flyrotary@lancaironline.net Mailing List Archive

ED,

I think that the backfire resulted, as you stated, a lean condition. I had several MAP points where the mixture was very lean. When reducing throttle to reduce the boost, I suspect that I transitioned through one of those lean spots. I think that I have all of that correct now, but the next flight will tell that for sure.

As far as the stock turbo, I am approaching 50 hours with it, but I definitely view it as the weakest link. I’m planning on going with the same setup the Dave Leonard has, with the hybrid turbo setup. I really like the “bolt on” aspect of that option.

Steve

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Ed Anderson
Sent: Monday, December 11, 2006 10:57 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Great Flight

Great to hear about your flight, Steve.

You will discover that even a few degrees difference in OAT is reflected in coolant and oil temps. I can usually detect a change of 2-5F OAT just from my coolant temps.

A back fire underboost may reflect running a bit lean - no harm to NA engines, but as you know - could be unhealthy for boosted engines.

Sounds like things are going well, I believe you are the only stock turbo that has survived thus far. So sounds like your boost management is helping reliability, keep it up.

Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda/index.html

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

From: Steve Brooks

To: Rotary motors in aircraft

Sent: Monday, December 11, 2006 9:24 AM

Subject: [FlyRotary] Great Flight

Yesterday, the weather was outstanding. A little cool at 56 degrees, but sunny and no wind. It was very nice to drive only 15 minutes to the airport, to take the plane up for a flight around the area.

On the flight bringing it up to NC 2 weeks ago, I thought that the engine was running a little rich, and after trying option 9 to lean it up, it really didn’t change too much. Then, in a moment of sheer brilliance, I decided to lean it a little more using mode 3. Still didn’t change the mixture much, but I was happy with it, so I left it alone. When I throttled back upon arrival, the mixture bottomed out, and the engine stumbled pretty bad. After a quick rotation of the mixture control, and a couple clicks on option 9, it was running good again, until I throttled back a little more, and started the cycle all over again.

A couple of days later, I went to the airport and decided at this point, my best option was to return to factory default, and start over, which I did. After tuning it for 10 minutes or so, I figured it was good enough for a flight.

After preflight and taxi, my oil temperature was at 140 degrees, but my coolant was still laying on the 100 degree peg. That is quite different than normal. I waited for a few minutes until it started to move, just to make sure that it was working. When I took off, I pushed the throttle forward, and the engine roared to life. It really roared to life, because it was running at about 8 lbs of boost. I backed it down a little to 5 lbs, and it backfired once, but then ran smoothly. After climb out to about 2000 feet, the water and oil were only at 160 degrees, which was really a surprise. It was a little cooler than normal, but the temperatures were running about 20 degrees cooler.

I flew for about 20 minutes, surveying my new flying area, and just enjoying the view. I then decided to check out the tuning and started lowering the power. I found several points where the mixture was really lean, and I made adjustments (option 9 only) to get it where it needed to be. I think that it probably tuned better now, than it ever has been, so I’m not going to mess with it anymore.

Temperatures never did get above 160 degrees, which makes me wonder if I had an air bubble in the cooling system that worked out during, or after the long flight 2 weeks ago. Whatever it is, I like it. I slowed up to 100 kits approaching the downwind, and made a perfect approach and landing. After the decent and landing, temperatures were at about 140 degrees, and the engine was running very good.

It’s very nice to can add fuel and fly, but I think that before my next flight, I’ll pull the top cowling, and just give everything a once over, to make sure that everything is still good. I’ll also re-torque the prop.

Steve Brooks

Cozy MKIV N75CZ

Turbo Rotary – 48 hours and counting.