ORIGINAL: TimBle
I can't see why the Venus II won't do a flat spin. Spins are part of the Patten routines.
Planes that get into a flat spin and out of it are usually anything with sufficient rudder authority, and can stall. Trainer s are poor at flat spins but sport planes are good and scale aerobats are great.
Tapered symmetrical wing, CG close to CP i.e neutral or whisker closeto nose heavy usually does it well.
Good throws on the control surfaces and a decently strong engine.
any plane with the Cg too far forward won't spin...
Planes with a longer tail span (such as the Venus and other pattern planes) have a harder time 'flattening out' - these planes are designed to do the exact opposite - track straight through aerobatic maneuvers. There are spins in pattern, but the planes maintain a nose-down attitude.
This is thread is a good idea. It would be cool to have a sticky in the beginner's forum detailing how to do basic (and maybe some not-so-basic) aerobatics.