US3412680A - Rotor supported flare - Google Patents

Description

Nov. 26, 1968 P. F. GIRARD ROTOR SUPPORTED FLARE 3 Sheets-Sheet 1 Filed March 1967 INVENTOR.

PETER F. GIRARD Fig. 3

5 Sheets-Sheet 2 P. F. GIRARD ROTOR SUPPORTED FLARE Nov. 26, 1968 Filed March 6, 1967 INVENTOR. PETER F. GIRARD max & 1413:

Nov. 26, 1968 P. F. GIRARD ROTOR SUPPORTED FLARE 3 Sheets-Sheet 5 Filed March 6, 1967 INVENTOR.

PETER F. GIRARD 14w: & 1M

United States Patent 3,412,680 ROTOR SUPPORTED FLARE Peter F. Girard, La Mesa, (Ialifi, assignor to The Ryan Aeronautical Co., San Diego, Calif. Filed Mar. 6, 1967, Ser. No. 620,883 8 Claims. (Cl. 10235.4)

ABSTRACT OF THE DISCLOSURE A conventional pyrotechnic flare is suspended from a simple, foldable rotor which is self-deploying on release to an auto-rotating position and supports the flare at a slow initial rate of descent; at a pre-set altitude an aneroid operated valve releases a stored liquid at a controlled rate to a boiler surrounding the flare, the heat of the flare vaporizing the liquid and the vapor being conducted to the rotor tips to drive the rotor by jet reaction and maintain a hovering position until the flare is exhausted.

Background of the invention The present invention relates to pyrotechnic devices and specifically to an aerial flare which is supported by a rotor.

Present aerial flares of any reasonable duration of illumination are usually supported by some type of parachute. They can be air dropped or launched from the ground by a mortar, rocket, or similar means. All parachute flares have a generally constant rate of descent, which causes continuous changes in the lighting conditions. Long duration flares must be initiated at relatively high altitude, from where their illumination of the surface is reduced, or else will drift too low in their final stages to be effective. It is very desirable to have a flare suspended at a substantially fixed altitude for the maximum portion of its useful life, so that illumination of the terrain is constant.

Summary of the invention The self-contained flare unit described herein has very simple, foldable rotor which is self-deploying and automatically stabilized to maintain substantially constant lift. To generate power for hovering the heat of the flare itself is used to vaporize liquid from a reservoir suspended from the rotor, the vapor being fed to jets at the rotor tips for reactive thrust. A substantially constant altitude is maintained by an aneroid operated valve which meters the flow of liquid and thus controls the thrust by regulating the available power.

Brief description of the drawings FIGURE 1 is a side elevation view of the complete assembly, fully deployed;

FIGURE 2 is a somewhat diagrammatic view of the assembly collapsed and stowed in a container, which is shown in section;

FIGURE 3 is an enlarged sectional view taken on line 33 of FIGURE 1;

FIGURE 4 is an enlarged top view of the rotor;

FIGURE 5 is a sectional view taken on line 5-5 of FIGURE 4; 7

FIGURE 6 is a sectional view taken on line 66 of FIGURE 5;

FIGURE 7 is an enlarged view, partially cut away, of the liquid reservoir and aneroid valve; and

FIGURE 8 is an enlarged view, partially cut away, of the flare and boiler unit.

Similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawings.

"ice

Description of the preferred embodiment The assembly includes three basic units, a rotor 10, a reservoir unit 12 and a flare unit 14, the reservoir being suspended directly from the rotor and the flare suspended from the reservoir, with flexible interconnections to permit folding.

Rotor 10 has a tubular rigid shaft 16 at the top of which is a head 18, illustrated as a simple rectangular block. Mounted on head 18 are a pair of hinge brackets 20, which are generally U-shaped in cross section and may be tapered outwardly for lightness, the inner ends of said brack ets having arms 22 which straddle said head and are pivotal on a common hinge pin 24 to swing in a vertical plane relative to the head. Rotor blades 26 may be of any suitable configuration, the simple constant chord type shown being satisfactory, and may be made from wood, plastic, metal, foam filled shells, or various combinations thereof. Since the rotor blades 26 are required to have limited freedom in pitch and coning angle, they are attached to hinge brackets 20 by some means which will provide the freedom of motion. In most instances the rotor will be used only once and it is desirable to keep the structure as simple and inexpensive as possible. The loosely bolted assembly shown has been found to be entirely adequate, but other means may be used if desired. Each blade 26 is held by a pair of longitudinally spaced bolts 28 passing through oversized holes 30 in the blade and through oversized .holes 32 in hinge bracket 20, the bolts being secured by lock nuts 34. Reinforcing plates 35 may be fitted at the bolt attachements if necessary. Bolts 28 are of suflicient length to leave a gap between each blade and its hinge bracket, so that the combination of loose fit and spacing will allow the blade to move vertical for coming and to rock back and forth for pitch change, as indicated in broken line in FIGURE 6. In operation, centrifugal force from rotation provides the basic stability and the blades do not tend to rattle or flop loosely around.

Projecting from the leading edge of each blade 26, at a suitable distance from the rotor axis, is a counterweight 36 to bring the center of mass of the blade forward near its chordal hinge point for better balance. The counterweight is shown as an arcuate element, and from the forward portion of each counterweight a pitch control cable 38 extends to a lug 40 fixed near the lower end of shaft 16. The length of cables 33 is such that, when the cables are just slack the blades are at the proper coming and pitch angles for autorotation at a predetermined rate. This type of rotor and its operation are shown and described in my copending application Serial No. 547,315, filed May 3, 1966 and entitled Gyroehute. The structure of the gyrochute is similar to that described herein, except that leaf spring elements are used in place of the loose bolt assembly to hold the blades.

At the tip of each rotor blade 26 is a rearwardly directed nozzle 42, which may be a simple tube, the nozzle being connected by a pipe 44 to a fitting 46 at the root end of the blade. Pipe 44 may be 'held or embedded in any suitable manner in the blade, depending on the blade structure. From each fitting 46 a flexible hose 48 leads to a coupling 50 on head 18, both couplings being connected to a chamber 52 into which the tubular shaft 16 is secured.

Rotor 10 is freely rotatable relative to the remainder of the assembly, the lower end of shaft 16 being journalled in bearings 54 in a rotary coupling 56. A labyrinth seal 58 is installed between the bearings to minimize leakage. In the lower end of the coupling 56 is a plug 60, into which is connected one end of a flexible hose 62 communicating through the coupling to the tubular shaft 16.

The reservoir unit 12 comprises a cylindrical tank 64 having an axial hollow sleeve 66, through which extends a vapor pipe 68. Carrying the vapor pipe 68 through the tank rather than outside makes a better balanced assembly, which is less prone to damage, and also helps to prevent freezing of the liquid in cold air by heating effect of the hot vapor. On top of tank 64 is a cap 70 with a coupling 72 to which the lower end of flexible hose 62 is secured. In cap 70 is a filler opening 74 fitted with a closure plug 76. The tank 64 has a vent 78 to the vapor pipe 68, the vent being fitted with a lightly spring loaded check valve 80 to prevent loss of liquid when the reservoir is inverted. At the lower end of tank 64 is a boss 82 into which a flexible hose 84 is secured to communicate with vapor pipe 68. Also at the lower end of tank 64 is an altitude control valve 86, the tank having an outlet 88 opening into a channel 90 leading to a lower coupling 92, in which a flexible hose 94 is secured. Channel 90 includes a small port 96, the opening of which is controlled by a needle valve 98 extending through a wall 100 of the valve body structure. Needle valve 98 is secured to one end of an aneroid bellows 102 contained in a chamber 104, the other end of the bellows being attached to a plug 106 which is slidable in a socket 108 in the outer end of said chamber, coaxial with the needle valve. An adjusting screw 110 is threaded into plug 106 and has an external knob 112 by which the aneroid can be adjusted. Any suitable graduations or scale may be used on the knob 112 or screw 110 to facilitate setting for a particular altitude. Plug 106 is biased into chamber 104 by a light spring 114 to prevent play in the assembly. Chamber 104 has a vent 116 to atmosphere for admission of ambient air. An ring 118 is fitted around needle valve 98 at its passage through wall 100, to prevent leakage of liquid into chamber 104. Since the needle valve is driven only by the bellows and must slide freely, the O-ring cannot be very tight, but the liquid pressure is negligible. However, a drain opening 120 may be provided in chamber 104 if necessary.

Flare unit 14 comprises a conventional pyrotechnic flare 122 suspended in any suitable manner from a frustoconical shield 124. Fitted around flare 122 is a boiler 126, which may simply be several coils of heat resistant tubing, the boiler having an inlet end 128 and an outlet end 130 which are fixed to and extend above the shield 124. Flexible hoses 84 and 94 are attached to the outletv end 130 and inlet end 128, respectively, by suitable connectors 132.

In stored position ready for use the assembly is enclosed in some type of container, as indicated at 134 in FIGURE 2. This particular container has a hinged lower end 136 held by a latch 138 and is suitable for dropping the flare from an aircraft. Other types of containers would be used for ground launching or special dropping techniques, the specific arrangement not being important to the flare assembly itself. The rotor is preferably stored with the head 18 at the top, so that the air flow during the initial part of the drop will open the blades. Flexible hose 62 is bent and the reservoir unit 12 is placed inverted at the side of the rotor, the flexible hoses 84 and 94 allowing the flare unit to be placed at the side of the assembly. The arrangement shown is somewhat diagrammatic to clarify the individual components, it being obvious that the assembly can be stowed much more compactly.

Flare 122 'has a conventional electrical igniter 140 which is connected by ignition wires 142, through a switch 144 to a battery 146. A lanyard 148 is connected to the latch 138 and to switch 144 to operate both when pulled.

To prepare the assembly for use the reservoir is filled with liquid. Water is the most suitable for cost and availability, but other readily vaporizable liquids may be used. To avoid drainage when filling, the port 96 can be closed by screwing in the adjusting screw 110 to seat the needle valve 98. When the reservoir is inverted in stowed position there will be no drainage and knob 112 can be turned to adjust the aneroid to the required altitude setting. Above the preset altitude the reduced ambient pressure on the outside of bellows 102 will allow the bellows to expand and close the needle valve.

To drop the flare the lanyard 148 is pulled, causing firing of igniter and releasing latch 138. The ignition wires 142 burn through or break away and do not impede the flare. As the assembly falls the air flow will open the rotor blades 26, which swing upwardly until stopped by cables 38, in which position the pitch angle will be such that autorotation begins. The reservoir unit 12 hangs below the rotor supported by flexible hose 62 and the flare unit 14 hangs on hoses 84 and 94. The loads are not excessive and the hoses have ample strength for the purpose, thus eliminating additional supports or rigging. As the rotor reaches its predetermined rotational speed, centrifugal force will flatten the coning angle of the blades and slacken cables 38, so that the pitch angle is reduced and the rotor stabilizes at the required speed for slow and steady descent. When the preset altitude is reached the bellows 102 will be compressed and needle valve 98 will open, allowing water to flow by gravity feed, at a rate controlled by the aneroid, into boiler 126. The heat of the flare will quickly vaporize the water and steam will flow through flexible hose 84, pipe 68, hose 62 and shaft 16 to the head 18, from where it is conducted through hoses 48 and pipes 44 to the nozzles 42. The resultant reactive thrust will drive the rotor at increased speed sufliciently to overcome the steady descent and cause the flare to hover. If altitude decreases, the aneroid opens the needle valve further and increases the water flow, so that the extra steam increases thrust and lifts the flare back to the required altitude. Conversely, if altitude increases the needle valve closes correspondingly and reduces power to the rotor. The self-governing of the rotor blades, due to pitch changes imposed by cables 38, is effective with or without propulsive power. The action is fully described in the abovementioned copending application. Thus the flare is held substantially at the preset altitude until burned out. In actual practice the flare will tend to rise slightly due to decrease in weight as the water and flare are consumed, and since a pressure decrease is necessary to operate the aneroid and adjust rotor power to compensate. For all practical purposes, however, the altitude of the flare is constant rather than steadily descending, as with a parachute. When the flare burns out the rotor will revert to autorotation and descend to earth.

By utilizing the heat of the flare itself to generate propulsive power, the need for special power sources is eliminated. This feature, combined with the self-deploying, self-stabilizing rotor, results in a very simple assembly which requires only the ignition of the flare and release in the air to fulfill its complete operation.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawings are to be considered as merely illustrative rather than limiting.

I claim:

1. The combination comprising:

a pyrotechnic flare;

a freely rotatable bladed rotor from which said flare is suspended;

and power generating means, operated by heat from said flare during combustion, connected between said flare and said rotor to drive the rotor and produce lift to support the flare.

2. The combination of claim 1 and including altitude responsive power regulating means connected to said power generating means to vary the power in response to changes in altitude.

3. The combination of claim 2 and including means to preset said power regulating means to maintain said flare substantially at a predetermined altitude.

4. The combination of claim 1, wherein said power generating means includes a liquid reservoir,

a boiler connected to said reservoir and mounted closely adjacent to said flare, said boiler having a vapor outlet;

said rotor having propulsive nozzles thereon, and said nozzles being connected to said vapor outlet.

5. The combination of claim 4 and including altitude responsive valve means to regulate the flow of liquid from said reservoir to said boiler.

6. The combination of claim 5 and including means to preset said valve means to a predetermined altitude.

7. The combination of claim 4, wherein said rotor has a hollow shaft through which said nozzles are connected to said vapor outlet, a freely rotatable coupling on the lower end of said shaft, said reservoir being suspended from said coupling, and said flare and boiler being suspended from said reservoir.

8. The combination of claim 7, wherein said rotor is foldable, and including flexible hose means connecting said reservoir to said coupling and connecting said boiler to said reservoir, whereby the assembly is collapsible for storage.

References Cited UNITED STATES PATENTS 1,897,092 2/1933 Weir.

2,659,556 11/1953 Doblhoif 244-17.11 X 3,013,493 12/1961 Fletcher 102-37.5 X 3,200,744 8/ 1965 Webb 102-35 .4

ROBERT F. STAHL, Primary Examiner.

Images