Nice plane.

You can do pattern with just about any plane, in spite of what some people may think. It comes down to the level you wish to attain. If you want true, pure pattern, then the airframes that are designed for pattern are the way to go. If you want a mix, well, then just about anything you can get that flys decently and straight will work too.

Obviously, 3D aircraft, such as the Yak, are aerobatic capable.

I own the Venus II and Excelleron 90, both are pattern design, and both are 1.20 size aircraft, not full 2 meter pattern planes. Both do very well, but neither are very well suited for 3D. The size of the control surfaces are not really what's neede for the extreme reactions necessary for some 3D stuff. And, yes, I bought them, first the Excelleron 90, then the Venus, for pattern flying.

Recently, as I think I've said, I bought and assembled the Goldberg Skylark 70, which is also a capable aircraft, but again, not 3D. Most likely, it would do some 3D stuff, as most aircraft will that have enough power and are prop'ed right, but nothing as way out as some I've seen.

So, we get back to your Yak. Here's my take on it. It is a very nice plane. Not particularly my "cup of tea", but I've also flown them. They are very nice in the air, but a bit to reactive for my tastes, but that's what they are for, right?

If you wanted to fly pattern with it, you could always have it set up with dual rates, one for 3D (extreme set up) and one for pattern (tamed down set up) and have the both of both worlds. It will do all maneuvers just as well as most pattern planes will provided you fly the plane. It takes some time to set it up so that it will fly straight and level with no quirks. Going vertical, for instance, watching what it does when headed straight up.. if it pushes or pulls either way or if it tends to roll slightly.. will take some time and effort to dial out. Then when rolling inverted, how much up it needs to hold the inverted will depend on the setup and the CG, among other things.

Setting up the elevator (if it has split elevators) will take some time too, just to get them straight so they behave exactly the same.

There is a lot to it, as there is with 3D setup, but I'm not all that familiar with that, but I imagine that it is pretty much the same.

So, yeah, that YAK will do the job for you just fine... and will be a great home for your YS engine.

Best of luck with that.

CGr.