Interpretando y mostrando la dispersión

LEARNING OBJECTIVE: Describe the components and operation of the canopy emer-gency jettison system.

The canopy emergency jettison system jettisons the canopy clear of the cockpit during emergency conditions that necessitate seat ejection and/or ditching. The canopy is jettisoned clear of the cockpit for normal ejection mode. Through the use of pyrotechnics, the canopy is automatically unlocked and jettisoned when ejection is initiated. It also may be jettisoned without initiating ejection by the aircrew (with canopy jettison initiator handles in the aircraft) or by a groundcrew (with an external canopy jettison initiator handle at each side of the aircraft). Figure 3-5

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Figure 3-5.—Canopy emergency jettison system components.

NFINED

displays the canopy emergency jettison system com-ponents. The following paragraphs will discuss the components and operation of the canopy emergency jettison system.

COMPONENTS

Components of the emergency jettison system include pyrotechnic cords, internal and external canopy jettison initiators, shielded mild detonating cord (SMDC)/gas initiators, gas generators, inert connectors and manifolds, explosive manifolds, and one-way explosive transfers.

Pyrotechnic Cords

Three types of pyrotechnic cords are used in the F-14 escape systems: expanding shielded mild detonating cord (XSMDC), flexible confined detonating cord (FCDC), and SMDC. Two XSMDC cords are routed parallel through each side of the canopy sills. When charged, the cords expand diametrically and sever hardware in all 14 canopy lock hooks, freeing the canopy. The firing of the canopy gas generator then jettisons the canopy. The FCDC, which is used in areas requiring mechanical movement, connects the canopy jettison gas generator to the SMDC, and starboard XSMDC to port XSMDC. The SMDCs are rigid tubes located throughout the cockpit fuselage and bulkheads.

Internal Canopy Jettison Initiators

Two internal canopy jettison initiators enable the aircrewman to jettison the canopy during emergency conditions without initiating seat ejection. One initiator is actuated with the CANOPY JETTISON handle on the pilot right instrument panel; the other initiator, with the CANOPY JETTISON handle on the NFO right instrument panel.

External Canopy Jettison Initiator

An external jettison initiator (fig. 3-6) enables the groundcrew to jettison the canopy during ground emergency conditions. Each initiator is manually actuated with its external canopy jettison handle.

Initiators (SMDC to Gas/Gas to SMDC)

The system has four SMDC to gas (two pilot and two NFO) and four gas SMDC initiators (two pilot and two NFO). The initiators are behind each ejection seat, mounted on an initiator manifold and connected to each seat with a pyrotechnic quick-disconnect. The gas to SMDC initiators are activated by pyrotechnic gas signals which result from pulling the ejection control handle. They provide the initial explosive signal for canopy jettison and seat ejection. The SMDC to gas initiators are activated by the aircraft sequencing system, sending a gas signal to the seat to eject the crewmember.

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CANOPY EXTERNAL

JETTISON INITIATOR

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VIEW LOOKING INBOARD

Figure 3-6.—External canopy jettison initiator.

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Canopy Jettison Gas Generator

The canopy jettison gas generator (fig. 3-7) is attached to the lower end of the canopy actuator. The canopy jettison gas generator provides high-pressure gas to the canopy actuator to jettison the canopy from the aircraft.

Inert Connectors and Manifolds

Inert connectors and manifolds (fig. 3-5) throughout SMDC lines allow the interconnection of SMDC lines.

Explosive Manifolds

Explosive manifolds within SMDC line routing incorporate an internal explosive crossover that permits SMDC to fire both output SMDC lines. The manifolds also provide structural support for mounting the SMDC lines to the aircraft structure.

One-Way Explosive Transfers

One-way explosive transfers (fig. 3-5), within SMDC line routing, provide unrestricted explosive

transfer in one direction only. If an explosive signal is introduced in the opposite direction, it is blocked.

OPERATION

Pulling the pilot or NFO ejection control handle initiates ejection. When the seat firing handle is pulled, a sear is pulled from dual redundant cartridges, sending a gas signal through the seat disconnect to the gas SMDC initiators mounted on the initiator manifold. This sends an explosive signal through S M D C l i n e s t o s a f e - a n d - a r m f i r i n g p i n s , canopy-separation charge (XSMDC), and canopy jettison gas generator. XSMDC lines, routed through the latch hooks, break the canopy latch frangible bolts.

This allows the hooks to rotate upward, releasing the canopy.

The canopy jettison gas generator produces high-pressure gas that forces the canopy actuator shaft upward, ballistically jettisoning the canopy. As the canopy leaves the aircraft, the lanyard becomes taut and removes the sear. This fires an explosive charge within the safe-and-arm seat ejection module. This signal is routed to the ejection seat via the sequencing system SMDC lines to fire the SMDC to gas initiators. The SMDC to gas initiators send a gas signal through the pyrotechnic quick-disconnect, ejecting the crew-member by firing the primary cartridge.

During ground emergency conditions, the canopy may be jettisoned clear of the cockpit by actuating the external canopy jettison initiator handle at either side of the aircraft. The pilot or NFO also may jettison it without initiating ejection with the internal canopy jettison handle.

The explosive signal provided by the canopy jettison initiator is blocked from entering the SMDC lines of the seat ejection system by the one-way explosive transfers. Inert connectors joining the SMDC lines transfer the explosive stimuli through the bulkheads, straight runs, tee connections, and 90°

bends. The canopy lock separates SMDC explosive manifolds within SMDC lines, which allows output SMDC lines to be initiated from one SMDC input. This assures system redundancy by providing dual-line initiation for the canopy-separation charge.

Q3-19. What types of pyrotechnic cords are used in the F-14 escape system?

Q3-20. What component enables the aircrewman to jettison the canopy during emergency condi-tions without initiating seat ejection?

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Figure 3-7.—Canopy jettison gas generator.

Q3-21. What provides high-pressure gas to the canopy actuator to jettison the canopy?

Q3-22. What component provides interconnection of SMDC lines?

Q3-23. Explosive manifolds provide support for mounting the lines to the aircraft structure.

Q3-24. What component prevents explosive transfer in one direction only?

Q3-25. The external canopy jettison handles are used for what purpose?

FRANGIBLE ESCAPE CANOPY