imperialissue
Hunter
Very impressive work!
I think you're well on your way to proving that.
I think you're well on your way to proving that.
Thanks for the kind words everyone! The templates I used were the ones posted by Alan here:
http://www.thedentedhelmet.com/showthread.php?t=10497
Alan is THE MAN! I never would have been able to do this without all his hard work.
I didn't make any exact templates for the dome- I just kind of winged it. I put up a kind of abbreviated tutorial here:
http://www.instructables.com/id/EB96DTBQ13ES9J6YYX/
I'm making the visor out of some flexible clear plastic. I'm going to try and see if I can scrounge some window tint for it.
Jerome
After an attempt of two at winging the dome construction like you said in your tutorial i decided to use a littl of my math skills to figure out the precise measurment for the triangles...
basically, since I wanted 10 triangles per quadrant, I had to solve for the perimeter of the base, calculate each arc, then the vector points for each angle of the ellipse... After which I then had to repeat the process vertically... something i had never learned in any trig class.. =(
after a few checks and rechecks i found that it worked phenomenonally! Each triangle matched up to form a perfect dome... I made the template in AutoCad LT and printed them off by quadrant. Unfortunately I cannot figure how to make the template into a .pdf file...
basically, since I wanted 10 triangles per quadrant, I had to solve for the perimeter of the base, calculate each arc, then the vector points for each angle of the ellipse... After which I then had to repeat the process vertically... something i had never learned in any trig class.. =(
The helmet is more of an elipse....if it was a hemi the triangles would have the same vertex...I think that is why you break into quadrants.I thought the dome was more of a hemisphere than an ellipse. Anyway, I'm interested to hear where you get the measurements for the circumference and for the dome radius (assuming you can treat it like a hemisphere.)
You used 10 triangles per quadrant???? I haven't tried this method, but I've gotta believe the vertex angle per triangle must be really small. You probably have the exact number, but how were you able to cut the material as precise as it seems this measurement would call for?
Did you lay out the boundaries of each quadrant like Honus did in post #8? If so, then wouldn't you need to use right triangles for the area right next to the quadrant boundaries? It seems if you don't you'll have a gap there. I'd like to see how your helmet turned out.
Things to know before I get into this are: I used wizardofflight's
templates, the base of the the dome is an ellipse with a major axis of 9
inches and a minor axis of 8.5 inches, the max height is something around
3.75 and the template for the dome height is not exactly an ellipse.
To find the small variation in distance that is caused by the shape of
the dome height template I first had to recognize that the template is,
in fact, made up of two ellipses connected tangently.
I know that every triangle (since I want ten) will differ by only 9 degrees.
Well folks I have updated the helmet template thread to include the flat pattern for the dome. Here is the link;
http://www.thedentedhelmet.com/showthread.php?p=141431#post141431
The dome is not a true ellispe as stated above. So I created a 3D mesh of the dome and then flattened it out. It is divided in to 3 pages with a total of 20 panels. Have fun!!
Alan