I came across a number of websites regarding home built aircraft. This include fixed winged aircrafts and helicopters. The engines used are comonly car subaru engine. What are specialty of this engine. Is it because the piston drive is punching to the side or is it more powerful than other engines? Does other engines with piston strokes upwards and downwards give a negative impact to the aircrafts when it fly? Any body kind enough to let me know please...?