The load analysis is to be on a single door. That is well and good. And if we had a full description of the door we could simply start from there and proceed with the analysis. But for some reason you are unable or unwilling to get the door information from the blueprints. You are trying to calculate the door parameters from other data. This calculation depends on the relationship of the door to the other components, including the other doors.
The doors are not all that flat. I calculate that in the deployed position at the top (relative to door) edge the sides of the door are about 1.8" below the center of the door. That does not seem negligible.
I am always leery of simplistic assumptions that a particular approximation is "close enough". I have seen too many serious mistakes (including my own) with such assumptions. A nice example of a situation where intuition as to the size of an effect is likely to fail can be found
here. This collaboratory is about how to use Mathcad, and I consider that one of the important reasons for using a powerful tool like Mathcad, rather than just a slide rule, is that you can avoid most of these assumptions. You can afford to do an accurate calculation on the actual geometry and see what is actually important or not.
The spring may not be part of the analysis. But it is a part of the stowed geometry. If it does what I think it does, allow the lower hinge to move relative to the door face, then far from the stowed door angle being a fixed reference point you don't even know the angle of the stowed door. You know the angle of the hinge line but unless you have accurate information on the relationship between the hinges and the door you know little about the door. There is not much point to knowing the hinge positions to three decimal places if the spring allows the hinge to move an inch or two from its nominal location (relative to the door surface).
You still seem to miss my concerns about the upper hinge. I fully understand that the two hinges work on a common axis, and that for analysis purposes are treated as a single hinge on that axis at the door centerline. But the actual points of attachement are off to the side, not on that centerline. If the hinges are mounte .8" from the front surface at the point of attachement, the projection to the centerline could easily be as much as a half inch or so in front of the door face, rather than the .8" in back of the face assumed. This make a difference in the relationship of the door angle to the hinge angle.
As to movement of the upper hinge, my assumption was that the .8" (which a distance perpendicular to the center line, not a position along it) is fixed and that it is possible to move the hinge position along the center line while keeping the perpendicular distance fixed. I don't see why changing the position of the upper hinge on the door would change the bracket design at the hinge position. What happens to the bracket depends on how the stowed door position is assumed to be affected. If the stowed door position (not just the angle) is assumed to be fixed then changing the upper hinge position will change the position of the bracket on the outer panel. That will affect the length of the bracket (distance from hinge to outer panel) and the mounting of the bracket on the panel (different radius and curvature at the new attachment point).
I don't quite understand the fixing of the stowed door angle as matching the outer plate. Since the outer plate is curved (not cylindrical or conical) the angle is a matter of what you use as the reference point on the outer panel. This could vary if the door position is allowed to vary. Making a fixed angle for the door implies having a fixed reference point on the outer panel.
Which inner cylinder dimension? The value that the computed value approximates (38")? Or the actual computed value (assuming a .75" clearance) of 37.98"? And apply how? Which other value should be recalculated or ignored based on this value?
A big gap between the doors, rather than their assumed meeting, would mean a large overestimate of the door widths and areas. How big a gap? And how will that affect the pressure when different deployment angles are used?
BTW, I worked a bit more with the integrals of the conical sections, fixing up the area element and doing some additional integrals. Somewhat to my surprise the direction of the net pressure force is not perpendicular to a plane through the center line. It approaches that as the subtended angle approaches zero, but is noticeably different.
� � � � Tom Gutman