Chen attractor
The Chen attractor is a two-winged chaotic system closely related to Lorenz, with wider lobes and a busier crossing between them.
Equations
dxdt=a(y − x)
dydt=(c − a)x − xz + cy
dzdt=xy − bz
The first and third equations have the same form as Lorenz. The difference is in the second, where y now feeds back on itself through +cy. The half-turn symmetry about the z axis survives, so the two wings are still copies. Chaos Studies uses a = 40; the value 35 is common in the literature.
History
Guanrong Chen and Tetsushi Ueta described it in 1999, from work on making systems chaotic on purpose rather than taming them.
What to look for
Compare it with Lorenz by switching between the two in the menu on the home page. Chen's lobes sit further apart, and the path between them is less of a clean jump and more of a tangle.