I have to admit that Im very interested to see how much thrust your setup will make. I have an OS 91 powered propjet that weighs about 13 lbs wet. The OS with tuned muffler I think makes about 9.5 lbs thrust at best.

If your setup can do what the Calc v3.33 suggest Id seriously consider changing to an electric setup.

Did you notice on the calc that the APC 12x6 E and the 12x6 EP (pusher I think) vary by almost 2 lbs thrust? E about 13. EP about 11 lbs.

Cheers.