Abstract: In an aircraft having an integrated turbo-ramjet engine system for hypersonic flight there is provided an air breathing system having an air intake arrangement which can be selectively functioned to supply air to the turbo-ramjet engine system when the aircraft transitions from a turbo-propulsion mode to a ramjet-propulsion mode and back to a turbo-propulsion mode.

Abstract: An improved S-duct for turbo-jet engined aircraft. The present invention allows a high volume of high energy air to traverse the S-duct at a high pressure recovery ratio.

Abstract: A supersonic aircraft includes an internal passageway, an articulated intake structure and an articulated exhaust structure which is connected to the intake structure by the passageway. The articulated intake structure defines an opening having a cross-section which is essentially equal to the cross-section of the aircraft's fuselage when configured for supersonic flight and smaller opening when configured for subsonic flight. Also, for supersonic flight, the cross-sectional area of the air intake structure decreases in the direction of air flow. For subsonic flight, the cross-sectional area of the air intake structure is relatively constant. For supersonic flight, the exhaust structure defines a cross-section which increases in the direction of air flow.

Abstract: A nacelle cooling and ventilation system for an aircraft gas turbine engine which includes a chin scoop and duct assembly for directing air through the engine bay where it is exhausted into the engine exhaust through an exhaust shroud eductor. The nacelle is enclosed so that effectively all of the cooling air entering the bay leaves the bay through the engine exhaust and is not dumped overboard, thereby adding to the effective thrust of the engine. An engine oil and generator oil heat exchanger is positioned in the cooling air duct into the bay so that the same air which cools the bay also cools engine and generator oil. The oil heat exchanger includes directional louvers which regulate and keep to a minimum the amount of cooling air and direct cooling air forwardly in the bay so that the entire bay area is cooled, and which can be shut as a fire control measure.

Abstract: An improvement in an aircraft of the type having a passenger cabin, a wing with a wall defining a leading edge and having a vent/air intake opening therein and a conduit communicating between the vent/air intake opening and the cabin to provide ventilating air from externally of the aircraft to the cabin. The improvement is an air flow blockage plate that is removably fixed to the wing wall so that in its operative position the air flow blockage plate intercepts and deflects the flow of onrushing air directed towards the vent/air intake opening away from the vent/air intake opening as an incident of the aircraft moving forwardly relative to an air mass.

Abstract: A variable-geometry duct having at least one moveable side wall, and a bellows interposed between the side wall and a back-up structure. The bellows creates a sealed cavity between the moveable side wall of the duct and the back-up structure. Pressurized fluid in the cavity is controlled so as to maintain a desired pressure differential between it and the pressure of the fluid carried by the conduit for all positions of the moveable side wall.

Abstract: Apparatus for separating relatively more dense particulate matter from a relatively less dense fluid flow comprising a separator member mounted for rotation about an axis, and including the following: one or more fluid inlets; one or more particulate matter outlets communicating with an associated fluid inlet and spaced from the axis by a first radius; and one or more fluid outlets, each communicating with an associated fluid inlet and an associated particulate matter outlet and located downstream thereof, each fluid outlet having an opening considerably larger than that of the particulate matter outlet associated therewith and being spaced from the axis by a second radius smaller than the first radius.

Abstract: A propfan turbine engine for an aircraft has a shroud and on the leading edge of the shroud, has one or several, preferably two, separate sector-like annular profile parts which via actuating devices can be moved from the shroud such that slots can be formed between the profile parts and the shroud. This arrangement prevents dangerous air-flow separations on the outside of the upper shroud region and on the inside of the lower shroud region at large angles of attack of the aircraft engine for both high and low power operation.

Abstract: An inlet ramp for an aircraft engine is constructed as a movable panel which is internally cooled by fluid coolant. At a selected time, the coolant flow is terminated allowing the panel to overheat and melt away so as to expose an underlayer of ablative material. The ablative material then begins to melt away thereby cooling the underlying surface of the aircraft via ablation.

Abstract: Variable chin-inlet for a missile wherein radially movable compression ramps vary the throat area so as to compress flow in the plane of the upstream boundary layer growth.

Abstract: A jet engine fan nacelle which maintains attached flow during engine windmilling. The nacelle includes a cylindrical airfoil body having an inner surface. A plurality of vortex generators are positioned on the inner surface between the nacelle body's leading edge and its throat within ninety degrees of rotation from the crown line hilite about the nacelle's longitudinal axis. The vortex generators energize the airflow to maintain an attached flow around the leading edge and along the outer surface of the nacelle's body without separating from the outer surface which would produce an undesirable increase in drag.

Abstract: A nacelle for a gas turbine engine (10) defines an air intake which is capable of meeting all the engine airflow requirements. The nacelle comprises a cowling (22), fixed upstream and in spaced apart relationship from an engine cowling (16), to define an annular passage (30) therebetween. Each of the cowlings, (22) and (16), have an air intake, (24) and (20) respectively, through which the mainstream flow of air passes into the engine (10). Depending upon the amount of airflow the engine (10) demands at different operating flight conditions air can flow in either direction through the passage (30). The flow in either direction through the passage (30) enables optimisation of both the internal and external nacelle requirements at all the different engine airflow requirements.

Abstract: A method and apparatus are disclosed for treating ice and debris in a gas turbine engine. More particularly, a specially configured and slidable scoop is positioned between the booster exit and the compressor inlet in a gas turbine engine. An actuator mechanism can be coupled through a linkage to the scoop to position the scoop within the core path at low power conditions and retract the scoop from the core flow path at high power conditions.

Abstract: An inlet system, which can be used for all supersonic or hypersonic engine inlets, comprises two or several separate parallel ducts which must be switched over in specific phases of flight. This is accomplished with a duct shaped parallel inlet element pivotably assigned to the inlet ramp of the inlet, which as a channel-connecting re-direction member alternately can close off the turbojet inlet duct as well as also the ramjet inlet. Preferably, the construction comprises a plurality of pivotably connected box-like elements interconnected in a movable manner.

Abstract: A variable air intake includes a movable ramp (2) driven by a carriage (6) that moves linearly on a drive screw (7). To protect the drive screw (7) from hot gases a thermal blind (13) is provided that moves with the carriage (6). The blind (13) is guided and supported by guide means (15, 18, 19) formed integrally with a structural unit (17) housing the drive screw (7), and is tensioned by tensioning means (16, 19).

Abstract: A near supersonic aircraft comprising an airframe that maintains subsonic air flow thereover within the flight envelope of the aircraft. The airframe comprises a right circular conical forward fuselage section, a right circular cylindrical intermediate fuselage section defining a passenger compartment, and an aft fuselage section having a generally circular frontal cross section and a generally rectangular aft cross section.A submerged semi circular air inlet is disposed between the intermediate and aft fuselage sections at the top thereof. A pair of forwardly swept wings are joined to the fuselage adjacent the circumferentially spaced ends of the air inlet whereby air flow over the fuselage and along the leading edges of the wings is directed into the air inlets at subsonic speeds and at all attitudes of the aircraft within its flight envelope.

Abstract: With surface sections vaulted with respect to the valve centerline the valve mates with a stationary companion surface on an annular casing lip to optionally shut off or expose the engine by having vaulted surface sections which are arranged at an axial distance an angularly offset over the circumference by essentially 180.degree. with the valve centerline, forming its largest relative diameter; where the vaulted surface sections form a valve of axially and circumferentially three-dimensionally displaced drop or mushroom shape.

Abstract: A turboramjet engine is provided having a ram air duct which is constructed between an outer duct wall and a housing-type shrouding of a basic turbo-engine, and having shut-off devices by means of which the ram air duct, when the basic engine is switched on and the ramjet engine is switched off, is to be shut-off on the air supply side, with the simultaneous release of intake air into the basic engine. In this case, among other things, the shrouding is to form an air shaft which is widened in a polygonal manner in the direction of the inlet-side end of the ram air duct and is to have breakthroughs there, the shut-off devices being flaps which are pivotally arranged at the breakthroughs and which, when the ramjet engine is switched on, expose the breakthroughs and in the process form a shut-off body of the air shaft which is symmetrically acutely folded together with respect to the ram air flow.

Abstract: A supersonic inlet flow duct (10) is provided with a pivoting bleed stability door (34) and biasing spring (42). The door (34) opens under the influence of increased static fluid pressure behind a shock front (24) which is displaced forwardly by a downstream pressure perturbation. The opened door (34) diverts portions (31, 44) of the inlet duct flow stabilizing the shock front (24a) and downstream shock train (25) within the duct (10) until the perturbation subsides.

Abstract: A hypersonic inlet and a hypersonic engine and flight vehicle having such an inlet. The three-dimensionally-swept inlet has an upper member with a caret-shaped lower surface portion producing a two-dimensional wedge flow below such lower surface portion. The inlet also has a lower member having two inverted and transposed semi-caret-shaped upper surface portions producing a two-dimensional wedge flow above such upper surface portions. An inlet aft portion connects together the upper and lower members and has an orifice defining the engine inlet throat which at least partially receives the two-dimensional flows.

Abstract: An hydraulically-pivotable inlet ramp with box-like shaped cross-section for supplying air into engines of supersonic or hypersonic airplanes. The inlet ramp, comprised of a plurality of relatively movable elements, can be adjusted into a number of different positions to optimize air flow under various mach conditions, as well as control a boundary air layer inlet.

Abstract: A method of operating a scramjet engine having an improved low pressure combustion cycle is disclosed. Apparatus for carrying out the method is also disclosed. The method includes the steps of providing supersonic compressed airflow to a combustor and supplying fuel to the combustor for generating a fuel/air mixture having a predetermined temperature less than a temperature required for spontaneous ignition of the fuel/air mixture. The method also includes igniting the fuel/air mixture for sustaining recombination reactions of the fuel/air mixture for generating combustion gases. In the preferred embodiment, the fuel/air mixture is ignited by generating a boundary layer of airflow having atomic oxygen and channeling the boundary layer into the combustor for mixing with a portion of the fuel for generating a boundary layer fuel/oxygen mixture subject to spontaneous ignition.

Abstract: A nacelle inlet for channeling airflow to a gas turbine engine having a longitudinal centerline axis includes an annular forward nacelle having a leading edge defining an inlet face for receiving the freestream airflow. A diffuser is disposed in flow communication with the inlet face, with the diffuser being defined about a droop axis inclined relative to the engine centerline axis. The forward nacelle includes a crown and a keel defining therebetween a scarf axis, with the keel extending axially forwardly of the crown so that the scarf axis forms an acute scarf angle greater than zero relative to a reference line perpendicular to the droop axis.

Abstract: An inlet having a single-piece, flexible inlet ramp skin is disclosed. A corrugated member is rigidly coupled to the interior surface of the ramp skin to hold the skin rigid in one direction but permit it to be extremely flexible in a second direction. A plurality of beams extend perpendicular to the ridges and grooves of the corrugated member to hold the skin in position in the second direction. Mechanical actuators are coupled to the beams for applying force to vary the shape of the beams and thus the shape of the ramp skin. The inlet area is varied as the ramp skin is moved. The beam member and ramp skin are elastically deformable from an intermediate position in a first direction to increase the area of the inlet and in a second direction to decrease the area of the inlet. Shaping the beam and ramp skin to be at an intermediate position when not deformed permits a greater range of movement and a more variable inlet area for a given material and weight.

Abstract: The invention relates to engine air intakes for aerospace vehicles in which a variable geometry ramp system is employed for matching air intake flow to propulsion engine demand. To alleviate the induced high pressure loads on the ramps and the ramp actuators arising from the air intake flow a reacting pressure is applied to the opposite face of the ramps. The ramp assembly in addition to defining the required air intake duct geometry further defines the adjacent boundary of an enclosure which is pressurized by ram air and vented as required as a function of the load on one of the ramp actuating jacks to give the desired load alleviation.

Abstract: In one form of the invention, different airflows across a temperature sensor in an aircraft are maintained during different flight conditions. A first airflow is generated during takeoff by a pressure differential existing between two surfaces of the aircraft. A second airflow is maintained during cruise by an air jet supplied by an ejector.

Abstract: The present invention comprises a cowling structure for a gas turbine aircraft engine which allows the aerodynamic characteristics of the inlet passageway to the engine to be varied in accordance with flight conditions. This structure includes an annular lip portion positioned at the front edge of the cowling defining an aerodynamically sharp contour and which is mounted on a set of support struts constructed for allowing the lip portion to be translated forwardly and backwardly from the forward edge of the cowling. The structure further comprises a mechanism for injecting pressurized air into the airflow along the trailing edges of these support struts in order to suppress turbulence induced in tha airflow such that noise as may be produced as a result of airflow is substantially decreased.

Abstract: A two dimensional supersonic air intake is provided for the combustion air f an aircraft engine comprising on one side a front flap (3) forming a visor and on the other side a fairing (4). The front flap (3) is movable about a pivoting axis (5) situated opposite the fairing (4). The front flap (3) is fast with a mobile fairing nose (6) situated in front of fairing (4) and moving in front of the latter when the front flap (3) moves in the direction which increases the air intake section.

Abstract: Two dimensional, supersonic and hypersonic air intake for the combustion air of an aircraft engine, comprising two front flaps (3) forming a visor, disposed symmetrically on each side of a longitudinal plane (P), each front flap (3) being movable about a pivoting axis (4) situated in the vicinity of the wall of the air intake which extends the front flap considered. The pivoting axis (4) of each front flap (3) is situated in the vicinity of a first boundary layer trap (5) disposed in the wall of the air intake which extends said front flap (3).

Abstract: An annular nacelle for a turbine engine of an aircraft has a variable contour annular air inlet. The variable contour annular inlet includes annular outer and inner surface-defining radially-spaced structures on the forward portion of the nacelle, an annular member disposed between the annular outer and inner structures and coupled to the annular outer structure for sliding movement along the interiors of the annular outer and inner structures, and a plurality of actuating mechanisms coupled between the nacelle body and the annular member. The actuating mechanisms are operable for moving the annular member between forward and rearward positions.

Abstract: A hybrid laminar flow nacelle for housing an engine of an aircraft includes an outer annular cowl having a leading lip and radially spaced and axially extending annular outer and inner forward surface portions which merge at the leading lip. The nacelle incorporates a suction bleed system between the surfaces and a tailored outer surface geometry shape for producing reduced friction drag laminar flow over the outer cowl at cruise operation of the aircraft and producing separation-free flow over the inner surface of the cowl at off-cruise operation of the aircraft.

Abstract: A mixed compression inlet having a forward ramp, an aft ramp, and a slot therebetween is disclosed. The aft ramp is coupled to the inlet to permit both fore-aft movement and rotational movement. The geometric throat of the inlet is located at the leading edge of the aft ramp. The slot opens into a plenum chamber. A vent permits air to exit from the plenum chamber. The pressure in the plenum chamber is maintained approximately equal to the pressure on the aft portion of the forward ramp. A servocontroller receiving input from pressure sensors of the forward ramp and in the plenum chamber controls the position of a vent door to ensure that the proper pressure is maintained within the plenum chamber.

Abstract: A horizontal inlet section of a jet engine diffuser extends to a transitional curved section which, in turn, extends to a horizontal outlet section offset from the horizontal inlet section to shield observation of infrared and microwave signals from a downstream jet engine. A vane between the inlet and transitional curved sections further shields the observable signals and deflects inlet airflow against the interior wall of the diffuser for minimizing separation of boundary layer airflow from the wall. A backward facing slot is formed in the wall transversely adjacent the vane for effecting low energy boundary airflow to further minimize boundary layer airflow separation.

Abstract: The invention provides a flight attitude control augmentation arrangement and method which is effective at both low speeds and at high altitudes, under conditions in which traditional flight control surfaces cannot provide sufficient air pressure differentials to develop effective control moments. The invention provides flight control surfaces at the engine air intakes of an aircraft. The flight control surfaces are flaps whose angular position determines the amount by which the intake airstream is perturbed by the flap and the consequent reaction force on the aircraft fuselage, which in turn determines the magnitude of the control moments generated by the surfaces. The net moments resulting from asymmetric deployment of the flaps are used to augment flight control moments generated by conventional flight control such as a rudder.

Abstract: The high cost of fabrication of a turbojet propulsion system 12 for a missile having an engine 18, mounted within a casing 14, including an inlet 20 to a compressor 22 and an exhaust gas outlet 24 is avoided in a structure having a propulsion system 12 with an inlet 26, 28; 37 located forward of the engine 18 for directing free stream air to the inlet 20 of the compressor 22, an outlet 30, 33; 38, 40 located aft of the engine 18 for directing exhaust gas into the free stream air, an engine starter 42 aft of the engine outlet 24, and a fuel storing bladder 46 forward of the engine 18.

Abstract: The present invention relates to turbofan gas turbine engines. In conventional high bypass ratio turbofans the large variations in the free air stream flowing into the fan duct inlet is accommodated by a thick lip and a long, thick fan casing to prevent air flow separation from the outer surface of the fan casing, but produces a heavy fan casing and large drag values. In the invention a turbofan comprises a core engine which has a core casing, and a fan assembly positioned downstream of the core engine. The fans operate in a fan duct defined by the fan casing. The core casing has an external form upstream of the fan duct inlet which affects the airflow streamlines flowing into the fan duct inlet to cause it to adopt a flow path which is near alignment with the length of the fan casing to reduce fan casing weight, length and drag.

Abstract: A propulsion system for an aircraft capable of hypersonic flight combines a turbo-jet with a ramjet which are so arranged that the ramjet or jets are located directly adjacent to the aircraft body while the turbo-jet or jets are located away from the aircraft body so that the ramjet or jets is placed between the turbo-jets and the body. This arrangement makes the turbo-jets much more accessible for maintenance and exchange work. Both types of engines have a common air intake which is provided with flaps capable of guiding the body boundary layer through the ramjet when the latter is not in operation. When the ramjet is in operation, the air intake flaps form the air intake in such a way that boundary layer turbulent air is mixed with undisturbed incoming air for the ramjet while the air inflow to the turbo-jet is closed off altogether.

Abstract: The invention is a short/vertical takeoff and landing aircraft. In detail, it comprises an airframe having aerodynamic lift and flight control surfaces. An engine is mounted in the airframe in a reversed position having the inlet facing toward the rear of the aircraft and the exhaust nozzle assembly, having a pair of exhaust nozzles, facing toward the front. The exhaust nozzles extend outward from the sides of the aircraft and are rotatable from a vertically downward position to provide upward thrust to a horizontally rearward direction to provide forward thrust. The thrust axis when in the vertical position is approximately through the center of gravity. A generally U-shaped engine inlet duct is mounted in the airframe having an inlet opening facing forward and an outlet coupled to the inlet of the engine.

Abstract: A gas turbine power plant, especially for helicopters, includes a main engine and a reduction gear transmission forming a self-sufficient auxiliary modular unit. A compensating arrangement includes an articulated outer cover and a shaft section inside said outer cover connected for transmitting power and for compensating any position disalignment between the main engine and the helicopter main gear drive. The reduction gear transmission is directly, rigidly force-coupled to the helicopter main gear drive, and the compensating arrangement including the articulated outer cover and shaft section is located between the main engine and the reduction gear transmission, whereby the axial length spacing between the main engine and the helicopter main gear drive is substantially reduced.

Abstract: An air intake system of an aircraft is improved so that a performance of the air intake system will not be degraded even during flight at a large angle of attack and at high mobility of the aircraft while at the same time secretiveness or security of the aircraft against radar beam irradiation from below will be maintained. The air intake system includes a main air intake port provided on an upper surface of the airframe of the aircraft, an auxiliary air intake port provided on a lower surface of the airframe, and a closure member for the auxiliary air intake port and which is movable between a closed position and an open position of the auxiliary air intake port.

Abstract: A superagile tactical fighter aircraft and a method of flying it are disclosed. The superagile aircraft is characterized by articulatable air inlets, articulatable exhaust nozzles, highly deflectable canard surfaces, and control thruster jets located around the nose of the fuselage, on the top and bottom surfaces of the propulsion system near the exhaust nozzles, and on both sides of at least one vertical tail. The method of operating the superagile aircraft comprises the step of articulating the air inlets and exhaust nozzles, deflecting the canard surfaces, and vectoring the thruster jets so that supernormal flight is attained. Supernormal flight may be defined as flight at which the superagile aircraft operates at an angle of attack much greater than the angle of attack which produces maximum lift. In supernormal flight, the superagile aircraft is capable of almost vertical ascents, sharp turns, and very steep descents without losing control.

Abstract: To effectively recover and stow hardware items from air launched missiles, a housing containing a rotor is mounted on the launching aircraft. The housing has a suitable opening and recess so that a lanyard can connect such hardware items as the missile air inlet cover to the rotor. The rotor has a spring therein under high tension sufficient to retract the missile cover into the housing recess in a short period of time. The spring powered rotor is activated by movement of the missile away from the aircraft but can be manually reloaded and the attachment point of the cover to the rotor manually reset, as desired.

Abstract: A ram air flow system for an aircraft or the like wherein a ram air duct is provided with an inlet through which air enters the duct and an outlet through which air leaves the duct. A fan is located in the duct between the inlet and the outlet and is located to define a bypass portion of the duct through which air can pass through the duct past the fan. Doors are mounted in the duct for movement between a first position covering the fan to allow air to bypass the fan, and a second position exposing the fan while blocking the bypass portion of the duct to allow air to flow through the fan.

Abstract: A construction is provided to aerodynamically affect a jet engine nacelle in its intake lip area primarily by forming and pivotally arranging flaps on a radially outer circumferential sector of the intake lip such that from a first extreme position, in which they are adapted to a cruise lip geometry, they can be moved into a second extreme position, in which they radially expand the outer contour of the intake lip while providing and exposing air blowoff ducts with their rear side, said ducts terminating at the outer wall of the nacelle at essentially a tangent therewith. Further air injection flaps are also provided in certain embodiments for forming air injection ducts through the intake lip walls during certain engine operating conditions.

Abstract: A gas turbine engine inertial inlet particle separator having anti-icing. The separator has inner and outer walls defining a main inlet channel and splitter walls dividing the main channel into inner and outer branches. At least one of the walls has a surface portion subject to icing and a partition on the separator is closely disposed behind the one wall to define therewith a narrow annular tunnel. An inlet passage ducts hot compressed air from the engine to one end of the narrow tunnel and a discharge passage ducts the hot compressed air from the other end of the tunnel to a discharge, the flow area of the tunnel being less than the flow area of at least one of the discarge and inlet passages so that the tunnel defines a high velocity, enhanced heat transfer segment of a heating air channel consisting of the tunnel and the inlet and discharge passages. Heat conducting bridges extend across the tunnel to further enhance heat transfer to the icing surface portion.

Abstract: An air inlet assembly for a gas turbine aircraft engine includes a fixed turning vane and a movable turning vane that is carried on the trailing edge of the air deflector door. To optimally direct and accelerate a flow of air into the engine intake, the low-pressure and high-pressure surfaces of the airfoil-shaped fixed turning vane lie in parallel planes at the trailing edge of the vane. The turning vane on the air deflector door has a low-pressure, convex surface that rests against the fixed turning vane when the door is deployed in the anti-icing mode. Under normal conditions, the door is stored and the two vanes cooperate to form an aerodynamic converging channel, which accelerates the flow and attaches it to the low-pressure surface of the vane on the door.

Abstract: The pressure drag on the skin of an aircraft is reduced by rigidly securing boundary layer influencing members to the skin of the aircraft, including the wings, the elevantor and fin/rudder assemblies, and the body near the tail end. These members may be vortex generators and boundary layer diverters and are always located in the attached flow. In addition, if the members are placed upstream of any air intakes, especially flush air intakes, the air intake efficiency is also improved. The influencing members have an effective height above the surface corresponding, at the most, to the displacement thickness portion of the boundary layer.

Abstract: A turbine plant intake housing includes an outer shell supporting radially extending arms which include a fixed part and a movable flap associated therewith. Each arm is provided with a metal tie rod having its radially outer end fixed between two forks supported by the outer shell, and its radially inner end co-operating with a metal insert embedded in layers of coiled filaments of composite material forming a floating hub supported by the tie rods. The radially inner end of each rod is attached to the insert of the hub by use of a nut which effects a prestressing clamping of the tie rod on assembly.

Abstract: The inlet of a jet engine is equipped with a pivotally displaceable deflector which becomes deployed when the aircraft is in a stalled, horizontally stabilized condition. As the aircraft undergoes vertical descent, vertically impinging airflow is reflected off the interior surface of the deflector and flows coaxially through the inlet thereby forcing continued rotation of turbine blades. Hydraulic and electronic control devices deriving power from the turbine may be maintained operative even though the aircraft is in a stalled condition, thereby permitting limited horizontal maneuvering of the aircraft as the vertical descent continues.

Abstract: A bulkhead structure for separating two compartments in an aircraft engine inlet cowl or the like and for promoting fluid flow between the compartments is described which comprises a first flanged member having a first flange attached to the periphery of the bulkhead and a second flange having in a surface thereof a plurality of corrugations extending across the width of the second flange, and a second flanged member having a first flange presenting a first surface for attachment to the walls defining the compartments separated by the bulkhead and presenting a second surface attached to the second flange of the first flanged member for defining with the corrugations a corresponding plurality of passageways past the bulkhead at the periphery thereof.