Mailing List flyrotary@lancaironline.net Message #6666
From: Perry Mick <pjmick@mail.viclink.com>
Subject: Re: [FlyRotary] Re: C mounting on a B plate?? Renesis & RD-1Cdrivetesting
Date: Mon, 22 Mar 2004 08:42:59 -0800
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Tracy,

I agree. I just built a composite prop for Cosman, 3 blade, 88" pitch, 72" in diameter. I carried the pitch twist all the way to the hub, which is 10" in diameter. The hub became very thick.


Tracy Crook wrote:

OK, OK, rub it in, but before you guys get carried away, consider the following:

The prop limitation was always my only reservation about using the higher ratio.  I must emphasize that in order for this to work, the prop must not only be long but has to have a good profile as far down toward the root as possible with the MUCH higher pitch.  I worked with Clark at Perf. Props and emphasized this.  It required a thicker than standard hub to get close to what was needed.

If you don't do these things, all you get is significantly higher rpm,  less performance, higher fuel burn and higher wear.  Look at the numbers from previous users of the 2.85 drive.  

Did I mention the three spinners, various spinner bulkheads, prop bolts that were now too short and other various things that went wrong  during the effort to make this work right?

Tracy

Finn Lassen wrote:

> Tracy Crook wrote:
>
>> 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.
>
>
> Sounds like Paul Lamar was right all along...
>
> I simply couldn't resist throwing that in here :)
>
> Finn
> (cleaning out my inbox to make room for responses)
>
>
That's what I thought too, but didn't have the guts to say it here.

It may not help us pusher guys though, we can't handle large diameter
props, possible prop strike on rotation.

--
Perry Mick
http://www.ductedfan.com




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