Structurally, the largely wooden wings were based on pairs of box spars and spruce and plywood ribs, with duralumin sheet stiffening the leading edges.
It had a 95 hp (71 kW) American Cirrus III four-cylinder, upright inline engine in the nose with an aluminium firewall and tanks in the wing roots.
At the rear the B-4 had a tripod tailskid with a vertical rubber shock absorbing extension of the rudder post.
[1] It was one of the aircraft taking part in the non-competitive 1,200 mi (1,900 km) First All-California Tour, which ended at Los Angeles on 7 November.
This event was intended to advertise the Western Aircraft Show held at Los Angeles from 9–17 November,[3] where the Cirrus was on display.
[4] Its tests were complete by January 1930,[5] though it never reached certification, partly because of the departure of its designer, Charles Rocheville, from the firm.
[6] His replacement Gerard Vultee, ex-Lockheed, decided to re-engine the sole B-4 with a five-cylinder radial, the 165 hp (123 kW) Wright J-6-5 Whirlwind.
van Stone, who built another airframe with a 185 hp (138 kW) Curtiss Challenger six-cylinder radial.