A PA44 pilot in left traffic for Runway 14 at X59 hears a helicopter taking Runway 28 for departure and goes around. During the go around a NMAC occurs when the helicopter makes a quick downwind turn.

Narrative

I was doing traffic pattern practice in Valkaria Aerodrome (X59) for about 15-20 minutes in the Runway 14 (left traffic pattern) with winds calm. When already on the final approach leg; a helicopter using the callsign 'Helicopter ABC' lined up on Runway 28 and took off for some traffic pattern work (he never did any radio calls while taxiing or lining up. He just said 'helicopter ABC departing Runway 28'). As he did not wait for me to land and vacate the runway before his departure; we had to go around. For some reason the helicopter made an early turn to downwind compromising my safety and ended up in a near miss situation. We had to take an evasive action. He did not bother about the situation and completed his landing as if nobody else were in the pattern. After that we rejoined the left downwind for Runway 14. I asked for his callsign; but he refused to give it to me. Next thing he decided to do was some upper air work over the hangars at an altitude below 1;000 FT; so I decided to leave the area as the situation become uncomfortable for my safety.