There is indeed axial movement on the swivel bearing on the mainshaft as I manipulate the cyclic. I only recorded the blades as I thought it more obviously shows what I'm talking about. Whether or not I'm inputting aileron or elevator is irrelevant as the collective change is observed when I give cyclic input in any direction, as shown in the video. This same collective cyclic interaction is also observed in check mode. I did not record in check mode as the heavy blades and fast acceleration of the servos in check mode makes it so that the model jumps violently when I move the sticks, and makes recording the alignment of the blades difficult.
There is indeed axial movement on the swivel bearing on the mainshaft as I manipulate the cyclic. I only recorded the blades as I thought it more obviously shows what I'm talking about. Whether or not I'm inputting aileron or elevator is irrelevant as the collective change is observed when I give cyclic input in any direction, as shown in the video. >>This is correct
This same collective cyclic interaction is also observed in check mode. I did not record in check mode as the heavy blades and fast acceleration of the servos in check mode makes it so that the model jumps violently when I move the sticks, and makes recording the alignment of the blades difficult. >> And this is correct
But it's not correct to use this for checking any part of a helicopter setup.
Let's focus on the issue I'm trying to highlight in the demonstration rather than whether or not anyone one else before has used this method to check for anything:
I am getting deviations in collective when I only manipulate the cyclic.
I'll attempt to break down what's happening in the video. With no cyclic input and zero collective we see the blades line up perfectly when folded up. When I give cyclic command in any direction, the swash center swivle ball gets pulled downward on the mainshaft, indicating an uncommanded change in collective, and this manifests as the previously lined up blades spreading apart.
If it helps we can forget the video altogether and just focus on the fact that my center swivel bearing moves up amd down on the mainshaft while only giving cyclic input, as already stated in the initial post.
Let's focus on the issue I'm trying to highlight in the demonstration rather than whether or not anyone one else before has used this method to check for anything:
I am getting deviations in collective when I only manipulate the cyclic. It will because your blades are folded together and the gyro would not compensate for this ether
I'll attempt to break down what's happening in the video. With no cyclic input and zero collective we see the blades line up perfectly when folded up. When I give cyclic command in any direction, the swash center swivle ball gets pulled downward on the mainshaft, indicating an uncommanded change in collective, and this manifests as the previously lined up blades spreading apart. Correct for checking zero pitch with midstick and no stick inputs.
If it helps we can forget the video altogether and just focus on the fact that my center swivel bearing moves up amd down on the mainshaft while only giving cyclic input, as already stated in the initial post. you can't go by this as all helis will do it.
I get what your saying but confused to why you are testing this with blades folded together, I've never seen this in manuals or from anyone apart from as mentioned just to precheck zero pitch @ midstick, if you fold out both blades and move full collective or negative then move full cyclic are you seeing any swash binding.
This demonstration is only to visualize what the collective is doing when I give only cyclic commands. We can forget about it if it ends up confusing you. The swash still slides up and down the mainshaft with the blades unfolded. If I draw on my experience with other helicopters, which were only rtf/bnf with proprietary FBLs yes this does also happen, but only at extreme swash throws when something does bind / servo endpoints reached, otherwise the swivel bearing stays put on the mainshaft with cyclic movement. The situation with the fireball is distinct in that the collective change starts as soon as I touch the cyclic and the effect increases gradually as i give it more cyclic. There is no binding of any kind and the servos are far from their endpoints. There's simply some servo speed mismatch between up and down, and the mismatch is even across all 3 servos, specifically down is a bit faster than up, as indicated by the swivel bearing being pulled down about the same amount when cyclic input is given in any direction. Which is weird as this speed difference is not observed when only manipulating the collective. The pitches for full positive and negative collective are dead even. I can tune out the interaction by decreasing the lower endpoints on all 3 servos but that would decrease my pitch on negative collective as well so hardly ideal.
There are no other interactions. Swash stays level through the entire collective range.
Ok someone on helifreak came through with a very compelling theory. The swashplate on this model is of the flat type, meaning the height of the ball joints for the servo linkages are below that of the ball joints for the pitch arms and swivle bearing, as opposed to swashplates where the arms for the servo linkages are curved up to put everything on the same level. There needs to be a parameter where you can specify this height difference and have this be taken into account. Or is there already one that I'm missing?