Thanks for the hints so far. Here are the measurements so
far at: 27degC, 40% humidity, including the numbers from the
Pe Reivers calculator (note: k prop is always 1.2 but might be not OK for some):


Diam Pitch Type RPM HP Kg Speed k prop.

12 7 APC-acro 13,200 2.10 5.2 141 1.2
12 8 APC-acro 12,200 1.88 4.9 149 1.2
12.5 5 Graupner 13,500 2.00 5.1 103 1.2
12.5 12.5 APC-acro 9,900 1.80 4.9 188 1.2
13 6 APC-acro 12,500 2.15 5.6 114 1.2
13 7 Sonic-G 12,300 2.35 6.0 131 1.2
13 7 Maro-wood 11,000 1.68 4.8 118 1.2
13 10 APC-acro 10,200 1.87 5.1 155 1.2
14 6 APC-acro 11,000 1.98 5.6 100 1.2

All is with 10% nitro and 18% castor, and OS-8 glow plug.

By the way, if looking at MACS tuning info, it seems to me more than strange
that those guys have for more than 2 years pending info on OS.91FX; why
is that ? Could it be that OS.91FX has not good gas-daigram from reso-pipes ?

Regards,
Nick