Date: 03 Nov 97 02:18:53 From: "Richard L. Grubb" <firstname.lastname@example.org> Organization: 3-7DSL References: 1
View raw article or MIME structure
JAK1959 wrote: > > Could someone please inform me as to where the reference point > is that body stations are measured from on commercial aircraft? > Is it the forward pressure bulkhead? Is it the mounting > structure for the weather radar? Please let me know. > > Also, are there any publications that have aircraft diagrams > that would include both body stations and stringers? > > And a final question. How does Airbus designate the body > stations? Please let me know. I have been told by a coworker who had this same discussion at another aerospace company, that once, a long long time ago (in a place far far away), Body Station 0.0 was placed at the tip of the nose and waterline 0 may have been placed at the point of contact between the main gear and ground. But when the first 'stretch' or derivative was designed, 'they' vowed never to do that again. Today (i.e. in my experience over the last 23 years), the origin is placed far enough in front of and below the airplane so as to never require the use of negative values for any reasonable stretched derivative. Of course, Butt Line 0 is placed on the centerline of symmetry. I have also been told that McD planes had waterline 100 placed at a prominent 'horizontal' feature and some other vertical feature such as a bulkhead would be given an arbitrary value such as BS 112.0. In this explanation, I have been using nomenclature for Boeing fuselages. Other components such as wings and tails or even control surfaces have their own reference systems. I believe Wing Stations are perpendicular to the rear spar. All of these coordinate systems are tied together on an airplane centerline drawing. All drawings are company proprietary data, but you may be able to write to the public relations department and request the information for particular models. On a side note, the loads engineers require that an 'all numeric' coordinate system be used in their calculations. Why would a coordinate system never be 'all numeric' you might ask? Well remember those derivative models with stretched fuselages? The fuselages are generally stretched by adding body plugs just in front of the wing and/or just behind the wing. For instance, on the 737 family of airplanes, forward plugs are placed between BS 500 and BS 520. The designers do not want to relabel all of the frame drawings aft of the plug, so the first frame aft of BS 500 is given the 'coordinate' 500A, and so on to BS 500I for the 737-800. This system is impractical to use in engineering numerical analysis. The loads group therefore define a coordinate system (referred to by the terms balance arm or panel station) that has the same numerical value for various derivative models at some point in the center section of the body. A point near the tip of the 737-800 nose then is at BS 130.0 or balance arm -68.0 -- Richard Grubb BCAG, 737NG Stress, Wichita email@example.com #include "std_disclaimers.h"