Step-Up Under-Flip Explained – Theme Park Definition

A step-up under-flip is a two-stage inversion invented by Rocky Mountain Construction. The train first "steps up" — climbing a rising, heavily banked section — and then flips underneath itself on the way down, so the roll happens on the descending half rather than at the crest. The result is a longer, slower rotation than a barrel roll and a hard shot of ejector airtime as the train falls out of it.

It is one of the figures that gives an RMC hybrid its distinctive feel, and appears on Steel Vengeance at Cedar Point, Zadra at Energylandia and Untamed at Walibi Holland — the first RMC conversion in Europe. Because the manoeuvre needs precisely twisted steel track on a wooden or steel support structure, it is effectively impossible on traditional wooden track.