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Tangential-Orbit ManeuverTangential-orbit maneuver occurs at the point where the velocity vector of spacecraft is tangent to its position vector, typically at perigee point.
Non-Tangential Coplanar Maneuver The orbit maneuver does not limited only at apogee and perigee point. If condition is allowed, the satellite able to perform the orbit maneuvers at any point. Figure 9- 1 shows the ∆V vector required for a non-tangential orbit maneuver, where α is the difference angle between the flight path angle of V1 and V2.
Hohmann Transfer The Hohmann’s transfer is the minimum two-impulse transfer between coplanar circular orbits. It can be used to transfer a satellite between two nonintersecting orbits (Walters Hohmann 1925). The fundamental of the Hohmann’s transfer is a simple maneuver. This maneuver employs an intermediate elliptic orbit which is tangent to both initial and final orbits at their apsides. To accomplish the transfer, two burns are needed. The first burn will insert the spacecraft into the transfer orbit, where it will coast from periapsis to apoapsis. At apoapsis, the second burn is applied to insert spacecraft into final orbit. Figure 9-7 represents a Hohmann’s transfer from a circular orbit into another circular orbit. A tangential ΔV1 is applied to the circular orbit velocity. The magnitude of ΔV1 is determined by the requirement that the apogee radius of the resulting transfer ellipse must equal the radius of the final circular orbit. When the satellite reaches apogee of the transfer orbit, another ΔV must be added or the satellite will remain in the transfer ellipse. This ΔV is the difference between the apogee velocity in the transfer orbit and the circular orbit velocity in the final orbit. After ΔV2 has been applied, the satellite is in the final orbit, and the transfer has been completed.
Date: 2016-04-22; view: 1076
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