Pilot chute crown line attachment system
RIGHTS OF THE GOVERNMENT 
     The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty. 
    
    
     BACKGROUND OF THE INVENTION 
     In parachute systems incorporating canopy inflation aids, such as the pull-down vent line, the pilot chute has been attached to the canopy crown area with long lines or with unsymmetrical canopy attachment methods. The long crown lines are susceptible to entanglement and unsymmetrical attachments may cause canopy damage and poor performance. 
     BRIEF SUMMARY OF THE INVENTION 
     According to this invention, the pilot chute is attached to the crown area of the main parachute canopy by means of a thong-disc assembly and a crown line assembly. 
     The thong-disc assembly consists of a fabric disc with six fabric thongs and a pilot chute bridle that are secured at equally spaced attachment positions on the fabric disc. The pilot chute bridle and six crown line loops are secured to the main parachute crown at equally spaced positions. A crown line assembly is secured to the pilot chute bridle and has a plurality of bridle attachment loops secured to a bridle loop on the pilot chute bridle. Six thong attachment loops are secured together with the bridle attachment at equally spaced positions on the crown line assembly. 
    
    
     IN THE DRAWINGS 
     FIG. 1 is a schematic diagram showing a parachute with a parachute vent pull down line and including the pilot chute attachment system of the invention. 
     FIG. 2 is a plan view of a thong-disc assembly used in the device of FIG. 1. 
     FIG. 3 is a partially schematic view showing the thong-disc assembly and crown line assembly of FIG. 1 attached to the pilot chute bridle. 
     FIG. 4 is an enlarged partially cut away schematic view of the pilot chute attachment system of FIG. 1. 
     FIG. 5 is a view of the device of FIG. 4 along the line 5--5. 
     FIG. 6 is a schematic illustration showing the thong attachment system for the attachment assembly of FIG. 1. 
     FIG. 7 shows the attachment system of FIG. 4 after partial inflation of the parachute canopy. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference is now made to FIG. 1 of the drawing which shows a main parachute canopy 10 with a pull-down vent line 12 which pulls down the vent portion 13 of the main parachute in a conventional manner. A pilot chute 14 is secured to the crown area 16 of the main parachute canopy by means of a crown line assembly 18 and a thong-disc assembly 20. 
     The thong-disc assembly includes a circular fabric disc member 22, of a material such as Nylon, with six fabric thongs 24, of a material such as 1 inch Nylon tape, with ends folded over, secured at spaced positions around the disc. The pilot chute bridle 26, of a material such as 2300 lb tubular Nylon, is sewn to the disc member 22 at a position between two thongs 24 with the thongs and bridle providing equally spaced attachments to the thong disc 22. 
     The crown line assembly 18, shown in greater detail in FIG. 3, has seven trapezoidal panels 30, of a material such as 1.1 oz rip stop Nylon, secured together by webbing member 32, of a material such as 1/2 Nylon tape. The pilot chute bridle 26 forms one of the webbing members between two panels 30. Panel 30&#39; is shown as separated, to permit a clear showing, but in the device, as used, parts 34a and 34b form a single panel, so that the crown line assembly has substantially a conical shape. Bridle attachment loops 36 of a material such as 550 lb test Nylon cord pass through a bridle loop 37 and are secured to adjacent webbing members 32. A plurality of thong-disc attachment loops 40, of a material such as 550 lb test Nylon cord, are also secured to webbing members 32. 
     The thong-disc attachment loops 40 pass through crown line loop members 42, of a material such as 550 lb test Nylon, which are secured to the crown area 16 of the canopy 10, and engage the thongs 24 as shown in greater detail in FIGS. 5 and 6. The crown line assembly 18 remains attached to the canopy crown area in this manner during the deployment of the canopy. 
     In the operation of the device, the pilot chute is secured to the crown area of the main parachute canopy through the crown line assembly 18 and the thong-disc assembly 20 with the thong-disc attachment loops 40 of the crown line assembly 18 passing through the crown line loop members 42 and engaging the thongs 24 on the thong-disc assembly 20. In this manner, the pilot chute deploys the main parachute canopy by applying a continuous and symmetrical force to the canopy crown area. As the canopy inflates, the radial inflating force pulls on the crown line loop members 42 to pull the thong-disc attachment loops 40 from the thongs 24 which releases the crown area of the canopy from the thong-disc assembly 20 and the crown line assembly 18. When the canopy 10 is fully inflated, the deflated pilot chute 14, the crown line assembly 18, and the thong-disc assembly 20 lay along the panel to which the bridle line 26 is attached. 
     There is thus provided a pilot chute crown line attachment system which eliminates crown line entanglement and poor performance and damage due to unsymmetrical attachment.