SF50 pilot reported an NMAC while on short final with a helicopter that was traveling in the opposite direction over the adjacent taxiway. SF50 pilot reported that it took approximately 8 seconds for the plane to climb due to flap and gear configuration and descended within 50 feet AGL before being able to climb.

Narrative

I was providing instruction during training in an SF50 Vision jet. We had been conducting closed pattern operations at ZZZ for the previous XX minutes or so. Each landing was to a full stop with a taxi back to runway XX for departure. CTAF radio calls were made by the flying pilot prior to taxiing onto the runway for departure; as well as during the crosswind; downwind; base and final legs of the traffic pattern. Conditions were clear with better than 10 miles visibility. While on short final; approximately 1;800 ft. from the threshold I detected a helicopter approaching nearly head on at the same altitude (50 ft. AGL) as we were. The helicopter appeared to be flying directly down the parallel taxiway in the opposite direction of landing traffic; at a high rate of speed; as well as climbing into our flight path. I called for control of the aircraft and I immediately banked to the left and initiated a go-around. Because we were fully configured with full flaps and gear down; as well as at Vref (our minimum approach speed); our aircraft continued to descend toward the ground. Approximately 8 seconds later we were within 50 ft. or so of contacting the ground (well left of the runway) before the aircraft developed enough power to begin climbing again.We had previously been in contact with multiple aircraft in the traffic pattern. At no time did I hear the helicopter announce their intentions on the CTAF. A subsequent call in the blind to the departing helicopter after the incident went unanswered.