The H-9 Arrow is more than capable of doing a Cuban 8

But a Cuban 8 is not the same as an Immelman or a Split S

Try doing 1/2 at a time. Start by entering a loop. At about 2/3 through the loop, stop pulling UP and let the airplane dive inverted toward the ground for just a split second - This will definitely put a lump in your throat the first few times you do it.

Then, a quick half-roll and pull out at the same altitude at which you started.

Once you are comfortable doing a half-Cuban, try pulling up into the second half.

Of course, you'll want to practice these at PLENTY of altitude until you get comfortable!