Patent Application
20070267537
For purposes of description, we will use a generally cigar shaped cylindrical vessel with a flexible skin or envelope, such as a blimp or dirigible, but it may be seen by one skilled in the art that the invention may be beneficially used with other shaped vessels, including irregularly shaped vessels.
Referring to
Radial members 90 attach to the central structural member 30 at a radial member joint 100. In a foldable design, the radial member joint 100 is hinged and/or capable of sliding longitudinally along the central structural member 30, and to be locked in place when unfolded. Such sliding can be accomplished by a ring structure about the central member 30 with a locking mechanism or a rail and slide or other mechanism well known in the mechanical arts. The radial members 90 optionally obtain lateral support by attaching to the envelope 20 at their outer ends 110. In a foldable design, the joints at the outer ends 110 of the radial members 90 are hinged and/or capable of sliding longitudinally along the surface of the envelope 20, and to be able to be locked in place when unfolded. The struts may be made so as to be able to telescope so as to alter their length whilst folding and unfolding.
In one embodiment, the joint at the outer ends 110 of the radial members 90 attaches to the envelope 20 along adjacent to the flexible members of a foldable ribbed envelope as described in Nachbar U.S. Pat. No. 6,793,180. Outer members 120 connect the outer ends 110 of the radial members 90 to the central structural member 30 at the front end 40 and tail end 50.
In one embodiment, the outer members 120 are flexible rope, cable or line. In a foldable design, the lengths of the outer members 120 may be lengthwise adjustable.
An alternative approach to obtaining lateral support for radial members 90 and outer members 120 is to attach the outer members 120 to the nose members 280 at the outer member nose intersections 410 and 420. Similarly, the outer members 120 can obtain lateral support by attaching to the tail fin struts 70 at the outer member tail intersections 430 and 440.
Nose struts 280 attach to the central structural member 30 at the nose strut joint 290. In a foldable design, the nose strut joint 290 will be hinged and/or capable of sliding longitudinally along the central structural member. The nose struts 280 may attach to the envelope 20 at the aerodynamic pressure zero-crossing point 250. This has the effect of relieving the envelope components of the longitudinal oriented stresses at the nose. In a foldable design, the attachment between the nose strut 280 and the envelope 20 may be hinged and/or capable of sliding longitudinally along the envelope and to be locked in place when unfolded. In one embodiment, the nose struts 280 will attach to a foldable, ribbed envelope as described in U.S. Pat. No. 6,793,180 along one of the ribs of the envelope. Each nose strut 280 may be limited from spreading outward beyond a certain point by a flexible tensioning member 300, such as a wire rope, connected at one end to the outer end of the nose strut 280. The other end of the flexible tensioning member 300 may be attached to the central structural member 30. The nose radial member 300 can attach to the central structural member 30 at any number of longitudinal points along the central structural member 30 including a point 310 as to make it oriented perpendicularly to the central structural member 30 the very nose of the ship 40, or it can attach somewhere between those two points.
Nose radial members 300 attach to the central structural member at the nose radial joint 310. In a foldable design, the nose radial joint will be hinged and/or capable of sliding longitudinally along the central structural member and to be locked in place when unfolded. The nose radial members 300 will attach to the envelope 20 at the aerodynamic pressure zero-crossing point 250. In a foldable design the attachment point between the nose radial members 300 and the envelope 20 will be hinged and/or capable of sliding longitudinally along the envelope 20 and to be locked in place when unfolded. In one embodiment, the nose radial members will only be under tension and may thus be realized as a rope, cord or cable or other flexible means known in the art.
The central structural member 30 carries the aerodynamic forces from the nose 40 in column to the thrusting force located on the tail 50. Forward thrust is provided by a propulsion means 320 located at the tail of the ship. Thus the primary main thrust and drag loads are carried longitudinally by the central structural member 30 rather than by the envelope material.
The central structural member 30 is stiffened against buckling and/or bending by one or more sets of radially oriented struts 90 located longitudinally along the central structural member. These radially oriented struts are themselves supported longitudinally by one or more guys 120 running to the nose and tail. This structure is very similar to the spreaders and guys that are routinely used to stiffen sailboat masts. The radial struts 90 are supported laterally by attaching them to the envelope materials preferably linking them to the ribs of a foldable envelope structure. (Note: The lateral loads that the radial struts 90 place on the envelope 20 are very small in contrast to the longitudinal loads the support.) Alternatively, the radial struts 90 and associated guys 120 can be supported laterally by attaching the guys to the nose struts 280 and/or tail fin struts 70.
The truss structure formed by the central structural member 30, radial struts 90 and guys 120 not only supports the compressive longitudinal compressive loads but also carries the bending moments and associated stresses placed on the envelope. When a bending moment is placed on the entire ship, it is transferred to the central structural member 30 where it attaches to the nose 40 and/or tail 50 of the envelope 20 and/or by the nose struts 280 and tail fin struts 70. The bending moment is then is carried as tension in the guys 120 and as compression in the radial struts 90 and the central structural member 30.
In addition to the nose struts 280 located at the aerodynamic zero-crossing point 250, one or more additional sets of struts 300 may be located at the longitudinal points near the nose 40 to transfer even more loads to the central structural member 30. Similarly, one or more additional sets of struts (not shown), comparable to the nose struts, can be added to the tail end of the vessel in order to carry loads from an even larger portion of the envelope to the central structural member 30.
An additional benefit of the internal support structure herein described is that hard points (external points supported by the internal structure) 500 and/or 510 can be provided to support landing gear.
It is beneficial to provide structural support of the envelope 20 other than merely conventional internal air pressure. Otherwise, the airflow could wildly distort the envelope 20 and destroy the pressure gradient described above. The forces on this underlying support structure may be reduced by matching the internal and external pressures.
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the principles of the invention are applicable to vessels other than lighter-than-air airships. Accordingly, other embodiments are within the scope of the following claims.
This application claims priority from co-pending U.S. patent application Ser. No. 11/135,555.
