Doing SAR, we routinely flashed our locations with signal mirrors by day and ACR/4F strobes at night, and the combination worked flawlessly. On one occasion, when my buddy and I stumbled onto a serious accident in the back country, we used a large bonfire to guide the helicopter in by night. At 174 lumens, your light ought to get the job done in style.

What really helps is bright colors and motion. Also, the pilot really wants to know the direction and velocity of wind on the ground at the LZ, so smoke of some sort is welcome. The standard practice is for the individual directing the helo to stand with back to the wind.