Originally Posted by
Theuns
I ran a 85mm exit tube now, it only read 1900 gr on the scale but the thrust on my hand at the back felt quite a bit more than with the 95mm tube, the smaller tube also sucked my hand onto the intake stronger.......I am rather confused with this. I theroy the larger exit tube should give better thrust.
Maybe my way of measuring the static thrust is not all that acurate and this is giving the confusing readings.
Theuns
The smaller exit should give you a higher air velocity but often gives less static thrust. You're moving less air, but faster. Without actual data on things, it's hard to diagnose anything. A Viojett turning 20,000rpm will sound like it's screaming, but if I remember my DF days (a LONG time ago), a well tuned BVM .91/Viojett would turn upwards of 25,000rpm on the ground.