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Author Topic: A genuine chicken hopper.  (Read 4663 times)

Offline Paul Smith

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A genuine chicken hopper.
« on: November 03, 2016, 11:05:05 AM »
While cleaning my barn I came across some genuine chicken hoppers.

Most people understand chicken hopper tanks, but a few are unclear on the concept.

When the red plastic dish fills to the point where the inlet is blocked by water, a vacuum is created and the water does not flow until some is consumed.

The glass bottle represents the big fuel tank on your plane.  The red plastic dish is the tiny tank from which the engine draws fuel.  Thus, the engine is always drawing from a tank with consistent and very low pressure.  The fuel level in the big tank does not effect fuel pressure.
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Offline Steve Helmick

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Re: A genuine chicken hopper.
« Reply #1 on: November 04, 2016, 01:52:00 PM »
Shouldn't you be stuffing the ballot box by now?  ;) Steve
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Offline Motorman

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Re: A genuine chicken hopper.
« Reply #2 on: November 04, 2016, 03:55:00 PM »
Most if not all tanks people call Chicken hoppers are really just big tank little tank. They don't maintain an air pocket even if the vent tube is inside the little tank.

MM
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Offline BillLee

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Re: A genuine chicken hopper.
« Reply #3 on: November 05, 2016, 06:33:55 AM »
Quote from: Motorman on November 04, 2016, 03:55:00 PM
Most if not all tanks people call Chicken hoppers are really just big tank little tank. They don't maintain an air pocket even if the vent tube is inside the little tank.

MM

Wow! Now THERE'S a sweeping generalization without basis in fact!
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Offline Motorman

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Re: A genuine chicken hopper.
« Reply #4 on: November 05, 2016, 07:49:12 AM »
Quote from: BillLee on November 05, 2016, 06:33:55 AM
Wow! Now THERE'S a sweeping generalization without basis in fact!

Welcome to Stunthanger.

MM
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Offline Paul Smith

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Re: A genuine chicken hopper.
« Reply #5 on: November 05, 2016, 01:05:47 PM »
The generalization is probably true to some extent.  The air gap is the key element that
 prevents fuel usage from changing the mixture.

« Last Edit: November 05, 2016, 05:36:53 PM by Paul Smith »
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Offline Brent Williams

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Re: A genuine chicken hopper.
« Reply #6 on: November 05, 2016, 02:15:59 PM »
Quote from: Motorman on November 04, 2016, 03:55:00 PM
Most if not all tanks people call Chicken hoppers are really just big tank little tank. They don't maintain an air pocket even if the vent tube is inside the little tank.

MM

So would you consider this a "true" chicken hopper tank?

http://www.tulsacl.com/Engines.html#anchor_45

« Last Edit: November 05, 2016, 02:48:14 PM by Brent Williams »
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Offline Motorman

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Re: A genuine chicken hopper.
« Reply #7 on: November 05, 2016, 04:44:45 PM »
That's what I call big tank little tank. What I call a true chicken hopper has to have an air pocket in the little tank not just foam wafting though holes. That's more or less just has a fancy baffle. There has to be a tube that extends into the little tank from the big tank to act like a true chicken hopper. If you want to call that a chicken hopper tank it's ok with me but, it doesn't work the same way as the picture in the OP.

MM

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Offline Paul Smith

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Re: A genuine chicken hopper.
« Reply #8 on: November 05, 2016, 05:39:26 PM »
Quote from: Brent Williams on November 05, 2016, 02:15:59 PM
So would you consider this a "true" chicken hopper tank?

http://www.tulsacl.com/Engines.html#anchor_45



This is a TRUE chicken hopper because the fuel level in the small tank will block the air vent and prevent fuel from transfering until some has been consumed.  The air gap is maintained.
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Offline Paul Smith

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Re: A genuine chicken hopper.
« Reply #9 on: November 05, 2016, 05:42:08 PM »
Quote from: Steve Helmick on November 04, 2016, 01:52:00 PM
Shouldn't you be stuffing the ballot box by now?  ;) Steve

No need to "stuff" in Macomb County.  Donald Trump is making his THIRD Macomb County visit tomorrow, only two miles from my house.
This is the best time ever have your name on the ballot behind an (R).
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Offline Mark Mc

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Re: A genuine chicken hopper.
« Reply #10 on: November 05, 2016, 11:48:43 PM »
Out of curiosity, does the fill/vent tube HAVE to go through the main tank?  Can the vent tube enter the front of the hopper like the fuel outlet tube?  Seems like it'd be simpler to assemble.

Mark
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Offline Steve Helmick

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Re: A genuine chicken hopper.
« Reply #11 on: November 06, 2016, 01:45:17 AM »
Out of curiosity, does the fill/vent tube HAVE to go through the main tank? No!

Can the vent tube enter the front of the hopper like the fuel outlet tube? Yes!

Seems like it'd be simpler to assemble. You betcha! I would much prefer to have the air inlet for the Uniflow tube be completely inboard of (and above) the fuel load.

About the worst thing about the drawing is showing a screw stuck into a piece of fuel tube to cap the overflow. Bad form, tends to be leaky. A rivet or BB in a length of fuel hose is much less likely to leak. There are also inexpensive plugs made for that purpose by various makers. Pretty sure Dubro has them, maybe Sullivan, GP and others.  D>K  Steve

Edit: Good luck with the Election, Mr. Smith! Please let us know how it comes out.  
« Last Edit: November 06, 2016, 01:07:31 AM by Steve Helmick »
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"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline BillLee

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Re: A genuine chicken hopper.
« Reply #12 on: November 06, 2016, 05:25:37 AM »
Quote from: Brent Williams on November 05, 2016, 02:15:59 PM
So would you consider this a "true" chicken hopper tank?

http://www.tulsacl.com/Engines.html#anchor_45


Well,.... like a good politician .... the answer is "yes and no". (Paul you can understand the politician stuff! :-) )

You have to consider where the fuel is during operation and what the forces are on the system.

From the drawing:

If the forces are all "outboard" and steady-state: yes, it acts as a chicken hopper, as per Paul's explanation.

But during maneuvering, the force directions change, the fuel level sloshes around and may or may NOT  let the tank act as a CH, then becoming nothing more than a baffled uniflow system. Which isn't bad at all!
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Online Brett Buck

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Re: A genuine chicken hopper.
« Reply #13 on: November 06, 2016, 03:36:50 PM »
Quote from: BillLee on November 06, 2016, 05:25:37 AM

But during maneuvering, the force directions change, the fuel level sloshes around and may or may NOT  let the tank act as a CH, then becoming nothing more than a baffled uniflow system. Which isn't bad at all!

  Exactly. The "chicken hopper" is acting like an isolated tank or tank baffles, presumably keeping fuel near the pickup despite maneuvering - which is the important feature. A conventional uniflow vent in a conventional tank operates on exactly the same principle as the chicken hopper shown above, you don't need a separate tank.

   The only consistent issue with a "chicken hopper" tank as used in CL is that they tend to be wider than a conventional tank, and when they are on a profile, provide a slightly lower feed pressure. It's a matter of experiment whether or not that causes more problems than the baffle solves.

     Brett

     
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Offline Steve Helmick

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Re: A genuine chicken hopper.
« Reply #14 on: November 06, 2016, 11:04:29 PM »
Looking at this diagram again, one more thing comes to mind. It appears to me like the "small tank" would not fill completely when sitting in a normal "on the wheels" attitude. Looks like there would be a bubble of air in the hopper unless some tipping, tilting, etc., are performed while filling. I'm not sure what that bubble would do, and it doesn't seem like the bubble would come out without being pulled through the spraybar. At the very least, it might make repeatable run times difficult. Don't need that. 

As for me, I'm more than happy to use a standard Uniflow tank and see nothing to be gained by using a "Chicken Hopper" tank in any stunt event, or for sport. I don't believe it's normal for F2A's or F2C's to use them, either.  D>K Steve   
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"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

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