Adrian, by my calculation, 15 oz. was under optimal mass -- but not by much. 15-18 oz. (in my sims) all came w/in 50' or so of each other. The top of the curve is pretty flat. Even jumping up to 20 oz. doesn't cost much / any altitude.

The gees were decreased with a heavier rocket, but not by much. All sims were 70+ gees.

Were it me, I'd build a touch heavier for durability and lower airspeed and gees....

I would've bet my lunch regular phenolic would have shred. I'm quite impressed / surprised that it did not. Seems like years ago I read in PML's FAQ that 38mm and 29mm would survive pretty much anything, but you should glass 54mm and up if you pushed it.

Having a lighter cone helped a lot. That flight probably pulled 70 gees. The PML website says that cone weighs 4.3 oz. That translates into a nosecone that exerts 19# under boost. The negative gees at burnout would have been another major factor... hard to do shear pins in those solid cones.

JW

I too got 15oz as under optimal, but close enough to not really matter. As for the acceleration, it actually did not follow the I600's thrust curve that closely. It only pulled 57 gees in boost (never thought that I would pair that with "only"), but it also had a 1.3 second burn (compared to the 1.1 seconds in the catalog). Also, the nose cone was actually screwed on - no shear pins there. The electronics were up there, so I did not want that cone to come off.