I have an OS 1.60 in the Gene Soucy Extra - same size etc...

The last week I've bummed every prop I could from people...

The 18x6W gives lots of vertical and good 3-D. However it's heavy - very heavy.. like double what a Menz 18x6 weighs. It spins up slow and I'm turning about what you are - on 10% getting 8700 rpm peak and backing off to about 8200.

A Menz 18x6 will spool up faster and give nearly the vertical the APC does - but not quite. WIth the Menz I can reduce my takeoff roll from 35 feet to about 25 feet but can't go straight up as far afterwards.

The only Mejzlik prop I could borrow was a 20x6. Sounds like a lot - but actually if you measure it - it's closer to 19" than 20". Haven't tached it yet - but it doesn't feel like the engine is totally bogged down like I thought it would be. Put it on right before dark so no flights on it yet.

I have a H9 Cap 72" wingspan - similar to the edge. With an Irvine 1.50 turning a 16x8 prop it's a lead brick to fly. Good for learning how to fly a heavy/overweight plane.

Last thing - have you weighed your H9 Edge? I know they say 10.5 to 12.5 pounds but I've seen similar ones that weighed 14+ with the same engine or right around 14 pounds. There's only so much a 1.60 can do in a 14 pound plane. I know my H9 Cap weighs 14 with the 1.50.