I got a chief aircraft Extra 300 90 that I got reciently. I'm putting my new TTpro .61 and was wonder what the best size prop I should use. I want to do scale aerobatics with this Extra, no 3D. So what would be a good size for power. I was thinking around 14x6. Any suggestions?

No 3D???!!!!!!!! You are in the wrong forum! Heheehehee ...

The TT61 will not take the 14x6 well ... I ran mine very well on 12x6 and 12x8 on a Black Horse Extra 300 60, you may be able to get away with the 13x6. I have run even a 15x4W on her before but that was on a Harrier 3D 90.

As for your choice of engine, it will be marginal or decent only ... you are better off with at least something that performs well like an OS91FX, best is if you can run a 108 2C. You will get good, not 3D, performance with a TT61 on a plane of less than 7.5 lbs.

No 3D! I don't see an aerobatic section on RC U, woops!

Anyway, my I want to do normal scale style aerobatics with this extra like you see at an airshow. I have a Fun Star that I've started to fly for 3D.

The plane has an advertised weight of 7.6-7.8 lbs and a wing span of 65" which sounds right up a .61 engines alley. I don't want to go any lower than a 13xwhatever. So do you think I could run a 14x just with a little less pitch?

then you're getting into the range of a 3d prop! ha ha ha

12x6

Set - go with a 12x8 perhaps, a little pitch for some speed for the plane. See what sort of RPM you get with that prop. Like what Flyfalcon says is true ... a 12x6 is definately a good prop to start with.

I also want to mention that I am at sea level, and don't think I need to over power my planes for elevation reasons.

I have a 12x4 wood prop on my .46 TT in my FunStar and it works fine. So I know I can go bigger on a .61 TT. Maybe a 14x4 or 14x5? The reason I don't want a 12 on the plane is because the Extra has such a big cowel, and would look funny with a little prop.

Here's the plane I have got....