WhizWheel

thingiverse

This SpinWhirl is used to visualize a satellite in orbit based on common orbital elements (COEs). Five COEs are assumed to be fixed for simple orbital motion: size, shape, tilt, swivel, and twist. Once those parameters are visualized, you've successfully simulated the orbit any given satellite is flying in. I printed this example at 120% the original size. I created a plastic pin to hold the orbit onto the center of the orbital plane. A screw can also be used to attach the orbit as shown. The pin or screw represents Earth at a focus of the orbit. To visualize a satellite in orbit, you'll need COEs (a,e,i,RAAN,ArgP,v) that describe size, shape, tilt, swivel, twist, and position of a satellite in an inertial coordinate frame. Size (a) and shape (e) of any orbit are defined by semi-major axis and eccentricity respectively. These parameters define the orbit piece attached to the center of the SpinWhirl. A highly eccentric orbit is provided here to help with visualization. The size or shape orbit can be modified if desired, but not recommended. The outer square of the SpinWhirl represents the inertial coordinate frame on the plane of the ellipse. The first inner gimbal represents the location of the right ascension of the ascending node (RAAN). Simply swivel the n vector from I by RAAN in degrees. Inclination or tilt of an orbit is represented by the next innermost gimbal. Simply tilt the orbital plane by inclination (i) in degrees - press down on the 270 degree simple for an accurate representation of direction of tilt. The angle to perigee is visualized by twisting the attached orbit so that perigee points to the angle defined by argument of perigee (ArgP). Once all COEs have been simulated on the SpinWhirl, you've successfully defined simple orbital motion of a satellite around Earth. The final COE is true anomaly (v), which defines the position of a satellite at a specific moment in time as measured from perigee. In simple orbital motion, this is the only COE that changes with time. For a low Earth orbit, a satellite may complete an orbit in roughly 90 minutes. But out at geosynchronous orbit, the satellite takes 24 hours to complete an orbit. The SpinWhirl is a useful tool for visualizing any satellite in Earth orbit.