Don,

If you're familiar with the Tsunami, pictured is one I did at exact scale down to 40 inches at 25 ounces. It was intended for the Norvel .06 but came in heavier than intended. With a just broken in Norvel .074 on 25% fuel, it will do (sloppy) knife edge loops. It flys exactly like the .40 size but looks faster due to its smaller size.

I didn't mean to disparage the original designers. It's just that I've seen too many 1/2A downsized versions of bigger aircraft that were that only in name and general look. I have found that ANY aircraft will fly about the same no matter what size even when scaled exactly the same. No need at all to re-design to make allowances for the smaller size. The key is to maintain a lower wing loading, the smaller you get.

There was only ONE, 1/2A engine that ran like the bigger ones. That was the VA .049 MK2 and the key was having a means to adjust the idle mixture. I was involved in getting the engine maker to offer a throttle with that feature. The CS engine in the video was a Brodak offering and didn't come with the adjustable airbleed. The engine would quickly load up at idle and sputter and often die when the throttle was advanced. The simple addition of an adjustable airbleed allowed all day idle at 5K with instant acceleration. Stuffing the running bits of an early, Norvel AAN engine took this one from 12K to 19K as shown.

The Norvel .06 suffered the same problems with idle and acceleration. Making the idle mixture adjustable allowed throttling performance exactly like any .40 or .60

But you are correct in offering designs for the OS .10. There's not much else out there and this is one engine that, despite having no means to adjust the mixture at idle, it throttles virtually perfectly.