RCGF 21CC-Twin Operator's Manual page 10

Drill and Install the Propeller
The easiest way to drill the propeller to fit the hub is to use a drill guide. If you do not
have a drill guide, you can use the following method to drill your propeller. Most
propellers within the recommended size range have a 0.393" [10mm] center hole pre-
drilled. If your propeller has this predrilled hole, move on to step 3. If not, start with step 1.
Or if there is no outer holes in the prop hub such as 10cc, 20cc SBM ,26cc BM , 21cc
twin , 30cc twin ,please ignore step 5 to 9 .
1. Remove the cowling from the aircraft. Use the included propeller
washer to mark the centering hole on the propeller
2. Once the location is established, use a drill press with a 10mm drill bit. In order to
achieve a clean hole opening on both sides of the propeller, drill only half way through
the propeller with the 10mm drill bit. Then flip the propeller over and drill completely
through the hole.
3. Next, set the engine at the top of the compression stroke. Note the position of the
ignition magnet with engine inverted.