A real stearman's engine quits when it goes inverted.
Maybe it's to do with what reality settings i'm using in FS2004 - not sure what they are, but I know I haven't changed them from the default settings, & please don't ask me to check my settings because I can't even get FS2004 to load at the moment & it's really annoying me.
Suffice to say, I dont't think that my reality settings were very high.
Cheers,
TSC.