Rigidized assisted opening system for high altitude parafoils
A parafoil for operation at high altitudes, in low density air, or at low airspeeds, and methods for opening same. Some versions of the parafoil comprise flexible members connected to the parafoil canopy. When the parafoil canopy is in a stowed configuration, the members are deformed, storing elastic energy. When the canopy is released from its stowed configuration, the members spring back to their undeformed shapes, thereby opening or assisting with opening the canopy. The flexible member may also be attached to a base structure, which is attached to the payload. The members may comprise rods or hollow tubes that can be flexed using a fulcrum near the base structure, or a spacer plate, so that the ends connected to the canopy are restrained by a parachute bag containing the stowed or packed canopy. The parachute bag can be opened prior to or during detachment of the parafoil from the flight vehicle.
1. A method of opening a parafoil comprising a canopy and a plurality of flexible members, the method comprising:
deforming elongated portions of the flexible members, thereby storing elastic potential energy along the length of the elongated portions of the flexible members, wherein a top end of each flexible member is connected to the parafoil canopy;
securing the parafoil canopy and the deformed flexible members in a stowed configuration;
attaching the parafoil to a flight vehicle;
detaching the parafoil from the flight vehicle;
releasing the parafoil canopy and the flexible members from the stowed configuration; and
releasing the stored elastic potential energy stored along the length of the elongated portions of the flexible members to cause the flexible members to return to their undeformed shape, thereby at least partially deploying the parafoil canopy.
2. The method of claim 1 wherein the deforming step comprises folding the parafoil canopy and the securing step comprises disposing the folded parafoil canopy in a parachute bag.
3. The method of claim 1 wherein the detaching and releasing steps are performed at an altitude greater than 25,000 feet.
4. The method of claim 3 wherein the detaching and releasing steps are performed at an altitude greater than 50,000 feet.
5. The method of claim 1 wherein the releasing step is performed before the detaching step.
6. The method of claim 1 wherein the releasing step is performed simultaneously with the detaching step.
7. The method of claim 1 wherein deforming the flexible members comprises deforming elongated portions of the flexible members.
8. The method of claim 1 wherein the flexible members comprise flexible rods.
9. The method of claim 1 , further comprising connecting a base end of each flexible member to a base member connected to a payload.
10. The method of claim 9 , wherein the connecting step comprises rotatably connecting the base end of each flexible member to the base member.
11. The method of claim 9 , the parafoil comprising one or more suspension lines, but not all suspension lines, supporting the weight of the payload during flight of the flight vehicle and before releasing the parafoil canopy from the stowed configuration, the suspension lines connecting the base member and the canopy.
12. The method of claim 9 wherein the deforming step comprises bringing the top ends of the flexible members together, the flexible members bending around a plate or fulcrum disposed between the top ends and the base ends.
13. The method of claim 12 further comprising:
after the releasing step, initially spreading the flexible members apart from each other past a vertical orientation; and
after the initially spreading step, gravity continuing to spread apart the flexible members until the parafoil canopy is completely deployed.