US1746344A - Light-weight girder - Google Patents

Description

Feb. 11, 1930. BURR 1,746,344

LIGHT WEIGHT GlRDER Filed Feb. 6, 1928 fn ven 2101' ua/wry 17422-2 Patented Feb. 11, 1930 UNITED STATES PATENT oFFlcE LUDWIG Dunn, or FRTETJBTCHSHAEEN, GERMANY, AssrGNoE 'ro LUETscrrrrrnnu zEPPELTN GESELLSCHAFT mr EESCHEANKTER HAETUNG,l or EETEDRICHSHAEEN,

BODENSEE, GERMANY LIGHT-WEIGHT GIRDER Application led February 6,' 1928, Serial No. 252,231, and in Germany February 15, 1927.

My invention relates to light weight girders or trusses and more especially to metal elements of this kind that are designed to be used in aircraft construction.

Generally these truss girders include channels or other structural elements serving as upper and lower chords which are connected by lattices forming the truss bracing or webs. It has become usual` in airship construction for example to arrange these lattices always in cross-Wise lrelation and in pairs. The crossed lattices are inserted in sequence between the members forming the truss chords and the distance from the end of one lattice cross to the beginning of the next lattice cross is less than the distance between the Shanks lof a lattice cross itself measured on the chords.

This means that the lattices are secured to the chords at irregular or un-even distances. Therefore when the truss is underload the chords will give way sidewise at those points where the above mentioned distances are greater.

According to this invention the disadvan-y tage mentioned is obviated by arranging the ends of the lattices at shorter distances which approximately equal each other, so that there are no more individual lattice crosses but every lattice of one side running in one direction crosses at least two of the lattices on the other side running in the other direction. Consequently, every lattice, besides having itsV ends fixed to the chords, is secured at least at two points along its length to the crossing lattices of the other side, by means of screws or rivets. Of course, in cases in which the distance between the chords is suflicient every lattice may cross and be riveted to three or more lattices of the other side running in the other direction. However, the principal feay ture is that the chords are held by the lattices at substantially regular and equal distances. This primary object of my invention may,

for example, also be attained by branching the ends of the lattices in such manner that the branches fastened to the chords hold them in regular or equal distances. But this manner of constructing the girders does not produce the same strength in the web between the chords as the first mentioned manner.

In Fig. l which illustrates one form ofv construction embodying the invention the lattices are riveted to the chords from one side, Whereas the lattices b1 are fastened to them from their other side. The distance d of the fastening points of the lattices on the chords are substantially equal to each other, so that .the channels or members forming the chords are held in regular or equal distances. The lattices b and b1 are connected to each other at their crossing points c.

In Fig. 2 the lattices b and b1 are soarranged as to cross each other at three places instead of two. Accordingly, each lattice is fastened to three other lattices. chords the distances d between the fastening On the points of the lattices again are substantially v In the-example representedlin Fig. 3 the s ame principle is applied, only the additional branches are not constructed as. individual parts but integral withthemain lattices b and b1. This construction is applicable with regard to trusses wherein relatively less lat-` tice strength or rigidity isl required and it has the advantage of saving some of the ri-veting work.

I do not want to be limited to the details described or shown in the drawings as many variations will occur to those skilled in the art.

What I claim is:

A light weight truss girder for aircraft comprising an upper chord, a lower chord, a series of substantially parallel lattices extending between said chords obliquely thereto, means for fastening such lattices to corresponding sides of the chords, a second series of parallel lattices obliquely arranged with respect to the chords transversely of the first series of lattices, the second series beingl fastened to the chords and to the rst series of lattices, relatively short struts having one endof each connected between the ends of a plurality of the lattices and having their other ends connected vto the chords, said struts extending transversely with respect to adjacent lattices and terminating at the location of their intersection therewith, and means for fastening the struts to the lattices. n

LUDWIG DURR.

Images