Mailing List flyrotary@lancaironline.net Message #24304
From: Tracy Crook <lors01@msn.com>
Subject: Re: [FlyRotary] Re: Geardrive comments
Date: Wed, 22 Jun 2005 16:22:24 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Message

 
Sorry Tracy,
Someone suggested your 2.85 drive is different to your 2.17 - apart from the obvious and necessary changes to the planet set-up.
 
No offence taken George and I know you meant no harm.  It's just that I know from past experience that an off-hand remark about me having "changed the design of the 2.85" is enough to set off a deluge of calls from 2.85 drive buyers wanting to know if they have the latest version and what the changes were.  Don't know who suggested it but the basic design approach, materials, lubrication scheme, etc are the same on all the drives in current production (RD-1A/B/C).  As you said, there are the obvious differences between fixed planet and fixed ring gear types.
 
If you taking off at 6,200 ( that is low for a 2.85), what is your cruise?
 
I cruise at 5400 - 5600 RPM.  This is an economy cruise setting but that's what I use unless I'm running out of time, daylight, or weather.  I always choose a prop to target the maximum desired engine rpm at top speed and let everything else fall where it may. 
 
There are a number of oil separators used on motorbikes which are small and would suit this purpose.
 
I'm on the lookout!  I usually end up fabricating something that will fit the space & shape available.  I have several of the excellent RX-8 oil-air separators but they won't begin to fit.
 
George ( down under)
Believe nothing of what you hear and only have of what you see!
 
Unless you can verify it one way or another, Amen! 
Tracy
 
Where do these stories come from?  : )  There has been no change to the 2.85 (RD-1C) design.  My takeoff RPM is around 6200 rpm (limited by fixed pitch prop) and top speed rpm is 7450 so far. 
 
Top speed runs have been limited due to oil mist blowing out of the crankcase vent at anything above 7000 rpm.  Still working on an oil / air separator needed for air racing.  No time for making this and new prop cuffs so I'll miss the Ohio to Oshkosh race this year.  Look forward to doing it next year in the 20B powered RV-8 which is moving ahead (finally).  I noticed they are separating the formula RV classes by engine displacement   Bwahh Ha Ha Ha! ....  : )
 
Tracy
 
 
 
MY PSRU is not dissimilar to Tracy's in regard to using the 2.85 Ford E4OD Planetary. Just differently configured, but then again I'm led to believe that Tracy has changed the design for the 2.85. I personally prefer different bearings. I don't plan on going over 7,500.
Someone mentioned to me Tracy didn't exceed 7,200 on take-off, with the 2.85.
 
I hoping for 115 to 125hp at 7,500 rpm, I think that's achievable!
 
George ( down under)
 
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