350iS
Thoughts on this combo, pro's and cons, in a RV-12. What does it do to the dry weight, and how much is left for #'s with a full tank of fuel for payload?
Durability?
Prop selection?
maintenance costs saved due to lack of a gearbox like on a 912 ULS?
Performance?
Fuel consumption?
Affinity for 100LL vs Mogas?
Maintenance expenses?
I have the UL350iS and am quite happy with it. There are a few builders who have the 260 and can provide their input, however, my advice is to go with the 350. It has more torque (236) and horsepower (130), but is essentially the same engine as the 260 with the only difference being a longer stroke. I weighed my engine with the oil in it and the wet weight hanging on the mount is 159.2 pounds, and then there is another 13 pounds for the fuel filters and pumps, dual ignition packs and ECU. The coil packs are best mounted on the firewall, the ECU is mounted in the instrument bay and the fuel pumps and filters are mounted below the baggage compartment with a header tank for a short, high volume suction line and longer high pressure line to the engine. You do need to run a return fuel line (incidentally, this is the same general design the 12iS now has).
The drawings say the 912 is 160 pounds, so they’re almost the same, however the engine CG is farther aft (no gearbox out front) which provides pushing the engine mount forward a couple inches which gives some extra room to reach in behind the engine if needed.
I have the WhirlWind GA-UL350-2B propeller, which works very well.
My airplane weighs 785 pounds, but that’s with a full IFR avionics, GTN625, dual G3X package, wing fuel tanks, heated seats, and many other modifications - it’s definitely E-AB. But I can load two people, full fuel and 100 pounds of baggage and climb out at Vy 1200 (GW)/ 1400 (solo) fpm, and cruise climb 800 (GW)/ 900 (solo) fpm @90KIAS at that weight. I economy cruise 120KTAS at 7500’. If you’re inclined, you can go faster.
I burn 91 unleaded, which is preferred over leaded fuel. You can burn 100LL, but that reduces oil changes to 50 hours down from 100 and you need to use mineral based oil instead of synthetic.
I’ve not had a Rotax, so I can’t speak to any savings in maintenance. For the UL engine, the maintenance is pretty simple and mostly consists of annual inspection, oil and filter changes. It has an EFII that provides instant starts and very smooth operation. As for durability, it has been reliable for me; I fly it almost every day as my work commuter and have over 200 flights since I started flying it last August, and it’s started every time.
The hardest part was getting the firewall forward put together, as in cowl, mount and oil cooler setup. But there’s lots of lesson’s learned available within our group of UL builders; so it’s fairly straight forward now. I’m pretty happy with the engine. It’s dirt simple to operate and maintain. The startup procedure is essentially, turn on the ignition, press the starter, wait for oil temp to get above 105º (which is there about the time i get to the runway), check both ignition packs (Right, left, back to both) and go fly.
If you’re serious about it, you should contact Ray Laurence at Kaolin Aviation and he’ll help you out.