flyrotary@lancaironline.net Mailing List Archive

I know what you mean about the range on the mixture control Mike. With just about any setup, full clockwise on it will give you a too-rich miss. I have considered reducing the range on it but wanted to make it possible for a builder to rapidly dial in a usable mixture no matter how badly the map table or injector flow rate was set up. It also gives a clue as to when these other things are set up OK. When they are right, the engine will miss at both ends of the mixture knob setting, too lean on the bottom and too rich at the top. My best power mixture is reached with the mixture knob set around 2:00. Lean cruise is around 10:00. Full CW will make it miss every time.

BTW, this characteristic gets even worse when bigger injectors are used. That's one reason I discourage their use. I'm getting ready to try a reduced mixture range on my 20B. It has the stock big turbo (550 cc) injectors and makes the mixture setting touchier than I would like.

Tracy

On Sun, Jan 3, 2010 at 9:38 PM, Mike Wills <rv-4mike@cox.net> wrote:

My comment wasn’t intended to be a criticism - as I said I considered it an operator error. This comes down as a matter of learning the operating characteristics of my installation. Obviously with a system as tunable as the EC coupled with so many variations in engine configurations, each is going to be different.

I'm sure there is more tuning/tweaking that I could do to optimize operation across the full power band. But right now things are working pretty well and I'm content to fly it as is and learn the idiosyncrasies. The fine tuning can come later.

As for full rich during takeoff/landing, in its current tune my engine will misfire (too rich) if set to full rich during the descent. I've found in my test flying to date that there are quite a number of power/throttle settings where the mixture knob has too much dynamic range - i.e. at some power/throttle settings going either full rich or full lean on the knob will cause misfire. Again, not a criticism, just a matter of learning proper operation of my particular installation.

I havent had to execute a go-around as of yet, but in all of my testing to date, sudden application of full power from a low power setting hasn’t caused any problems yet. Time will tell...

Mike

From: Tracy Crook

Sent: Saturday, January 02, 2010 12:18 PM

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: first flight of the new year

I can't really know what the whole story is on Mike's engine characteristics (a lot of it depends on how the EC2 is set up, tuned and operated) but keep in mind that the EC2/3 is an open loop system with none of the benefits of feedback from the O2 sensor. It was never intended to be a FADEC type single lever power control that many expect.

It was assumed from the start that airplane builders would be familiar with mixture control requirements of aircraft engines so would not mind similar requirements when running EFI in an experimental.   In a typical GA aircraft, it is normal to set the mixture to rich (best power) on takeoff and climb-out, then lean the mixture in cruise for better fuel economy. It can be leaned even more at lower power settings (ie in descent) to eek out the last MPG and I do that myself out of habit.   But when it is time to land, it is altogether normal (and necessary) to set the mixture back to rich when entering the pattern. If not, you can fully expect the engine to sputter a bit if the throttle is advanced for a go around.

Tracy Crook

On Sat, Jan 2, 2010 at 2:01 PM, Bill Bradburry <bbradburry@bellsouth.net> wrote:

Maybe so, but it seems no farther than it is in the car and that has to work quicker than it does in our app. Cars don’t go all squirrely when you coast down a long hill??? We all need broad band sensors so we can tell what is really going on. I am hoping that Ed will get upset by all this and build one we can buy from him for about a buck!   :>)

When can we expect the prototype, Ed??

Bill B

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mike Wills
Sent: Saturday, January 02, 2010 12:16 PM

To: Rotary motors in aircraft
Subject: [FlyRotary] Re: first flight of the new year

My exhaust header is an equal length type with 28" inch primaries into a 2 -> 1 merge collector. The O2 sensor is threaded into the collector so I estimate it is about 36" from the exhaust port. It usually takes about a minute for the readings to settle down after a cold start, but I've always assumed that they were accurate - even at idle. Maybe that is an incorrect assumption.

Mike

From: Bill Bradburry

Sent: Saturday, January 02, 2010 6:48 AM

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: first flight of the new year

Happy New Year everybody!

Mike,

How far from the exhaust ports is your O2 sensor located? Does anyone know what the minimum temp is for the O2 sensor? 800 degrees?

Bill B

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Saturday, January 02, 2010 8:31 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: first flight of the new year

Happy New Year to you, Mike

Wow. I’ll bet you are glad to be in a different year and glad the old one gone.

I noted your comment on the lean/rich possible O2 cause. Do you have a heated (3-4 wire) O2 sensor or an unheated one??

Ed

Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews, NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.rotaryaviation.com/Rotorhead%20Truth.htm

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mike Wills
Sent: Friday, January 01, 2010 9:43 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] first flight of the new year

Hope the holidays are treating you all well. Things are kind of slow on the list this week. So figured I'd get things going.

I havent flown for almost 2 months. First my nephew's accident (he's recovering amazingly well). Then travel for work. Then had to do an annual on the airplane. Finally, had surgery to remove my appendix and gall bladder. Been a busy couple of months.

But I'm feeling pretty good now, the airplane is ready for its first flight after the annual, and today was a spectacular day here with clear blue sky, unlimited visibility, light breeze, and temps in the mid 60s. I resolved a number of minor issues during the annual, including the gas smell that I've been living with for a while now. Found my left tank vent line was loose where it penetrates the bottom of the fuselage so was venting into the cockpit. The smell is now completely gone.

Also found a solution to a problem I've been noticing since I've started flying further from the airport. I'd noted on previous flights when returning to the airport with a long low power descent that the engine runs quite lean as I enter the pattern requiring the mixture knob to be turned full rich. On a couple of occasions I've had some misfiring as I turn final - quite an attention getter! Today I realized the problem was a non-problem, in other words operator error. While descending (and for that matter, frequently at other times) I tweak the mixture based on the mixture monitor reading. Today I ignored the monitor and just left the mixture alone which worked just fine. I think during prolonged low power descents the O2 sensor cools off and provides an inaccurate reading. The occasional misfire was the result of running too rich (the mixture monitor indicated mid range readings).

So todays flight was trouble free and gets me an hour closer to the end of phase 1. 18 hours down, 22 to go.

Mike Wills

RV-4 N144MW

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