Large fluxes of energetic heavy ions (M / q ≈ 16) were observed in the inner magnetosphere during the geomagnetic storm of December 17, 1971. The observations were made by a set of energetic‐ion mass spectrometers covering the energy range 0.7–12 kev on board the polar‐orbiting satellite 1971‐089A (800‐km altitude, ≈0300 LT). Significant heavy‐ion fluxes were observed for a period of approximately 48 hours during the main phase of the storm. The heavy‐ion fluxes frequently exceeded the proton fluxes in the 0.7‐ to 12‐kev energy range. The heavy‐ion spectrums were highly variable and frequently contained a peak of several kev. The heavy ions were observed over a wide latitudinal range (2.4 ≲ L ≲ 9) and generally extended to somewhat lower latitudes than the protons. The peak energy flux of these ions was approximately 0.4 erg/cm² sec ster, which is substantial in terms of expected observable ionospheric effects. They may also contribute significantly to the storm‐time magnetic‐field depression (Dst), since at the same flux they represent an energy density greater by a factor of 4 than that of the protons.

Mathematical models of a motorcycle and rider dependent on three alternative assumptions concerning the tyre behaviour are developed. Stability characteristics deduced from them are compared, and minimum requirements for the model greater than have been previously satisfied are established. Using the most sophisticated of the models, the effects of design changes are calculated, and the design implications are discussed.

Abstract.Starting from an existing advanced motorcycle dynamics model, which allows simulation of reasonably general motions and stability, modal and response computations for small perturbations from any trim condition, improvements are described. These concern (a) tyre/road contact geometry, (b) tyre shear force and moment descriptions, as functions of load, slip and camber, (c) tyre relaxation properties, (d) a new analytic treatment of the monoshock rear suspension mechanism with sample results, (e) parameter values describing a contemporary high performance machine and rider, (f) steady-state equilibrium and power checking and (g) steering control. In particular, the "Magic Formula" motorcycle tyre model is utilised and complete sets of parameter values for contemporary tyres are derived by identification methods. The new model is used for steady turning, stability, design parameter sensitivity and response to road forcing calculations. The results show the predictions of the model to be in general agreement with observations of motorcycle behaviour from the field and they suggest that frame flexibility remains an important design and analysis area, despite improvements in frame designs over recent years. Motorcycle rider parameters have significant influences on the behaviour, with results consistent with a commonly held view, that lightweight riders are more likely to suffer oscillation problems than heavyweight ones.

A satellite‐borne energetic ion mass spectrometer experiment has detected fluxes of O+ and H+ ions flowing up out of the ionosphere in the auroral and polar regions. The observed ions have energies in the keV range, narrow pitch‐angle distributions aligned along the magnetic field direction and peak flux intensities of the order of 108 (cm²‐sec‐sterad‐keV)−1. The observations were made at altitudes between 5000 and 8000 km on both the day and nightsides of the earth.

0+ ions with energies of approximately 1 keV have been observed flowing upward out of the ionosphere with a pitch angle distribution having a minimum along the magnetic field direction and maxima in about the 130°–140° range. The measurements were obtained with an energetic ion mass spectrometer experiment on the satellite 1976‐65B at an altitude of about 7600 km in the northern dayside polar cusp. The data are interpreted as resulting from a mechanism which accelerates ambient ionospheric ions in a direction perpendicular to the geomagnetic field.