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Flight Report - 5th Flight

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Today I made my fifth flight with Cozy N75CZ. Today was also my longest flight to date with .7 hours. I have a Mazda Turbo charged rotary engine, and I’ve had some high temperature issues that I’ve been working on. I mad excellent progress, and today’s flight with the OAT at only 71 degrees was much better. My coolant was running a steady 190 degrees, but the oil temperature was still a little high at 217-220. I think though that I may have not had the temperature probe into the oil stream, and may have been measuring the temperature of the metal housing, instead of oil temperature directly. I re-tapped the 1/8 NPT hole running the tap all the way down, and the probe is now about 3/16” further down. I ran a ground test, and the oil was tracking below the coolant, but I’ll have to fly it again to be sure that it made a difference.


Upon landing my oil was 175 and the coolant was down to 160. That lower RPM glide certainly cools things down.


If my oil temperature still runs high, I think that I will make a curved deflector, and glass it in to the shroud to divert more airflow to the oil cooler. If that doesn’t do the trick, or raises the coolant, I will add a front end to my air scoop, which would attach to the landing gear cover. I’ll taper it outward to increase height and width to increase the air pressure in the intake. I’ll attach this scoop with six screws into nutplates in the gear cover, so that I can remove it during cooler weather. I think that if I do need it at all, it will only be during the summer months.


The only squawk on this flight was with the front landing gear. I had to hit the override on the auto extension unit (AEX) to get it to retract, and then it kept extending the gear again, even though I was flying more than fast enough at 120 knots. I continued flying, but had to keep hitting the override about every 20 seconds to keep it retracted. I found that it was also pretty easy to tell when I hadn’t hit the button, because the nose pitches down some when the gear comes down.


Once on the ground, I found that the tube running from pitot air to the AEX unit had come off. I put it back on, but if I pulled on it very hard at all, it just came off again. The hose passes through a hole in the plastic case and slides onto a nipple inside the box. I finally decided to put a little RTV on the hose where it passed through the plastic case to hold it in place. It was either that, or remove the AEX so I could open it up and see if I could clamp it somehow. Given the short length of pitot hose, and the location of the AEX, I decided that would be a major issue requiring removal of the canard and I/P cover.


The good news is that the plane flies great, and the rotary engine is running extremely well. The power is smooth, instant, and plentiful. I worked on making some turns, especially since I’d been flying around the pattern on previous flights, I decided that some right turns would be nice. It was also very smooth at 9:00 AM this morning, so I could trim the plane for hands off flying. That really makes a big difference.


At this point, I would like to see my oil temperature a little lower, but all-in-all, I couldn’t be happier with the plane, or the engine. Both are perfuming well beyond my expectations. My take off and landings have also greatly improved as I get a better feel for the aircraft.


Attched is a photo that a freind (and ground crew) took today on takeoff.


2.2 hours TT 37.8 to go.



Steve Brooks


Turbo Rotary


Steve Brooks


Mazda 13BT

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