I love rotary engines, and would really like to see them become a more popular option, but in all the years I've hoped for this, it just doesn't seem to be making that much progress. The only thing that seems to be helping is the availability of redrives, and engine controllers from Tracy Crook. There is also a fellow that makes motor mounts for rotaries, which eliminates another major hurdle. Other products are coming, but not at a high rate of speed, and not in any mass quantities.
The area of rotaries that's been the most frustrating to me is the smaller engines that keep appearing for aircraft use. For some reason, as nice as some of these look on paper, they just never seem to pan out. There really are some nice engines out there, but they just don't seem to be making their way into aircraft in any measurable quantity. With the current Sport Pilot aircraft push, a 100 HP, two rotor engine has the potential to be a 912S killer.
At the moment, one of the best options for a 100 HP rotary is the single rotor based on Mazda parts. This would be a reasonable power/weight option for aircraft that used typical aircraft engines, since the rule of thumb has always been 2 lbs per HP. Unfortunately, if the single rotor is going to be useful as a 912S replacement, it's going to have to go on a diet. There are a number of ways you can save some weight, but what is desperately needed is aluminum end housings, since that would lop about 25 lbs off with one "simple" change. There are at least a few folks working on aluminum housings, but so far, none are ready for use.
Another problem is redrives. I've owned a few of Tracy's drives, and while they work great for the 2 and 3 rotor engines they were designed for, they just don't work well with a single rotor engine, and it's really heavy for this application. The single rotor just has some nasty torque reversals to deal with, and the drive will need a much better torque dampener. Neil's Autoflight drive looks promising, and I think they were going to test one on a single rotor engine, so keep your fingers crossed. Any report on that Neil?
I currently have a single rotor engine that has run, and was mounted on a Kolb Slingshot. I have sold the aircraft, and have decided that I'd like to used this engine on a Dominator. That's the plan anyway, but I have to clear this RV-8 out of my garage first
Cheers,
Rusty (the rotary engine wacko)