1
$\begingroup$

I'm trying to decrypt a US aircraft manufacturer's plan. Could W.L. (waterline) and Sta. (station) references use different units?

For example, I have different distances from W.L. 0 to W.L. 200 and from fuselage Sta.3000 to Sta.3200. Are these references always in inches?

|improve this question|||||
$\endgroup$
  • $\begingroup$ If I had to guess, I would say that imperial units aren't used, and what you are looking at is millimeters. If the fuselage started at Station 0 and ended at Station 3200 and was in inches, that would mean the fuselage was 266 feet long. An A380 is only 239' long. $\endgroup$ – Ron Beyer Sep 15 '16 at 14:07
  • $\begingroup$ Thanks for your response. It is a plane longer than the A380 indeed, never build , Boeing 2707-200. Found it was supposed to be 318' long. On the plan i'm working on , the nose starts at Sta.200 and fuselage ends at Sta.4016. It can't be millimeters. $\endgroup$ – galgot Sep 15 '16 at 15:27
  • $\begingroup$ Edit : 4016 - 200 = 3816 and that is 318' , so Stations are in inches for sure... But I don't understand that smaller W.L units. $\endgroup$ – galgot Sep 15 '16 at 15:34
  • $\begingroup$ What is the distance that you measure for the water line? $\endgroup$ – Ron Beyer Sep 15 '16 at 15:36
  • $\begingroup$ OK… I think I understand why. That line noted W.L. is not the true WaterLine on the Plan, it’s used to mark the angle with another angled line noted « Ground line for minimum ventral clearance… » starting at the base of the main LG. Just for angle reference with the clearance line. Should have noticed that , the same W.L line is legended as « W.L. (ref) » on another sheet . So the true W.L. is lower, but not traced on the plan. Thanks for your help anyway :) And sorry for the inconvenience. $\endgroup$ – galgot Sep 15 '16 at 17:19
2
$\begingroup$

Coordinates should always be in the same units. For a US manufacturer, that will be inches. The SI units are generally millimeters. This makes it much easier to locate coordinates, and for calculating things like volumes or distances.

|improve this answer|||||
$\endgroup$
  • $\begingroup$ Imperial units of millimetres? $\endgroup$ – Nij Sep 18 '16 at 19:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.