Three designs preceded the final Pander S.4 Postjager:
- S.1 four light engines in the wing leading edge, tractor propellers.
- S.2 four light engines in the wing, pusher propellers. 500kg payload.
- S.3 triple-engined high-wing aircraft with underwing engine gondolas
Source: ¨Pander - Een Haagse vliegtuigbouwer" by Harm J. Hazewinkel, All Media Productions, Hilversum, 2006
In his book, Harm Hazewinkel states the S.2 design was meant to have four 120hp De Havilland Gipsy engines. He supposes the same engines were to be used for the S.1. A model of the S.3 seems to have undergone windtunnel-tests. In various sources, the S.1 is said to be a six-engine twin-boom design. Hazewinkel disagrees, he claims the S.1 is confused with another design by T.E. Slot, the De Schelde S.26, which was to be a 50-passenger aircraft.
Tophe has made a reconstruction of the S.26. in "The end of 'Forked Ghosts' "
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