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HelicopterMain Discussion › Why don't more people use uniflow?
12-02-2005 05:30 PM  12 years agoPost 21
Nitrohuffer

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Bloomingburg,NY

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In reference to exhuast pressure, I guess that is exactly why I did not notice a change. The one with the uniflow is has a ksj pipe that is 50% bigger than the one without the uniflow that it running a smaller TT pipe.

Lungs transformed to take in water.

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12-02-2005 05:56 PM  12 years agoPost 22
Al Magaloff

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I go UniFlo on everything. I don't need to, but UniFlo is good science. You'll never see me in here asking why my Hyper does this, or why my heli slows/speeds up inverted, or why my heli changes tune as the tank empties, etc,etc.

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12-02-2005 06:07 PM  12 years agoPost 23
Gary Jenkins

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Nowhere, US

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I tried it and my heli engine still changes tune as the tank empties.

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12-02-2005 09:06 PM  12 years agoPost 24
Wisdom-Seeker

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Danville, CA

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The thing I don't understand about Uniflow is why, when the engine stops, that the muffler doesn't fill with raw fuel? The tank is pressurized, and there's nowhere for the fuel to go but back up the pressure line to the muffler. If anyone knows differently, can they please explain why this does not happen?

--

Wisdom-Seeker
Protest letter to insurance co.: What do you mean "Act of God"?

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12-02-2005 09:50 PM  12 years agoPost 25
Gearhead

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Vt

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"why it works" in short, as CY said (in his link) the uniflow system produces LESS pressure, so you have a more even pressure level from full tank to low tank, unlike a standard setup that has more pressure with a full tank and less pressure at a lower fuel level,,, most likely one will have to open his needles with the uniflow system...


Wisdom-Seeker,,, ""when the engine stops, that the muffler doesn't fill with raw fuel?"" (as above) because there is so much less pressure in the tank..

Jim

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12-02-2005 10:35 PM  12 years agoPost 26
Louisiana Helicam

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West Monroe, LA

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I haven't personally felt a power difference between the two setups. I understand what Curtis is saying and I've tried it both ways just to be sure but the only difference that I've noticed is better consistency with my particular setup. I'd recommend anyone to try it both ways to determine what works better for their particular setup.

www.louisianahelicam.com

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12-02-2005 11:50 PM  12 years agoPost 27
Al Magaloff

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There is no power difference. UniFlo is just a more quality control of tank pressure/ mixture settings. If you run Uniflo and still have issues ( Gary) you don't have the mechanical set-up to optimum. 50% throttle opening at 0* pitch. Wisdom, if the perssure line is too short, it will.

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12-03-2005 12:33 AM  12 years agoPost 28
Jeff H

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Cincinnati, OH

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"why it works" in short, as CY said (in his link) the uniflow system produces LESS pressure, so you have a more even pressure level from full tank to low tank, unlike a standard setup that has more pressure with a full tank and less pressure at a lower fuel level,,, most likely one will have to open his needles with the uniflow system...


Wisdom-Seeker,,, ""when the engine stops, that the muffler doesn't fill with raw fuel?"" (as above) because there is so much less pressure in the tank..
Yet again Jim you astound all of us with your ignorance.

Wisdom-Seeker: With my set-up, you could see the fuel flow twards the muffler as soon as you throttled back to idle. If you were done with a flight, you had to be quick to clamp off the pressure line so that you didn't flood the engine... This was using a MPII with the pressure fitting on the header. YMMV


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12-03-2005 12:39 AM  12 years agoPost 29
Al Magaloff

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I don't read anything the bug posts. I do clamp the muffler pressure line and the carb inlet line just before shutting of the motor.

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12-03-2005 08:35 AM  12 years agoPost 30
nivlek

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Norfolk England

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I thought uni-flow sounded like a load of bull , but before spending the best part of £100 to equip two of my more troublesome helis/engines with pumps , I decided to give it a try . It saved me the £100 .

At the end of the day , it gets dark .

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12-03-2005 03:26 PM  12 years agoPost 31
GMPheli

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W. Bridgewater, MA USA

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I tried uniflow on my Intrepid which has the exhaust running under the heli. When I tried to start it, it would fill the pipe with fuel. The pressure pulses would some how start a siphon or something. I really don't understand why. You would think the pressure would stop the fuel. It must've acted like a pump. The pressure line came in from the top of the tank and went a good inch or more above the tank. Interestingly enough, this heli does not want to start on the first flight of the day (without uniflow) without blocking the exhaust for a few seconds to get fuel to the carb. It has to have somthing to do with the setup. The pipe is just a regular airplane tuned pipe with the pressure tap located about in the middle.

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12-04-2005 02:22 AM  12 years agoPost 32
Al Magaloff

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You don't have a firm grasp on Uniflo. Come back when you do, and we'll discuss it more. Loose the seneca and angelo from california attitude also, while you're at it.

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12-04-2005 02:25 AM  12 years agoPost 33
Louisiana Helicam

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West Monroe, LA

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BuddyKitchen, go take a hydraulics course and come back when you're ready to discuss in a more educated manner.

www.louisianahelicam.com

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12-04-2005 09:34 AM  12 years agoPost 34
nivlek

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Norfolk England

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For all you rocket scientists out there, explain how venting exhaust pressure into a fuel bath makes one iota of difference,
Actually , it isn't rocket science , it's quite simple . With fuel lines to the carb and exhaust at the same level , the "head" of fuel works evenly on both lines regardless of the fuel level , therefore they cancel each other out and all you are left with is exhaust pressure .

At the end of the day , it gets dark .

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12-04-2005 01:17 PM  12 years agoPost 35
RayJayJohnsonJr

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Midwest

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I just checked Nivlek's profile. He's not a rocket scientist.

I'm still trying to wrap my little head around this idea and am still having some problems.

It would seem to me that for any given power setting the leak in the tank (fuel going to the carb) and the pressure at the muffler pressure nipple are constant. The pressure in the tank as a result of muffler pressure will be the same REGARDLESS of where the pressure enters the tank and regardless of fuel level. The ONLY thing that is changining during this process IS the level of the fuel and the head pressure at the carb nipple WILL change as fuel is removed from the tank. Where am I going wrong here

-Mark

There, their and they're. It's really that simple.

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12-04-2005 01:42 PM  12 years agoPost 36
nivlek

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Norfolk England

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The ONLY thing that is changining during this process IS the level of the fuel and the head pressure at the carb nipple WILL change as fuel is removed from the tank.
Exactly , but if the pressure line is at the same level as the fuel line , the fuel head pressure will be acting against the exhaust pressure on the exhaust line as well as helping to supply fuel on the carb line - regardless of the fuel level . So , no matter what the fuel head pressure is , as it is the same on both clunk lines it cancels itself out .

At the end of the day , it gets dark .

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12-04-2005 04:35 PM  12 years agoPost 37
GMPheli

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W. Bridgewater, MA USA

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Think of it this way. Picture a tank, sitting on the bench. The clunk and pressure lines exit halfway up the tank. (this point really does not matter, but for visualization it helps). With a normal setup (vent to top) when the tank is full the fuel will flow because of gravity until it reaches the halfway point. Now it will take a vacuum to get fuel out. The vacuum required to pull the fuel out of the tank will increase as the fuel level drops until the tank is out of fuel. Now visualize a uniflow setup. The vent is now a clunk, and there is a tube on the vent that goes above the tank. When the tank is full, no fuel will flow because of gravity, because you now have to pull air down the clunk tube to the bottom of the tank. It is a self cancelling sytem.

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12-04-2005 04:42 PM  12 years agoPost 38
Al Magaloff

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For all you rocket scientists out there
To some, , most things are rocket science.

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12-04-2005 04:46 PM  12 years agoPost 39
ESWLFSE

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Liberty Hill, TX

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Can someone post some pics of their setup? It seems like such a hassle and messy to clamp off the pressure line and open a capped vent line every time you fill. Has anyone made this easier and cleaner somehow with a valve or a otherwise nice setup?

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12-04-2005 04:49 PM  12 years agoPost 40
Al Magaloff

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Actually, once you get into the routine, it's quite simple really. You get into trouble with UniFlo, when some of your helis have it, and some don't. At present, all seven of my helis sport UniFlo.

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HelicopterMain Discussion › Why don't more people use uniflow?
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