The full-scale distance between each of the "station" lines showing distance between a chord line and the outer edge of the window glass (e.g., 1-7/16 in., 1-31/64 in., 1-17/32 in.) is 1 in. Measure any one of these 1-in. distances with your ruler and you get about 3/4 in.
You're right, but if I scale the drawing to match the 1 inch station lines, the thickness of the plexi will be larger than the 1/8 inch specified. Are we to assume that the thickness of the plexi shown in the drawing is not drawn to scale?
Ric,
Trying to tie up a loose end from the earlier discussion in this thread about the scale of the copy of the Lockheed drawing you have ....
I think I have figured out why your approach of measuring the thickness of the window on your copy of the drawing didn't work. Looking again at your photo "scaled curve.jpg" back in Reply #40 in this thread, the thickness of the window you measured on your copy of the drawing appears to be slightly less than 1/8 inch, by perhaps 1/64-th of an inch. Possibly the difference from 1/8 in. is smaller less than that.
The text of the 1996 TIGHAR report on the pieces of plexiglas (
http://tighar.org/Publications/TTracks/1996Vol_12/40552.pdf and
http://tighar.org/Publications/TTracks/12_1/PartNumber.html) says that Lockheed Drawing No. 40552 shows a change, dated 15 January 1937, of the thickness of the window glass from the previous 5/32 in. to 1/8 in.
Assume the drawing was drawn showing the window thickness as 5/32 in. I argued up-thread that your copy of the drawing is 3/4 the size of full-scale. This would make the thickness of the window as measured on the copy of the drawing
5/32 X 3/4 = 15/128 in.
This is slightly less than 1/8 = 4/32 = 8/64 = 16/128 in. and seems to approximately match what you measured for the window thickness on the copy of the drawing, as shown in your photo "scaled curve.jpg".
The thickness of the window should obviously be shown somewhere on Drawing No. 40552. Note in "scaled curve.jpg" that there are two arrows on the drawing immediately to the right of the word "glass" in the "shatter proof glass" label which are set up to show the thickness of the glass. If the writing to the immediate left of the upper arrow in this pair is the actual measurement, it is unreadable. However, note that there is a circled letter "A" immediately to the right of the word "shatter" and also a circled letter "D" below and to the right of the circled "A". These refer to notes A and D in the "changes" section of the title block of the drawing. These notes were apparently used to track the changes in the thickness of the window (and also changes in the window material) rather than changing the actual drawing each time to show the new window thickness. (At the very top center of "scaled curve.jpg", there is also visible what looks to be one half of a circle, probably another circled letter indicating another change note. My guess would be this is circled "C", which would correspond to change note "C", indicating the change from plate glass to shatterproof glass.)
In doing this little study of the drawing, I noticed a couple errors in your transcription of the dimensions on the drawing and some other possible errors:
(1) In the transcribed version of the changes section of the drawing, Note D reads "thickness 1/8 was 1/32". Based on the information in the text, Note D almost certainly should read "thickness 1/8 was 5/32".
(2) In the transcribed version, near the center of the drawing showing the curvature of the window, the overall height of the window is shown as "12-15/64 +0, -1/16". However, all distances between "stations" for the window are shown as 1 inch except the bottom-most one, which is shown in the transcribed version as "31/64". So either the fractional portion of the overall window height should be 31/64, or the bottom-most station measurement should be 51/64 -- can't tell which one is correct.
(3) (Possible errors in transcription) At the top of the window, the transcribed measurements for the chord line-to-outer window surface are shown as 1-9/64, 1-13/64, 1-23/64, and 1-29/64 inches for the first four window "stations". The corresponding differences between these measurements are 4/64, 10/64, and 6/64 inches. This doesn't seem to make sense for a smoothly curved window surface -- the 10/64 difference looks to be out of place, making the chord line-to-outer window surface transcribed measurements suspect..
Jeff P.