Apollo Capsule 3D Model

Hi,

I am trying to model the Apollo Space capsule as a 3D shape in MATLAB but I am unsure of how to even begin doing so. If any one could possibly point me in the right direction, that would be very much appreciated. Many thanks in advance!

[Cedric]

You could try to ask the person who started this thread: http://www.mathworks.com/matlabcentral/answers/59039-trouble-with-finding-appropriate-conditions-for-logic where he found his model.

Answer 1

[ChristianW]

doc patch

Depending on your model complexity, you could use 3D CAD software and save as *.stl. There's a function called rndread, converting stl to patch input.

[Fredrick_jong]

Its just a basic 3D shape which I have dimensions for ie: Spherical Blunt nose radius = 3.95m Spherical nose radius = 4.595m Shoulder Radius = 0.186m Back shell inclination angle = 32.5deg relative to axis of symmetry Overall length L = 3.522m

With that, would you recommend using a CAD software(Pro-Engineer) or is there possibly a way to do that in Matlab itself?

[ChristianW]

I can't clearly assign your geometry data without a picture.

Here's a cone example:

n = 20;
[X,Y,Z] = pol2cart([linspace(0,2*pi,n) 0]',[ones(1,n) 0]',[zeros(1,n) 1]');
% plot3(X,Y,Z); axis equal
verts = [X,Y,Z];
faces = [1:n; 2:n+1; (n+1)*ones(1,n)]';
% faces(end+1,1:n) = 1:n; faces(faces==0) = NaN; % bottom surface

p = patch('Faces',faces,'Vertices',verts,'FaceColor','g'); axis equal

[Fredrick_jong]

Hi,

Sorry for the late response. I have found some pictures of what the model I am looking for is meant to look like. I will attach them here once I figure out how that is done. Once again, thanks a lot for your help.

[Fredrick_jong]

 http://imageshack.us/g/27/apollocapsule1.jpg/

That should provide you with the images I found. Hope it works.

[ChristianW]

Maybe this works for you:

p = [-0.000000219377116  0.000019037643653  ...
     -0.000695680017162  0.013659012592243  ...
     -0.150372230012195  0.815648271244546  ...
     -0.696731668656325  ];
x = linspace(1.033625312069473, 23.633886177386074,20);
y = polyval(p,x); % plot(x,y,'r')

[X,Y,Z] = cylinder(y);
surf(Z,Y,X)
axis square, set(gca,'color',[1 1 1]*0.8), grid off
colormap([1 1 1])

Check plot(x,y). I made a fast approximation. You just need to fix y(x) to your exact profile.

[resh]

Thank you. That looks very much like what I am expecting it to. I have a question. How did you approximate those values to get a shape as such? If you let me know the method that you used, then I could approximate the values for myself. Thanks once again.

[ChristianW]

I made the shape with ginput and polyfit, but thats fast and dirty.

axes; disp('Define shape with 20 Mouseclicks or press Return.')
[x,y] = ginput(20);
plot(x,y,'.k'), hold on
p = polyfit(x,y,6);
X = linspace(0,1,100);
Y = polyval(p,X); % roots(p) for the Polynomial roots
plot(X,Y,'r'); axis([0 1 0 1])

As I said, you should use the exact profile form. That is like a big circle than a small circle, a straight line and a small circle. At each transition the gradients are the same.