Cockpit canopy cutting gas generator

A pyrotechnic egress system may comprise a case defining an opening, a gas generator disposed within the case, the gas generator configured to generate a gas flame in response to being ignited, and an ignition line disposed at the opening and configured to ignite the gas generator, wherein the case directs the gas flame through the opening for deflagrating a window.

FIELD

The present disclosure relates to a pyrotechnic egress system, and more particularly to systems which facilitate emergency egress from air or water vehicles.

BACKGROUND

Pyrotechnic egress systems explosively sever materials such as aircraft canopy transparencies, egress panels, and other structural members. Operation of this type of system may communicate at least some energy inwards toward the crew in the form of a pressure wave. Furthermore, in aircraft which operate in a maritime environment, the pressure wave may be magnified in an underwater egress situation.

SUMMARY

A pyrotechnic egress system is disclosed, comprising a case defining an opening, a gas generator disposed within the case, the gas generator configured to generate a gas flame in response to being ignited, and an ignition line disposed at the opening and configured to ignite the gas generator, wherein the case directs the gas flame through the opening for deflagrating a window.

In various embodiments, the gas generator comprises a pyrotechnic composite.

In various embodiments, the case is filled with the gas generator.

In various embodiments, the case is tapered towards the opening.

In various embodiments, the case is manufactured of a metal.

In various embodiments, the ignition line comprises a braided cord disposed in a tube having a vent facing the gas generator.

In various embodiments, the ignition line comprises an electrically conductive wire heated by electrical current.

In various embodiments, the case comprises an outer case and an inner case, the opening defined between the outer case and the inner case.

An emergency egress structure is disclosed, comprising a window and a pyrotechnic egress system coupled to the window, the pyrotechnic egress system comprising a case defining an opening, a gas generator disposed within the case, wherein the gas generator is configured to generate a gas flame in response to being ignited, and an ignition line disposed at the opening and configured to ignite the gas generator, wherein the case directs the gas flame through the opening for deflagrating the window.

In various embodiments, the window is separated into at least two separate pieces in response to the gas flame deflagrating the window.

In various embodiments, the case is filled with the gas generator.

In various embodiments, the window is manufactured of an acrylic.

In various embodiments, the gas generator comprises a pyrotechnic composite.

In various embodiments, the pyrotechnic egress system extends around a periphery of the window.

In various embodiments, the case comprises an outer case and an inner case, the inner case coupled to the window.

In various embodiments, the opening is defined between the outer case and the inner case.

A method of manufacturing a pyrotechnic egress system is disclosed, comprising disposing a gas generator into an outer case, positioning an inner case with respect to the outer case to define an opening, and disposing an ignition line at the opening.

In various embodiments, the method further comprises curing the gas generator in the outer case.

In various embodiments, the ignition line is disposed at the opening before the gas generator is fully cured.

In various embodiments, the method further comprises bonding the ignition line to the gas generator.

DETAILED DESCRIPTION

In various embodiments, a pyrotechnic egress system, as disclosed herein, may be used for forming an egress in a window during an emergency event. The pyrotechnic egress system may use deflagration to cut through the window. Unlike the supersonic pressure waves produced by detonation, deflagration produces subsonic pressure waves. In this regard, the pyrotechnic egress system as disclosed herein may be capable of use under water without producing supersonic pressure waves. The pyrotechnic egress system as disclosed herein may be capable of use both underwater and in the air.

FIG. 1is an interior plan view of a vehicle frame10, in accordance with various embodiments. The vehicle frame10may be fabricated from a metal material, carbon composite material, or any other suitable material for land vehicles, air vehicles, or water vehicles. The vehicle frame10includes a window12supported by a window frame14. In various embodiments, window12is an acrylic window, e.g., a product marketed under the trademark PLEXIGLAS® by Rohm and Haas Co. of Philadelphia, Pa. In this regard, window12may be an acrylic window, in accordance with various embodiments. In various embodiments, window12is between 3.175 mm (0.125 in) and 25.4 mm (1.0 in) thick, and in various embodiments, window12is between 3.175 mm (0.125 in) and 12.7 mm (0.5 in) thick, and in various embodiments, window12is between 6.35 mm (0.25 in) and 9.525 mm (0.375 in) thick. However, a pyrotechnic egress system, as disclosed herein may be suitable for any thickness of window.

A pyrotechnic egress system20may extend around a periphery16of window12. An egress area may be defined by periphery16. Pyrotechnic egress system20may be activated during an emergency event to allow for rapid egress from within vehicle frame10. In response to being activated, pyrotechnic egress system20may cut through window12via deflagration allowing the portion of window12that is circumscribed by pyrotechnic egress system20to be detached from vehicle frame10. Pyrotechnic egress system20and window12may be collectively referred to herein as an emergency egress structure.

With reference toFIG. 2A, a cross section view of pyrotechnic egress system20installed onto window12is illustrated, in accordance with various embodiments. Pyrotechnic egress system20may comprise a case22defining an opening24. Pyrotechnic egress system20may comprise a gas generator28disposed within case22. Gas generator28may at least partially fill case22. Stated differently, gas generator28may be placed into case22such that the case22is completely or almost completely full with gas generator28. Gas generator28may comprise a pyrotechnic composite comprising a fuel and an oxidizer, such as, for example, ammonium perchlorate (oxidizer) and aluminum powder (fuel), among others. Gas generator28may be comprised of a formulation that provides high oxygen content in the gas produced to increase the burning of the window material (e.g., acrylic). In this regard, gas generator28may generate an oxidizing gas flame. Gas generator28may be capable of burning at atmospheric pressure. In various embodiments, gas generator28may comprise an ammonium based pyrotechnic, a calcium based pyrotechnic, potassium based pyrotechnic, or any other suitable pyrotechnic for generating an oxygenated gas flame. Gas generator28may comprise a formulation of: 80-95% oxidizer (e.g., ammonium perchlorate, potassium perchlorate, etc.), 0-2% metal powder (e.g., aluminum), 0-2% burning rate modifier (e.g., iron oxide), 4-20% binder polymer (e.g., polyethylene glycol, polypropylene glycol, etc.), and 0-4% curative (e.g., isocyanate curative), in accordance with various embodiments. One example formulation is: 90% ammonium perchlorate, 1% aluminum powder, 1.50% iron oxide, 5% polypropylene glycol, and 2.50% isocyanate curative. Gas generator28may further contain a scavenger, such as potassium nitrate, that will convert hydrogen chloride exhaust products to less harmful products.

With combined reference toFIG. 2AandFIG. 3, pyrotechnic egress system20may comprise an ignition line26. Ignition line26may be disposed at opening24. In various embodiments, ignition line26may plug opening24. Stated differently, case22and ignition line26may enclose gas generator28such that gas generator28is not exposed. Ignition line26may extend along the length (Z-direction ofFIG. 3) of pyrotechnic egress system20. In various embodiments, ignition line26is a pressurized fuse. In various embodiments, ignition line26may burn at a rate of approximately 508 mm (20 in) per second along the length (Z-direction ofFIG. 3) of ignition line26. Ignition line26may be activated in response to an emergency event. Ignition line26may comprise a pyrotechnic composite. Ignition line26may be configured to ignite gas generator28. In this regard, ignition line26may heat gas generator28to its ignition point, causing gas generator28to ignite. In response to being ignited, the hot gases generated by gas generator28may combust ignition line26and/or may eject ignition line26from opening24.

In various embodiments, ignition line26may comprise a braided cord coated with a combination of black powder and/or boron-potassium nitrate, encased in a tube40made of a combustible material (such as cellulose nitrate), with a vent42on the side facing the gas generator28, in which the casing material pressurizes the braided cord so that it burns rapidly, even under water, and directs its flames principally into the gas generator28.

In various embodiments, ignition line26may comprise a resistive igniter line comprising an electrically conductive wire heated by electrical current.

With reference toFIG. 2B, a cross section view of pyrotechnic egress system20in an activated state is illustrated, in accordance with various embodiments. Once ignited, gas generator28may generate a gas flame32. Case22may route the gas flame32out through opening24. The gas flame32may contact window12whereby the gas flame heats the window12causing it to burn away via deflagration. The gas flame may initially burn a trench34into window12.

With reference toFIG. 2C, a cross section view of pyrotechnic egress system20in an activated state is illustrated, in accordance with various embodiments. Gas flame32may continue to deflagrate window12until window12is separated into two separate pieces12a,12b. Upon separation, an aperture may be formed in the window12whereby a pilot and/or passenger may egress from vehicle frame10, with momentary reference toFIG. 1.

As illustrated inFIG. 2BandFIG. 2C, as gas generator28burns, starting from opening24and working towards the opposite end of case22from opening24, the exposed burning surface29,30may grow. Stated differently, exposed burning surface29may comprise a smaller surface area than exposed burning surface30. In this regard, the gas flame32may progressively grow as gas generator28burns due to the increased burning area (i.e., exposed burning surface29and exposed burning surface30) of gas generator28. In this manner, the gas flame32may reach deeper (negative X-direction inFIG. 2C), due to increased mass flow, into window12as trench34becomes deeper. In this regard, case22may be tapered towards opening24.

With reference again toFIG. 2AandFIG. 3, case22may be made of steel or other rigid material capable of withstanding the heat and pressure generated by gas generator28during ignition while tending to resist eroding, softening and/or flexing in a manner that would prevent the gas flame32from being directed into window12. In various embodiments, case22may be coated with a liner or inhibitor to prevent the spread of the gas flame32between gas generator28and case22. Case22may comprise an outer case22aand an inner case22b. Inner case22bmay be configured to hold pyrotechnic egress system20against the window12. Inner case22bmay be bonded to window12. Inner case22bmay be configured to inhibit the surface of the gas generator28to prevent the spread of the flame into the area between the gas generator28and the case22or the window12. Inner case22bmay be composed of metal, metal lined with a plastic inhibitor, or plastic. Opening24may be defined between outer case22aand inner case22b.

With combined reference toFIG. 4andFIG. 5, a method500for manufacturing a pyrotechnic egress system420is illustrated, in accordance with various embodiments. Method500includes disposing a gas generator428into an outer case422(step510). In various embodiments, gas generator428may be pressed into outer case422. In various embodiments, gas generator428may be poured into outer case422wherein the gas generator428may cure and harden. Method500includes positioning an inner case423with respect to the outer case422to define an opening424(step520). In various embodiments, inner case423may be coupled to outer case422. In various embodiments, inner case423may be bonded to outer case422. Method500includes disposing an ignition line426at the opening424(step530). In various embodiments, ignition line426may be pressed onto gas generator428before gas generator428has fully cured. In various embodiments, ignition line426may be bonded to gas generator428.