FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1928
1928 - 1113.PDF
NOVEMBER 29, 1928 97 THE AIRCRAFT ENGINEER SUPPLEMENT TOFLIGHT tapping machine (Fig. 18). The threads have to be kept strictly to B.E.S.A. tolerances, and it has been found that these cannot be maintained with machine tapping. Base Struts.—These occur at each end of the frame longi- tudinals, in the base of the triangle, and also form the third side of the triangle of which the other two sides are formed by the main radial struts. In other words, the base struts form the common base of the frame longitudinal triangle and the radial struts triangle. They can be seen in the photo- graph of the assembly jig for frame longitudinals (Fig. 26). and in more detail in Fig. 19, which shows one of the struts with fork ends loosely in place, in the jig, and finished with shear bushes in place. The method adopted in producing these struts is to finish the fork ends and then hold the tube with the fork ends in a special jig, drilling and reaming for shear bushes in this jig. Duralumin Girder Webs.—These are used extensively in the girders of the transverse frames, i.e., inner and outer ridge girders and radial struts, of which they form the webs while the flanges are formed by bulbous booms in either steel or Duralumin according to location in the framework. The the jig and one taper pin put through each fork end. The girder is then removed from the jig, and the final taper pinning done on the bench. It is, of course, finally inspected with the jig set to the required length. Double Radial Struts.—The pyramid ends for these struts are prepared before the general assembly in order that the tubes for each jig should butt joint in the various end sockets. To enable this to be done in the easiest manner, special adjustable end gauges are used, and the length of each tube is determined b3' these. The purpose of the jig used for this operation (Fig. 24), is to control the size and angles of the pyramid. The final assembly of the double radial struts is carried out with a jig (Fig. 25) arranged to reproduce the geometrical conditions that have to be satisfied. The required angle is obtained by means of the clinometer bar and clinometer shown in Fig. 25. As in the case of other jigs, the sliding head is dowelled for each length, and the setting positions are determined from standard end bars. The Longitudinals.—The final erection of the frame and main longitudinals is carried out between jig plates mounted Fig. 27. General view of main longitudinal in jig. Other longitudinals ready for trueing. webs are produced by pressing from Duralumin strip, the first operation being to punch the lightening holes. The press tool used for this operation is shown in Fig. 20. The punched strip is then treated in the salt bath, and the strip passes on to the next press in which the lightening holes and sides are flanged-up. The tool is shown in Fig. 21. Assembling The finishing of what may be termed " small parts " having been completed, the assembly into girder units begins. Ridge Girders.—These consist of Duralumin flanged webs and bulbous booms. The webs and booms are cut to exact length and are then assembled and put in a jig (Fig. 22) which has standard plug ends to suit the triangular form of the girder. The drilling and partial riveting is done in this jig, and the girders are then removed and final riveting completed on the bench by pneumatic hammers. The girders are then passed on to the ridge girder fork-end- ing jig (Fig. 23), which carries fork ends arranged at the correct triangular spacing. One end frame is fixed, and the other is adjustable, but is dowelled in place for each length of ridge girder required. The longitudinal spacings are obtained by the use of standard end rods. The fork ends are assembfed in the girder, and the assembly is first placed in on steel benches. The fittings on the end of the jig plates are set out to the standard triangular section of the longi- tudinals, and the distances between these plates are deter- mined by rod end measurements. The inclination of the end plates to the vertical is determined by careful plumb line measurements. The booms forming the longitudinals are cut to length, and have the fork ends inserted in jigs specially made for this purpose. The method adopted in all cases for drilling these longitudinals was that of finishing the fork ends, then holding the fork ends and booms in correct position in the jigs, and drilling through the fork end and tube while in the jig. The whole of the longitudinals are cambered, and the cambers are set in the final assembly jigs by tensioning the bracing wires and taking measurements from the bench at different points. A frame longitudinal is seen in its assembly jig in Fig. 26, and a main longitudinal in Fig. 27. Special Main Longitudinals.—Between frames 12 and 13 the longitudinal system of the airship changes from 15 to 16 sides. The problem of constructing this particular set of longitudinals from frame 12 to frame 13 naturally became somewhat complicated. The method adopted was to use the frame longitudinals for each ring set in their relative 1020o
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
