the prototype was converted to a single-engined aircraft powered by a 200 hp (149 kw) curtiss v-x-x engine, also in a pusher configuration, during 1917, being redesignated as the curtiss hs-1 (for h model with single engine). the prototype was re-engined for use as a testbed for the new liberty 12 engine, becoming the hs-1l, flying in this form on 21 october 1917.