ENGINEERING NOTES 1109For 2700°F ot allowable lower-surface temperature, bank angles of 80 to 85 deg and minor circle indices greater than 0.5 are possible at 190,000 ft. The 2700°F temperature allows a lower cruise altitude and hence a higher L/D, which results in better weight fractions. Thus, the effect of temperature restraints on the aerocruise is an indirect one; the temperature restraint simply determines the permissible cruise altitude on which the maneuver L/D is strongly dependent. Figure 2 also shows that the aerocruise synergetic maneuver offers significant advantages over the extra-atmospheric orbital plane-change mode for orbital plane-change angles in excess of 3 deg for the 80 naut-mile-orbit case considered. These advantages increase for larger plane changes. For an orbital plane change of 25 deg, the aerocruise maneuver allows a saving of 30% of the initial weight. Conversely, for an allowable remaining weight fraction of 0.6, the 2700°F temperature vehicle allows an orbital plane change of 26 deg as compared to only 11 deg for the extra-atmospheric planechange maneuver.
ConclusionsThese results indicate that lower-surface temperature restraints can substantially reduce the synergetic orbit planechange performance of high L/D radiation-cooled spacecraft and should be considered in any synergetic analysis of these spacecraft types. These reductions are more severe for the aeroglide than for the aerocruise mode of the maneuver, indicating that the aerocruise is the superior mode. Also, the temperature restrained aerocruise synergetic maneuver is superior to the extra-atmospheric plane-change maneuver. Nomenclature a = semimajor axis when elliptic, R/(l -e) e = eccentricity h = angular momentum k = unit vector in the crossrange direction Ri, R; = position magnitude and vector at iih point Ri = radial component of Vi R p = position magnitude at perigee Vij Vi = velocity magnitude and vector at iih point v = true anomaly increment Xi, Yi, Zi = position coordinates of iih reference point Xi, Yi, Zi = velocity coordinates of iih reference point 5 = perturbation T-= time increment between reference points
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.