Ernie, I'd skipped the article but just read through the section you're referring to. I disagree with the blanket premise that non-inverted system aircraft must modify a figure such as a Half Cuban in order to fly it safely. It's just not the case. Quite a few pilots do very well in Sportsman without inverted systems. The inverted system issues alone have nothing do to with safety. The author's goal in making this statement was to suggest that newbies who have not necessarily mastered the technique associated with rolling on a constant line modify the figure to avoid overspeed/G issues as many (especially RV) acro newbies may be prone to. Generally, pilots of non-inverted system aircraft have only developed the primitive "Hoover roll" technique, which if applied to a Half Cuban where the half roll is begun after reaching a 45 degree inverted attitude could cause an excessively steep attitude and airspeed condition after the half roll. In this case the suggestion was to begin the half roll before reaching the 45 inverted attitude so that you're not excessively steep after performing the positive G half barrel roll associated with the primitive roll technique most "messing around" acro pilots use. All this is fine, but pilots must understand the deductions that will be made by the judges when modifying a figure in this way.
However, if you understand and can perform the proper roll technique, there is absolutely nothing wrong with flying the figure to competition standards without inverted fuel/oil. As you've already learned, if you have a carb, your engine will quit as soon as you hit the -G inverted 45 line, but will windmill and re-start the instant you're back upright. Your oil pressure will also drop for a few seconds during this time. But there is no need to draw long lines, so the exposure is very minimal, and will not hurt the engine. Even with an inverted oil system, your pressure drops for a couple seconds as the ball valve moves into the inverted position before inverted oil pressure comes back. Sportsman level sequences have no sustained negative G figures like you'll see beginning with the Intermediate category. If you have fuel injection, the engine will never miss a beat. It'll give you at least 5 seconds of fuel before the fuel in the line is out. Anything longer than that requires a flop tube in the tank.
The only caution in flying the brief negative G lines associated with Sportsman figures is monitoring oil loss if you don't have a separator/slobber pot. Aside from possibly having to clean oil off the belly of the airplane, you don't want to end up critically low on oil. Some RV pilots have reported a 2 quart loss on a long practice flight with lots of these short negative G lines. Your flying style, length of flight, and aircraft setup affect how much is lost.
Eric
