GMax Rudder Rotation Problem

[thanosnaranja]

My Problem is this. I can't seem to duplicate the rotational movement I see used in rudders on aircraft with rear swept vertical stabilizers. My rudder moves as though it's axis of rotation is on a vertical line (straight up and down)through the Pivot Point instead of along an angualr axis though the Pivot point to emulate rear swept rudders, as designed. I have had some advice prior to this to align the vertical axis of the Pivot point with the leading edge of the Rudder and I did this - it didn't work. In fact it doesn't seem to matter which way I align the Pivot point. Once I unclick "Affect Pivot Point Only" and try to rotate the fudder with the Select and Rotate Tool the Rudder does the same 'ole thing. So I must assume I am still doing something wrong. I was hoping someone could upload a working vertical stabilizer and rudder with a rear swept angular axis that I can load into GMax and examine more closely. The following pictures hopefully illustrate my problem.

[lionheart]

When I get a part that doesnt want to behave, the first thing I do is reset its scale, make sure it doesnt connect via Hierarchy to something else that moves (in animation of course), and just as well, resetting the X-Form. (X-Form is a big one and usually is the culprit besides odd Hierarchies).

Caution, save as next model up before resetting X-Form. If it is this and the problem lies there, it will destroy (tweak out wierdly) your part. Usually this is caused by Hierarchy structure connections, which means disconnect it from ALL trees and you should be fine when you reset the X-Form.

Hope that works,

Bill

[andyjohnston]

How does it respond in flight simulator? How it reacts in Gmax will often be different then how it acts in flight sim, because you're rotating it using the pivot for the whole part and not the pivot you have adjusted with affect pivot only. Test it in flight sim, see what happens, and report back :)

[thanosnaranja]

Since I am a beginner I often find myself asking questions I subsequestly discover I should not have bothered people with. But I am So new at this that even at this juncture I am not sure I still should not have asked the question. I think one of the reasons I am having so much trouble with this particular Rudder problem is the compound angle of Vertical Control Surface swept to the rear and tilted five degrees away from the fuselage. Since my post yesterday I went back to GMax and created a primitive vertical stabilizer and rudder. Set the Pivot point to the desired location, rear swept the Rudder (what should I really call that?) and tested the hinge properties with some rotation. It worked perfectly of course... until I cranked in five degrees of lateral tilt. And it did what my model does - rotated off center from the Stabilizer so that the foot and head of the rudder kick out into the windstream in a manner that would result in them being ripped off on an actual aircraft. So this is a matter of getting the angles right. The problem is that if this were Autocad or Solidworks I would simply add hinge points at the two ends of the rudder to constrain its motion. GMax does not apparently provide this ability. I'll have to get out the brain grease or wait for an answer from the FlightSim community. This new pic is a three view of the compouind angle I'm talking about.

[FelixFFDS]

POSSIBLY...

When setting your rotation in gmax, make sure you've chosen "local" for your "Reference Coordinate System" is set to "LOCAL" rather than "View"

[img]http://www.flightsim.com/dc/user_files/98040.jpg
[/img]


Felix/[link:www.aerodynamika.com/forum.html|FFDS]
Pegasus Aviation Design

[thanosnaranja]

That did it! The Rudderon is now rotating relative to the local axis, or hinge line of the control surface. This is exactly what I was looking for; and let me say right off that any previous failed help is undoubtedly a result of my inability to adequately describe the problem. This brings a great number of questions to mind. I suppose that "local" is subject-object oriented. What I'm wondering now is how this local versus world differentiation affects the operation of or is related to the Sim. It posits that there is a 3-D world inside a 3-D world in the gmax design environment, but the inter-relation of these virtual worlds is bending my brain.

Where is the Gmax University you guys went to? This reminds me of when I was learning Photoshop.

http://www.flightsimnetwork.com/dcfo...iles/98060.jpg

[FelixFFDS]

>Where is the Gmax University you guys went to? This reminds
>me of when I was learning Photoshop.
>

Any knowledge I have of gmax is the direct result of lurking on this and other design forums, patiently reading the postings of true experts in the matter - who have learned their craft by perseverance and experimentation. Of course, their having read and done the gmax tutorials helped their knowledge.

I spend more of my time playing with gmax than actually being able to build anything.

The Gmax University is co-located with the "School of Hard Knocks".

Felix/[link:www.aerodynamika.com/forum.html|FFDS]
Pegasus Aviation Design

[n4gix]

>Where is the Gmax University you guys went to? This reminds
>me of when I was learning Photoshop.

I'm glad you got the problem of the axis alignment sorted. I'm apologize for not making the "Local" axis selection part of my earlier advice on the issue (in whatever forum it happened in, I don't remember now...). My incorrect assumption that you knew about "View" vs. "Local" coordinate systems lead you to waste a lot of time and experience a lot of unnecessary frustration... I feel like a :+ ...

BTW, the Help files in GMax will throughly explain "View," "World," and "Local" coordinate systems...

I'll bet you will remember "Local" from now on though! ;)