Author Topic: "Palmer" tank (Read 2138 times)

FLOYD CARTER · « **on:** October 14, 2010, 10:34:32 AM »

I did a search on "Palmer, tank", but my questions remain:

I recently studied a diagram for Bob Palmer's stunt tank, and it features some strange things that I don't understand.
It is a uni-flo, but the uni-flo tube ends at the FRONT, next to where the fuel pickup exits the tank. This would indicate that the uni-flo tube would be uncovered in a vertical climb, or when the fuel level got toward empty. I have always put the uni-flo tube exit at the rear of the tank, and next to the end of the fuel pick-up tube.

Another puzzler: His tank has a baffle placed about 1/2" ahead of the back, with the fuel pick-up also ending at the baffle. That would indicate that the pick-up would be uncovered when the tank is near-empty and in a vertical attitude.

Centrifugal force would tend to keep the remaining fuel in the wedge at the outside of the tank, but gravity also plays here. The resultant force vector would tend to favor fuel toward the outside rear.

I hesitate to try a Palmer tank, because I've had OK luck with the ones I've made. I just want to understand how these beasties work!

Floyd

Jim Thomerson · « **Reply #1 on:** October 14, 2010, 01:59:36 PM »

The story I heard is that Bob took a matchbox, put some mercury in it, and put it on a turntable to see where the mercury would go. I have made uniflow tanks with the uniflow at the front, like the Palmer tank, and at various places along the outside edge back to the usual position. So far as I could tell, they all ran about the same. The Russians flew tanks like the Palmer tank, but with the pickup going through the baffle back to the back outside corner of the tank, as is usual. There is still some magic and uncertainty in what we do.

rustler · « **Reply #2 on:** October 14, 2010, 02:01:29 PM »

Tankwise I've used nothing but a Palmer tank since I learned of them over 50 years ago. Never a failure. They work as published. I have since put the vent tube at various distances along the tank, from front to back, and it does not seem critical.
When someone complains to me about their engine run, I always say "Use a Palmer Tank".
I'll let someone else explain why.

Kim Mortimore · « **Reply #3 on:** October 14, 2010, 03:45:42 PM »

Quote from: Jim Thomerson on October 14, 2010, 01:59:36 PM

......There is still some magic and uncertainty in what we do.

Good point. As one speed flier told me, "Getting a good engine run is 60% careful preparation. The other 60% is black magic."

Back in his IC days, Paul Walker built 5 identical tanks, except that each tank had the end of the uniflow tube in a different place from front to back, starting at the front corner and ending in the usual place, a little ahead of the pickup. He ran a series of tests and found that the tank he liked best had the uniflow tube end midway between the front and back of the tank.

Actual practice trumps armchair fizziks every time.

FLOYD CARTER · « **Reply #4 on:** October 15, 2010, 12:23:58 PM »

Good responses! It answers only one of my questions. But I STILL don't understand WHY.

Floyd

Rafael Gonzalez · « **Reply #5 on:** December 26, 2010, 06:49:00 PM »

I will try and answer this without going way into physics. A tank and the fluid in it, traveling in a circular motion with constant speed, experience a gravity separate from our gravity. It is called "centripetal force" not centrifugal. Centrifugal is the opposing resulting force that keeps the object wanting to go out of the circle. It is a resulting action not an active. According to laws, a force that is 90 degrees from another do not interact. So our "gravity" would only exert an effect when we are diving or climbing and in between (loops, etc.) not at level flight. A climb, will apply a leaning effect on our engines as the "Earth's gravity" works against the engine suction (engine forward of tank). A dive on the other hand, will raise the tank above the engine making it easier to feed. The perfect run we are looking for!
A tank on pressure, will experience the same since we adjust for the speed at level but much less pronounced. Those are the only forces acting on a tank causing the change in speed on our engines. By adjusting compression, timing, fuel, venturi, etc. we are creating a system that responds sensitively to slight changes in fuel pressure.
Here comes the uniflow.
I can not explain the different set ups for uniflow that are mentioned by different names, but I can describe the physics of a uniflow. At normal atmospheric pressure (typical vent), a tank full of a fluid will have more pressure at the bottom when it is full and will loose it gradually (pressure) as the fluid level gets closer to the bottom (less weight of fuel at the centripetal). If the atmospheric pressure is balanced to the point where the output is located (uniflow next to the pickup point) then the fluid pressure remains constant at all levels due to the tank's inner pressure remaining balanced. The level changes but it is inhibited by the immersed uniflow. When the tank is full, it is hard to let fuel out as the same pressure is exerted to the venting air (at uniflow) As the fuel level gets closer to the pick up tube (tank closer to empty), the venting gets easier due to less pressure on the uniflow vent. It will only overcome the balance when the uniflow tube is no longer immersed and a lean mixture will occur, hence the slight leaning at the end of the run.
By moving the uniflow away from the pickup tube (forward), we will change the point at which we only use atmospheric pressure and the engine will run as if it had a regular tank. Try this:
Have two equal tanks, one uniflow and one regular. Turn them sideways and watch the flow on both.
I am new to stunt but not new to physics...

I hope this helps the understanding of uniflow tanks...

Jim Kraft · « **Reply #6 on:** December 26, 2010, 07:44:11 PM »

On most of my uniflow tanks, I have found they run richer after the uniflow tube is uncovered. My reasoning is that you have to set the needle richer for a uniflow tank than for a standard vent tank, because of the pressure on the uniflow tube when in flight, and less pressure on the pickup tube. But when the uniflow tube is uncovered you have the full pressure of what is left in the tank, and acting like a standard tank at that point. Shortly after it goes rich, it will go lean for a few seconds as the last few drops of fuel are used up. Just to confuse things, my McCoy 40's will richen up through the whole flight on uniflow, but will run very consistant through the whole tank on standard vent, with just a slight leaning toward the end. I can put a McCoy 35 on the same plane, with the same tank, and it will run steady on uniflow, but lean out a lot on a standard vent.

Rafael Gonzalez · « **Reply #7 on:** December 27, 2010, 09:20:48 AM »

I have had the same results on some engines last summer(I do not remember which!) On another note, I can guess that when people move up the uniflow tube along the outside, they are changing the timing of the lean/rich switch. There are so many variables that the ultimate run needs many trials with all the possibilities. I am just starting to experiment with stunt. In combat or speed limit combat you do not need to worry about 4,2,4... you just go as fast as you can. Perhaps, if the engine is the type that tends to go lean after the uniflow is opened one can time it to give that extra power on the overheads at the end of the pattern? I am starting to realize that the perfect run for stunt is quite a feat to accomplish in itself.

Rafael Gonzalez · « **Reply #8 on:** December 27, 2010, 09:27:08 AM »

I do not know why your engines react that way. I do know that the fuel pressure is the same on both pick-up and uniflow until the uniflow is above the fuel.

Jim Thomerson · « **Reply #9 on:** December 28, 2010, 07:03:03 PM »

I've never experienced the problem of the needle setting changing over the uniflow submerged part of the run, but others have mentioned it, as Jim Kraft said a richening in particular situations. When the uniflow comes out of the fuel the engine will richen up. This is more or less noticeable depending, and is less obvious with muffler pressure. End of tank richening is a good thing as it tells you how close you are to running out of fuel.

Bill Little · « **Reply #10 on:** December 28, 2010, 08:24:11 PM »

Hmmmmmmm..... I just set the needle, fly the pattern, and land.......... usually have very good to excellent engine runs, according to others. And have even experienced what is called a "perfect" run! LOL!! Did have a slight "charging" problem once, had taken the muffler pressure off the Vulcan/Aero Tiger .36 and forgot to put it back on....... Uniflow on everything EXCEPT Fox .35's. And I do use the occasional R/C plastic clunk tanks, but I was told how to set them up and listened.. But for at least the last 20 plus years, I have just done what some Walker Trophy winning pilots, and engine building gurus, have told me to do. Boring for some, but it works for me. And I don't have to experiment, fiddle or cry myself to sleep. just have to remember what they say. I let them do all the hard work, and I thank them for the lessons!

Now if I had started like this 45 years ago and never quit, Paul wouldn't have won all those dang NATS! LOL!!!!

Big Bear

Jim Thomerson · « **Reply #11 on:** December 29, 2010, 02:01:30 PM »

I've run nothing but uniflows on Fox 35's for years, and they run to suit me.

Rafael Gonzalez · « **Reply #12 on:** December 29, 2010, 09:51:45 PM »

Quote from: Bill Little on December 28, 2010, 08:24:11 PM

Hmmmmmmm..... I just set the needle, fly the pattern, and land.......... usually have very good to excellent engine runs, according to others. And have even experienced what is called a "perfect" run! LOL!! Did have a slight "charging" problem once, had taken the muffler pressure off the Vulcan/Aero Tiger .36 and forgot to put it back on....... Uniflow on everything EXCEPT Fox .35's. And I do use the occasional R/C plastic clunk tanks, but I was told how to set them up and listened.. But for at least the last 20 plus years, I have just done what some Walker Trophy winning pilots, and engine building gurus, have told me to do. Boring for some, but it works for me. And I don't have to experiment, fiddle or cry myself to sleep. just have to remember what they say. I let them do all the hard work, and I thank them for the lessons!

Now if I had started like this 45 years ago and never quit, Paul wouldn't have won all those dang NATS! LOL!!!!

Big Bear

Well Bill, you got 20+ years ahead of me at "listening"! I just started stunt this year after 40+ years of fast/slow combat, carrier, Q500 (R/C), etc. So for me, I have a lot of "listening" to catch up to. Maybe some day I'll get to your level of perfection. But today, I am asking questions and "listening". Perhaps, you could write about your perfect engine setups so we can learn and have the same performance out of ours...

Bill Little · « **Reply #13 on:** December 29, 2010, 10:35:04 PM »

Quote from: gonzarafa on December 29, 2010, 09:51:45 PM

Well Bill, you got 20+ years ahead of me at "listening"! I just started stunt this year after 40+ years of fast/slow combat, carrier, Q500 (R/C), etc. So for me, I have a lot of "listening" to catch up to. Maybe some day I'll get to your level of perfection. But today, I am asking questions and "listening". Perhaps, you could write about your perfect engine setups so we can learn and have the same performance out of ours...

Hi Rafael,

I was being a "little" bit *tongue in cheek*, and a "little" bit factual. Didn't mean to offend you, if I did I'm sorry..

If you are really sincere, I could write a lot but I don't do anything "special", that's all. If I have used a specific engine, I can tell you what I have been told to do to get it to run right. I do what others have told me to do. I learned many, many years ago, through a completely different venue, that the KISS principle is always best. And to ask the best how they do it, that way I don't have to re-invent the wheel. In the "Stunt" realm I am "lazy" when it comes to the "technical side", I just want to know what to do to fly better.

I use muffler pressure on my "non piped" set ups. And Uniflow on all except the Fox .35, which is also the one example where I don't run muffler pressure. Jim T., and others, use uniflow and it works for them just fine. I tried uniflow on a Fox .35, had problems, and went back to straight vent. I'm a huge believer in "If it ain't broke, don't fix it".

I make sure I the tank can move up and down if it's a hard tank. I make sure there are no leaks in the system, first, before I go out to fly. And I try not to use old fuel, plus the right plug for the engine and set up.

I ain't the best there ever was in this "stunt deal", and never will be, now. But I am more than intelligent enough to learn from those who are.

For those who need to know the whys and wherefores, that's great. More power to them, but for me, I just need to know the "do's and don'ts". I am more interested in the "How" than the "Why".

Don't take me the "wrong way", I ain't a "Sexual Intellect".

Bill Little
AKA: Big Bear

Rafael Gonzalez · « **Reply #14 on:** December 30, 2010, 06:32:53 AM »

Quote from: Bill Little on December 29, 2010, 10:35:04 PM

Hi Rafael,

I was being a "little" bit *tongue in cheek*, and a "little" bit factual. Didn't mean to offend you, if I did I'm sorry..

If you are really sincere, I could write a lot but I don't do anything "special", that's all. If I have used a specific engine, I can tell you what I have been told to do to get it to run right. I do what others have told me to do. I learned many, many years ago, through a completely different venue, that the KISS principle is always best. And to ask the best how they do it, that way I don't have to re-invent the wheel. In the "Stunt" realm I am "lazy" when it comes to the "technical side", I just want to know what to do to fly better.

I use muffler pressure on my "non piped" set ups. And Uniflow on all except the Fox .35, which is also the one example where I don't run muffler pressure. Jim T., and others, use uniflow and it works for them just fine. I tried uniflow on a Fox .35, had problems, and went back to straight vent. I'm a huge believer in "If it ain't broke, don't fix it".

I make sure I the tank can move up and down if it's a hard tank. I make sure there are no leaks in the system, first, before I go out to fly. And I try not to use old fuel, plus the right plug for the engine and set up.

I ain't the best there ever was in this "stunt deal", and never will be, now. But I am more than intelligent enough to learn from those who are.

For those who need to know the whys and wherefores, that's great. More power to them, but for me, I just need to know the "do's and don'ts". I am more interested in the "How" than the "Why".

Don't take me the "wrong way", I ain't a "Sexual Intellect".

Bill Little

AKA: Big Bear

Thank you for your explanation, Bill. Apology not needed. I am "very" new to this forum as well as the stunt environment and do not know the folks in here yet. I am the type that likes to know both: why's and how's. There are many ways to get the same results in many things. The more ways you know, the better you can apply a solution. :-D

Best regards,
Rafael Gonzalez

Bill Little · « **Reply #15 on:** December 30, 2010, 10:39:36 AM »

Hi Rafael,

From your past experiences, you have to know a thing or three about "engines". I'm happy I wasn't offensive.

In truth (and I could get flamed for saying this) the best run for most of us (those of us that will never fly in the Top Five at the NATS, or the finals at the Worlds) is one that is simply "consistent", and not doing the "WRONG THINGS" so to speak.. Very few get "optimum runs" EVERY time! LOL!! Even at the World Championships. But from outside the circle is isn't always obvious. One can get really "Anal" searching for the "perfect run", but that's OK, too. But not if it detracts from your "flying". I have been beaten more than once by a pilot who had a less than optimal engine run, but he made up for it on the handle. Most of the time, if the set up gets honed in, a bit less than "optimum" still allows the plane to fly as good as, or better than, the pilot can perform. and the very best pilots know how to adjust when it happens. I ain't close to "one of the very best pilots" so I just muddle along grinning like a "Fox eating briers"! LOL!! it amazes me sometimes when someone comes up and says "You had a great engine run". I know it was, but it didn't help my score any (or maybe it did?)! LOL!!

Brett buck has a Walker Trophy to his name. he did some experiments a few years back and came up with a great set up that works outstandingly in the right size model. He was searching for a modern substitute for the good old Fox .35. He hit on the OS .20FP completely stock out of the box with a 9-4 APC prop. It runs just like a good pipe run if done like he recommends. All the ones I have tried have been excellent. And it will handle a model like a Flite Streak, Sky Ray 35, or similar size/weight full fuselage stunter with great results. But the specs have to be to his recommendations And it doesn't do a traditional "2-4" run. Just an example of a set up that is proven to work, but is as simple as all get out!

Have fun doing this. And ask about specific set ups when you are getting ready to use them. There are truly a large amount of the best "Experts in the field" here, and they will give you honest answers. That's the best advice this old "Coach" can give.

Bill

Rafael Gonzalez · « **Reply #16 on:** December 30, 2010, 03:59:03 PM »

Quote from: Bill Little on December 30, 2010, 10:39:36 AM

Hi Rafael,

From your past experiences, you have to know a thing or three about "engines". I'm happy I wasn't offensive.

In truth (and I could get flamed for saying this) the best run for most of us (those of us that will never fly in the Top Five at the NATS, or the finals at the Worlds) is one that is simply "consistent", and not doing the "WRONG THINGS" so to speak.. Very few get "optimum runs" EVERY time! LOL!! Even at the World Championships. But from outside the circle is isn't always obvious. One can get really "Anal" searching for the "perfect run", but that's OK, too. But not if it detracts from your "flying". I have been beaten more than once by a pilot who had a less than optimal engine run, but he made up for it on the handle. Most of the time, if the set up gets honed in, a bit less than "optimum" still allows the plane to fly as good as, or better than, the pilot can perform. and the very best pilots know how to adjust when it happens. I ain't close to "one of the very best pilots" so I just muddle along grinning like a "Fox eating briers"! LOL!! it amazes me sometimes when someone comes up and says "You had a great engine run". I know it was, but it didn't help my score any (or maybe it did?)! LOL!!

Brett buck has a Walker Trophy to his name. he did some experiments a few years back and came up with a great set up that works outstandingly in the right size model. He was searching for a modern substitute for the good old Fox .35. He hit on the OS .20FP completely stock out of the box with a 9-4 APC prop. It runs just like a good pipe run if done like he recommends. All the ones I have tried have been excellent. And it will handle a model like a Flite Streak, Sky Ray 35, or similar size/weight full fuselage stunter with great results. But the specs have to be to his recommendations And it doesn't do a traditional "2-4" run. Just an example of a set up that is proven to work, but is as simple as all get out!

Have fun doing this. And ask about specific set ups when you are getting ready to use them. There are truly a large amount of the best "Experts in the field" here, and they will give you honest answers. That's the best advice this old "Coach" can give.

Bill

Thank you Bill. I appreciate your "coaching". I am kind of sorting some of the info on this forum. Some of it seems (to me) way too radical to make any difference in the flying of a stunt ship. I agree with you that it is the pilot and not so much the machine. It all comes down to common sense. It is the KISS that I also believe in. Before I ask a question, I always do a search first in order to avoid the repetiveness, as it becomes a nuisance after it has been answered so many times by others.
Thank you for your time and patience. I am sure I will be asking many questions if I do not find them in here.
Best,
Rafael

Author Topic: "Palmer" tank (Read 2138 times)

FLOYD CARTER

"Palmer" tank

Jim Thomerson

Re: "Palmer" tank

rustler

Re: "Palmer" tank

Kim Mortimore

Re: "Palmer" tank

FLOYD CARTER

Re: "Palmer" tank

Rafael Gonzalez

Re: "Palmer" tank

Jim Kraft

Re: "Palmer" tank

Rafael Gonzalez

Re: "Palmer" tank

Rafael Gonzalez

Re: "Palmer" tank

Jim Thomerson

Re: "Palmer" tank

Bill Little

Re: "Palmer" tank

Jim Thomerson

Re: "Palmer" tank

Rafael Gonzalez

Re: "Palmer" tank

Bill Little

Re: "Palmer" tank

Rafael Gonzalez

Re: "Palmer" tank

Bill Little

Re: "Palmer" tank

Rafael Gonzalez

Re: "Palmer" tank