Harry is right on. I flew a full-scale S1-T Pitts in IAC for several years. The standard aerobatic turn is one of at least 60 deg bank during a pattern sequence. Hauling it over to 60, pulling to maintain altitude, at full power setting yielded 2G's on the meter every time.

Radius of turn depends on airspeed on entry at a constant bank angle. That's why an SR-71 doesn't do standard rate turns (3 deg/sec) on an instrument approach, like you do in a Skyhawk. You'd end up in the next county.

Speed decays rapidly due to induced drag, but will reach an equilibrium based on power, weight and wing design. That equilibrated state is what you strive for when the FAA examiner has you do constant airspeed, constant altitude, 720 deg steep turns at 45 & 60 deg bank. Round and round you go till you puke! And then you reverse from R-L to L-R and get the puke going the other way!
It get's more exciting, the steeper the bank of course. If you let the nose drop just a little at 75 deg bank, the vectors tilt, and you enter the infamous graveyard spiral in a heart beat in high performance planes, like Bonanzas, and our jets for instance. Guys like to call it "Tucking" in the turn. The steeper the bank, the faster it happens, especially in planes with adverse tip stall characteristics.

Now if you change the flight plane from horizontal to vertical, then look out. A moderate pull-up to a loop at full power in a Pitts gets you 4G with only a light pull, and 8G with a hard pull. A vertical loop is similar to a horizontal turn with 90 deg bank---not exactly the same, but aerodynamically close.

By the way, Tony Tehan of Mini-Hobbies had a neat little recording G-meter at Superman 2002 for those who don't want to spring for the JetCat GPS.

Tom