Hubs and spinners
F5B props are designed for very high speeds and so often have a very high pitch which will prevent them from folding flat to the fuselage. This creates more drag on the glide which we definitely don't want.
If a prop hub is made with the blades offset from the centre line it will help the blades fold flatter against the side of a circular fuselage.
F5B props are designed for very high speeds and so often have a very high pitch which will prevent them from folding flat to the fuselage. This creates more drag on the glide which we definitely don't want.
If a prop hub is made with the blades offset from the centre line it will help the blades fold flatter against the side of a circular fuselage.
Another approach is to make the prop blades with a lower pitch than required so they will fold flatter, but use them on a special hub with extra "twist" at the blade mounting to get the right pitch when open. For example the RFM 17x18 props are only 17x18 when used with a hub that has a blade twist of +5 degrees.
Hubs with both twist and offset are quite common in F5B.
The RFM site explains which of their blades need the special hubs.
The RFM site explains which of their blades need the special hubs.
Hub removal
Sometimes a prop hub will seem to get stuck on the motor shaft - this is usually when you are in the greatest hurry to get the hub off for some reason, so a means of pulling it off quickly and simply without damage to model or motor is useful.
Faced with this problem recently, and after a rummage through the spares box and a trip to the local hardware store, I made the hub puller shown here. It works quite well and is now kept in my model box.
Sometimes a prop hub will seem to get stuck on the motor shaft - this is usually when you are in the greatest hurry to get the hub off for some reason, so a means of pulling it off quickly and simply without damage to model or motor is useful.
Faced with this problem recently, and after a rummage through the spares box and a trip to the local hardware store, I made the hub puller shown here. It works quite well and is now kept in my model box.
The pictures should make it all clear, and you can click on them for a larger version if needed.
The harware required is an old Aeronaut prop centre, and 3 x 50mm M6 screws. The original version used the domed thin headed screws (designed for roofing panels) as these fit into the spinner easily, but I soon changed the middle screw to a normal hexagon headed one as it is easier to do the "pulling" by turning it using a spanner than it is with a screwdriver.
The middle screw needed to have the threads filed down a bit to fit into the 6mm hole in the hub, and it may help to file the end into a point . A recess was filed into the Aeronaut prop centre to stop the nut on the middle screw from turning.
The harware required is an old Aeronaut prop centre, and 3 x 50mm M6 screws. The original version used the domed thin headed screws (designed for roofing panels) as these fit into the spinner easily, but I soon changed the middle screw to a normal hexagon headed one as it is easier to do the "pulling" by turning it using a spanner than it is with a screwdriver.
The middle screw needed to have the threads filed down a bit to fit into the 6mm hole in the hub, and it may help to file the end into a point . A recess was filed into the Aeronaut prop centre to stop the nut on the middle screw from turning.
