Ok guys, finally got to that rx-1 test running with 1 (and 2) of the 4 cylinders down: Yamaha RX-1 Performance Test on 3 cylinders: Ok, so part of my decision to go yamaha was that (since it does not have dual ignition) it would perform adequately on 3 cylinders if one were lost to a bad coil, spark plug, carb blockage, stuck/burned valve, etc. So I put the theory to test out on the snow today by pulling a coil lead off a cylinder. Results were better than I expected, with an easily started motor, good idle, and an estimated 80 hp output. Details of test: (All speeds are off the snowmobiles "dreamometer", which are accurate in comparison to one another, but all read high by approx 8%). 2005 Yamaha RX-1, 30 deg F day (heat wave here in MN!) through 2" of loosely packed snow. Top speed 78 mph with the #2 cyl coil unplugged. That compared to a MUCH lighter 2012 Ski Doo 600 ACE (60 hp 4 stroke). Top speed 64 mph. For the 100 lb heavier RX1 to go 14 mph faster than the ski doo in loose snow would probably take between 15 to 25 more HP. (Note that a lighter 90 hp ski doo I ride occasionally would have gone about 85 mph in those conditions) So I am happy in those results. The engine sounded and ran surprisingly well! And 80 hp would be plenty to fully operate my kitfox 5 which was designed to use an 80hp rotax 912 as the normal powerplant. Conclusion IMO is that dual ign is great, and would be preferred.... but it does only cover ignition redundancy. I prefer the yamaha (with it's extra power reserve) which could carry the day very well with ANY failure of power output from a single cylinder.
Running on 2 cylinders test: Test results running on 2 cyls (#2 and #3 coils unplugged): I'm really surprised by this one, started right up, idled fine on the all cyl idle stop, ran 53 MPH down the trail!! That's gotta be 50 HP! I was guessing it would have done less, but that would keep me in a gentle drift down in the plane... giving 10 times the options and time for a emergency landing. Really happy to see it perform like that!
Yep, I just added you over on the Yamaha Aircraft Conversions group. I am an admin over there... I go by "Anatoli". Glad to have you there Ian! Teal reccomended you and told me about your areas of expertise. As far as a modeled engine I know of no one who has done that yet. Morten Wiik has modeled up an engine mount, but it would be great if someone were to scan the entire engine someday. Put up a post about that on Facebook and we'll see if we can get a taker!
Yeah misrigged tail wheel on my KF2 handed me two loops in my first day (only two I've ever done... saving my next for a big audience at a fly in somewhere LOL ). A more experienced pilot could have powered out of what I continued to try to salvage that day, but I was too green, and the instructor next to me was giving little help. Mech and I figured out the misrig (in my case the old maule wheel would hit caster click out with 3/4 left rudder application.. and not re-engage. Brakes were too soft... pilot too green... instructor not teaching the critical point (power up the tail!).... perfect setup for having my ass handed to me LOL! A quick rigging adjustment and I was off knocking out my endorsement. I was lucky not to bend anything that day! And I brought that learning to my tailwheel flying in the years to come, which I was better off with when flying more expensive planes in the future.
I am very sure there is at least a provision to ferry a plane in to a facility to get an overdue xpdr cert done. Guess I would go along those lines. Mark it inop and to be recertifiied as soon as practical.
As far as my research on the scimitar shape, I found that it runs smoother and quieter, cruises very slightly more efficiently, and has better trans-sonic properties if you were to get the tip speed above .89 mach. Downside is that it has a little less static pull. So I decided to go a little longer scimitar than I would have gone with a straight blade (to regain lost thrust) that will turn with higher tip speeds... but it should be able to handle that better.
Need a aerodynamics expert here, but I was thinking about putting some of these on the underside of the fuse... right across slightly fwd of where the lift strut attaches and the fuse makes the bend up to the tail. Speed mod, keeping airflow from separating as much around that bend. Nutty idea? I'm thinking it might be good for about 0.25 mph. LOL