M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)
Deleted by request of (c)Schiffer Publishing
H.King Sopwith Aircraft 1912-1920 (Putnam)
With his usual professional touch Harald Penrose thus summarised the salient facts: 'At Kingston, Tom Sopwith's great factotum, the dour determined Fred Sigrist, as a result of discussion with Hawker on the possible form of a replacement two-seater with enhanced performance and safer characteristics, modelled a new fuselage on the 807 [see 'Folder Seaplane'] using a bigger fin having a rounded nose of bent tube, and stiffened the main wing spars in order to employ a single bay with outward-raking struts, shortening the lower wing proportionately [N.B. The 'Sigrist Bus', unlike the 'definitive' 1 1/2 Strutter, had wings of unequal span]. To reduce bending moments of the upper wing he used steel centre-section struts steeply sloping from the top longeron to a point well out in the spar bay, and then braced the centre-line juncture of port and starboard spars within inverted V-struts arranged like a trestle, resulting in a widespread transverse W. The machine had been growing slowly in a corner of the old Kingston Skating Rink, for Sigrist was preoccupied with production matters, and it would be another month or more before the framework was ready for covering. Meanwhile it was jocularly referred to by the workmen as 'Sigrist's Bus’.