Patent Application
20120280085
1. Field of the Invention
The present invention relates generally to a system that extracts a cargo from an airborne aircraft and then deploys the cargo parachute. More specifically, the present invention relates to a system that during a normal extraction transfers a force from an extraction parachute to deploy a descent parachute and that, in the event of a failed extraction, jettisons the extraction parachute.
2. Description of the Prior Art
During a typical operation for the extraction and deployment of cargo from an airborne aircraft, a drogue parachute first deploys an extraction parachute which acts to extract the cargo from the aircraft. As the load leaves the ramp of the aircraft, the connection between the extraction parachute and the cargo is released. As a result, force from the extraction parachute is transferred to extract the descent parachute which, once deployed, carries the cargo during the descent. A conventional extraction assembly with cargo is illustrated in
During a normal deployment, only the connection between the cargo and the extraction parachute is released. However, an emergency situation can arise during a failed extraction, such as when the cargo platform becomes immobile or when the extraction parachute does not disconnect from the cargo. In this situation, the connections to both the extraction parachute and the descent parachute must be severed and the cargo is not deployed.
Various conventional approaches are known for separating an extraction parachute from a deploying cargo during a failed extraction. For example, one approach involves manually cutting the lines that connect the extraction parachute to the cargo so as to release the parachute. The manual approach, however, can pose a substantial safety risk to aircraft personnel.
U.S. Pat. No. 5,816,535 discloses an Emergency Cargo Extraction Parachute Jettison System that in one configuration eliminates the need to manually effect the release. The system includes a load transfer coupling attached to each extraction parachute for releasing the extraction parachute from the cargo container upon receipt of electrical power. A first circuit, coupled to the load transfer coupling, provides electrical power to the load transfer coupling of the next ejectable cargo container upon receiving an actuation signal to release the extraction parachute. A second circuit is used to sense when each of the plurality of cargo containers has been ejected from the aircraft and to provide the cargo container ejection signal to the first circuit upon such ejection. The actuation signal is provided to the first circuit if the ejection signal is not received within a specific time after initiation of the cargo ejection sequence. A third circuit is used to manually provide the actuation signal to the first circuit to enable immediate jettison of the extraction parachute.
The U.S. Government uses a standard mechanical release Extraction Force Transfer Coupling (EFTC) as shown in
The U.S. Army has also adapted an Extraction Parachute Jettison Device (EPJD) into the EFTC for payloads with a maximum extracted weight of 21,000 lb. The EPJD, however, does not incorporate any redundancy in the release unit. In addition, the Army's EFTC and EPJD are installed in series and, because of the three-point link design, necessarily include multiple mechanical assemblies.
Finally, the U.S. Army's EFTC is used with a nylon concentric loop extraction line that varies in length and number of plies depending on the extraction weight and type of aircraft being used. This nylon line stretches as much as 25-30%, resulting in the storage of a considerable amount of energy during the extraction event. Consequently, the nylon line has a tendency to rebound or send a standing wave back into the aircraft during the extraction parachute deployment.
In order to overcome the above-described drawbacks of the prior art devices, the present invention provides an electronically controlled system that extracts cargo from an airborne aircraft with an extraction parachute and then deploys the cargo with a descent parachute. During a normal extraction, the extraction parachute pulls the cargo from the aircraft via a cargo extraction line. Upon severing of the extraction line, a deployment lanyard subsequently deploys a descent parachute. In the event of a failed extraction, the assembly severs both the extraction line and the deployment lanyard so as to jettison the extraction parachute.
By combining both EFTC and EPJD capabilities into a single assembly, the present invention facilitates the extraction of payloads ranging from 5,000 to 100,000 lb at both low and high altitudes.
The present invention also includes an ultra high molecular weight polyethylene rope that is a braided assembly of the extraction line and the deployment lanyard. The single piece rope serves as both the extraction line for the cargo and the deployment lanyard for the descent parachute. The rope exhibits very low elongation under load, and therefore does not exhibit the standing wave phenomenon associated with conventional nylon extraction lines.
Another feature of the present invention is its mechanical simplicity. By virtue of the ability to use a single rope for both the extraction and deployment functions, the link assembly is of relatively simple construction and avoids use of the conventional three-point link.
Still another feature of the present invention is that by virtue of using the ultra high molecular weight polyethylene rope, the system can employ pyrotechnic cutters to effect the release of the extraction line and deployment lanyard rather than conventional mechanical interlocks. Pyrotechnic cutters are far more efficient and reliable than mechanical assemblies, especially when the tension in the load member is relatively high. Therefore, the present invention is capable of reliably deploying loads that are substantially heavier than the loads associated with conventional EFTC systems.
Yet another feature of the present invention is the ability to vary the time delay of the extraction force transfer coupling, as well as the ability to jettison the extraction parachute in any type of emergency.
Accordingly, it is an object of the present invention to provide an electronically controlled system that extracts a cargo from an airborne aircraft with an extraction parachute and then deploys the cargo with a descent parachute, while also having the capability to sever both the extraction line and the deployment lanyard to jettison the extraction parachute.
Another object of the present invention is to combine EFTC and EPJD capabilities into a single assembly.
Yet another object of the present invention is to provide a system that uses a single rope for both the extraction and deployment functions, thereby providing a link assembly that is of simpler construction and more reliable than the conventional three-point link.
Still another object of the present invention is to provide an ultra high molecular weight polyethylene rope that can be severed using pyrotechnic cutters and which exhibits very low elongation under load.
A further object of the present invention is to provide an EFTC assembly having variable time delay capability.
A still further object of the present invention to be specifically enumerated herein is to provide an extraction force transfer coupling and parachute jettison system in accordance with the preceding objects that will conform to conventional forms of manufacture, be of relatively simple construction and easy to use so as to provide a system that will be economically feasible, long lasting, durable in service, relatively trouble free in operation, and a general improvement in the art.
These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like reference numbers refer to like parts throughout. The accompanying drawings are intended to illustrate the invention, but are not necessarily to scale.
Although preferred embodiments of the invention are explained in detail, it is to be understood that other embodiments are possible. Accordingly, it is not intended that the invention is to be limited in its scope to the details of constructions, and arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, in describing the preferred embodiments, specific terminology will be resorted to for the sake of clarity. It is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. Where possible, components of the drawings that are alike are identified by the same reference numbers.
Referring now specifically to
The system 10 includes an EFTC link assembly, generally designated by reference numeral 20, mounted on a load platform 70 and electrically coupled to an electronic control box 100. The electronic control box 100 receives signal inputs from an EFTC switch box 90, which is coupled to an EFTC actuator 80, and from an emergency jettison box 110, all of which are mounted to the platform.
The EFTC link assembly 20 is connected to an extraction parachute 15, as shown in
The extraction line and deployment lanyard rope 40 is manufactured from a high-tenacity material which reduces the amplitude of the standing wave that is often associated with extraction parachute deployment using conventional extraction line material as previously discussed. A preferred material of construction for the rope 40 is ultra high molecular weight polyethylene (UHMWP). In one preferred embodiment, the rope 40 is made from a UHMWP rope such as the product sold under the trademark PLASMA by Cortland Cable of Cortland, N.Y. The PLASMA rope is constructed of high modulus polyethylene fibers produced by gel spinning ultra high molecular weight polyethylene, and has an excellent strength-to-weight ratio, the highest abrasion resistance of any fiber, and excellent dynamic toughness. The PLASMA rope also exhibits excellent flex fatigue resistance, low resistance to heat, and very low elongation, stretching only approximately 3-5% under load which results in less stored energy and reduced standing wave magnitude.
In a preferred configuration of the extraction line and deployment lanyard rope 40, the extraction line 42 is a 1⅝ inch diameter, twelve strand, PLASMA line, and the deployment lanyard 44 is a 1⅛ inch diameter, twelve strand PLASMA line that is braided into the extraction line 42 at the junction 46. This configuration provides a rope 40 that has an ultimate tensile strength of approximately 295,000 lbs.
As shown in
During a failed extraction, however, pyrotechnic cutter 60 is activated. If pyrotechnic cutter 50 has not already been triggered by the EFTC actuator 80, control circuitry activating the pyrotechnic cutter 60 will first trigger the extraction line pyrotechnic cutter 50 to sever the extraction line 42 just before the deployment lanyard 44 is severed. Hence, activation of pyrotechnic cutter 60 effectively results in the severing of both the extraction line and the deployment lanyard, as shown in FIG. 7. Thus, pyrotechnic cutter 60 functions essentially as an extraction parachute jettison device (EPJD) to release the extraction parachute 15 in the event of an emergency or abnormality in parachute deployment.
Activation of the pyrotechnic cutter 50 is initiated by the EFTC actuator 80 which is connected to the EFTC switch box 90 via a control cable 85. The actuator 80 includes an actuator arm 4 (see
Block diagrams setting forth the transfer coupler control circuitry are provided in
To operate the control system, power is first switched on via an On/Off switch 204. Two independent power sources 206, 207 provide dual redundancy, with a power management circuit 208 being configured to provide continuous power to vital components of the EFTC such as the timing circuit 210 and the test circuit 312. Upon start up, the power management circuit 208 takes its supply voltage from a power A rail 214 by default. If there is a fault, however, then the power management circuit 208 switches to receive its supply voltage from a power B rail 215. The power rails 214, 215 are constantly monitored and the power management circuit 208 has the ability to switch to either the power A rail 214 or the power B rail 215 should there be a fault.
Assuming a successful start-up, the transfer coupling control circuit enters an operational mode in which the EFTC swing arm 4 and the EPJD activation switch 202 are continuously monitored. For purposes of discussion, the circuit as powered by power A rail 214 is described. However, persons of ordinary skill in the art will recognize the same discussion is equally applicable to the circuit flow as powered by power B rail 215, as shown in parallel on the right-hand side of
While the cargo load is inside the aircraft, a circuit trigger 300 remains open and the EFTC cannot be activated. Movement 303 of the actuator arm 4 in response to load exit 302 from the aircraft 302, however, activates the EFTC to trigger the circuit 304 which starts a first timer 306 within timing circuit 210.
Once the first timer times out at 308, a second timer within the timing circuit 210 begins at 310. When the second timer times out, the timing circuit 210 produces an output via control lines 115, 117 to a firing circuit 220 to activate the pyrotechnic cutters 50 to sever first and second bridgewires 222, 224 to release the extraction line 42. In the microprocessor-controlled embodiment, the timing circuit 210 is embodied as a microprocessor 240 which provides a high output 238 to a plurality of optocouplers 242 that in turn output main power 244 to the cutters 50 to sever the bridgewires 222, 224.
If the EPJD activation switch 202 is activated, the timing circuit 210 or microprocessor 240 initiates a 250 millisecond time delay 246 before the respective firing circuits 220 or optocouplers 242 activate the pyrotechnic cutters 50. During this delay period, corresponding firing circuits 221 or optocouplers 243 are activated to initiate operation of pyrotechnic cutters 60, via control lines 119, 121, which act to sever third and fourth bridgewires 252, 254 to release the deployment lanyard 44. Following this release, i.e., about 250 milliseconds later, the first and second bridgewires 222, 224 are severed by pyrotechnic cutters 50 to release the extraction line as already discussed.
As shown in
The present invention provides many advantages over the prior art. To summarize, the rope 40, which is attached to the EFTC link assembly 20 with no mechanically released components, eliminates the need for the traditional three-point link mechanical interlock assembly used in the conventional EFTC system. Thus, the present invention advantageously eliminates many of the mechanical components normally associated with this type of airdrop hardware, reducing cost and simplifying operation. Instead, the system 10 of the present invention employs modern electrical controls combined with pyrotechnic cutter technology that has proved to be highly efficient and reliable. The pyrotechnic cutters 50, 60 are far more reliable than conventional mechanical assemblies, especially when the tension in the load member is relatively high. Therefore, the present invention is capable of reliably deploying loads that are substantially heavier than the loads associated with conventional EFTC systems.
Another advantage of the system 10 according to the present invention is that the extraction line 42, deployment lanyard 44 and extraction parachute rigging/installation will be the same as or similar to that of the current U.S. Army system. In a C-17 or C-130 aircraft, for example, the electronic control system of the present invention can be integrated with the current control system at the loadmaster station, which presently controls the U.S. Army EPJD-light, controller, and platform interfaces.
It is not intended that the present invention be limited to the specific apparatus and methods described herein. The foregoing is considered as illustrative only of the principles of the invention. For example, while the various embodiments of the invention have been described in the context of deploying a single cargo, in another possible embodiment the system described herein can be used to deploy a succession of cargo platforms.
In addition, while the invention has been described in the context of a single extraction parachute and a single descent parachute, in another possible embodiment the system described herein can be used with cargoes requiring a plurality of extraction parachutes and/or a plurality of descent parachutes.
Additionally, while the invention has been described in the context of a rope 40 that is of braided ultra high molecular weight polyethylene construction, in another possible embodiment the rope can be of a different construction as long as it can fulfill the requirements of the service described herein.
Further, numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and, accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
