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Greetings,

Below are the notes from = today's=20 adventure. As you'll read, there are certainly some=20 vibration issues.

A question for Richard- = Have you run=20 your single rotor with a realistic sized prop, or just with the drive=20 itself? Have you added any flywheel weight? =

Rusty

Spent quite a=20 bit of time running the engine today, and tying some various = tests. The good news is that the = fluids all=20 stay inside the engine where they belong, so no more leaks. The bad news is that there = are=20 certainly some vibration issues.

Running the=20 engine without the prop does not show any significant vibration, = except for=20 the expected roughness at low rpms, below about 1800 or so.

Running the=20 engine with the 3 blade Warp=20 Drive prop, gives a few different = vibrations. The best bet for =93idle=94 = is about 2200=20 rpm right now. Reducing = rpm below=20 that point hits a pretty severe =93rattle=94 at about 2000 rpm. This = is the same=20 as the rattle I got with the redrive on the 13B, but it was around = 1100 rpm on=20 that engine. Reducing = below that=20 will get out of the severe rattle, but into the expected single rotor=20 roughness. It=92s = possible to idle=20 around 900 rpm, but you wouldn=92t want to.

If you start=20 at 2200 rpm, and slowly increase the throttle, all is well until about = 2500=20 rpm, then a high frequency vibration starts. The vibration increases in = frequency,=20 and amplitude as the rpm increases, right up to 3100 rpm. At 3100, as you increase = throttle,=20 initially nothing happens, but then the engine will suddenly jump to = 3300-3400=20 rpm, and be smooth. = It=92s just=20 like someone flipped a switch to get rid of the vibration. This vibration is pretty = severe, and=20 you can see things like the air filter shaking until they=92re just a = blur.

The=20 3^rd problem is an odd =93beat frequency=94 sort of = vibration that=20 happens at all rpms. If = you stand=20 directly in line with the prop arc, you can see the prop tips = oscillating=20 forward and back about every second or so. I only watched this at idle, = but other=20 observers said that it gets much worse at higher rpms, and I can = certainly=20 feel it. I don=92t = really have a=20 clue what this is, unless it=92s some sort of interaction between the = 2.85=20 drive, and the ratio of eshaft to rotor rpm. 3 blade prop??? Gotta think about this some. =