DRILLING PROPELLERS

With gas engines, it is extremely important to attach the propellers correctly. Typically, anywhere from four to six prop bolts can be used, depending on the propeller’s manufacturer. So, proper drilling techniques are a must to avoid ruining an expensive propeller and minimizing engine vibration.

Steps for Drilling

Place the propeller on the crankshaft and turn the engine over until you feel the piston start to enter compression in the cylinder. Leave the crankshaft in that position, turn the propeller to the 1 o’clock position and mark the location of the propeller mounting holes.

For accuracy, use a drill press (always wearing safety glasses) to keep the bit and drill chuck perpendicular to the work table. Use the proper drill bit size for the bolts being used to hold the propeller in place.

Insert the drill jig for your engine into the rear face of the propeller and align the propeller on the drill press flat on the table. The drill bit should be perfectly aligned with the first hole in the drill jig.

Slowly drill the first bolt hole into the propeller.

Insert a propeller bolt into the hole, then align the drill bit with the next hole (located directly across from the first hole) and drill that hole.

Repeat this process of drilling a hole, inserting a prop bolt and drilling the next hole until all the holes have been drilled. Once completed, remove the drill jig and clean out any debris from the holes and remove any chips. Keeping the propeller flat against the work table ensures all the holes are square to the propeller face. If the holes are not drilled perpendicular to the prop face, the bolts will not align properly with the threaded holds in the engine’s prop hub. Be sure to rebalance the propeller before starting your engine.

Atribute to Dave “Mr. Scale” Platt who, over the years, has won every type of scale event at the AMA Nationals: R/C, Control-Line and Free Flight, the annual free-flight, rubber-powered contest at Top Gun continues to be very popular with the contestants. It is open to anyone involved with Top Gun, including judges, staff and non-pilots. Started by Dave, the rubber-power free-flight event has been part of Top Gun from the very beginning. It has started as a fun diversion from the intense RC competition and to way to connect with the early days of modeling.

Starting with next year’s 2022 Top Gun event there will be no size requirements, and any rubber-powered scale model will be eligible and no documentation will be required. We hope that more builders will decide to come and join in the fun!