sentences:  The tail unit comprised a cantilever tailplane with a single fin and rudder.The prototype aircraft was powered by two Pobjoy R radial engines; the production aircraft however were fitted with the Pobjoy Niagara III radial engines.The engines in the Scion were mounted with thrust-lines below the chord-line of the wings; in the Scion II they were raised so that the thrust-lines were aligned with the chord-line, to avoid trim changes in pitch with changes in power.