Stage separation mechanism and method
A missile or other flight vehicle has a stage separation mechanism for separating a downstream stage from an upstream portion of the missile. The mechanism includes one or more holes in fluid communication with a cavity between the upstream and downstream portions of the missile. The holes are located downstream of one or more shocks produced by one or more local variations in the outer surface shape of the missile. The one or more local variations in outer surface shapes produce the one or more shocks as the missile is flown at supersonic speeds. These shock(s) produce downstream pressure rises, and these pressure increases are communicated to the cavity by the hole(s). The increased pressure in the cavity provides a mechanism for separating the downstream stage from the upstream portion of the missile, after release of a mechanical coupling between the upstream portion and downstream stage.
1. A flight vehicle comprising:
an upstream portion; and
a downstream portion aft of the upstream portion;
wherein one of the portions has a local variation in surface shape, whereby the local variation in surface shape produces a shock in supersonic flow;
wherein one or both of the portions have one or more holes, downstream of both the local variation in surface shape and the shock produced by the local variation in surface shape, in fluid communication with a cavity defined at least in part by the portions, and between the portions;
wherein the local variation in surface shape includes protrusions protruding radially outward from at least one of the portions;
wherein the protrusions include a series of tabs protruding radially outward from at least one of the portions;
wherein the holes are in the downstream portion; and
wherein the holes allow fluid communication between the cavity and a region that is both outside of the downstream portion, and downstream of the tabs.
2. The flight vehicle of claim 1 , wherein the protrusions protrude at least 2.5 cm (1 inch) out from a fuselage of the flight vehicle.
3. The flight vehicle of claim 1 , wherein the holes are 7.6 cm (3 inches) or less downstream from the protrusions.
4. The flight vehicle of claim 1 , wherein the downstream portion includes a rocket booster.
5. The flight vehicle of claim 1 , wherein the local variation in surface shape is in the upstream portion.
6. The flight vehicle of claim 1 , wherein the local variation in surface shape is in the downstream portion.
7. The flight vehicle of claim 1 , further comprising one or more latches that mechanically couple the portions together.
8. The flight vehicle of claim 1 , further comprising one or more explosive bolts that mechanically couple the portions together.
9. The flight vehicle of claim 1 , wherein a diameter of the cavity is at least 50% of a diameter of the downstream portion.
10. The flight vehicle of claim 1 , wherein an effective area of the downstream portion that pressure in the cavity acts upon is at least 50% of a cross-sectional area of the flight vehicle perpendicular to an axial direction along the flight vehicle.
11. The flight vehicle of claim 1 , wherein the flight vehicle is a ballistic missile.
12. The flight vehicle of claim 1 , wherein the protrusions are spaced around a circumference of the flight vehicle.