Hacker A60 18L Prop?

[gdwyer]

Hi there, I hope someone can help me....
I have converted a BH Glasair 120 to EP, using a Hacker A60 18L and an Masterspin 99 opto which was previously underpowering a 180 size edge 540.

I am using a 12s setup, I have an 800g setup (2x2500) and 1kg setup (2x3300) and while tried out a 22x12 mejzlic prop (M, which suggested 10kg of thrust using the "tied to a tree" test.

Great performance with this, although the plane is 6.5kg with the 1kg lipos, the recommended weight is 5.2kg

However very poor ground clearance with the prop here and I snapped shaft and broke prop on a heavy landing.

I have put on an 18x8 mejzlic prop, it tachos at 9,000 rpm full tilt but only pulls 4kg on the restraint.

I see gas versions use this prop with success, not sure how it will handle an extra 1.3 kg

I am worried about trying out the prop, can anyone guide me as the proper thrust / weight or suggest a prop? Is there an online calculator I can put in all the info?? Any help or advice would be much appreciated.