Early helicopter designers had an interesting dilemma. You have a set of blades rotating on a spinning shaft. Some how, you have to come up with a way to angle those blades in different directions, while they’re rotating at high speed. Not an easy task at all, but the solution they came up with was the swashplate.
The swashplate is an ingenious solution to this complex problem. Let’s take a look at how it works in the context of our subject helicopter, the blade MSR.
The swashplate is made up of two pieces of plastic. Each piece fits into a bearing. One piece fits on the inner race of the bearing while the other fits on the outer race. This allows the two pieces to rotate independently of one another. The inner piece slips over the mast of the helicopter. Now when the mast spins, so does the inner portion of the swashplate. Thanks to the bearing, we can make the outer portion of the swashplate to remain stationary at the same time.
In order to keep the outer portion of the swashplate in a fixed postion, there is a little pin that hangs off of it. The pin fits into a retainer that is attached to the main frame. By doing this there is no way for the outside of the swashplate to rotate but the inside is free to rotate along with the rest of the mast.
The way that the inner swashplate sits on the mast allows the entire swashplate to be tilted in all directions without upsetting the rotating mast. So by tilting the outer swashplate, the inner swashplate will follow. Now that the outer swashplate is stationary, it is possible to connect some linear servos to it in order to control that tilting.
Now the inner portion of the swashplate rotates with the mast and can be tilted by activating the linear servos that are attached to the outer swash. The next step is to transfer the tilting at the swashplate to the blades. This is easy to do since the blades and the inner swashplate are now rotating at the same rate. Connect buckles can be used to connect the inner swashplate directly to the blade holders. The blade MSR handles things a little differently though.
Instead of connecting the blade holders directly to the swashplate, the MSR has the swashplate connected to a mixing flybar. So when the swash plate is tilted, the flybar follows suit. In flight, the tilting of the flybar causes the helicopter to follow and the blades will eventually catch up. This setup is a bit laggy though, so in order to keep the MSR a little more responsive, there is also a secend set of connect buckles to connect the flybar to the blade grips.
As you can see, this whole system is actually quite elaborate. The servos attach to the stationary outer swashplate which connects to the inner swashplate through a bearing. The bearing allows the inner swashplate to rotate freely with the mast. The movement that transfers from the servos to the inner swash are then connected to the flybar which in turn connects to the feathering shaft. Quite brilliant if you ask me.
So there you have it. The inner workings of the swashplate on the blade msr.
