A very good day
 2006.06.02
 


Wednesday. This is not just another day. This is a big day. The day I have been working toward for a year. Numerous unfinished versions of this note were started, but stalled without the verdict on oil cooling. Now we have it.

The 0-290 first flight and breakin and the self imposed restricted period have been very deliberate, to say the least. A couple of notes to come on that. There were a few fairly unique engine elements that bore watching, and I watched. The last year has included many pattern flights as the components were evaluated, often one by one. Sometimes I exerted ferocious discipline to change only one thing and then go fly and see what happened. Nice excuse to escort the sunset. The airport critics developed a whole nother verse of how much work those gol derned Ezs take.

The operational expansion process has been fascinating to me, but tedious for those watching. When they come around, I sometimes mention that the airframe was not an issue, nor the CHTs, but only the oil cooling. And anyway the stories that they make up are better than my trying to explain what some particular little gizmo spoiler had done on the last flight.

The oil cooling elements have seen numerous iterations in an attempt to get cooling at full power, with only the minimum and optimum air introduced.

Yesterday it did it. It helps that the plane has flown six days in a row, three times. Did I say that right? Over 18 flights in the last 30 days and still counting. The tedium aside, I love it.

Yesterday I had finally remembered to attach some twine to the right canard tip so I could again enjoy the very tame canard tip vortex. Per the normal drill, I knew that I would have time to take off and get to 2500 feet over the airport and run for a few minutes before backing off for the oil temp. I was watching for traffic and enjoying the pristine twine vortex and noticed after a third scan pattern inside that the oil temp was stable at 210. Several images of retesting the gauge passed through my mind. It took three oil temp gauges from AC Spruce to get an accurate one. This one was right on. A good secondary indication was the oil pressure.

Wow. Suddenly the canard tip vortex was not nearly as alluring as the gauge needle. I hadn’t known that so much pleasure could be derived from watching a needle not move. I had made another iteration in the ducting the night before but with the hot day I didn’t expect any improvement. The thrill of the flight was to open her up a little more and with the added speed, watch the oil temp lower from 210 to 202. Miraculous. Even after landing and putting the plane away I don’t think my feet touched the ground but every third step.

Thursday. I sit here tonight again, radiating from the day’s runs. Two runs. The first was in the heat of the day to confirm yesterday’s numbers. The miracle held and it was a good run and after landing and refueling I started to taxi back to the hangar. But the sky was purpling up with the gold glow just getting going good, and it was cool, and it would serve a technical purpose to watch the temps on a takeoff when the engine was still hot. Any reason will work. The rose-hued takeoff was spectacular, with a couple of friendly comments from the taxiway gallery.
Airborne again, I could heartily feel the difference of tons of jettisoned temperature distractions that had been bogging down the previous flights. For the whole 0.8 there was some kind of control problem, just couldn’t keep her straight and level. 205, another wingover. 202, another wingover. 195, another wingover. 190, another wingover.

Inbound at dusk the plane was zipping along as smooth and sweet as anytime I remember. I think it’s Hertzler’s prop. Anyway, I called entering for an overhead break. A taxiing KingAir announced they would be taking the runway, so I extended a little to let them get going. They stopped at the hold short line and a different deeper voice announced that the KingAir would be holding to watch the Eze land.
Gave them a pretty good one.

Details
More to come, but basically there is now a little smile of an inlet in the lower cowl about 14 inches wide x ¾ inch where the mustang scoop would normally be. It puts air on the oil pan and creates a rearward flow along the inside of the lower cowl that also draws air through the oil cooler, which, after three other locations, is again mounted a couple of inches aft of the spar with a 1.5x5 inch male scoop under it. This scoop in the mustang location will be minimalized a couple of times before finalizing it and making it look socially acceptable, as well as the oil cooler scoop.

The difference now is that there is enough proper air draw for the air coming in the oil cooler to get out of the back of the cowl. Should have done that first!

Specifically, exit air ramps a la Cory Bird’s yellow plane are used on the lower cowl aft of the lower plenums. Picture in March 06 SPORT AVIATION in the cooling article. The excellent article also points out details on the NACA inlet.

A few days ago the test flight included a reworked outer lip on the right NACA inlet into the plenum. By improving the inside surface and thickening the lip more like described in the article, the two CHTs on that side lowered about 20 degrees. Details, details. Wish I was like you guys and got all this right the first time. There is still more to be tried from that article. I have read it about ten times and am still chewing.

Looking back
When Avery initially talked about sending some stories in, I declined, since I wasn’t flying at the time. A little later somehow he found out that I had flown the 0-290 and said it was time for me to start sending in notes. Since there were a couple of fairly unique 0-290 engine installation details to peruse, the development and test flights were very deliberate. Not being entirely confident of what I had wrought, I confirmed their operation while kinda reluctantly sending some of my favorite non-0290 notes to Avery and you guys. I feel better now. Today I am an expert on oil cooling, Tomorrow? Well, we’ll see.

Little by little, the elements were validated. One irresistible, distracting, counterproductive practice that I couldn’t get away from was with any glitch, to immediately suspect my new component as a culprit.

Early on, in fact, an erratic rough engine was caused by a leaking intake valve where the oil sucked in fouled the plugs. That intake valve problem was isolated with the help of our senior A&P and it was taken for repair. A month or so later, the engine was running erratic and rough again. After much head scratching and watching his mastery of troubleshooting, the same A&P helped determine that it looked like they fixed the wrong (exhaust) valve out of habit rather than the intake. I removed it and took it back and they disputed that they did the wrong valve, but graciously offered to do the intake for no charge.

Not long after, it was erratic again. After holding a gun to all of my components again, we confirmed it wasn’t oil fouled plugs, but isolated a cool cylinder and took the aircraft spark plug to the A&P and he tested it in his pressure contraption and reported was firing but had an orange spark instead of blue, which was defective. Less than 30 hours on it.

That sequence was fairly tedious, but interesting, and from my position looking back right now, very rewarding.

Many of the flights were perplexing. On a couple of nights I had the challenge of trying to go to sleep after observing airflows in oil in the cowl that were the opposite of what I had expected. I have mentioned in the past that I don’t think that the prop always pulls air out of the cowl… I hate when that happens. If you look at the March SPORT AVIATION article close enough, you will notice him say something similar, referring to an aft facing outlet I think.

The flush of today’s success has spurred several notes. Some on the technical details may be interesting. One set of gizmos that were very useful were four little spoilers that were made by cutting a 4 inch long, two-inch aluminum pipe lengthwise into four curved strips. They were temporarily riveted in a few places as spoilers and did in fact generate some additional exit airflow, which I observed as reduced temps on that side. Am working on some pictures.

Have a very good day y’all
Bill James, Fort Worth VariEze

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