That's one of those loose terms, unlimited. The answer would be no to both the YS and OS 1.20 engines. Neither one would have been good for something like 3-D but both will pull the plane at about a 60 or 70 degree angle very well for a high climb to do something like a flat spin, maybe even more. They will pull the plane over for as big of a loop as you can do from level. The YS 1.40 was another story though, it would pull the plane at a straight vertical as long as you wanted. I can get my plane with my YS 1.20 to hover but it won't pull it out. The OS wasn't a bad choice but there is a bit of power difference between the OS and YS. I have gotten it to hover with the OS too, just not as long but I can't fly 3-D so it could just be me. If I ever rebuild my YS 1.20 I'm sure there will be a lot more there? Pretty sure anyway!