We're not tricking ourselves into anything. Like we have mentioned numerous times before: We are providing the 3D model with a location in space where a known point should be co-located with. We still do (and always have) provide phi, theta, and psi, which are the same regardless of the point of reference. We know at all times the aircraft body-frame vector from the CG to the VRP (visual reference point). We know the body-to-local frame conversion matrix at any time. Thus, we know the real world location where the 3D model VRP should be placed so that the motion calculated by the FDM is properly reflected in the motion of the 3D model.
Jon
If you know everything about both frames all the time, then why is there ever a need for any adjustment figure? Everything was calculated, all needed reference points were known already from the VRM to the FDM, you didn't adjust anything there was no need.
Some of these factors weren't known at first if people can draw planes of any relative size in the drawing program. You are figuring out the size relationship somehow, it is not set if they can just draw the model any size. If one person can draw it twice as large as another, and you can match the FDM to it, then you are matching more than just the nose point somehow. You are making your scale bigger somehow, or shrinking their drawing, if you can match the bigger model. If not then you have to move your nose around to match, then change every motion constant in the FDM to make a large drawn model act large, and a small model act small. And even then the modeler has to draw it the right size, they have to make the model 30 feet if it needs to be 30 feet.
I know you're doing it correctly. The models, once adjusted, look and act properly. It is your explanation of how the two reference frames fully match is what's lacking. You say no no we only adjust the nose, when really you are doing other things too to match the visual and FDM frames with your adjustment figure, even if you don't see it. You are making every point match in scale in both frames, not just the nose. Your adjustment figure is from the nose in one frame to a reference in the other. Your scale is either known set or adjusted along with this adjustment through other factors.
And when you get a new model, and move it around with your nose adjustment figure, and aligning your reference point, you are aligning your CG's even if you don't say you're aligning your CG's. Yes, they fall into alignment when you get your reference points matched and your nose was in the right place. But how is it you know when your reference point looks like it matches? By the CG. You may look at only your reference point. But when you move the plane, and you're saying 'hey it looks like we got the nose and reference point right', how do you tell? You judge it's motion relative the motion of the CG. You are matching the CG of the FDM to look in the right spot. Even if you say 'No, we are only looking at this other spot swinging around the way it should', you are really looking at it swinging around another point, the CG, when you check it visually. Like it or not that is how you are almost guaranteed to be aligning the visual model. There is very little else to accurately gague in a visual model in motion than 'is the model rotating correctly around the CG?' When you're aligning the visual with your number you're aligning the CG point, even if you do it through reference to some other reference point.
Regardless, there is a 3 or 4 sentence explanation of exactly how every point in your FDM frame, and the entire visual model frame, match. This includes matching any model of any size. It can be said easily, without saying "We only align the nose, you're not getting it." You are leaving something out of your objective explanation of how they match. You put it all in no doubt with the relative points match since it works in the program. But there is a simple overall description of how it matches that is much more accurate than 'we just align the nose'. No wonder you've discussed it to the point of being blue in the face if you haven't got the simple full reference match description to rattle off.
Don't worry about writing more trying to explain. If you guys aren't seeing the simple objective explanation I was originally asking for, you could write all day and never say it.
I will look at the FDM adjustments and adjust several models. And put a different model of a different size on one and change the numbers until it works and see how the visual to FDM scaling is done. I will then come back and give you a 3 or 4 sentence explanation of how all points in the visual model match up and are adjusted for size and position to the FDM. Maybe a picture or two if it's needed for clarity.
I am not the one not getting it. There is a simple relationship between the frames, not described fully by just saying 'we're fixing the nose'. You have a correct reference to reference model in your head no doubt. You likely have a correct idea of how the sizes and shapes match up. But you do not give the simple explanation of 'this forest matches and aligns completely and is size matched to this other forest by these these 3 or 4 steps'. You keep describing how this tree relates to that tree relates to that other tree and so on. You're so busy trying to explain every little tree you don't give out the simpler explanation of how everything is adjusted by your points and adjustments not just your nose. There is a simple transform formula for every point in the VRM to fix to every point in the FDM to align and scale for any size drawn model. And you're not giving all of it when you say you just align the nose.
Again, no need for reply. I will come back in a day or two with a complete description of how all points are transformed by your 'nose point' and your adjustment figure, and how any scaling is accomplished or if it's fixed from outside convention. And how you can adjust the adjustment to position any size visual model correctly. I'm pretty sure you do it by moving your adjustment number till the nose and reference point align and are the correct distance, and I'm pretty sure you tell they're aligned by looking at the model in the program and seeing it. And I'm pretty sure that is done by when everything's rotating around the right reference point and it all looks right, and that's the CG as the main reference point for looking to see if everything's rotating around right. Even though you say you're not visually aligning the model by the CG but really your nose adjustment to some other point.
Alan
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