flyrotary@lancaironline.net Mailing List Archive

Sounds like all around great news on the new gearbox and prop. Keep the reports coming.

If such a "retrofit" of a B shell to C internals is possible and economical then that could move the trend toward the 2.85 even quicker.

Shucks, if you used NA rotor housings it sounds like you wouldn't even need a muffler {:>).

I am somewhat surprised that you can get the same airspeed with only about a 5% difference in rpm - sounds like my initial assumption that a higher rpm (and fuel burn)would be required to get the same airspeed is not valid. Perhaps the much greater pitch gets more work done per revolution. I wonder if possibly the fact that at higher rpm you not only get the benefit of more power strokes per second, but at the higher rpm the airflow in your manifold (assuming you are using the same dia tubes as before) is at a higher velocity and therefore great inertia for stuffing even more air/fuel mixture into the combustion chamber when the port opens.

In any case, sounds like all pluses for us guys with nose gears {:>)

Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC

----- Original Message -----

From: Tracy Crook

To: Rotary motors in aircraft

Sent: Monday, March 22, 2004 11:02 AM

Subject: [FlyRotary] Re: C mounting on a B plate?? Renesis & RD-1C drivetesting

The -C drive has very different internals but I will look at the feasibility of reworking the -B housing to receive the -C guts. I think it can be done. Yes, the -C bolts right up to the same adapter plate. I think you are right about the 2.85 becoming the preferred ratio, but only if you can handle the longer prop.   You nose draggers have the advantage here.

The more I fly it the better I like this setup.   The higher rpm was very disconcerting at first but I acclimated rapidly.   And now that I have digested the fact that the actual rpm difference at normally used throttle settings is only about 5%, I absolutely love it. Another good sign is that the manifold pressure is now more than 5% lower at any given airspeed that I've tested so far. Even if the wear rate is up 5% or so it would be a non issue.

One more plus for the 2.85 is something I hesitate to mention. It's kind of like the "engine making oil so I have to drain some out" thing, kind of unbelievable.   It makes sense that there would be less prop noise but I'm also getting less engine noise.

I was getting tired of the increased noise with the Hushpower II muffler and was almost ready to put the Spintech back on even though it costs at least 5 - 6 mph in drag. But with the -C drive things have quieted down substantially. I think part of the credit for this goes to the difference in RPM moving the vibrations away from the resonance point of the sheet metal panels in my RV-4 but even observers on the ground have mentioned that the engine sounds quieter.

I better shut-up now, this is starting to sound too good to be true.

Tracy

----- Original Message -----

From: Ed Anderson

Sent: Monday, March 22, 2004 8:30 AM

To: Rotary motors in aircraft

Subject: [FlyRotary] C mounting on a B plate?? Renesis & RD-1C drivetesting

Sounds great thus far, Tracy

    Imagine having so much thrust that you can't hold the aircraft still for maximum static, must be tough {:>). If you initial observations hold regarding fuel consumption and performance, then I predict the 285 will soon become the standard. If the fuel burn/performance is a wash then only engine wear from higher rpm might be a factor, but since the rotary seems to only have no/ minimum wear in any case, that probably will not be a significant factor.

So how much are you given for 2.17:1 trade ins? Seriously, will the B model mounting plate accommodate the C model gear box housing (looks like you mount it the same way). I presume it would not be so simple as swapping out the internals as I am certain the internal mounting/housing is different in the two.   Third, in case you consider getting rid of that old performance prop, put me on top of your list.

Ed