The reason you don't see more of these engines, especially in speed applications, is that you lose a fair amount of power through the gear system. A standard configured engine can easily be cowled to produce very little drag without worrying about adequate cooling. The last time I read an article where one of these engines was present, the writer noted that the flyer had continous cooling problems. These inline type engines are also expensive and more complicated to produce. Too many negatives offset the positives.

But, they sure are neat!

John