Rysium: You may have to keep more air speed on take off and landing up so the rudder has more control. Or maybe set the rudder control faster. Capt,n

HEY GUYS!!! Look at this http://www.stukerjurgen.de/Englisch/Glow%20Control.htm it may keep our gas/glow engiens running even better! Capt,n

Am I reading it correctly? You are using 5 parts gas to one part glow that is 15% nitro and 18% lube? So that gives 2.5 % nitro and 3% lube in the tank, right? What kind of gas, premium? I am asking because the 15/18 ,no castor, is what I use any way.
Thanks

Yes. I use Wildcat glow fuel and Chevron 91oct gas. The reason I'm using so little methanol in the mix is that my ZAMA carb does not meter enough fuel to run the required mixture. And that forced me to keep glow plug powered all the time. 1:5 is the most I can run through that carb. I could run just gas-oil but I get abot 250 rpm less. And idle is not as smooth as with 1:5.

Poulan 42 using stock carb and a type F plug. Zinger 18x6 prop.
I tried 4 gas to 1 fuel. Using 15/18. Gives me a 4 to 1 and 3/3.6
Idle was a problem. All else seemed ok. Transition is unbelievably fast. Almost as fast as I can pull it open manualy. Top rpm, 6800.
Then I mixed 2 parts fuel,15/18, with 1 part methanol. Makes 10/11.88. Then mixed that 2/1. Gas/fuel. Makes 2/1 at 3.3/3.96
Idle was noticably better. But then I discovered that the low mixture screw needed to be a lot richer to be able to get low rpm control. Otherwise it went fron idle to midrange with nothing in between. I think if I had played with the mixture more with the other concoction I may have been able to get the idle better.
I tried unsuccessfully to get a good 2 stroke idle. Idles low and reliably (1800) with a 4 stroke idle. But it shakes the test stand more just as it would a plane. And I think it sounds like some detonation at the lower/midrange rpms. And in transition. Full throttle is too noisy to tell.
Top rpms....... First batch was 6800 with a Zinger 18x6.
Second batch, well I can't remember for sure but I think it was 8600. She was screaming. Flying buddy 3 blocks away heard it and came to check it out.
So at this point if I could get a nice 2 stroke, or close to it, idle and get rid of the detonation, if that is what I am hearing, then all would be good.

captinjohn


Could you explain? Do you have a finger exercise or what?

As for the CoroCub, the problem was in toe-in. I got great explanation what's going on. We fixed it and there is no more a problem. More info in CoroCub thread.

As for the Poulan 25 - the engine is running great. We measured now 7000 rpm on the ground. Looks like the ring is settling in. More compression too. I started it by hand just starting opposite way. This time it worked . I tried to see how low it will get and at 1700 rpm Zinger prop started going backward. I guess this wooden prop is to light. I will repeat this test again with my MA Classic.

Now there is a weird thing. On the ground the engine runs 7000 rpm - it is screaming. When the plane is flying the full throttle it sounds more like 6000 rpm (I need to measure it recording the sound). I see there are two possible reasons.

1. The mixture is getting lean why flying, but weird thing is, that engine sounds OK, just has lower rpm.
2. When airplane is moving the prop starts to work more efficient and loads the engine more (takes better "bites" of the moving air), while on the ground it "slips" through the air not loading the engine as much (it is like clogged vacuum cleaner - it screams but does not push the air)

Mike.....what do you mean "finger exercise" it has been my experience is the faster the air moves past rudder, the better the airplane will go strait on take-off. Capt,n

captinjohn sent you a PM Mike

Rysium: If the mixture is going lean in air...it seems like a lean mixture would give it more RPM. Maybe the mixture is going rich...because of pressure on diaphram. You could run a line from carb diaphram plate to inside of fuse. Just a off the wall Idea. Capt,n

I have been following the "other thread" about E85. So tonight I tried a few things. First of all I tried some different glow plugs using the same fuel mix as yesterday's second batch. I couldn't tell any difference between an F or 8. Then an idle bar plug. No idea what it is. But it didn't do near as good at idle. Top end seemed about the same. Then a KB-1L,ducted fan plug. Better than the idle bar but not as good as the F at idle. Still had what sounded like detonation with all of them.
Then I mixed up a batch of 1 part 15/18 fuel to 3 and 1/2 parts E85.Gives 3.3% nitro and 4% lube. Too much lube maybe. First thing I noticed was it starts easier. Or maybe it was just my luck tonight. But I started it several times. Tuning is a litle more fussy on the low end but not a whole lot. Top end is about the same near as I could tell. At a faster low idle I could open the low needle beyond adjustment of engine speed (no change in sound) and it still ran. And also if I set the top end just a hair above the richest setting that didn't blubber it would get hot and not want to idle down all the way immediately upon throttle closing.
In the end when I decided that I had achieved the best tune it would run good thru all stages. Just a little rich at the low and mid ranges. Speeds. Same as 2/1 gas/alcohol mixture. 1800 reliable idle, 20 minutes, and 86 to 8700 top end. Maybe a little better on the top end. But tuning changes it quickly.
Starting it? If I flipped it very fast thru the stroke then I could start it in the normal rotation. If I was a little lazy then it would start and run backwards most times.
Tuning? I had to turn the needles a lot, compared to using gas, to get a repsonse. So next time I will try the trick of raising the needle arm a little to get the carb to run a little more rich.
So far I like what I see. Just wish I could get a little more of a 2 stroke idle out of it. Would help smooth out the idle a lot.
Forgot to mention. It seems like the detonation noise is gone with the E85 mixture.

Eagle Flyer: Very complete report. Did you notice the viabration levels with all fuels you used. How much vibration do you get with the engine you are testing? P.S. Is the poulan 42 the engine are still testing? Thanks Capt,n

Like captin said very good and complete report. I had the detonation problem with my ST40 on gas/glow. It does not have any detonation noise on E85 even with 15% nitro. I changed and started mixing some glow fuel in with my E85 mainly because I have cases of it and want to use it up. I could fly about 15 to 18 minutes on a tank of glow fuel before running out before and now with E85 mix I can fly 20 minutes and still have fuel in the tank. I am guessing about 5 minutes more left in the tank. Haven't dead sticked it yet so I don't have an exact number before empty. When I first started mixing E85 and adding nitro and oil I didn't think I would be getting much cost savings. After seeing that my fuel lasts longer I may get the savings I was looking for.

No, I have setup the mixture on the max - 100rpm (about 1/16th turn). If I lean it the engine's rpm goes down.

What does your engine RPM do when you richen it? Capt,n[:-]

The vibration is from the four cycling at low idle and just off of it. A total 2 cycle run would obviously be smoother. I can get it to run at an idle almost fully 2 cycle but then it is too lean to control. I am wondering if a carb designed for larger engines would flow fuel better and help out. If it isn't to big in the venturi for the engine cc size. I have a couple laying around I am going to check out.
maybe the 4 cycling idle wouldn't shake the plane to bad. It is presently on a test stand. And yes it is still the 42 I am working on.

Same thing - rpm drop but the sound is kind of different. When I lean the engine rpm just drops without changing the sound. When I richen up the engine starts inserting 4-cycle strokes. Rpm of course drops, but the engine does not run as smooth as if it is to lean. What I heared in the air was more like a "lean sound".

The carb is mounted that way, that the regulator hole is facing backwards (the firewall). I wonder what kind of effect the moving air might gave on the preasure measured in there. Look at the picture below.

On the good note my muffler is holding up. This time I used welding rods I bought at Harbor Freight Tools. First I cleanded the muffler well with dremel (sanding drum) and brake pads cleaner. Then I wrapped the muffler in glass cloth to prevent from heat to escape and mounted in vise I used standart butane torch. I was able to heat it to the rod's melting point. Working with the rod for a couple minutes I achieved wery good spread and looks like a solid bond. So far I had 5 flights and the muffler is holding up (on the picture the pipe on the right side).

Hey gents, tell me where I can get me a glow adapter for a homelite 25 and about how much $ are they please?
After I get my engine going, I would like to try it without a coil/magnito to loose the weight . And when I install the adapter, will I be able to just stick my glow driver on the plug and fire it off as usual?
Thank you,
John

You can get a velocity stack from Horizon real cheap. You may want to try one to see what that does. Meantime take vent cover off carb and solder a short piece of brass tube or use a pressure tap so you cau run a piece of fuel line into fuselage. That may cure it!!! Capt,n P.S. the velocity stack keeps fuel from spitting back out and improves fuel economy. Sometimes a bit more RPM

Thanks capt'n - now I have full hand of options. Doesn't hurt to give it a try.

As for the glow adapter you can get from Horizon

http://www.horizonhobby.com/Products...rodID=ZEN23445

Of course, most of us made our own "home-gown" made of gutted spark plug - but that requires some tools and a bit of skils

Yup...that is where ( Horizon) I got my glow plug adapter. Also a good place to get many other small items. Good luck with your 42cc engine and cub. Best Regards Capt,n

I beleive these are the same as Horizon. Check out their site, they have always been #1 in all dealings with
me. They have gladly taken the 'extra step' to make things happen promptl and correct.

http://www.ch-ignitions.com/#cat
75. Spark plug, Adapter, 14mm to 1/4x32 .................................................. ............................... $9.95

Good service and nice site.

These are the better ones, I have both.
The CH-ignition's have enough room for your glow stick to fit on.
Horizon's don't.

RysiuM: Forgot to say...that is a strong looking weld you done on muffler. Maybe I will get some aluminum sticks from Harbor F. Capt,n

I'm to cheap to do that While my son was answering the door and children were screaming on the street I run my late and in not long time I made my own piece. I used derlin (lighter and cheaper than aluminium) as I did not have such big aluminium rod laying around. On the picture below you can see it already mounted on the plane. On the second picture you can see a a vent cover that is facing the firewall. I will modify this if velocity stack doesn't help.