CRRC Pro GF26I

[ericb]

	Quote: Originally Posted by GreyEagle
	Guy's I've a fairly new CRRC 26 I ordered up from Jody this spring and have got around 8 great flights on it and really very satisfied. Lil sucker is an animal. My question : I think I may have a flake y ignition module. For a bit it would intermittently cut out on the starting bench and a few time we even got a belch and a brief run backwards. What we do notice : that we will see the optical kill switch flicker on and off a bit during the attack of the demon's. We have the module nested deep in soft foam - theirs no strain on the inductive pick up, or high tension lead, the shield cap is on tight and no strain on the current lead going into the module. The problem kinda cure's itself if you lightly press on the plastic module box. Are these known to have cold solder joints inside the module, or a few defective ignition's??? Kinda spooky / not sure to either buy a new ignition, or another motor because of the cost value of the ignition box. ANy Other Experiences on the Phenomenon ??? Fun lil motor

What opto kill do you have on it?

[Crashis Clay]

better yet, Hitec Programmable digitals do that and more!

[GreyEagle]

Sorry for the delay - I'm not sure whom's Optical is on it - I t came with the motor as a promotion when I purchased from the distributor. Seem's like the ignition has calmed down

But now it has a unusually behavoir that "any time" I;m up side down, a loop / roll / hard corner - It act's as though it want's to stutter and almost die. Basic two line tank - vent and supply. Good clunk line. Motor is mounted inverted and exposed to open air. Tank is higher than the carb center line.

Soon as you level out it comes right back on. I can cause this at will, on command ! It's like your alway's gona have a dead stick. We can not duplicate it on the ground what so ever.

It's either a fuel flow issue or a ignition box issue.

[Jedijody]

It's probably an air flow issue effecting the metering diaphragm in the carburetor. In some applications, certain flight attitudes can cause air pressure to hit the small hole in the metering side cover on the carb. Solder a nipple over the hole and run a fuel line either into the fuse or drill an under size hole in the velocity stack and force the hose into the hole. This will help give the carb a stable reference pressure that won't change no matter how the air flows over the engine and carb.

[GreyEagle]

Sincere thanx Jody : I'll make it up tomorrow and try it as it sure won't hurt anything

Little confused about routing it into small port hole drilled into the plastic intake ventury. I would think it's an area of low pressure or vacuum - but it sure would make thinks tidy.

Thanx again ! I'll report back - promise ::

PS: I'm hearing drum beats of a little twin ??? around 50cc ?? Could be Yummy

[Jedijody]

On this side of the throttle valve there is neither pressure nor vacuum, it is merely a constant air flow. This constant air flow is what helps prevent the pressures, positive or negative, from effecting the metering diaphragm. The carburetor requires a reference atmospheric pressure, the more stable that reference, the more stable the metering of fuel will be. The atmospheric pressure on your hand sticking out the window while driving down the freeway is the same as it would be if you were sitting on a park bench.

[3Dguy]

CRRC with beam mounts?!

[Jedijody]

GF26I V-2

http://www.crrcpro.com/product_show.asp?id=229

[3Dguy]

Any significant differences from the other version?

[Jedijody]

From the cylinder gasket up is all the same, everything below that is different. It's not new, it's been out for over a year.

[ec121]

I have one of the rail mount 26s. Seems to be a fine motor. The mounts are rigid. After I ran it an hour on my test stand, it leaned out to 8400 on a cheapo Zinger 16x8 breakin prop. Starts great. I made an extension arm for the throttle to have more resolution. I'm not thrilled about the spring loaded,latching choke mechanism, but there is always a work-around for these things. As Paladin said "Have Dremel, will travel." This is a test. How many of you are old enough to know who Paladin was?

[Jedijody]

It was one of the corniest shows ever made.

[edwal07]

	Quote: Originally Posted by Jedijody
	On this side of the throttle valve there is neither pressure nor vacuum, it is merely a constant air flow. This constant air flow is what helps prevent the pressures, positive or negative, from effecting the metering diaphragm. The carburetor requires a reference atmospheric pressure, the more stable that reference, the more stable the metering of fuel will be. The atmospheric pressure on your hand sticking out the window while driving down the freeway is the same as it would be if you were sitting on a park bench.

Hi Jody,
I agree with your statement in parts, however it is misleading. The sentences about air flow and the hand out the window is somewhat true, but you just left out the air pressure (velocity) of the wind on one side and the low pressure area (vacuum) on the other side of your hand. Atmospheric pressure is the same but many variables are involved. Also without pressure or vacuum you cannot have air flow. In your attchments you show the line in the velocity stack, however you just opened up a can of worms, you just created a venturi effect (otherwise known as Bernoulli's principle) over the tube. As air flow passes over the tube it creates a low pressure area in the tube, the air flow changes as engine speed either increases or decreases causing a change in the vacuum produced. This is the primary principle of how the carb works on the other side of the throttle plate pulling fuel out of the jets or in a 2 stroke in the needle valve. The velocity stack also changes the air flow as it causes the air to stablize in flow and to increase in speed , as its name implies. The same happens on the diaphram cover of the carb when air passes over the plate with the hole, if it is pointed toward the front you have positive air pressure, if it is pointed toward the rear or sides it will have a vacuum effect. These changes are minute but will affect the pressure in the diaphram housing you are talking about. In your setup you are creating a vacuum in the tube and air side of the diaphram no matter how minute and is far from stable. The setup you spoke about with the line running into the fuse is the best of all evils.
Personally unless you are out to achieve a perfect tune (which would be nearly impossible as atmospheric pressure, temperture, and humidity change constantly) the small minute changes would be negligible in normal flying. Unless you are a prefectionist, only an occasional retune is called for 98% of the time, unless drastic weather contidions exist. This does not take into account break-in adjustment.
Until we have computer controlled fuel injection along with all the atmospheric sensors, differential pressure sensors and mass air flow sensors we will have to hand tune our engines.

[GreyEagle]

Promised you that I 'd report back .

Made up the nipple / installed in the metering diaphragm cover per spec, and ran the remote atmospheric tubing into the fuse.

First flight started off good : Then Just Like Tossing a Switch - on the " 1st roll" coming back - it started - and just kept it up every corner loop ect. Even pulled the power -out back to 1/2 and gently just cruised. Thinking the carb needed time to recover. Just keep's getting worse. Then it becomes a " How big a chaona's you have " Better land - before it's a dead poney.

Repeated the same event , 5 X's as a demo for other's - " Hey watch this " . We can't duplicate it on the ground - even with one of us - holding it in different positions on the ground. Run's like a champ !

It's definitely got some thing to do when in a corner or a G - load. It's got to be a cold solder joint or loose wire going into the CDI or a fault or hairline open in the board.

We took the liberty to open and peak in the box and it appears to be partially potted with resin. I can see the leads going into the board under the partial resin. I 'm Leary to lift the board out - wish I could just peek at the connections as it would just a heart beat to inspect.

Dang thing is just past warranty - Just over a gallon on it.

Update: 10/2/10 to past question on who's optical isolation - It's a RCxel that cmae with it

[3Dguy]

	Quote: Originally Posted by GreyEagle
	Sorry for the delay - I'm not sure whom's Optical is on it - I t came with the motor as a promotion when I purchased from the distributor. Seem's like the ignition has calmed down But now it has a unusually behavoir that "any time" I;m up side down, a loop / roll / hard corner - It act's as though it want's to stutter and almost die. Basic two line tank - vent and supply. Good clunk line. Motor is mounted inverted and exposed to open air. Tank is higher than the carb center line. Soon as you level out it comes right back on. I can cause this at will, on command ! It's like your alway's gona have a dead stick. We can not duplicate it on the ground what so ever. It's either a fuel flow issue or a ignition box issue.

Might be a faulty carb. My CRRC had one that wouldn't tune right, and would continually dead-stick in the air.