I am considering buying a Sig Four Star 40, but I've noticed that the rudder and elevators are smaller than usual. Is this plane capable of easily performing 3D maneuvers?

I have a 4*-60 with a clipped wing, enlarged rudder, thats also balanced, and elavator. The plane can flip and toss all over the place. Im not sure if the ailerons are enlarged though. Id say go for it and do some small mods to improve the performance of the plane, I had a ball with mine when it had a engine in it.

The 4* is not intended for 3D, but enlarging the control surfaces, increasing the throws and strapping on a large enough engine will allow almost any aircraft to perform some degree of 3D manuevers.

If you want a 3D plane why are you even thinking about a 4*?
Dennis-

I think a U-Can-Do 3D is the plane will want for a ball, I have a friend that loves his.

If you want an easy to build 3D kit aircraft... try the Sig Somethin' Extra. Its got a "fatter" airfoil and proportionately larger control surfaces than the 4*40. Uses the same engine.

The 4*40 is intended as an aerobatic trainer or transition model from the high wing "classic" trainer designs. It is capable of being used as a first airplane with the use of Buddy-Box instruction. (It is a trainer. It comes with Sig's beginner's guide that assumes you NEVER flew one before.)

The 4 star makes a poor 3D plane.
Try the something extra.

the 4* is a good flying plane that can glide for ever, well it was a good flying plane. i haven't flown it since september, and the last time it went in[&o] and i "had" it back together but had to re cut it in half because the darn thing wasn't strait, and now i am out of glue to fix it and won't get to the lhs for a few days or weeks... but i hope it flies like it did before it went in.....

Well, most are true about the 3D capabilities of the 4*, but by moding a few parts youll be on your was to a more capable 4*, however, i would go with the somthing extra,

If you want to go to the extremes, try a sig Fazor, but beware, the plane is quik on the controls and full throttle flat out is a no-no. fun plane once you get the hang of such a touchy plane.