (1), while the second mode (2) couples into the input of the amplifying element (3). The output (8) of the oscillator (30) is obtained from the first mode (1). Optional injection lock can be used for greater stability by means of coupling a stable a.c. reference (9) into the cavity (12) in alignment with the second mode (2). Optional electronic frequency tuning comprises a phase or frequency comparator (11) and a reference a.c. source (13), producing a d.c. feedback signal fed to varactor diodes (10). Coupling ports (4, 5, 6, 7) of the cavity (12) can be, e.g., irises, capacitive probes, coaxial probes, or any combination thereof. The electrical field associated with each port (4,5,6,7) is aligned with the electrical field of the mode (1 or 2) coupled thereby. A dielectric resonator can be positioned within the cavity (12) to allow for physical shrinking of the cavity (12) while maintaining the electromagnetic characteristics of the cavity (12).
摘要:
An impedance transforming coupler (27,28) is disclosed which may be used as a power divider or power combiner at microwave frequencies. The power division or power combination ratio is arbitrary, and the impedance transformation ratio is arbitrary. These couplers may be used in a circuit to power-combine amplifiers (11, 12). The insertion loss of the circuit is low and the bandwidth is improved by an order to two to one over prior art systems which had separate circuits for matching the impedance and providing power combining. The coupler is optimally a branch line coupler having four curved branches a quarter wavelength long at the center frequency. The output ports are 90° out of phase. Simple formulas are given relating the desired admittances of each of the four branches to k, the desired power coupling ratio, and Y, the desired admittance transformation ratio.
摘要:
An externally powered twin-barrel machine gun includes a shuttle (42) having two firing chambers (64),(66). The shuttle linearly moves between two positions sothatthefiring chambers are alternately fed a round of ammunition and discharged. A feed system (21) has a pair of augers (23,24) each with a helical groove (26) therein which receives a round of ammunition which obtains a dwell position on a zero pitched section (28) of the grooves. A ramming system (91) rams a round of ammunition to the firing chamber aligned therewith and simultaneously ejects any spent cartridge through a forward aperture (62) in the housing (16). The spent cartridge is frictionally engaged by an axially aligned acceleration belt (76) which quickly withdraws the spent cartridge from the firing chamber and accelerates it onto a deflection cam (88).
摘要:
A accumulator arrangement (10) for a machine gun has a handling conveyor (17) passing through a supply channel (16), a bypass channel (14), and a return- channel (18). The supply channel leads to a freed system (12) of a machine gun. At the junction of bypass channel and return channel there is connected to a return conveyor (46) leading from the feed system. A gate (24, 50, 52) is mounted at the junction of the bypass channel and supply channel operably between two positions, one position directing ammunition (58) on the handling conveyor onto a supply conveyor (44) leading to the feed system and a second position directing ammunition on the handling conveyor through the bypass channel via the return channel. Upon release of a trigger mechanism operably connected to the gun, the gate moves from its first position to the second position. The feed system continues its forward operation to clear itself of any live ammunition therein. The handling conveyor maintains a forward mode directing ammunition into the bypass channel. A reversing mechanism reverses the handling conveyor to retrieve live ammunition from the bypass channel to the supply channel after the feed system is cleared of all live ammunition. So the live ammunition intermediately accumulated in the bypass channel can be fed to the feed system during the next operation of the machine gun. The accumulator arrangement and feed system might also be used for article handling systems in general which handle individual linkless articles other than ammunition in rapid sequence.
摘要:
A projector for projecting optical signals for controlling a missile comprises means for producing two alternately orthogonally scanned rectangular beams (p,y) from a single incident beam derived from a single source of laser radiation (2) and a modulator for pulse modulating said source at a plurality of pulse rates over first and second ranges of frequencies corresponding to respective ones of said two beams. The beam producing means is formed by two prism elements (14, 16) relatively movable with respect to each other by a transducer (12) to cause rotation of the beams. A Pechan prism (10) with a reversion axis oriented at 45° with respect to the length of the rectangular beam is preferred for use as the beam rotator.
摘要:
An opening (14) in the nose (12) of a missile allows entry of ram air during missile flight to a central chamber (18). Oppositely oriented steering jets (22),(24) are innerconnected with the aft end of the central chamber (18). A diverting mechanism (26) is located between the central chamber (18) and each of the steering jets (22),(24) to allow either one or none of the steering jets (22),(24) to provide correctional steering forces when desired. The rotatable diverting mechanism (26) is pneumatically driven by ram air communicated to an actuation chamber (44) located aft of the valve and controlled by electrically energized solenoids (60).
摘要:
A technique for making a honeycomb structure includes bonding a less than totally cured composite skin (16) to a possibly contoured honeycomb core (8). The composite skin (16) comprises fibers and a resin chosen to maximize the strength and stiffness of the skin (16) when cured. Non- contiguous adhesive fillets (5) are prepositioned onto faying surfaces of the honeycomb core (8). The adhesive (5) is preselected, independently of the preselection of the resin, to maximize the strength of the bond between the skin (16) and the core (8). A thin, lightweight scrim cloth (14) is interposed between the starting skin (16) and the filleted core (8). The scrim cloth (14) prevents resin from flowing into the core (8) and allows a safe place for the intermingling of resin and adhesive (5). The assemblage is heated under pressure, cocuring the adhesive (5) and the resin. The fillets (5) are preferably prepositioned on surfaces (10) by means of applying an adhesive-coated fabric to the faying surface, heating the fabric-covered core (8) so that some of the adhesive (5) flows out of the fabric (1) and into the core (8) at a region near the faying surface, cooling the core (8) so that the only substance remaining adhered to the core edges (10) is the adhesive fillets (5).