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Date: Sun, 21 Nov 2004 10:51:04 -0600
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: how do you carry, and measure oil?
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What I'm trying to say is that testing for the wrong things or testing 
under the wrong conditions can lead to conclusions that have no meaning 
or importance to the issue at hand. The point of my question is this: if 
everyone flying a rotary is finding unburned premix oil in his crankcase 
oil, is this oil really burning? Is it likely that some percentage of 
the oil is burning away completely with no residue & the rest is 
completely unaffected by the heat & is swept into the crankcase? 
Assuming that is what's happening, then what part of PL's oil from 
skillet test was unaffected by the burning & where did it go? IIRC, PL 
heated the various oils to somewhere around 500-600 degrees for his 
test. How was this temperature selected for the test? Is that the 
surface temperature of the rotor housing & rotor? Is that the combustion 
temperature? (Obviously not.) If combustion temperature is, say, 1800 
degrees, why wasn't the test done at that temperature? Would the residue 
be the same if the oil was cooked to that temperature? Would the residue 
be the same if the skillet was sealed & raised to combustion pressure 
before cooking?

I wouldn't pretend to have the answers, but after 15 years of trying to 
absorb everything I can about homebuilding aircraft I can say that if we 
ask the wrong questions we aren't likely to get the right answers.

If a problem exists for which there is no solution, it makes sense to 
methodically search for a workable solution. But if a solution has been 
empirically proven to work, as is the case with Tracy's use of MMO for 
hundreds of hours, does a 'test' attempting to show that it doesn't work 
make any sense at all?

It's my understanding that Dave Atkins is still using crankcase oil 
injection in his RV-6. Street rotaries carbon up, but they are operated 
at average power levels of 15-30 hp and most get driven in city traffic 
with long idling at traffic lights, etc. Piston engines driven in these 
conditions carbon up also. Piston engines driven almost exclusively on 
the highway (still low power levels but little idling & stop-&-go 
operation) rarely have 'carbon' problems. Do rotaries driven on the 
highway have carbon problems? Anybody out there that's got 150k miles on 
a stock, highway-use-only RX-7?

I'm not pushing MMO; I've never even opened a can & poured it in an 
engine (or gas tank). I am in favor of methodically searching for 
answers & understanding that "Better is the enemy of good enough," as a 
writer for a prominent computer magazine frequently points out.

Charlie

Bulent Aliev wrote:

>Something was gumming up the seals in the car engines? The racers started
>mixing the 2 cycle oil and had no problems.
>
>On 11/20/04 11:28 PM, "Charlie England" <ceengland@bellsouth.net> wrote:
>
>  
>
>>Is burning oil in a skillet relevant when seemingly unaffected 2 stroke
>>oil ends up in the crankcase? Might it be that the oil isn't burning at all?
>>    
>>