Abstract: A retractable environmental seal for use in sealing the opening of the exit cone for a rocket nozzle comprising a diaphragm-like cover having a central region adapted to be seated in sealing relation with the periphery of the opening and characterized by radially extended failure zones for facilitating a pressure-induced rupture of the cover, and a plurality of angularly spaced tension springs connected with the peripheral portion of the cover for retracting fractured segments of the cover from the opening subsequent to a pressure-induced rupture thereof.

Abstract: Apparatus is disclosed which permits the use of a large proportion of the solar spectrum in the coversion of solar energy to electricity by means of photovoltaic cells. The apparatus comprises a collecting element which concentrates the incident radiation, a collimating element which forms the concentrated incident radiation into a beam of parallel photons, a spectral separation element, such as a prism, prism plate or diffraction grating which spectrally separates the solar radiation in the collimated beam and a plurality of photovoltaic cells disposed in the separated spectrum, the energy gap of the cells being matched to the energy of the photons in that portion of the spectrum in which the cells are located.

Abstract: A keyhole-less magnetically actuated lock, the key having magnets borne on concentric rings rotatable by a dial, the lock having magnetically responsive switches (for example, reed switches) within the lock actuatable by the key, some of the switches providing a series GO function and some providing a parallel NOGO function. In one form, the GO function powers an electric motor within the lock to withdraw the lock bolts, and in another form the actuator is a thermo electric device. Several NOGO techniques are shown, including a toggled circuit breaker and a bucking coil in the motor. A circuit is shown for inverting the GO and NOGO functions to change the combination of the lock, and one embodiment shows placement of two magnets on one ring in the key to render the key unique. Another embodiment shows use of a covert grid of locator marks to direct correct placement of the key against the lock.