Owen N
Mechanical
- Jul 13, 2017
- 22
The Quadcopter design, without the cyclic pitch control, seems to develop massive bending torques at the rotor head mount, when cruising at speed. (5m rotor) I looked at some helicopter shaft-rotor join detail drawings on Pinterest, and they seem much lighter built.
Has anyone seen drawings for a system which produces bigger bending torques? the 1.5 inch shaft is way too small, and the gearbox
cannot fit a bigger shaft without needing to be massively scaled up.
I was thinking spline drive into a top-hat, and a ring of bolts holding the rotor-head base-plate in place (a little like a gyrocopter head arrangement). This would require a set of ball thrust bearing races with a 6 inch center bore, which seems rather big.
Is there a more compact way of doing this?
The size is dictated by the ring size of pinch bolts needed to resist the bending moment.
The thrust bearings would be mounted in a sandwich housing, and then bolted to a custom gearbox housing,
or through-bolted with long bolts to pick up the coupler housing at the other end, which the electric motor is also bolted to. The gearbox is single-stage epicyclic, so fairly short. See my other thread on gearbox selection.
I suppose I could use a massive hollowed spline shaft with thread, say 2.5 inches diameter, then a a step to support the rotor hub, then a big thrust bearing flange, and the gearbox output shaft running in another spline inside the stub shaft. Making it one piece is a bit of a stress raiser...
This would bring the thrust bearing race center holes down to about 3.5 inches.
Has anyone seen drawings for a system which produces bigger bending torques? the 1.5 inch shaft is way too small, and the gearbox
cannot fit a bigger shaft without needing to be massively scaled up.
I was thinking spline drive into a top-hat, and a ring of bolts holding the rotor-head base-plate in place (a little like a gyrocopter head arrangement). This would require a set of ball thrust bearing races with a 6 inch center bore, which seems rather big.
Is there a more compact way of doing this?
The size is dictated by the ring size of pinch bolts needed to resist the bending moment.
The thrust bearings would be mounted in a sandwich housing, and then bolted to a custom gearbox housing,
or through-bolted with long bolts to pick up the coupler housing at the other end, which the electric motor is also bolted to. The gearbox is single-stage epicyclic, so fairly short. See my other thread on gearbox selection.
I suppose I could use a massive hollowed spline shaft with thread, say 2.5 inches diameter, then a a step to support the rotor hub, then a big thrust bearing flange, and the gearbox output shaft running in another spline inside the stub shaft. Making it one piece is a bit of a stress raiser...
This would bring the thrust bearing race center holes down to about 3.5 inches.
