Patent Application
20080149775
1. Field of the Invention
The present invention relates in general to deployment brakes operative during the opening of parachute canopies and, more particularly, to a deployment brake release system that is configurable for use with canopies of different types and sizes.
2. Description of the Related Art
Precision cargo delivery relies upon unmanned aerial vehicles (UAVs) to guide cargo parachutes to preselected GPS coordinates. The UAV includes an airborne guidance unit (AGU) having a structural frame that contains at least one battery, a motor, an avionics computer with GPS receiver, a motor controller, a processor, etc. A compass or other rate sensing instrument may also be included.
The precision cargo delivery parachute systems are similar to those used in personnel parachutes and can include low gliding round parachutes and higher gliding ram-air parachutes, as well as cruciform parachutes of the type disclosed in U.S. Pat. No. 6,443,396. Often the parachute systems have many operational procedures that are normally carried out by personnel and therefore must be automated in the cargo setting. One such operational procedure is the release of the deployment brakes after full inflation.
During parachute deployment, at least part of the trailing edge of the canopy is deflected. Such deflection is effected by the same mechanism used to steer the canopy once it is in flight. For example, to turn the parachute to the left while in flight, one or more steering suspension lines connected to the trailing edge on the left side of the canopy are shortened, i.e., pulled downwardly, by the motor in the AGU. This shortening deflects the corresponding trailing edge and causes the parachute to turn left. In the case of initial deployment, suspension lines attached along nearly all of the trailing edge act as brake lines and are held in a shortened configuration. The resulting trailing edge deflection prevents the canopy from rocking back and forth and provides greater canopy stability during inflation.
Peak load on the brake/suspension lines occurs during initial inflation when opening forces and the rate of deceleration are the greatest. To withstand the peak load, the motor attached to the brake/suspension lines must be relatively heavy duty which increases cost and weight, both of which are undesirable characteristics in parachute product design.
To overcome this difficulty, prior art approaches have secured the brake/suspension lines to the frame of the AGU with connection lines having associated pyrotechnic cutting devices. Once the canopy has fully inflated to the extent possible in this deployment configuration, the pyrotechnic cutters are activated to sever the connection lines and thereby release the trailing edge. While this can be effective, pyrotechnic devices require proper timing and add unwanted complexity and expense, particularly in the context of routine and repeated airborne delivery of equipment and supplies such as is needed for troop support during military operations.
Accordingly, a need exists for a deployment brake release system that is simpler and less expensive than the prior art approaches, while offering highly reliable and reusable operation.
In view of the foregoing, the present invention is directed to a deployment brake release system for use with an airborne guidance unit (AGU) of a parachute suitable for precision cargo delivery. While primarily directed to high-gliding ram-air parachutes, the present invention is applicable to any parachute having a requirement for steering line stowage or deflection upon opening including low gliding round parachutes and cruciform parachutes.
The cargo-delivery parachute according to the present invention includes deployment brake lines secured at one end to the trailing edge of the canopy and connected adjacent the other end to motor control lines, preferably through looped ends. The motor control lines are, in turn, engaged with the motor of the AGU. The deployment brake release system includes at least one hook mounted to the AGU frame. The looped ends of the deployment brake lines are engaged with the hook during rigging so that, upon deployment, opening forces are applied to the hook mount rather than to the motor. After full canopy inflation, the motor, via the motor control lines, pulls on the looped ends of the brake lines to disengage them from the hook mount. The brake lines can also be released sequentially, with appropriate programming of the AGU. By retracting the motor control lines, either simultaneously or sequentially, the brake line loads are thus transferred to the AGU motor for the duration of the flight.
It is therefore an object of the present invention to provide a deployment brake release system in which the AGU motor is not subjected to opening force loads, thus enabling motors of lower cost and lighter weight to be used.
Another object of the present invention is to provide a deployment brake release system for use with UAVs that supports simultaneous or sequential release of multiple brake lines.
A further object of the present invention is to provide a relatively simple deployment brake release system for use with UAVs that employs hook mounts on the AGU frame that are fully reusable.
A still further object of the present invention is to provide a deployment brake release system for use with UAVs which is both reliable and secure in use and easy to rig, with minimal opportunities for snagging hazard.
Yet another object of the present invention is to provide a deployment brake release system that can be readily adapted to fit and work effectively with a wide range of UAV parachute sizes and styles without requiring adaptation of the existing parachute structure.
It is yet another object of the invention to provide a deployment brake release system for UAVs that is not complex in structure and which will conform to conventional forms of manufacture so as to provide a brake release system that is economically feasible, long-lasting and relatively trouble free in operation.
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 numerals refer to like parts throughout.
In describing preferred embodiments of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.
As summarized in the diagram of
A first embodiment of the present invention is shown in
As is known, deployment brake release lines 30 are attached to the trailing edge 32 of a parachute canopy 34 during rigging to effect downward deflection of the edge 32 during initial inflation. The deployment brake release lines 30 are subsequently released to allow full inflation of the chute at the appropriate time and, in the case of the left and right outer brake release lines, to provide steering for the parachute after deployment brake release.
According to the present invention, the ends of the left and right brake release lines 30a, 30b remote from the canopy have looped portions 36 which are coupled to corresponding looped portions 38 on left and right motor control lines 40a, 40b. Each motor control line 40 is wound upon a respective spool 42 so as to be extendible and retractable under the control of a respective motor 44 which rotates the spool 42. There are thus two motors and two spools, with a motor and spool combination on each of the left and right sides of the AGU frame 28. The motors and spools are protected by a housing 46.
With reference to the left hook 24 as shown in
Upon deployment of the parachute system 10 having the brake release system 20, the initial opening force load from the trailing edge 32 of the canopy 34 is applied against the neck of the hook through the brake release line 30. Once the parachute has stopped decelerating and steady state flight has been achieved, the motor 44 is activated by the AGU 14 to pull on the motor control line 40 and, through the looped connection of looped ends 36, 38, on the brake release line 30. This downward pull breaks the fastening element 54 and disengages the brake release line from the hook. As a result, brake line loads are transferred from the hook to the AGU motor 44 for the duration of the flight.
At this point, the motor control line and the brake line act as a single line, with the motor being able to directly deflect the trailing edge of the canopy through retraction of the motor control/brake release line for parachute steering purposes during the flight. Hence, as used herein, a motor control and brake line acting as a single line is referred to as “a steering brake line”. As shown in
By directing the canopy opening forces to the frame of the AGU through the hook mount 22, with the motors only having to withstand the steady state load, benefits in weight and cost can be achieved in that the brake line loads during steady state flight are approximately 15% of the peak opening load. As a result, the present invention allows lower capacity and less expensive motors to be used in a field where cost and weight are significant drivers in product design.
A second embodiment of the present invention especially useful for larger cargo parachute systems is shown in
In the embodiment shown in
If both the inner and outer brake lines are to be released simultaneously, then the outer brake lines are looped over the hooks first so as to be highest on the neck, as shown. The looped ends 36 of the inner brake lines are then stacked under the looped ends 38 of the outer brake lines and both the inner and outer brake lines are secured on the hook in this stacked configuration by a fastening element 54. Upon deployment, the inner and outer brake lines deflect the trailing edge of the canopy as has already been discussed. Once a steady state flight condition has been reached, the left and right motors are activated by the AGU to pull down their respective motor control lines. The downward pull on the outer brake lines 62, 66 breaks the fastening elements and, because of the stacked arrangement of the inner brake lines 60, 64, the downward travel of the outer brake lines forces the inner brake lines off the hook as well.
Release of the outer brake lines 62, 66 from the hooks transfers the canopy load to the motor control lines 40 since the outer brake lines and the motor control lines are connected to one another. The inner brake lines 60, 64, by contrast, are connected by their looped ends only to the hooks. Thus, once the inner brake lines are pulled off the hooks, they are free to flap about and possibly interfere with parachute operation, unless restrained in some way. Therefore, the third line, termed a “lazy line” 68 because it does not “work” to deflect the canopy as do the deployment brake release lines, is provided. A lazy line 68 is connected to each non-steering inner brake line and to the frame of the AGU. These lazy lines 68 act to restrain flapping of the non-steering inner brake lines upon their release from the hooks.
In addition to the simultaneous release of multiple brake lines as just described, the present invention also provides for the sequential release of multiple brake release lines. This is advantageous in that the motors are then only required to be strong enough to withstand the forces incurred by the release of one brake line at a time, rather than the combined loads of all of the brake release lines at once.
To effect sequential release of multiple brake lines in the embodiment shown in
As in the simultaneous release configuration, when rigging multiple brake lines for sequential release, the outer brake release line 62 that is connected to the motor control line and which will act as the steering brake line in flight is looped onto the hook first. This is followed by the additional release loop 70 on the motor control line 40 and then by the looped end 36 of the inner brake release line 60. The result is a stacked configuration consisting of the looped end of the outer brake release line 62 at the top, the looped end of the inner brake release line 60 at the bottom, and the additional release loop 70 on the motor control line 40 in between the inner and outer brake lines.
Upon deployment and activation of the motor, as illustrated in
As the motor continues to draw the motor control line inward onto the spool, winding force on the motor control line is next applied to the outer brake line 62, as shown in
Additional brake lines may be secured to the hook for sequential release by adding a further release loop 72 to the motor control line 40, as shown in
As canopy size increases with cargo weight, more brake release lines may be needed than can reasonably be accommodated by one hook without undue congestion. Accordingly, the hook mount 78 may be formed to have more than one hook for the brake release lines on each side of the parachute, as representatively shown in
The sequential release of the multiple brake release lines as rigged in
The motor control line 40 is then released from its engagement with the deflection roller 86 (
Continued movement of the motor control line 40 then exerts a downward pull on the looped end 36 of the last brake release line which is uppermost on the upper hook (
As noted, activation of the motors is initiated by the AGU which can be programmed to commence activation at a predetermined velocity. The AGU can also be controlled by a radio frequency signal from a ground-based signal, or by any other means as would be known by persons of ordinary skill in the art.
Two further embodiments of hook mounts having multiple hooks are shown in
In the hook mount embodiment shown in
Each of the embodiments shown in
These differences notwithstanding, suspension lines are rigged on the hooks of hook mount 88 in the same manner as on hook mount 78 of
In the release sequence of the left side hook mount 78 shown in
Other hook mount configurations could also be constructed without departing from the scope of the present invention. The embodiments shown herein were designed to have an overall shape, angle and hook location that demonstrate ease of release, minimum interference with the spool and motor control line during navigation mode, minimum opportunity for snagging hazard, and security of the loops to the hook from aircraft exit to main canopy inflation.
While each of the embodiments described herein has referred to systems with two control motors, a combination of any number of motors and any number of hooks is clearly within the scope of the invention. In fact, the scalability of these designs in both loadings and number of release elements, as well as the ability to provide sequential release, are some of the advantages of the present invention. Other advantages include the reusability and simplicity of the hooks which reduces complexity and cost.
The foregoing descriptions and drawings should be considered as illustrative only of the principles of the invention. The invention may be configured in a variety of shapes and sizes and is not limited by the dimensions of the preferred embodiment. Numerous applications of the present invention will readily occur to those skilled in the art. Therefore, it is not desired to limit the invention to the specific examples disclosed or the exact construction and operation shown and described. Rather, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
