Yes. Feed well as long as plane does not suffer bad vibrations. Especially useful in short nose profiles needing extra fuel capacity.



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Chicken hoppers regulate head pressure well. Better than conventional hard tanks. Dan Banjock and Mike Palko use 21 ounce chicken hoppers in their dynajet stunters. These planes do the pattern, big shapes, but recognizable. Dynajets are hyper sensitive to fuel flow. Fuel flow needs to be even as possible matched to the jetting required to fit air density/temperature of the day. Otherwise they flame out quick. Chicken hopper tanks apparently work well in this difficult configuration.

Perhaps fuel head in chicken hoppers is determined by the small tank attached to the larger tank. In other words engine behaves as though it is fed from a small footprint tank.

We use chicken hoppers a lot in our club. Work well. Feed well. On profiles common issue is vibration that causes foaming and bubbles. Hoppers will not cure that. We have a long list of stuff to try. Solutions vary.


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Chicken hoppers regulate head pressure well. Better than conventional hard tanks.

  No, they don't regulate it at all, at least in the sense I meant it. They are no different from any other tank in terms of the quasi-static pressure head, and, they don't know what happens to it after it leaves the tanks and maybe travels 2 1/4" or so, uphill, against 2.5Gs worth of acceleration. Which is the key issue I was addressing.

   The pressure at the fuel outlet is entirely determined by the depth of fluid from the reference pressure, the density of the fuel, and the acceleration (which is about 2.5G, with the exact value being determined by the speed and circle radius). The pressure at the needle valve is the outlet pressure at the tank, +- the fuel density, and the distance it has to travel against acceleration, and the acceleration. The shape of the container does not matter.

   The reference pressure is set by the pressure at the vent, and the position of the vent. For a classic suction tank open to the air, it's the air pressure at the tank vent referenced to inboard edge of the fuel surface. For a uniflow tank, it's the air pressure at the tank vent at the position of the uniflow vent.

Dan Banjock and Mike Palko use 21 ounce chicken hoppers in their dynajet stunters. These planes do the pattern, big shapes, but recognizable. Dynajets are hyper sensitive to fuel flow. Fuel flow needs to be even as possible matched to the jetting required to fit air density/temperature of the day. Otherwise they flame out quick. Chicken hopper tanks apparently work well in this difficult configuration.

   They are sensitive to *bubbles*, a single bubble or missed pulse will probably cause them to quit. That's why you want a chicken hopper, and why they were invented.

    Brett

Chicken hoppers must be kind to head pressure. Dynajets are very sensitive to rate of fuel feed since this will immediately effect fuel/air ratio. Danny often needs to juggle jets to match atmospheric conditions. It’s a subtle dance. If head pressure varied much mix would be off engine would quit. They run through the tank when jetted right.


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For the 20FP and 25LA, and particularly for the 25LA,  I suggest that the outboard edge of the tank on profile not go beyond 1 1/2" from the bottom of the mounting lugs , with no muffler pressure, and maybe 2" max with muffler pressure. The feed pressure does matter, in fact, it is critical.

     Brett

The Chicken hopper tanks you see for sale are not true chicken hoppers they are big tank little tank with various holes connecting the two and both are full of fuel. A true chicken hopper maintains an air space in the small tank that keeps the pressure from the big tank at bay. So before you get a bee in your bonnet make sure you know which design you're talking about because they are apples and oranges.


Motorman

Hello
Went looking for pictures of the different styles and found this interesting post that covers Uniflow and Chicken hopper tanks
http://controlline.org.uk/phpBB2/viewtopic.php?printertopic=1&t=4343&postdays=0&postorder=asc&start=0&finish_rel=-10000

Always thought of C.H  just as an 'sump' but more to it....

Regards Gerald

Regards Gerald

Hello I have not used C.H tanks on a profile as I was always worried how far outboard it put the pickup and associated leaning out. I wonder if the hopper could go on the outboard side and main tank body on the inboard side in a profile ?
 Also if using muffler pressure is there is no advantage in using uniflow as you cancelled its affect and just need a vent to inboard side, is this correct?
I haven't run an inboard tank for 30+ years as they always went too rich in flight but are there better ways to manage them?

Regards Gerald

Uniflow and chicken hopper tanks utilize (different) ways of handling fuel and air pressure to regulate fuel flow.  Both are nullified by muffler pressure or any other pressure system.

I agree about inboard tanks giving too much boost.  Also, outboard fuel tanks challenge the engine's ability to draw fuel.  So keep the fuel directly behind the engine.

When the birds eat enough food, a bubble enters the tank.  A true chicken hopper.

CL theorizing must be a subset of our hobby. Often engaged, rarely agreement. Track explanations for how uniflo works. Not much overlap in the different explanations. Our discussion of chicken hopper tanks seems headed there. In any case I’ll upload a picture of my long time flown jrStreak powered by an Fp15. Overpowered great fun. Tank has been a 2 ounce chicken hopper. Never an issue with the tank, despite the high speed turns. The tank definitely looks weird at first. Fuel feed tube exits near the top of the cylinder. It works. Engine runs very well through maneuvers. I’ve used chicken hoppers on many profiles. Engines range from 15 to 46 in size.

I read the Greeks frequently. Poetry and plays. Apparently your brilliance Brett does not match the practical experience of folks who use these tanks all the time.


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I read the Greeks frequently. Poetry and plays. Apparently your brilliance Brett does not match the practical experience of folks who use these tanks all the time.


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     Do yourself a favor, and search out Jim Thomerson's explanation of uniflow and chicken hopper tanks. They have the origins in steam power applications. I think he did some with illustrations and diagrams. I think you will be impressed, no, I KNOW you will be impressed. Jim was a member of our club here in St. Louis for many years until his retirement and is missed and often remembered. He used to make models of the system using cardboard and soda straws. We just cleaned out a club member's basement shop last weekend and I found one of those there, and sorry to say it got thrown away in a weak moment.
  Type at you later,
   Dan McEntee

You guys are putting me on right. Greek steam engine uniflo chicken hopper moon rocket. The one designed and built by Brett in his past life.


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Oh ok. You guys are in a snit because my honest accounts of how this tank performs in a toy airplane does not confirm your whatever theories. Let that sink in will you. Brilliant Brett accuses me of what offending the memory of someone I know nothing about because and furthermore... I have no idea why. Brilliant Brett Mr Fp20 is offended. Ridiculous. I built these airplanes at 10 or 11. You did too. Grow up.


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   I ain't in a snit about nothin'! Just thought you would like to expand your horizons a bit with some pertinent information on the subject. You seem to be the one in a snit. Like the old saying says, you can lead a horse to water, but you can't make him drink.
  You're welcome,
   Dan McEntee

Ditto


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    Gerald mentioned something about running a tank on the inboard side of a profile plane & I did this 30 years ago I remember how Gerald described it is exactly what happened to me. Was running a FP .40 which would lean out & quit. Some guy that was Miles ahead of me mention moving the tank inboard. It worked but would go rich after launch. So I built an Imitation profile with a cutout in the nose allowing me to adjust the engine run , richness by sliding the tank  left  or  right.   

Where the hell are the Moderators?

This is exactly the reason I no longer post here.

So Chris you slogged through a bunch of posts-- topic Chicken hopper --and found some members have a strong argumentative personality.....there is was/is no moderation needed --yet....the argument did not escalate out of control. In fact until your note, the issue was dropped

like I say in every " I hate off topic politics post" :

This is NOT THE TWILIGHT ZONE   you do have control over the channel....if something YOU SELECTED OFFENDS YOU....stop reading....select Netflix or Hulu, or Disney....

or if you must be offended...... drop all the way down to "supporters forum and" vent at your leisure

Gentlemen,  I no longer post here in any meaningful way,  and from time to time only browse the forums.

And as to the don't read it if you don't like it idea,  how does one form an opinion unless it's read first?

OK,  having said that I object to -
The authors style of questioning,  it's always so broad that it leads to the responders being precise and then the argument starts and then it gets personal. And the author has used the same tactic for years and over many sites, the correct  answer to such non specific questions always a "depends" one and he rarely responds to any answer given but prefers to sit back and watch posters rip holes in beach other.
Let see, we ask Christmas stocking filler questions like "Do chicken hopper tanks work on profile models?" (sorry should have added a dozen?? To make the heading seem like its useful).
Bit like asking how long is a bit of string - and oh yes the answer is always depends. But responders fall for the trap time and time again By trying to help.

That and if any argument starts to attack the person and not the content you know it's lost legitimacy.

These two points alone should attract moderation but I suppose  I am now the target of the verbal Barbs for drawing attention to it.
The real thing missing in all of this is a reply,  a thank you or a return question from the author,  but no and I left it to stew for months in an effort to give a reasonablre amount of time in order to do so.

Threads like this are deliberate bait and I simply can't wait for another like "Do carbon fibre props work on my Fox? " or "What oil do I use after run? " Topics and questions like this turn forums into bear pits  and Mods should be aware of them.

What qualifies me to say this,  I am one myself.

back in the 50's and early 60;s there was a lot of work done with chicken hopper tanks for FAI team  racers,until they found that they could get just as good results with a uni flow tank with half the plumbing

I have a true chicken hopper team race tank but cant post pictures here. if any one wants, I can email u pictures of it and all it's plumbing