ORIGINAL: samtech
anybody know who makes an 8x11 or even an 8x12?
ORIGINAL: Mike Connor
Actually a 8x12 (if you could find one or cut a larger prop down) is less load then a 9x8 according to ThrustHP.
Hi,
the GS-45 is a rugged cheap engine that can be modded with nice results, though I would not recommend running them above 20K unloaded due to insufficient long-run conrod strength.
8x11 or 8x12 speed prop sizes belong to another category of speed engines, namely to 10 to 15 cc converted ducted fan engines. So when talking anything below 10cc capacity, there’s a huge lack of torque for those oversquared prop sizes. For instance the most powerful superduper modified OPS 60 VAE engines over here turn 8x12 CF props about 22000 statically and up to 26000 unloaded. For that kind of rpms we
need about solid 4 to 5 HP!
A highly modded GS-45 on the other hand will put out a maximum of maybe 2.5 HP (a short lifetime only untill the conrod blows).
Generally by calculating oversquared props using THRUST HP software, the results are complete bullsh.t. [sm=thumbs_down.gif]
For the Wildhare LR1 (called Speedcat over here in Europe), you can’t use props effectively having more than 9“ of pitch. For bigger pitches we need a much more clean airframe plus a rear exhaust engine setup with full cowl. So for best speed results a
8x8“ APC prop should be the optimum choice in combination with your GS-45 on the Wildhare LR1.
P.S. Simply cutting down an APC 12x12 to 8x12“ for instance will result in catastrophic prop aerodynamics.
