SonexBuilders.net

Another engine curiosity question.

I know two-strokes are considered passé nowadays, but has anyone used, considered using, or know anyone who uses one of the Hirth flat-fours? To my inexperienced eyes, they look like a good option: about the same power and price as an AeroVee Turbo, but about fifty pounds lighter, including cooling fans and reduction drive. They're also available with factory EFI for a modest upcharge.

Are they just not widely used because of a general distaste for two-strokes, or is there another reason?

MisterKrinkle,

There have been no installations of a Hirth in a Sonex that I'm aware of. You're not going to find much practical information on this board. You may need to seek out users of that Hirth model to get their input.

Having said all that, sticking with an approved installation is the fastest way to get flying, but perhaps not the most interesting. If you do go down the custom installation route, don't underestimate the amount of time and effort it will require. If can be very rewarding, but it'll take time to be the first.

Jeff

Fifty pounds lighter could be a problem. Have you run basic CG numbers with that?