Peter Garrison, contributing editor for "Flying" magazine, has said that "in my opinion ... the most promising engine for aviation use is the Mazda rotary." Mazda rotaries have worked well when converted for use in homebuilt aircraft. However, the real challenge in aviation is to produce FAA-certified alternatives to the standard reciprocating engines that power most small general aviation aircraft. Mistral Engines, based in Switzerland, developed purpose-built rotaries for factory and retrofit installations on certified production aircraft. The G-190 and G-230-TS rotary engines were already flying in the experimental market, and Mistral Engines hoped for FAA and JAA certification by 2011. , G-300 rotary engine development ceased, with the company citing cash flow problems.