Aeronautics and astronautics – Spacecraft – With fuel system details
Reexamination Certificate
2000-02-10
2001-11-13
Jordan, Charles T. (Department: 3644)
Aeronautics and astronautics
Spacecraft
With fuel system details
C244S164000
Reexamination Certificate
active
06315248
ABSTRACT:
OVERVIEW OF THE INVENTION
The present invention relates to a method for injecting a satellite into a prescribed orbit using a booster with a solid fuel rocket motor. The prescribed orbit can be an arbitrary free fall path in space and the present method will steer the missile to a point on this path at the instant of rocket motor burnout. The present invention achieves the required trajectory without the need for thrust termination.
The basic concept for providing closed-loop control to the required orbit is to make use of two degrees of freedom which are available in the injection stage rocket motor burn. The first of these is the time of injection stage ignition, which can be computed in flight to provide accurate control of the initial “along-track” relative position. As discussed subsequently, this along-track or X direction is defined to be along the initial relative velocity vector. Timing of the injection stage ignition then insures that the displacement between the missile and the desired satellite orbit along this direction of relative motion is at least initially correct.
Control of the remaining “lateral”, or Y component of relative position, which is perpendicular to the initial relative velocity vector, can then be obtained by shaping the maneuver used to burn off excess injection stage fuel. It is here assumed that the non-thrust-terminated injection stage will normally have fuel in excess of that required to satisfy the velocity requirement; and the concept is to use this extra energy to provide the necessary position control. It is noted that this excess energy can also be used to make continual adjustments to the along-track position, and thereby desensitize the initial along-track timing control to injection stage motor variations.
The remainder of this disclosure describes the manner in which this path control concept can be implemented, assuming the availability of sufficient injection stage fuel. It is pointed out, however, that the complete guidance concept does provide for a default, or backup control when the lateral position requirements exceed the injection stage motor capability. This condition will be checked in flight during the exit coast, and prior to injection stage ignition. In the event that the position requirement cannot be satisfied, the missile will be guided with steering algorithms that simply seek to achieve a subset of the desired orbital conditions. For example, a backup velocity control which simply nulls the velocity-to-be-gained for achieving a circular orbit at the current position and in the current trajectory plane could be used. In this case, any excess fuel, although not sufficient to completely satisfy the position requirement, will be used to minimize the position error.
REFERENCES:
patent: 4387865 (1983-06-01), Howard et al.
patent: 5186419 (1993-02-01), Scott
patent: 5242135 (1993-09-01), Scott
patent: 5681011 (1997-10-01), Frazier
patent: 6193187 (2001-02-01), Scott et al.
Best Christian M.
Jordan Charles T.
Tarlano John
The United States of America as represented by the Secretary of
LandOfFree
Method for satellite injection using a solid fuel rocket motor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for satellite injection using a solid fuel rocket motor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for satellite injection using a solid fuel rocket motor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2592616