Crab
Crab
Crab, yes it does.
It starts from basic physics, not from modelled behaviour, which makes it quite unique, but a formidably complex mathematical project (even including ground effect, tail fin down-wash interference etc...) This setup was specifically deveopped to have a precise view on full rotor dynamics during all parts of flight.
In the scenario shown here, model was operating in what I call 2-D mode, auto-pilot feature was doing lateral cyclic and tail rotor. That is an approriate set-up to answer Levi's question, not for your question of lateral transients.
The problem is -as discussed years ago with Nick Lappos- in order to have reproducible data, autopilots capable of flying predetermined paths need to be developped, which is again a project, and as it was supposed to run of a PC, not a super-mini, there is a CPU limitation. We found -as Nick predicted- that it is not possible to get reproducible data by hand flying the sim, you cannot fly it that precisely. So a number of path controllers were added to te sim.
Further more the amount of data produced is enormous, rendering, graphing up to generating full 3D sim like films etc, is again a project.
Development stopped 5 years ago, because the goals of simulating advanced auto rotations at many different configurations (W&B, RPM, density etc...), all sorts of low G situations, the said Frank's Wiwa and all sorts of coning/delta3 related rotor dynamics. Where do you think my alias comes from, I assume you should know that delta3's are related to lateral rolling....
It was for instanced used on this forum while discussing good old Lu's big problem = he strongly believed the R22/R44 was fundamentally not well designed, dynamically speaking. The model showed that it is not the rotor but the rotor/body interaction that is the limiting factor (combination of theetering rotor and R22/R44 inertial body behaviour)
You quote a "role to the advancing side" and put it as a absolute given for sim-consistency, where does that come from?
Years ago there was also the 90° precession dogma...
From all the tests I have seen, these coning related transitional rotor dynamics are very specific to a given rotor and riging, which can be very different, the only common factor is coning.
As I stated many years ago, personally I was surprised by the balance in the simple design of Frank's rotor that minimizes that lateral behaviour. Frank called it WiWa, because a simple way of reproducing it, is tracking the betas when just putting cyclic forward/backward and monitoring the rotor at different coning angles, the reason behind is that the tilting motion also creates transvers flows, even skids on the ground. I am sure that by 'over riging' the rotor I could get a different lateral behaviour, perhaps even a role to the other side. I cannot speak in great detail of other rotor systems, but I know that for instance a stiff four blade rotor has quite different dynamic behaviour than a theetering 2 blade.
Currently I do no longer have the time nor the environment to do elaborate experiments, I am lucky that a basic working setup still is available to do some simple check's (see for instance a fairly recent thread on low rpm blow back during autorotion, or delta3 positive versus negative in the 407 TR).
Given a full working system I could extract precise beta graphs of the blades that precisely show you the blade dynamics during the current experiment, which would answer your question in detail.
d3