This answer contains some nice plots of deep space spacecraft trajectories. Noticing that Voyage 2's heliocentric velocity dropped substantially just before 1990 I wanted to see why. Wikipedia's Voyager 2; Neptune describes its August 25, 1989 flyby.
But later in the mission the article shows the plot below. Since the planetary orbits are fixed I assume this is in an inertial frame.
I see that Voyage 2 (red) and Pioneer 2 (green) have substantial clockwise (prograde) "knees" or bends or deviations in their trajectories in the space between Unanus and Neptune's orbit. Are these accurate?
It shows all orbits traveling retrograde around the Sun until probably encountering an inner planet. That can't be right, can it?
I also noticed that when trajectories change course, the radius of curvature of the deflection is several AU. For scale note that the first planet plotted is Saturn's a = 9.6 AU orbit.
Is it possible that the plot mixes frames somehow? I can't make heads or tails of these plots.
Image cropped from source Voyager 1 extends to the right (purple) and Pioneer 10 extends to the left (dark blue).