IF the VGs are generating a vortex and are placed the right distance apart, closely spaced spinning vortex of air mass may act as an extension of a cowl flap area by preventing/hindering the higher pressure/velocity external flow from equalizing the pressure as soon.

Just an opinion (and that is about all it is)  about why a set of VG MIGHT give some benefit.

Ed

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

From: Tracy Crook

To: Rotary motors in aircraft

Sent: Sunday, September 20, 2009 6:03 AM

Subject: [FlyRotary] Re: Another mixed day / Cooling experiments

 

"It IS seeping from the filter seal and NOT the two hose connections...no doubt on this. "

Just from observing many rotary installation 'de-bugings' over the years (including my own) I noticed that difficult to solve problems are almost always caused by false assumptions.

It is possible to get several bad filters or two bad filter mounts but the mathematical  odds are staggeringly small.  You haven't offered your test proofs as to why you know they are bad and leaking but if I were betting, I'd put my money on something else.  The assumptions about the wiring might need examination as well.

This reminds me of an oil leak the Ed Anderson had.  The oil was showing up on the back side of one of his rads.  There was an oil line running very close (< 1" as I recall) to the rad so the assumption was made that the oil line was leaking.  Long story short, the oil leak was actually coming from something at the opposite end of the engine.  What exactly was it Ed?  It defied all logic in that it was not even close to where it showed up and the oil was traveling against the assumed airflow under the cowl.  

Speaking of assumed airflow, my cooling experiments are blowing away all my own assumptions.   I kluged up the cowl flap I mentioned and fixed it in the open position.  The trailing edge of outlet is about 1 1/2 " below  where it was.  The temperatures were down a little but not near what I wanted.  Only a little better than the big giant opening I tried.  At this point I was ready to conclude that the underside of the airplane was bad place to put a cooling outlet.  Keep in mind that my working assumption is that the pressure under the cowl is too high to allow good airflow through radiator and oil cooler.  I had installed a pressure probe under the cowl but forgot to look at the reading.   Figuring I might as well know how big a problem I had, I made another flight to check the under cowl pressure.  Duhh,  almost nothing!  Checked the probe to make sure it was not blocked, pinched, etc, and everything looked OK.   I need to check pressure in a few other spots to be sure about this.  There is something odd going on with airflow under the cowl but I'm back ti head scratching mode again.

One builder on the RV list said he got a big improvement in cooling by installing VGs on the trailing edge of the cooling outlet.  This is so non-intuitive that I can't imagine why it would work but its so easy to try I might have to do it while scratching my head.

Tracy
.

On Sun, Sep 20, 2009 at 1:37 AM, Chris Barber <cbarber@bellairepolice.com> wrote:

Made it out to the hangar for most the day and decided to take the advice here and modify my start up routine based on what was suggested here and in the manual.  So, I cranked the mixture full rich with no priming and it started up in a few blades.  Ran for a while, shut down and started back up with mixture in about the 2:00 oclock position....and it started fine.  Kewl.

 

The first bad news is that I replaced my romote oil filter mount and installed a new filter.  As I have mentioned here I have had it leaking at the rubber filter seal.  The old one looked ok, but since replacing the filters no less than three times and knowing that the eye cannot see all inperfections, I replaced the mount AND filter (K&N 2004 filter).  But, NO JOY. It is still leaking where the filter mounts.  It IS seeping from the filter seal and NOT the two hose connections...no doubt on this.  I know the rotary's oil pressure is higher than other engines but I would not think it would be so much that it is overwhelming this standard mount and seal.  This is just a standard screw on remote oil mount made out of AL...Made in the USA.  Looks like many others I have seen.  Y'all have any ideas. 

 

Second good thing is a guy from a few hangars down turns out to be a welder by trade.  He came down as I was working on the new stainless turbo exhaust manifold the other day after offering to help me modify my manifold..  As was mentioned here before, the old cast iron manifold I had wold work if mounted upside down.  It puts the turbo lower (the oil return being about 2 inches higher than the oil inlet return in the pan) to the rear of the engine and it clears my aileron control link.  I will have to make a very small modification to the lower cowl to give me proper clearance EXCEPT the wastegate interfeared with the Mistral intake fuel rail.  So, I ordered a stainless copy of the cast iron one I had, based on John Slades suggestion.  My welder friend said it would not be too big a job to turn the wastgate extension around which should allow it to miss the fuel rail completly.  We looked at the options and he took the manifold with him saying he would cut off the old wastgate extention and come back to fit the new part on in a few days. Kewl.

 

The second bad news is that I was doing some continued tuning.  I even transferred A to B as B was a bit rough from the factory and it worked fine.  HOWEVER, later in the day, after feeling pretty good about the lasted progress (excepting the continued leak) the engine stopped. Huh?  It will not restart.  I checke the first fuel filter and it is clear.  I decided to start at the beginning and just run the EC2's diagnostice test.  Damn, no chattering of the injectors (even though I was able to hear an individual click when I primed it).  Put on a test plug and wire and got no spark.  All the other electrics are working fine.

 

I pulled my extra EC2 out and installed it and I got injector clattering away and spark on three of the inectors.  The secondary on Rotor one did not seem to fire.  Hmmmmm?  I put on an extra injector that I had and tried again, and it didn't fire...then fired for a few seconds and then stopped. Looks like I have some more wire issues.  Damn, I though I had really gotten past most of those.

 

I am really confused about the EC2 seeming to just shut down.  The other electrical componants are all working, but the EC2 componants are not.  Strange since I thought each items (injectors and coils) had there own power source thus should not shut down as a "team" like this.  Yes, it is the same on A and B.  Currently I am very discouraged so I stopped for the night and decided to crawl into bed with a hot blond and sulk (she was actually gracious enough to hang out in the hangar with me for a few hours...whata gal)....well, she helps me from sulking too much.....this dating in my 40's ain't all that bad <g>

 

I anxiously wait commentary and possible explanations from y'all.  Upon my return to the hangar (today was MY Sunday) hopefully tomorrow night after work I will be looking at my, apparntly piss poor, wiring.

 

As always my friends, Thanks.

 

All the best,

 

Chris Barber

Houston

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