Abstract:
An apparatus for reorientation of an airborne vehicle during decent employs a handle rotatably attached to the airborne vehicle and connected to a parachute. Once the parachute is deployed, rotation of the handle reorients a deck angle of the airborne vehicle with respect to the parachute.

Description:
BACKGROUND INFORMATION 
     1. Field 
     Embodiments of the disclosure relate generally to the field of aerodynamic deceleration systems for airborne vehicles, and more particularly to a system and method for a selectable alignment angle for aerial descent and landing of an airborne vehicle. 
     2. Background 
     Reentering spacecraft which are not aerodynamically configured and controlled are typically recovered using aerodynamic deceleration and landing parachutes. Mercury, Gemini and Apollo spacecraft all employed this form of recovery system that includes an attachment of parachute risers to a fixed point on the spacecraft. However, in certain cases it may be desirable to have differing angular presentation of the spacecraft during descent and/or prior to landing to accommodate such issues as water versus hard surface landing conditions. 
     It is therefore desirable to provide an attachment system for parachute risers which allows angular adjustment of the spacecraft orientation. 
     SUMMARY 
     Embodiments disclosed herein provide an apparatus for reorientation of an airborne vehicle during decent employing a handle rotatably attached to the airborne vehicle and connected to a parachute. Once the parachute is deployed, rotation of the handle reorients a deck angle of the airborne vehicle with respect to the parachute. 
     In one embodiment, a command module (CM) includes a parachute attachment system that employs a handle rotatably attached to the CM. The handle has an unrotated position and a rotated position and a suspended deck angle of the CM is altered between the unrotated and rotated position. An attachment plate on the handle attaches to risers of a parachute and at least one release assembly is operable to release the handle from the unrotated position to the rotated position. 
     The embodiments provide a method of reorientation of an airborne vehicle during descent through attachment of a parachute to a rotatable handle connected to the airborne vehicle. The parachute is then deployed and, if an alternative deck angle is desired, the handle is rotated to reorient the airborne vehicle deck angle. 
     The features, functions, and advantages that have been discussed can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a isometric view of an example spacecraft on which the disclosed embodiments may be employed; 
         FIG. 2  is a side view of the spacecraft suspended from risers with a handle in the initial unrotated position; 
         FIG. 3  is a side view of the spacecraft suspended from risers with the handle of  FIG. 2  in the rotated position for reduced deck angle; 
         FIG. 4A  is a detailed isometric view of a support structure and handle according to one embodiment; 
         FIG. 4B  is a detailed exploded partial isometric view of the elements of hinges according to one embodiment; 
         FIG. 5A  is a front view of the handle; 
         FIG. 5B  is a side view of the handle; 
         FIG. 6  is a pictorial view of a damper according to one embodiment; 
         FIG. 7A  is a pictorial view of a damper and handle in an unrotated configuration according to one embodiment; 
         FIG. 7B  is a pictorial view of the damper and handle of  FIG. 7B  in a rotated configuration; and, 
         FIG. 8  is a flow chart showing a method for adjustment of hang angle of an airborne vehicle such as the example spacecraft. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments disclosed herein provide a mechanism that allows for the reorientation of an airborne vehicle or load such as a reentering spacecraft, shuttle, command module (CM), or cargo using a parachute or similar type deceleration method to allow for landing on land or water. A handle having a structure for parachute attachment is attached to the CM with hinges and may be stowed and locked down under a thermal protection cover using a support structure that carries the parachute opening loads. The handle is fastened to the CM in the stowed unrotated condition using separation nuts. After parachute deployment the handle is rotatable about the hinges to reorient the capsule under one or more parachutes to provide a nearly flat deck angle. Dual mode operation is enabled since the handle may be left in the stowed configuration (high hang angle) for water landings (similar to Apollo), or rotated about the hinges to create the flat or nearly flat hang angle for land landing operations. The handle further simplifies the parachute riser line routing and management of those cables during deployment. 
     The release of the handle for rotation may be achieved by actuating separation nuts that secure the handle to the CM. When the handle is released, the handle is allowed to rotate freely about the hinges and rotation of the handle may be limited by a damper to prevent over rotating. 
       FIG. 1  shows one example of an airborne vehicle, such as CM  10 , and an attachment/deceleration system which allows for angular adjustment of the CM during aerial decent. The CM  10  includes a blunt base  12  with a heat shield (not shown) for re-entry. A nose  14  of the CM  10 , shown with the thermal cover removed for clarity, houses various systems including an exit or docking mechanism  16 . A support structure  18 , to be described in greater detail subsequently, is integrated into the CM  10  at a forward bulkhead  20 . In one embodiment, a handle  22  may be attached to the support structure  18  with hinges  24 . An attachment plate  26  may be located at or near the center of the handle  22  for attachment of risers or cables  28  that attach to one or more parachutes or a similar type device used to decelerate the CM during retry and recovery. The undeployed parachute system may be stored in various containers  29   a - 29   c  arranged in the nose of the CM  10 . 
     As shown in  FIG. 2 , when initially deployed the risers  28  of the parachute system (not shown), which may comprise one or more parachutes and generally referred to herein as the “parachute”, are attached to the unrotated handle  22 . The offset position of the attachment plate  26  with respect to a central axis  30  of the CM  10  results in the CM  10  being suspended from the risers  28  with a deck angle of nominally 37° between a horizontal reference  32  and a reference station plane  34  for the example embodiment shown. In this configuration the CM  10  may undergo a water landing or provide the desired deck angle for other operational considerations. 
     As shown in  FIG. 3 , if desired to accommodate a landing of the CM on land (hard surface) or for differing operational considerations a lower deck angle is desired, handle  22  may be released for rotation about hinges  24 . In this regard, handle  22  is oriented substantially vertically or parallel to the CM central axis  30 . Rotation of the handle  22  may be limited by dampers  36 , to be described in greater detail subsequently. In the example embodiment shown in  FIGS. 1-3 , the hinges  24  are laterally displaced from the axis  30  on the support structure  18 . In the unattached or deployed position, this nominal displacement induces a hang angle due to a center of gravity offset which in turn provides a suspended deck angle of approximately 10° between the horizontal baseline  32  and the reference station plane  34 . For the embodiment shown, the offset of the handle  22  and support structure  18  precludes undesired impact on or interference with the docking mechanism  16 . In alternative embodiments, a relatively more central or symmetrical configuration of the handle  22  and support structure  18  may be desired. Specific desired hang angles may also be obtained by limiting rotation of the handle  22  using a controlled release of the damper  36 , and intermediate stops between the initial 37° deck angle and the ultimate 10° deck angle. Additionally, a center of gravity that is off-axis from the central axis  30  will result in an off-axis hang angle that may be sustained or altered by placement of the locations of the hinges  24  or rotation angle of the handle  22 . 
     Details of the support structure  18 , the handle  22 , and the hinges  24  are shown in  FIG. 4A . Support structure  18  incorporates vertical hinge fittings  38  which are attached at a bottom flange  40  to the forward bulkhead  20 . Hinges  24  are supported in clevises  42  extending from the hinge fittings  38  distal from the bottom flanges  40 . Hinges  24  may be spherical bearings or similar rotational support elements engaged by pivot pins  25  inserted through the clevises and retained by washers  27   a  and clips  27   b  as shown in detail in  FIG. 4B . Handle  22 , which is also shown in additional detail in  FIGS. 5A and 5B , may have an arcuate shape for the example embodiment but may be of alternative geometric shapes in other embodiments as may be required to accommodate structural loads or overall CM geometry such as a single hinged rod, a triangular handle, a rectangular or other multilateral handle. Tangs  44  extend from terminal ends  46  of the handle  22  to support the hinge elements and are received in the clevises  42 . On or near a central portion  48  of the handle, an attachment plate  26  is provided for attachment of the risers  28 . 
     In the unrotated or stored position as shown in  FIG. 4A  (and  FIG. 3 ), the handle  22  is engaged at or near the central portion  48  by a support bracket  52  that extends from the forward bulkhead  20 . For the example embodiment, the central portion  48  of the handle  22  is constrained to the support bracket  52  using separation assemblies such as pins or bolts  54  secured with handle release separation nuts. The separation assemblies may be mechanical or pyrotechnic and provide a controllable mechanism to release the handle  22  from the support bracket  52  for rotation to the extended position show in  FIGS. 5A and 5B  (and  FIG. 2 ). In one example embodiment, two ¾ inch pyrotechnic separation bolts were employed to secure and release the handle  22 . For the embodiment shown a drogue attach fitting  58  is also attached to the support bracket  52  providing an attach point for drogue shroud lines  57  (seen in  FIG. 1 ) proximate the attachment plate  26 . Canisters  59   a  and  59   b  (also shown in  FIG. 1 ) for storage of the drogue chutes are provided in the nose of the CM in a manner comparable to the containers  29   a - 29   c.    
     For the example embodiment shown in  FIG. 5B , the handle  22  incorporates a dog leg geometry allowing an offset from a neutral plane  60  extending through the hinges  24  and attachment plate  26  for attachment bosses  62  to connect dampers  36  (seen in  FIG. 4A ). The dog leg angle  66  allows alignment of an upper portion  64  of the handle  22  parallel to the central axis  30  in the deployed condition or for other adjustment of desired hang angle or requirements of deployment dynamics. 
     The dampers  36  in certain embodiments may be mechanical, hydraulic or pneumatic shock absorbers  68  as shown in  FIG. 6 . The shock absorbers  68  extend from the forward bulkhead  20  for connection at the attachment bosses  62  on handle  22 . The shock absorbers  68  may be adjustable or actively controllable for extension length to limit rotation of the handle  22  at desired angles for altering the hang angle of the CM  10  during descent and landing. In alternative embodiments, as for the primary example shown in the other drawings, dampers  36  may be an extendible strap  70  connected from the forward bulkhead  20  to the attachment bosses  62  as shown in  FIG. 7A . 
     For the embodiment of  FIG. 7A , the straps  70  may be folded and secured with frangible bands or other means for compact storage with the handle  22  in the unrotated position. Upon release of the separation assemblies allowing the handle  22  to rotate about the hinges  24  to the extended position, the straps  70  extend and limit (dampen) rotation of the handle as shown in  FIG. 7B . In one embodiment, the straps  70  may be of a textile material fabricated from aramid fiber materials such as Kevlar®, liquid crystal polymer fiber materials such as Vectran®, Nylon or comparable materials. 
     The embodiments described provide a method for altering a hang angle of an airborne vehicle such as a CM  10  suspended by risers for a parachute descent and landing as shown in  FIG. 8 . The risers  28  of a parachute are attached to an attachment plate  26  disposed on a handle  22 , step  802 . The handle  22  is connected to the airborne vehicle through a support structure  18  with hinges  24  for rotation of the handle  24 , step  804 . Upon deploying the parachute, step  806 , the airborne vehicle assumes a first deck angle based on the unrotated position of the handle  22 , step  808 . If an alternative deck angle is desired, release assemblies such as pyrotechnically actuated bolts  54  are employed to release the handle  22  from the unrotated position, step  810 . The handle  22  then rotates to reorient the airborne vehicle deck angle, step  812 . Rotation of the handle  22  may be constrained with a damper  36 , step  814 . 
     Having now described various embodiments of the disclosure in detail as required by the patent statutes, those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein. Such modifications are within the scope and intent of the present disclosure as defined in the following claims.