Abstract: A foldable linear explosive charge (FLEC) comprising a plurality of similar tubular members which are hinged to each other at their ends so that they can be extended co-linearly to form a long tubular member or can be hinged and relatively rotated 180.degree. from each other to form a zig-zag folded system suitable for transport or storage. While in extended form, with the tubular members co-linear, they are wound with a helix of linear explosive compound (LEC). At the joints between each pair of tubular members, the LEC passes directly over the hinge, so when that joint is rotated from closed (folded) to open (linear) position, the explosive member is not moved, except for a rotation, in which it returns from a slight torsion. The FLEC is carried in a container in the folded condition and when it is to be inserted into a drilled shot hole, each successive pair of sticks is unfolded into a co-linear position and lowered into the shot hole.

Abstract: In an electronic fuze for a projectile the ignition energy, upon firing of the projectile, is produced by a generator and stored in a storage capacitor. An electronic circuit serving for the barrel safety i.e. to prevent premature detonation of the projectile in front of the barrel, delaying ignition upon impact, the delay-free ignition upon impact and the self-destruction of the projectile, controls the delivery of the energy stored in the capacitor to the detonator or ignition cap. To ensure that the energy of the storage capacitor is sufficient the electronic circuit of the fuze must work with extremely low current. This is realized by providing for the circuit a stabilizer, a switching-on element, resetting elements, blocking elements and time-delay elements, the stabilizer and time-delay elements being structured as solid-state circuits.

Abstract: A safety and arming device for a directed missile warhead using a rotor hng a plurality of explosive paths therethrough. A central shaft guides axial and rotary movement of said rotor. Missile launch is sensed and unlatches the rotor. Missile launch acceleration causes the rotor to move axially. Receipt of a second signal causes the rotor to rotate, thereby arming the device by aligning the explosive paths and the detonators. Circuit breakers may also be included on the housing and rotor to produce a continuous electrical path for the firing circuits only when the device is armed.

Abstract: The tamping head on a mobile track tamper includes a pair of rigid tamping tool units each consisting of a T-shaped holder whose vertical arm is mounted on a vertically movable carrier and whose transverse arms each have a tamping tool mounted therein. The tamping tool units are vibrated by an eccentric shaft and reciprocated by hydraulic drives linked to the eccentric shaft and to the vertical arms of the holders, respectively. A housing defining an oil sump in the lower portion thereof is mounted on the carrier and holds the eccentric shaft, and bearings which rotatably mount the eccentric shaft in the housing and link the hydraulic drives to the eccentric shaft being lubricated by the oil from the sump.

Abstract: A lading support carrier for handling packaged goods in conjunction with an overhead conveyor, such as a monorail conveyor. Includes a support member suspendable in generally upright position from the conveyor and spaced apart, generally outstanding bars hingeable and detachably connected thereto to receive the goods such as package goods to be moved. Provision is made for suspending the support rack for movement along an overhead conveyor. The outstanding bars may be selectively hinged in aligned relation with respect to the upright support member to vary the space between any two extending support bars to accomodate larger packages or goods. All outwardly extending support bars may be hinged for greater convenience in handling and/or shipping. Where used in a food processing plant, the outstanding bars may be readily removed for sterilization and quickly replaced. The material from which the unit is made may be provided of substantially corrosion proof and impermeable material.

Abstract: A train rail gear assembly for use with truck mounted railroad cranes and the like, including fluid actuated cylinder and compression spring means operably associated to one another for raising and lowering rail gears and for shifting weight from the vehicle frame to the compression spring means.

Abstract: A side dump rail car tilted by means of hydraulic cylinders at each end of the car which are centrally located. The edge of the car is retained by an engagement lug slid into place hydraulically to determine direction of tilt.

Abstract: A storage arrangement for a passenger compartment in a railway passenger vehicle including a vertical panel extending between and removably secured to the ceiling and floor of the vehicle and having a cabinet shell secured thereto to provide an easily assembled and maintained baggage containment or storage arrangement within the compartment.

Abstract: A rail car having an interior cavity defined partially by vertical rail car side walls and a roof structure with an inwardly and upwardly directed portion to improve car clearance is disclosed. Access to the cavity for loading and unloading lading is through an end opening. A pair of door assemblies, each of which includes a plurality of panels, each panel of which is pivotally movable with respect to the others, are included for closing the end opening. Pivot means for mounting each of the door assemblies are provided to move the door assemblies between their respective folded open positions and unfolded closed positions. The pivot means are mounted for movement toward and away from the interior of the rail car to permit storage of the folded door assemblies within the rail car along the car side walls. Top panel portions extend from the top of the door assemblies angularly inwardly relative to the opening and in spaced relation with each other and the roof structure.

Abstract: A wood pallet includes a top deck, a bottom deck and spacer members. The top deck includes a pair of end members, a pair of side members, and a plurality of intermediate load supporting members. The side members include means forming inwardly facing recesses for receiving the end members, the recesses including end facing abutments to engage the inside edge of the end members so that inwardly directed forces are transmitted into and partially absorbed by the side members. The end members include beveled ends which are received against complementary beveled surfaces within the recesses to assist in securing the end members to the pallet. The bottom deck is provided with a relatively large surface area, but with openings to accommodate the wheels of a hand transport. The top and bottom decks are separated by means of spacer members including longitudinally extending stringers on which are mounted blocks of plywood.

Abstract: A freight carrier having a base structure forming a freight carrying platform which is provided at each corner with a corner post pivotally mounted for movement between an upright erect position and a folded position in which the post lies parallel to the platform. An interlocking mechanism is provided at each corner of the carrier to enable the carrier with the corner posts in their folded position, to be interlocked with a similar carrier which is stacked thereon and the interlocking mechanism includes a clamping arrangement to enable the stacked interlocked carriers to be clamped together. The interlocking mechanism is also arranged to lock an associated corner post in the erect position and clamps the corner post to the base structure in this erect position.

Abstract: A flat pallet including a supporting deck, sheet metal supporting feet connected to the deck, each of the supporting feet having a tapered, skid-like configuration, and horizontal flanges connected to the feet, and fastened to the deck, with the supporting feet and flanges together being constituted by a plurality of uniform, shaped sheet metal strips.

Abstract: Safety device in the general form of an apertured disc which aids in keeping sparks and flames from paper, kindling, wood etc., from shooting up the chimney and possibly causing fire; the device also helps to stop soot build up and it controls the rate at which the wood burns, saving fuel.

Abstract: A compact rectangular boiler for hot water heating systems serves as a booster or helper boiler but can be used in some cases as a primary boiler. A boiler power module consisting of fire tubes and a surrounding water chamber is readily removable like a sliding drawer for cleaning and repair, when necessary. Beneath the boiler power module is a sturdy refractory lined fire box for burning wood or other solid fuel including a cast iron grate. Beneath the grate is a readily removable ash receiving drawer or pan. The boiler power module may employ an alternate heating source in the form of an electrical heating element. Forced draft and manual draft arrangements are included.

Abstract: An incinerator bag that is primarily utilized for the storing of and subsequent destruction of classified documents. The bag is made of a three-ply construction which includes an inner and outer ply or layer of inflammable material such as paper and a middle ply of nonflammable open mesh material bonded therebetween. The nonflammable material may be in the form of, for example, glass fiber, metal wire or a non-metallic nonburnable material such as NOMEX. In addition, a closure element having a handle incorporated therewith is removably attached to the bag for utilization in sealing the bag when the bag is to be transported.

Abstract: An apparatus and method for supporting and starting up a fluidized bed in which a grate is disposed in a housing for receiving a single bed of particulate material, portions of which are combustible. The interior of the housing below the grate is divided into a plurality of compartments, and an air damper is disposed in each for selectively controlling the flow of air through the compartments and through the respective portions of the grate to selectively fluidize the corresponding portions of the bed of particulate material. A start-up burner is provided for igniting that portion of the combustible portion of the bed of particulate material extending above one of the compartments and additional combustible particulate material is selectively supplied to the portions of the bed.

Abstract: Planting apparatus including a supporting frame adapted to be connected to a tractor or similar vehicle; a seed hopper mounted on the supporting frame for containing a supply of seeds, and seed metering mechanism spaced beneath the discharge outlet of the seed hopper for controlling the movement of the seeds discharged from the hopper on the ground. A magnetic seed treating device is disposed in the path of seeds discharged from the hopper for causing the seeds to pass through a magnetic field to magnetically treat the seeds as the seeds are planted.

Abstract: An automatic sewing apparatus for air cushions that includes a carriage having four circular tables that are sequentially movable to a plurality of circumferentially spaced work stations for receiving a pair of circular sheets of fabric and for sewing the peripheral portion thereof. Each table is combined with a circular cover that pivots into engagement with the sheets of fabric located on the associated table so as to maintain the sheets in position while the peripheral portion is being sewn.

Abstract: A sewing aid device, particularly for inserting slide fasteners, collars, sleeves and the like into partly-finished garments, comprises a frame in which the materials to be sewn together are held in fixed relative position. A guideway on the frame cooperates with corresponding means on a sewing machine foot so that the machine sews around the guide without the need for constant operator adjustment.

Abstract: A module including a frame which supports a motor, reduction gearing and a belt driving pulley is mounted in a sewing machine for position adjusting movements in one direction effective to set tension in a shaft timing belt, and position adjusting movements in another direction effective to set tension in a hook shaft timing belt.

Abstract: The invention as disclosed provides an improved mainsail and/or mizzensail furling device for use on sailboats and includes a furling drum mounted on the gooseneck connecting the boom to the mast. An upper masthead holding device is movably mounted relative to the mast and includes a pair of pivoted mast engaging flanges. A first pair of substantially longitudinally extending arms are connected to the flanges and maintain a swivel a given distance from the mast. The halyard is connected to the swivel in a convenient fashion, and a second pair of arms are attached in such a way as to lead the halyard from the top of the swivel device at an angle of approximately 45.degree. to the mast, to maintain the flanges substantially parallel to the mast to facilitate raising and lowering the device as well as a snug fit against the mast when the halyard is made taut. The flanges are pivoted to the first pair of arms so as to grip a variety of mast sizes and configurations.

Abstract: A propulsion system for a hydrofoil, planing or semi-planing sea-going vessel having a hull having a port pump water inlet formed therethrough on its port side, a starboard pump water inlet formed therethrough on its starboard side and first, second and third outlets formed therethrough, comprises a booster first stage system in the hull coupled to and driven by the motors. The booster first stage system comprises a first axial water jet pump at the port pump water inlet and a second axial water jet pump at the starboard pump water inlet. A second stage water jet system in the hull aft of the first stage system comprises a third axial water jet pump functioning as a turbocharger.

Abstract: A signalling device for underwater divers, in the form of an inflatable bladder held within a container and attached to a reel. The device can be attached to a diver, being strapped to his arm or to his air tank, for example. The device can be actuated by pulling a handle, which releases a gas cartridge to inflate the bladder as it is simultaneously released from the container to float to the surface. Rescuers can then follow the line down to the reel to locate the diver.

Abstract: There is disclosed a pressure responsive device incorporating a snap action disc spring having arms for actuating an indicator plate with indicia thereon. In one arrangement the arms extend from the inner peripheral edge of the disc spring, and in other arrangements the arms extend from the outer peripheral edge of the spring. The indicator plate is adapted for rotational movement with lateral movements of the arms when the spring snaps, as by direct connection to the ends of the arms or by means of gearing or other provision of converting linear motion to rotary motion of a pin or shaft of the indicator plate. The plate is below a cover that has openings in which the indicia are aligned upon its rotation to the position caused by the snap action of the disc spring in response to predetermined level of pressure of fluid applied to the pressure responsive device.

Abstract: In a spraycoating apparatus for round workpieces such as drums, the drums are supported on turning cones while being sprayed. The turning cones are supported on pins moved round in part of a circle from an inlet to an outlet about a horizontal axis. Spray units for putting on the spraycoating material are able to be changed in angle and to undergo adjustment.

Abstract: A magnetic image decorator is disclosed wherein two or more rotatable cylindrical magnetic augers disposed in a sump of magnetically attractable toner are used in conjunction with cooperating knife blades to decorate a surface containing a latent magnetic image and to distribute and redistribute toner particles to maintain a level sump.

Abstract: An apparatus for detecting the concentration of toner particles contained in the developing powder is disclosed wherein the developing powder comprising a mixture of magnetic carrier particles and the toner particles is transported while being adsorbed by a magnet roll, and rubbing an electrostatic recording surface lightly to develop an electrostatic latent image. After development, the developing powder is separated from the magnet roll, flows along a guide path, and forms a magnetic path for a flat detecting coil with the flat surfaces thereof placed in the guide path in the same direction as the flow of the developing powder. In response to the magnitude of the inductance of the detecting coil, an electrical circuit produces an electrical signal corresponding to the mixing ratio between the magnetic carrier particles and the toner particles in the developing powder.

Abstract: Aquatic animals can be kept in a living condition over a long period of time, without feeding them, by placing the aquatic animals, at a large density of more than 200 kg/m.sup.3 in environmental water; maintaining the temperature of the environmental water in a lowest possible range in which it is possible for the aquatic animals to exist; controlling the concentrations of ammonia compounds, water-soluble organic compounds and carbonic acid radical in the environmental water so that their levels do not exceed 20 ppm, 150 ppm and 1,000 ppm, respectively; and regulating the concentration of molecular oxygen dissolved in the environmental water so that it is 3 ppm or more.

Abstract: A method and associated apparatus for carrying out fluidized bed combustion and transferring heat produced thereby to a boiler includes providing a fluidized bed of particulate matter and introducing fuel particles thereinto, causing a portion of the fluidized bed constituents to flow upwardly through a heat exchanger which is essentially free of any obstructions to said flow, and reintroducing the portion of fluidized bed constituents which flow through the heat exchanger, back into the fluidized bed. As preferably embodied, the portion of fluidized bed constituents flows into an inlet at the bottom of the heat exchanger from a quiescent zone adjacent the combustion bed and a gas having a combustible component is introduced into the heat exchanger. Advantageously, additional fuel particles are also introduced into the heat exchanger to flow upwardly therethrough.

Abstract: A boiler having a firebox in which combustion of fuel fed thereto is initiated, a flame tube leading from the firebox in which combustion of fuel may continue and an array of smoke tubes through which the products of combustion issuing from the flame tube are fed to a chimney. The surfaces of the firebox, flame tube and smoke tubes are surrounded by a chamber containing a heat transfer medium, peferably water. A superheater in which steam generated in the chamber is superheated may be included. The superheater is preferably located at the end of the flame tube.

Abstract: A method of fueling an internal combustion engine using explosive dust, characterized by making a slurry of particles of grain dust, jetting said slurry to arrange said particles seriatim, drying said seriatim particles, injecting said dried particles in a series of computer controlled program of successive rasters into said engine, adding dried oxygenated air to said dried injected particles and igniting said rasters of dried dust particles inside said engine to drive the piston.

Abstract: Water is pumped from a holding tank through nozzle means to an area above the carburetion means on an internal combustion engine. The pumping means is controlled by diaphragm means reacting to intake manifold pressure as well as manual control. Filtering means are provided to allow the use of normal tap water. The diaphragm control means operates only after intake manifold pressure has risen to a certain point and ceases to operate after it has arisen above a second point or pressure. In another version, a variable pump is used to provide water in direct relationship to the manifold pressure over the indicated or selected range. The nozzle and the carburetion means act together to provide proper atomization of the water in the fuel air mixture.

Abstract: An internal combustion engine 10 wherein only some compression is carried out in the engine 10 and including a tank 30 of compressed air, a pressure regulator 34, a fuel injector 28, and means 40 and 50 for connecting the foot pedal 38 to the pressure regulator 34 and the fuel injector 28, for controlling air and fuel feed to the combustion chambers 22 in response to throttle demand during high power demand conditions. The engine 10 compresses its own air for cruise conditions but uses stored compressed air (charged from a wayside source) for higher power demand. The engine can use spark or heat ignition, provides full expansion, can be two or four stroke and of the diesel or gasoline type. Compressed air can be generated more efficiently using central station power with a vast savings in the amount of oil consumed. Oxygen enriched (60-80% O.sub.2) compressed air can be used without high temperature problems because of the only partial compression and the high (cooling) expansion ratio and higher rpm.

Abstract: The invention is an electronic fuel control system for an internal combustion engine having a first capacitance which is charged to a value indicative of the engine's speed during a first rotational interval of the engine. At the end of the rotational interval, a potential indicative of the charge on the first capacitance is transferred to a second capacitance which is further charged at a predetermined rate during a second rotational interval. A comparator compares the value of the potential on the second capacitance with a signal indicative of the engine's load. The comparator generates a pulse width signal indicative of the engine's fuel requirements during the interval the potential on the second capacitance is less than the value of the load signal.

Abstract: A device for metering fuel in an internal combustion engine which comprises sensors for operating parameters, an acceleration detecting stage with a subsequently connected pulse generating stage as well as a pulse lengthening stage, and a fuel metering system wherein the acceleration detecting stage is indirectly and/or directly associated with at least one of a plurality of components including an oscillation stopper (to prevent renewed triggering in case of an oscillation-carrying input signal), a blocking stage (for unequivocal and secure triggering), a repetition stopper (to avoid multiple triggering during gradual and longer-term signal rises), and a switching suppressor (to prevent a voltage rise after a switching step from being evaluated as an instance of acceleration) so that the device serves to operate the acceleration enrichment of the fuel-air mixture for the internal combustion engine with a minimum of disturbance thereby attaining optimum acceleration processes.

Abstract: An induction unit for a petrol injection engine has an induction manifold formed with seats for respective fuel injectors, the injectors being retained on their seats by a retaining plate which is secured to the induction manifold C-shaped spring clips releasably snap-engaged in recesses in the retaining plate.

Abstract: An injection valve to control the fuel injection into the intake duct of an internal combustion engine. The injection valve, which is preferably mechanically actuated, is placed in a supporting opening in the wall of an intake duct, and is provided with a gasket between the outer wall of the injection valve housing and the outer wall of the support. The injection valve housing is arranged contact-free in the support opening and the thus-produced annular slit is closed by a bellows member. The injection valve housing is associated at its free end with a fuel distributor element. In this manner a greater freedom of movement of the valve housing in the support opening is thereby provided in addition to a substantial increase in thermal insulation, whereby manufacturing tolerances and thermal fluctuations are not significant.

Abstract: A unique drive for an engine or compressor piston, including an angularly inclined piston wrist pin, an inclined throw along a crankshaft, a piston connecting rod therebetween being additionally slidable along the axes of the wrist pin and throw at each rotation of the crankshaft, and a guide and shift device for sliding the connecting rod for long or short strokes, the device being slideable transversely through an engine cylinder.

Abstract: A multi-cylinder engine comprising a carburetor housing forming therein at least two branch mixture passages. Each of the branch mixture passages is connected to a respective intake port. A throttle valve of the carburetor is provided for each cylinder. Each of the throttle valves is arranged in the respective branch mixture passage and attached onto a common throttle shaft. A wedge shaped groove is formed on the upper inner wall of each of the branch mixture passages, and the common throttle shaft is arranged in the wedge shaped groove for causing the mixture to flow only along the bottom wall of the branch mixture passage. A single common connecting passage and branch connecting passages which are connected to the common connecting passage are provided. Each of the branch connecting passages opens into the respective intake port in the vicinity of the rear face of the valve head of the corresponding intake valve.

Abstract: A method of controlling the timing of spark ignition for an internal combustion engine by monitoring the magnitude of vibration of the engine caused when the engine is knocking. A vibration sensor is mounted on the engine to detect the magnitude of the engine vibration, and the average value of the magnitude of vibration of the engine prior to the engine piston arriving at the top dead center position is compared with the instantaneous value of the magnitude of vibration of the engine caused after the arrival of the piston at the top dead center position. Consequently, when the instantaneous value of the vibration is greater than the average value of the vibration, the spark timing is retarded to prevent the occurrence of knocking in the engine. To accurately detect knocking in the engine, the average value of the vibration is obtained by dividing the integrated value of the monitored vibration by the monitoring time.

Abstract: Disclosed is an air-fuel control device for an internal combustion engine which includes: an O.sub.2 sensor for detecting the oxygen concentration of exhaust gas; a control circuit having a comparator for comparing the output voltage from the O.sub.2 sensor with a reference voltage (V.sub.R), so that the air-fuel ratio of the mixture discriminated as rich or lean with respect to a stoichiometric air-fuel ratio, and; an installation for supplying fuel into an intake passage, so that when the air-fuel ratio of the mixture is leaner than the stoichiometric value the amount of fuel is increased and when the air-fuel ratio of the mixture is richer than the stoichiometric value the amount of fuel is decreased. This device further includes a sensor for detecting the accelerating operating conditions of the engine, and a mechanism for changing the reference voltage (V.sub.R) to a value (V.sub.R2) different from a predetermined value (V.sub.

Abstract: An air-fuel ratio control system for an internal combustion engine which includes a carburetor in which the air-fuel ratio is set on the lean side rather than at a controlled air-fuel ratio. Fuel injection valves are provided for injecting additional fuel so that the air-fuel ratio is controlled to a correct value. A control circuit is provided for basically controlling the fuel injection rate in accordance with the RPM of the engine and the air intake pressure. The control circuit also corrects and controls the fuel injection rate in accordance with transient operating conditions of the engine.

Abstract: Constant differential pressure valves, one for each cylinder of the engine, supply liquid fuel to the injection nozzles. The liquid fuel supplied to the valves is delivered from a chamber within a metering member mounted to turn within the bore of a stationary sleeve. A plate carried by the metering member has notches on its periphery which cooperate with openings in the enclosing sleeve to form variable orifices. The metering member is turned in proportion to the rate of air flow through an air intake passage for the engine.

Abstract: For use in a swirl-producing recombustion chamber of a Diesel engine, a glow plug comprises a shell which can be screwed into an engine block so as not to protrude into the precombustion chamber and a cylindrically shaped heating head attached to a plunger which is received in the shell and can be electromagnetically or hydraulically moved relative to the fixed shell. The heating head can be protruded from the shell so as to extend into a central region of the precombustion chamber when preheating of air is necessary but, at other times, can be retracted almost entirely into the shell so as not to obstruct violent swirling of air in the precombustion chamber.

Abstract: A valve guide for installation in cylinder heads of internal combustion engines which includes a hollow body, a beveled pilot flange, a locking flange to flow material into, an annular groove to receive and pack displaced material and lock the valve guide to the workpiece to prevent axial movement.

Abstract: A rotary engine with rotary tubular valves for gas inlet and for gas outlet is described. The engine is of the type wherein at least one rotor is eccentrically rotated on a shaft in a housing with variable volume compartments between the rotor and housing. The rotary tubular valves are spaced around and through the housing with the tube axes parallel to the longitudinal axis of the shaft which mounts the rotor and are parallel to each other. The valve tubes are slotted as is the housing leading into the compartments such that in the proper sequence a power providing gas is introduced through the inlet valves into a compartment to provide a movement of the rotor, and then is exhausted through the outlet valves by the rotor. Preferably there are at least two spaced apart cylindrically shaped rotors eccentrically mounted on a single shaft in separate closed housings and the compartments provided by sliding abutments around each rotor and housing.

Abstract: An internal combustion engine has a fuel injection pump and an air/fuel ratio controller. The controller has a lever that is connected to the pump lever. An aneroid moves the controller lever as a function of changes in intake manifold vacuum to maintain a constant air/fuel ratio to the mixture charge. A fuel enrichment linkage is provided that modifies the movement of the fuel flow control lever by the aneroid in response to changes in manifold gas temperature levels and exhaust gas recirculation to maintain the constant air/fuel ratio. A manual override is provided to obtain a richer air/fuel ratio for maximum acceleration.

Abstract: The device includes a main part, or launcher, in the form of a slingshot, of large size, for operation by three people. The launcher includes a funnel acting as a holder for the balloon to be launched, secured to a pair of elastic strings respectively secured at their outer ends to handles. A balloon filled with water is placed in the holder, and one person holds each of the handles, while a third draws the holder back and releases it, this action flinging the balloon at a target. The device also includes a container for the launcher, and the container has a cover which also serves as a flying saucer.

Abstract: A gas-fueled oven having energy saving capabilities provided by a thermostatically controlled gas supply valve which supplies fuel to the gas burner at cycled intervals, and a flue restricter which is operatively connected with the thermostat to move into closing relation to the oven exhaust flue when the burner is cycled off, thereby retaining within the oven cavity an amount of heat which would normally be allowed to escape through the flue if the flue restricter was not utilized.

Abstract: A cleaning device for cooking grills, especially barbecue grills, consists of a rectangular frame providing an open grid over which is stretched and supported a thin flexible metal sheet, specifically a sheet of aluminum foil. The device is placed over the grill, causing heat capture and consequent combustion of the residues thereon to a readily removable ash. The spaces in the grid are desirably of a specific size range and the metal sheet is sufficiently flexible for the portions bridging the grid spaces to "balloon" upward into the grid spaces under the action of the combusted gases. The simplest embodiment is of fixed size; an adjustable size embodiment is also provided and a further embodiment includes a storage spool for holding a roll of the flexible metal sheet.