atul

Hi All:

I finally managed to run the YS115 (that I picked up last week in Japan), today. Here are the results.

Prop: 16x8
Fuel: 30% Nitro with 20% oil (all synthetic: Klotz)

Starting was a breeze. There is no regulator to mess with so the engine is obviously a lot simpler to set up and run than the YS110 (which I also have).

I set the HSN to 2.25 turns just to keep it extremely rich and ran the engine at about 3000 RPM for about 10 mins. This was followed by a complete cool-down. Ran it again for two 10-min periods at about 3500 RPM. With the HSN set to 2 turns out, the engine runs *extremely* cool. In fact, at 3000 RPM the engine got downright cold on one of the runs and cut the Glo! Running it at 4000 RPM ensured it worked well.

After two full 400cc tanks, I decided to check the top-end while still keeping it rich. At about 1.8 turns out, the engine hit 9450 RPM at peak. I did not want to lean it in any further since it's brand new. I'm pretty sure it will hit 9600+ with a 16x8 once run in properly (15+ flights at least).

Transition: with a 16x8 prop, the transition between 3000 and 7000 RPM was very good indeed. After 8500 RPM, the move to 9400 takes slightly more time (probably because the engine is new). For most pattern flying, however, the transition should prove to be excellent. The new regulator seems to be set up so as to keep the whole run a little rich, which is probably a good thing.

I did notice that, like the YS110, the engine is extremely sensitive to the HSN setting. Going even slightly lean (1.7 turns, in this case), resulted in the engine heating up almost immediately. So the key seems to be to keep it on the richer side, as with the YS110.

Low-speed Setting: After about 3 full tanks and setting the HSN to 1.75+ turns, checked the Low-speed setting. The factory setting was definitely right. As with the YS110, there's an air-bleed screw which has to be turned counter-clockwise to lean the low-end. With the factory setting, the engine would get progressively rich if run just below 2000 RPM. After three 1/4 turns, the LSN was finally set properly. The engine now idles fairly reliably at 1900+ RPM and transitions well. The HSN setting does seem to affect the low-end somewhat, in the sense that if the HSN is too rich then the transition after a *long* idle can sometimes result in hesitation. But this could simply be because the engine is brand new.

Overall, the engine is excellent: very easy to set up (as long as one keeps it rich - any lean run will seriously mess up the piston-rings/piston: I know, since I've done it twice with a previous YS110!). Transition is excellent with a 16x8, and should be similar with a 15x10, though I plan to continue with the 16x8 for a while.

Flight testing this weekend with a Focus Sport. The 115 is already bolted in. Can't wait to get it in the air!

Atul Saini