Were WWI rotary engines like the Clerget and Rhone prone to neg G cutouts?

They didn't have a normal floatbowl carburetor.

From : Don Stackhouse

The problem wasn't the "carburetor" (or the crude intake pipe and fuel jets that sufficed for one back in those days); it was the fuel tank. There was no "flop tube", just a simple fuel line running from the bottom of the tank to the engine. When the plane flew inverted or otherwise pulled negative "G", the fuel sloshed to the other end of the tank, and the fuel line started sucking air.

Of course the airfoils typically used in the planes of that era weren't much good inverted either, so the fact that the engine had problems wasn't necessarily the overriding concern. Also, on at least some of those WW I fighters (the Fokker Triplane in particular), the aileron response also got pretty awful under negative "G", a characteristic that our Roadkill Series Fokker Triplane dutifully replicates. A barrel roll (which has positive "G" all through the maneuver) goes pretty smoothly. However, try to do a truly axial roll and the roll rate slows to a crawl while the plane is inverted.

Don Stackhouse
DJ Aerotech