ORIGINAL: dick Hanson

Calculated thrust is really not worth much.
There isn't a calc chart that is even remotely accurate .
Thrust can be measured -easily -on the plane or on a simple rig.
I am adding a pic of a rig I use for electric motors .
This could be done for gassers but it would be a much sturdier setup .
Why aren't calc figures any good?
Simply - you can't add in the variables of the prop shape
you can add in rpm and the "calculated prop shape -but props change in efficiency as they pass thru different speeds .
I know some people swear by calculated data - but I have never seen prop charts which are any good.
Try and compare - you will see what I mean