Autonomous helicopter blade end lighting device

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a lighting device and, more particularly, to an autonomous lighting device for helicopter blade end (tip).

A helicopter (chopper) is an aircraft that is lifted and sustained in the air horizontally by rotating wings or blades turning on vertical axes through power supplied by an engine.

Helicopters are used for civil, military and law enforcement applications. Some heavy helicopters are adapted to carry dozens of passengers (e.g., worriers) and their equipment.

In some cases, helicopters fly in a close formation which includes a pair or more of helicopters, under low visibility conditions (e.g., at a dark night), which increases the chances of a collision between closely navigating helicopters.

Indeed, in 1997, two Israeli helicopters of a pair formation crashed in the north of Israel due to collision therebetween causing the death of all 72 crew and passengers.

Helicopter blade end lighting systems are known for several years. Such systems include a light source which receives power from the main power source of the aircraft. These prior art systems are controlled by the pilot from the cockpit. As such, these systems are wired both to the cockpit and to the main power source via sliding contacts at the rotor's shaft.

However, in modern helicopters, such as, but not limited to, BLACKHAWK, COBRA, APACHE, wiring between the blades and the aircraft's body is not feasible, since in such helicopters the blades are each a bulk of composite material and has no inner cavity adapted for wiring, and further since such helicopters lack sliding contacts at the rotor's shaft.

There is thus a widely recognized need for, and it would be highly advantageous to have, an autonomous helicopter blade end lighting device.

SUMMARY OF THE INVENTION

According to the present invention there is provided an autonomous helicopter blade end lighting device.

According to further features in preferred embodiments of the invention described below, the device comprising a light source being connectable to a helicopter blade end, and a power source being connectable to the helicopter blade end for providing the light source with power for operation.

According to further features in preferred embodiments of the invention described below, provided is a method of lighting a helicopter blade end comprising the step of attaching an autonomous lighting device to the helicopter blade end, the autonomous lighting device including a light source being connectable to the helicopter blade end, and a power source being connectable to the helicopter blade end for providing the light source with power for operation.

According to still further features in the described preferred embodiments the device further comprising a housing connectable to the helicopter blade end, the housing holding the light source and the power source.

According to still further features in the described preferred embodiments the power source is a battery.

According to still further features in the described preferred embodiments the battery is oriented such that its pointed end faces away from the end of the blade.

According to still further features in the described preferred embodiments the battery provides at least three volts and at least 1500 milliampers·hour.

According to still further features in the described preferred embodiments the battery is a lithium battery.

According to still further features in the described preferred embodiments the battery is a lithium thionylchloride battery.

According to still further features in the described preferred embodiments the power source is a voltage generator (e.g., a dynamo).

According to still further features in the described preferred embodiments the voltage generator includes a wind operated turbine.

According to still further features in the described preferred embodiments the power source and the light source are resistible to <i>g</i> forces developing at the helicopter blade end when rotated.

According to still further features in the described preferred embodiments the power source and the light source are resistible to 1200 <i>g</i> force.

According to still further features in the described preferred embodiments the light source is an infrared light source.

According to still further features in the described preferred embodiments the infrared light source emits in a wavelength detectable by night vision systems.

According to still further features in the described preferred embodiments the infrared light source emits in a wavelength between 750 and 900 nm.

According to still further features in the described preferred embodiments the light source is detectable from 300 meters.

According to still further features in the described preferred embodiments the light source provides a beam of about 30° in vertical width.

According to still further features in the described preferred embodiments the light source is a semiconductor light source.

According to still further features in the described preferred embodiments the light source is a light emitting diode.

According to still further features in the described preferred embodiments the light emitting diode emits at 750-900 nm.

According to still further features in the described preferred embodiments the light source produces light intensity of at least one milliwat, preferably at least 20 milliwat.

According to still further features in the described preferred embodiments the device further comprising a background light sensor for limiting the operation of the light source to background light below a predetermined threshold.

According to still further features in the described preferred embodiments the background light sensor is resistible to <i>g</i> forces developing at the helicopter blade end when rotated.

According to still further features in the described preferred embodiments the background light sensor is a photoresistive sensor.

According to still further features in the described preferred embodiments the device further comprising a centrifugal switch for limiting the light source to operate only above a predetermined <i>g</i> force value.

According to still further features in the described preferred embodiments the predetermined <i>g</i> force value is 150-200 <i>g</i>.

According to still further features in the described preferred embodiments the device further comprising a magnetic field sensitive switch bypassing the centrifugal switch, magnetic field sensitive switch serves for conducting maintenance functionality tests of the light source.

According to still further features in the described preferred embodiments the housing includes a hardened molded substance for supporting and protecting the power source against <i>g</i> forces and vibrations.

According to still further features in the described preferred embodiments the device further comprising a second light source connectable to the helicopter blade end and receiving power from the power source, the light sources being arranged tail to tail.

According to still further features in the described preferred embodiments the device weights less than 100 grams.

The present invention successfully addresses the shortcomings of the presently known configurations by providing an autonomous, self powered, helicopter blade end lighting device which operates only when the rotor of the helicopter rotates in the dark. Additional preferred features and advantages of the lighting system according to the present invention will become apparent to one ordinarily skilled in the art from the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention herein described, by way of example only, with reference to the accompanying drawings, wherein: <ul id="ul0001" list-style="none" compact="compact"><li>FIG. 1 is a block diagram describing the components of the autonomous lighting device for helicopter blade according to the present invention;</li><li>FIG. 2 is a top view of the autonomous lighting device according to the present invention;</li><li>FIG. 3 is a cross sectional view of the autonomous lighting device according to the present invention;</li><li>FIG. 4 is a perceptive view of the autonomous lighting device according to the present invention and of an end of a helicopter blade designed to accept the device;</li><li>FIG. 5 is a perspective view of a helicopter supplemented with the autonomous lighting device according to the present invention and serves to demonstrate preferred lighting effects; and</li><li>FIG. 6 is a schematic depiction of an electrical circuit of the autonomous lighting device according to the present invention.</li></ul>

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of an autonomous lighting device for helicopter blade end which can be used to render the rotor of the helicopter detectable by a pilot of a second helicopter in a formation. Specifically, the present invention can be used to reduce the chances of a collision between helicopters flying in close formation.

The principles and operation of a lighting device according to the present invention may be better understood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

Referring now to the drawings, Figure 1 is a block diagram of the relations among the basic components of the lighting device according to the present invention. Figures 2-4 illustrate the basic components of the device according to the present invention, which is referred to hereinbelow as lighting device <b>20</b>.

Thus, lighting device <b>20</b> includes a light source <b>22</b>. Light source <b>22</b> is connectable (either directly or preferably indirectly via a housing as further detailed below) to a helicopter blade end or tip <b>21</b>. Device <b>20</b> further includes a power source <b>24</b>. Power source <b>24</b> is connectable (either directly or preferably indirectly via a housing as further detailed below) to the helicopter blade end <b>21</b> and provides light source <b>22</b> with power for its operation.

According to a preferred embodiment of the present invention lighting device <b>20</b> further includes a background light sensor <b>26</b>. Sensor <b>26</b> serves for limiting the operation of light source <b>22</b> to background light below a predetermined threshold value, e.g., below 1 - 50 Lux (twilight equals about 10 Lux, deep twilight equals about 10 lux). As a result, source <b>22</b> operates only when required and power is saved.

Sensor <b>26</b> is preferably a photoresistive sensor, which therefore includes a resistor having resistivity which depends on light level to which it is exposed. A suitable sensor is distributed by EG&amp;G (U.S.), Cat. No. VT20N. Sensor <b>26</b> is alternatively a photodiode, e.g., a P.I.N photodiode.

According to another preferred embodiment of the present invention lighting device <b>20</b> further includes a centrifugal switch <b>28</b>. Switch <b>28</b> serves for limiting light source <b>22</b> to operate only above a predetermined <i>g</i> force value, say 150-200 <i>g</i>. As a result, source <b>22</b> operates only when the motor of the helicopter rotates, typically upon flight, and power is saved.

Thus, when in, combination, sensor <b>26</b> and switch <b>28</b> ensure that source <b>22</b> operates only when the motor of the helicopter is operated in the dark. A suitable centrifugal switch is distributed by Interia (Switzerland), Cat. No. 6UO-200.

According to another preferred embodiment of the present invention lighting device <b>20</b> further includes a magnetic field sensitive switch <b>30</b>. Switch <b>30</b> is implemented such that it bypasses centrifugal switch <b>28</b> and serves for conducting maintenance functionality tests of light source <b>26</b>. Closing switch <b>30</b> is effected by providing a magnet in its proximity. A suitable magnetic field sensitive switch is the REED SWITCH which is distributed by Philips, Cat. No. RI-23AAA.

According to yet another preferred embodiment of the present invention lighting device <b>20</b> further includes an electronic control card <b>32</b>, i.e., a P.C. board. Card <b>32</b> electronically communicates with the other components of device <b>20</b>, ensuring their operation as herein described. A suitable card is distributed by International Technologies (Lasers) Ltd. (Israel) Cat. No. ITL473100100.

According to a preferred embodiment of the present invention power source <b>24</b> is a battery <b>36</b>. Battery <b>36</b> is preferably oriented such that its pointed end <b>38</b> (as opposed to the flat end), which seals battery <b>36</b> during its manufacture, faces away from end <b>21</b> of the helicopter blade when assembled therein, such that <i>g</i> forces acting on the electrolyte within battery <b>36</b> will force the electrolyte away from pointed end <b>38</b>, to prevent leakage therefrom of the electrolyte.

Battery <b>36</b> is preferably engaged within a battery housing <b>37</b> which includes a spring <b>39</b> positioned away from blade end <b>21</b>, such that it serves to maintain the contacts of battery <b>36</b> with housing <b>37</b> even under the high <i>g</i> forces developing. Thus, in sharp distinction from prior art battery housing wherein the spring engages the flat end of the battery, according to the present invention the spring engaged the pointed end of the battery.

According to a prefered embodiment of the present invention battery <b>36</b> provides at least three volts (e.g., 3.6 volts) and at least 1500 milliampers·hour. Battery <b>36</b> is preferably a lithium battery, most preferably a lithium thionylchloride battery. A suitable battery is a lithium 3.6 V AA battery, distributed by SAFT (France), Cat. No. LS14500, having a total weight of 15 grams. This battery is adapted to perform under a wide temperature range (-50 °C to +80 °C).

According to an alternative embodiment of the present invention power source <b>24</b> is a voltage generator (e.g., dynamo) <b>40</b> (shown in Figure 7), e.g., capable of transforming mechanical energy into electrical energy. A suitable voltage generator, for example, includes a wind operated turbine <b>42</b>, which is rotated by wind associated with the rotational rotor action and/or vectorial flight itself. Alternatively, voltage generator <b>40</b> includes a vibrateable magnetic element. One ordinarily skilled in the art would know how to devise and implement voltage generator <b>40</b> within device <b>20</b>.

According to a preferred embodiment of the invention light source <b>22</b> is an infrared light source, which emits in a wavelength detectable by night vision systems, e.g., in the near infrared spectral range, say between 750 and 900 nm, preferably 830 nm.

An infrared light source is the preferred embodiment for military applications, wherein helicopters flying at night are preferably darkened, such that they are harder to detect and target. However, as the scope of the present invention is not limited to military applications, the light source may also emit in the visible spectral range (e.g., yellow or red light).

According to a prefered embodiment light source <b>22</b> is detectable from 300 meters, either to the naked eye or when assisted with night vision systems (e.g., AN/AVS-6 - aviator night vision system, Litton, ITT defense (U.S.).

Light source <b>24</b> is preferably selected and/or implemented such that it provides a vertical lighting angle α of, say about 30°, preferably between 0° and 30°, wherein 0° is defined as the rotation plane of the helicopter blades. Light source <b>24</b> is preferably further selected and/or implemented such that it a horizontal lighting angle β, which is wide enough to generate a ring of light when the blades are at maximal speed, e.g., 60° (see Figure 5).

Light source <b>24</b> is preferably a semiconductor light source, most preferably a light emitting diode (LED), which produces light intensity of at least one milliwat, preferably at least 20, 30 or 40 milliwat. Suitable LEDs are distributed by Hitachi (Japan), Cat. No. HLP 20RG or 30RG or 40RG or Model C, 830 nm.

Especially for military applications, light source <b>22</b> is preferably deployed such that it emits light upwardly and sideways, such that it is not vieable from the ground.

As shown in Figure 3, a second light source <b>22</b> connectable to helicopter blade end <b>21</b> and receiving power from power source <b>24</b> may be employed in a head to tail configuration with the first light source <b>22</b>, such that device <b>20</b> is better viewable by other aircrafts. Another option to achieve substantially the same effect is to equip blade end <b>21</b> with a reflective surface positioned to reflect some of the light radiation emitted from a single light source in directions from which it is not directly perceived at any given moment.

In any case, both power source <b>24</b> and light source <b>22</b>, and in that respect all of the other components of device <b>20</b> as herein described, are selected resistible to <i>g</i> forces developing at helicopter blade end <b>21</b> when rotated at maximal speed, e.g., 1200 <i>g</i> force.

According to another preferred embodiment of the present invention lighting devic<i>e</i><b>20</b> further includes a housing <b>34</b>. Housing <b>34</b> is connectable to helicopter blade end <b>21</b> and serves for holding light source <b>22</b>, power source <b>24</b> and other components of device <b>20</b>, as applicable.

Housing <b>34</b> preferably includes a cover <b>48</b> removably attachable thereto, such that access to power source <b>24</b> is allowed, e.g., for easy replacements of source <b>24</b> when exhausted.

According to a preferred embodiment of the present invention housing <b>34</b> is filled with a hardened molded substance <b>35</b> (see Figure 3). Substance <b>35</b> serves for supporting and protecting power source <b>24</b> and other components within housing <b>34</b> against <i>g</i> forces and vibrations associated with helicopter rotor operation.

Housing <b>34</b> is formed with an opening <b>50</b> positioned above sensor <b>26</b> for allowing sensor <b>26</b> to sense the level of background light radiation.

Housing <b>34</b> is preferably formed with a special protruding habitat <b>37</b> which serves for holding and securing light source <b>22</b>, such that when device <b>20</b> is implemented over blade end <b>21</b>, source <b>22</b> is elevated and therefore rendered more detectable by other aircrafts.

As shown in Figure 4, housing <b>34</b> is shaped and designed acceptable by a recession <b>23</b> formed in blade end <b>21</b>, such that the level to which device <b>20</b> protrudes from the surface of the blade is minimized, so that the aerodynamic properties of the blade are affected to a minimum degree as possible.

Both housing <b>34</b> and the blade are provided with screw holes <b>52</b> to assist in screwing device <b>20</b> and the blade together. Further attachments may, for example, include adhesives resistible to the <i>g</i> forces developing upon rotor rotation. Examples include, but are not limited to, LOCTITE by Loctite Inc., U.S.

According to a preferred embodiment recession <b>23</b> is formed in a cover element <b>27</b> which is designed to replace a conventional cover (not shown) of the weights housing typically deployed in helicopter blade ends.

According to a preferred embodiment of the present invention the overall weight of device <b>20</b> is selected low, e.g., about or below 100±1 grams, such that the functionally of the blade will be minorly affected.

Figure 5 shows a helicopter <b>60</b> having a body <b>62</b> and a rotor <b>64</b> connected via a shaft <b>65</b> on top thereto. Rotor <b>64</b> includes two blades <b>66</b>, one of which is equipped with lighting device <b>20</b>.

When rotor <b>64</b> rotates, the lighting effect is of a light ring <b>67</b> having a radius which is dictated by the distance in which device <b>20</b> is implemented with respect to rotor axes <b>65</b>. When angles α and β are selected as described above, light ring <b>67</b> is undetectable from the ground.

Figure 6 shows an electric circuit <b>70</b> which is suitable for device <b>20</b> as described herein with respect to its preferred embodiments.

Circuit <b>70</b> includes a printed circuit board (PCB) driver, wherein <b>W1</b> to <b>W8</b> are connection terminals. Circuit <b>70</b> includes a power source <b>S</b> which is preferably a lithium battery of 3.6 volts, a centrifugal switch (marked as <b>SW2</b> or "G" switch), one or two light emitting diodes (<b>LED1</b> and <b>LED2</b>), a magnetic field sensitive switch marked as <b>SW1</b>, photoresistive sensor marked as <b>LDR1</b> and a transistor <b>Q4</b> which functions as a current switch.

The negative pole (-) of lithium battery <b>S</b> is connected to circuit <b>70</b> via connection <b>W4</b>, which serves as a common ground for circuit <b>70</b>. The positive pole (+) of lithium battery <b>S</b> is connected via terminal <b>W3</b> to switch <b>SW2</b> and switch <b>SW1</b> which are parallel connected normally open switches. When either of switches <b>SW2</b> or <b>SW1</b> is closed, current is able to be drawn by consumers <b>LED1</b> and/or <b>LED2</b> of circuit <b>70</b>.

Capacitor <b>C13</b> functions as a high frequency filter to protect circuit <b>70</b> from electrical spikes that may cause improper operation and/or damage.

Transistor <b>Q4</b>, sensor <b>LDR1</b> and resistor <b>R1</b> are functioning as a current switch which is sensitive to an ambient light. When sensor <b>LDR1</b> is exposed to light, its resistance drops and as a result transistor <b>Q4</b> cannot supply <b>LED1</b> and/or <b>LED2</b> with current. Resistors <b>R3</b> and <b>R4</b> serve for current adjustment for the operation of <b>LED1</b> and/or <b>LED2</b>. It is clear that circuit <b>70</b> is not intended to be limiting, rather to serve as a simple example.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.