Author Topic: clunk tank for stunt (Read 10979 times)

Bootlegger · « **on:** August 29, 2011, 12:40:39 PM »

You fellow that are running a pastic clunk tank on your profile stunt ship's would you share how you are venting it?
This hard tank keeps leaking, so I'm looking at a plastic clunk.
Oh, be a specific as you can please..
Thanks a lot, Gil

Alan Buck · « **Reply #1 on:** August 29, 2011, 12:53:54 PM »

Gil go to the www.tulsacl.com site. to the workshop under engines and tanks. they show how to make clunk tank

Tim Wescott · « **Reply #2 on:** August 29, 2011, 12:59:14 PM »

I have run plastic tanks, briefly, in the past. Between problems with what should have been a perfectly good tank (it had only been in storage for 30 years, after all) leaking, the fact that I can paint a metal tank to match the plane, and the fact that metal tanks are quite cost-competitive with plastic when you build them yourself from tin cans, I went to metal.

When I do use a plastic tank, I make it uniflow, with the uniflow vent held as rigidly as possible at the desired level and a clunk arranged to flop around on the outside-circle side of it. There's an overflow vent in there someplace, which gets capped when I'm done filling the tank.

I'm no expert, though, and from what I gather it's not nearly as important to have a uniflow setup when you use muffler pressure -- if that's the case, you may be able to just set it up the way you'd set up any old RC tank and have it work well.

Kick the back of the tank over to the outside of the circle by 1/8 or 1/4 of an inch, to make your end-of-tank run more dependable (this applies whether you're using a metal or a plastic tank).

Garf · « **Reply #3 on:** August 29, 2011, 05:46:52 PM »

I made my NoblARF clunk tanks from old Kap-Pak rectanks. God only knows how old they are. All 3 work well. I made a tank for my partners BiSlob the same way. Works fine.

http://hangarflying.proboards.com/index.cgi?board=wire&action=display&thread=2426

Balsa Butcher · « **Reply #4 on:** August 29, 2011, 06:07:32 PM »

If you do a search on this forum for "John Miller Clunk Tank" you can access John's description of how he sets them up along with a diagram of. I have had good success doing them like this but still prefer metal.

John Stiles · « **Reply #5 on:** August 29, 2011, 06:16:44 PM »

I'm phasing out all my metal tanks because #1 most have lead solder, and #2 they all develop leaks. There's nothing more frustrating than a leaking tank. I have bought plastic tanks from way back in yore that still don't leak. If they do, it's always a fuel line and not the tank. Knockin on wood as I say that....I always position the vent in the foward most and left most upper corner.

Brian Massey · « **Reply #6 on:** August 29, 2011, 06:41:24 PM »

I run 3 outlets on my plastic tanks; the type that have a "plug" on the front. Besides the "clunk" line to the engine, I run one vent to the inside (of the circle), front/top of the tank, this is my muffler pressure line which I remove from the muffler during filling to allow release of air without inadvertently flooding the muffler. The end of this line in the tank should be above the full fuel level to prevent siphoning. This line requires a pretty good bend in the tubing to make it. The other extends into the tank near the top, and is my fill line; it is plugged as soon as the tank is filled. And yes, the back of the tank should be shimmed out about 1/4 inch; that really does help the end of run.

I've tried uniflow with no luck; no matter what I do, I do not get a good consistant engine run with it. I do with the tank mentioned above.

Brian

Steve Helmick · « **Reply #7 on:** August 29, 2011, 09:10:29 PM »

I found this picture on Stuka Stunt. It's pretty much the way Danny Dirt is rigging his Hayes tank now, except that he's using a "Slimline". Being thinner is probably a good thing. Da Dirt and I would both suggest drilling out the auxilliary spigot before you assemble the tank. You could hook muffler pressure to the spigot most outboard, if you want uniflow/muffler pressure. You can hook the uniflow inlet (the brass tube on the inboard side of the fuselage) to the aux. spigot and then fill there and cap the brass tubing. It probably would not matter, as long as you don't forget to cap the tube off. If you want to try uniflow without muffler pressure, then hook the tube from the brass uniflow vent to the outer-most spigot, and cap the aux. spigot after filling.

I am using the same tank as shown in this picture on my F'Twister, except it is rotated so that the "shoe" or "foot" is down and forward. This is the way Dirt used to recommend ("Exactly the way they're used in an R/C plane"). My muffler line hooks to the top spigot, the uniflow to the aux. spigot, and the uniflow intake capped after filling through it. My setup leans out for the last couple of laps, but never burps. The rear of the tank is shimmed outward a little. Works fine, and the Hayes tanks just won't leak. I have put together two Sullivan tanks, and had one that worked fine, and one that leaked like a pig. FWIW.

Either way you setup the Hayes tank will work fine, tho turned sideways like the picture is the only way to rig it for Uniflow, but then it's a hassle to fill.

Steve

Brian Hampton · « **Reply #8 on:** August 30, 2011, 12:48:38 AM »

This is the tank set up I used on a profile I built as a trainer for my son and mounted sideways compared to the normal RC useage. The Uniflow line (connected to muffler pressure) is brass tubing bent to lay along the outside wall and ending around 3/4" from the rear of the tank so as not to interfere with the clunk. The vent line with it's cap is fairly obvious but what may not be so obvious is that I'd fitted the filter the wrong way round

. This particular tank is tapered so when laid flat against the fuselage it has a natural off set at the rear. No problems with leakage but I do screw on the cap as tight as I can.

SteveMoon · « **Reply #9 on:** August 30, 2011, 07:32:36 AM »

Doc: Doug and I have used plastic clunk tanks exclusively for 15 years now. We always
set them up the same way whether it's for a profile plane, 4 stroke motor, pipe motor,
full body, etc. It doesn't matter they always work. We learned this method from Tom
Farmer and Bob Gieseke.

We use the Sullivan tanks with 3 lines. One outlet is the vent line to the top of the tank.
Second is the pressure line. This is a curved brass tube that goes about an inch or so
into the tank and then curves back to the front of the tank towards the inside of the
circle and inline with the center of the tank. The third is the fuel pick up line. This is the
clunk and it is important this move freely in the bottom or back of the tank.

We've always had great success with these tanks, and they always work.

Steve

Allan Perret · « **Reply #10 on:** August 30, 2011, 09:34:09 AM »

Quote from: SteveMoon on August 30, 2011, 07:32:36 AM

Doc: Doug and I have used plastic clunk tanks exclusively for 15 years now. We always
set them up the same way whether it's for a profile plane, 4 stroke motor, pipe motor,
full body, etc. It doesn't matter they always work. We learned this method from Tom
Farmer and Bob Gieseke.

We use the Sullivan tanks with 3 lines. One outlet is the vent line to the top of the tank.
Second is the pressure line. This is a curved brass tube that goes about an inch or so
into the tank and then curves back to the front of the tank towards the inside of the
circle and inline with the center of the tank. The third is the fuel pick up line. This is the
clunk and it is important this move freely in the bottom or back of the tank.

We've always had great success with these tanks, and they always work.

Steve

So you dont use uniflow ?
Dont your lap speeds increase toward end of flight ?

Jerry Leuty · « **Reply #11 on:** August 30, 2011, 09:58:32 AM »

I have been using clunk tanks for the past 12 years now. I use a two line system for the profiles. I also run muffler pressure. The pressure line is short and generally makes a 90 degree turn up towards the top of the tank. You just have to make sure that the pressure line has no kinks or sharp bends in it anywhere. The pressure line has to feed pressure or else the engine will run for about 5 laps then die for starvation of fuel. Ask me how I know. I always get a full run from each tank. This causes me to have to gauge the amount of fuel to not over run the judge's stop watch.

dennis lipsett · « **Reply #12 on:** August 30, 2011, 01:54:15 PM »

I'm suprised that no one has used plastic tube for vents. Sullivan gives you a piece with every tank and it is probably the best thing available to make the overflow vent out of. It is simplicity itself to form the radius to get to the top of the tank and it's main advantage is that is is flexable enough to get into the neck of the tank without having to resort to contortions to get the vent lines and stopper seated.
In R/C it is not unusual to use the inner tubing of a Nyrod set up for all vent applications. I just came across a few from 15 years ago and they are still useable. You will also find that fuel tubing has a tendency to really get a grip on plastic tubing.
On my most recent uniflow tanks I copied an idea that some other friends were using and that is to use 2 clunks for feed and uniflow. They are not joined in any way and are left free to flex in the tank.I will say that the settings are consistant with this method and the engine speeds up for about 3 laps and then quits as if a switch had been thrown.
dennis

SteveMoon · « **Reply #13 on:** August 30, 2011, 02:51:40 PM »

Allan: No, the lap times do not speed up. With the tank plumbed the way I
described as soon as the plane is released and moves forward the pressure
line is uncovered and stays that way the entire flight, so it stays the same
for the whole flight.

Later, Steve

John Stiles · « **Reply #14 on:** August 30, 2011, 02:57:22 PM »

Quote from: dennis lipsett on August 30, 2011, 01:54:15 PM

I'm suprised that no one has used plastic tube for vents. Sullivan gives you a piece with every tank and it is probably the best thing available to make the overflow vent out of. It is simplicity itself to form the radius to get to the top of the tank and it's main advantage is that is is flexable enough to get into the neck of the tank without having to resort to contortions to get the vent lines and stopper seated.
In R/C it is not unusual to use the inner tubing of a Nyrod set up for all vent applications. I just came across a few from 15 years ago and they are still useable. You will also find that fuel tubing has a tendency to really get a grip on plastic tubing.
On my most recent uniflow tanks I copied an idea that some other friends were using and that is to use 2 clunks for feed and uniflow. They are not joined in any way and are left free to flex in the tank.I will say that the settings are consistant with this method and the engine speeds up for about 3 laps and then quits as if a switch had been thrown.
dennis

Now that's exactly the kind of info I've come to expect from you dennis...heck, I hate using brass, copper next, and finally aluminum. I'm fixing to re config. two tanks right away!

Tim Wescott · « **Reply #15 on:** August 30, 2011, 03:55:52 PM »

Quote from: dennis lipsett on August 30, 2011, 01:54:15 PM

It is simplicity itself to form the radius to get to the top of the tank

I'm too complicated to understand that answer -- how do you get it to bend and stay bent?

Allan Perret · « **Reply #16 on:** August 30, 2011, 06:06:58 PM »

Quote from: SteveMoon on August 30, 2011, 02:51:40 PM

Allan: No, the lap times do not speed up. With the tank plumbed the way I
described as soon as the plane is released and moves forward the pressure
line is uncovered and stays that way the entire flight, so it stays the same
for the whole flight.

Later, Steve

What you described is not the typical uniflow set up, which I thought was the only way to not have lap times decrease with fuel burn off.
I understand what you said about the pressure line uncovering early on, but you would still have a decreasing head pressure as fuel burns off.
I am not doubting that it works for you, just asking do you know why it works ?
I have a profile been having problems with getting good engine run, will have to try your set up on it..

John Stiles · « **Reply #17 on:** August 30, 2011, 06:10:10 PM »

Quote from: Tim Wescott on August 30, 2011, 03:55:52 PM

I'm too complicated to understand that answer -- how do you get it to bend and stay bent?

I thought about that too, Tim....but I'm a diehard fabricator and I'd be willing to bet it has to do with heat.

Allan Perret · « **Reply #18 on:** August 30, 2011, 06:13:49 PM »

Quote from: Tim Wescott on August 30, 2011, 03:55:52 PM

I'm too complicated to understand that answer -- how do you get it to bend and stay bent?

Heat. When I setup a plastic clunk tank for uniflow, I heat form the plastic tube for the uniflow, and a short soft brass or copper for overflow. Makes it easy to get everything thru the neck.

Howard Rush · « **Reply #19 on:** August 30, 2011, 06:45:47 PM »

Quote from: Garf on August 29, 2011, 05:46:52 PM

I made my NoblARF clunk tanks from old Kap-Pak rectanks. God only knows how old they are. All 3 work well. I made a tank for my partners BiSlob the same way. Works fine.

http://hangarflying.proboards.com/index.cgi?board=wire&action=display&thread=2426

This is a strange twist on an old joke. About 1960 somebody-- maybe Darwin-- sold a metal tank with a flexible pickup. It went clank, so it was given the name Clank Tank, which amused everybody. Somebody adapted this to a plastic tank and called it, also onomatopoeiacally, a "clunk tank". Now Garf has reverted to metal without reverting to the former nomenclature. It needs a new name. I move it be known as a Tink Tank. It's still onomatopoeiacal, but uses alliteration, rather than rhyme. Where's Dennis Moritz when you need him?

dennis lipsett · « **Reply #20 on:** August 30, 2011, 06:48:39 PM »

Quote from: Allan Perret on August 30, 2011, 06:13:49 PM

Heat. When I setup a plastic clunk tank for uniflow, I heat form the plastic tube for the uniflow, and a short soft brass or copper for overflow. Makes it easy to get everything thru the neck.

As Allen has said your heat gun is your friend here. You can make some rather serious bends with a heat gun. You can easily take it straight up from the rubber stopper to the top of the tank and never kink the tubing. Try doing that with brass or copper so easily. Granted a torch will let you do the same thing but your better off to buy the alreaty annealed tubing if you have to do a lot of bending. Done correctly iIcan fill my tank and not leave so much as an air bubble at the top of the tank.

To answer Howards reply about the 'clunk' tank. I think that credit goes to Harold Debolt who made a round brass tank with a tube in the middle of the frontplate. the next larger sized tube was slipped over that and bent to the bottom of the tank. A brass pivot was soldered to the radius of that tube to keep it in place aby putting a slight pressure on the back of the tank. It left the assembly free to swivel a full 360 in that tank but it made a clunking sound while it did it. I really liked those tanks and used them on a Debolt Combateer. As I wrote on another forum the tanks worked great, the Combateer was a p.o.s.

Dennis

Howard Rush · « **Reply #21 on:** August 30, 2011, 07:04:59 PM »

Yep, DeBolt. I found this, amongst some other stuff: http://images.rcuniverse.com/forum/upfiles/467098/Bw71618.pdf

Garf · « **Reply #22 on:** August 31, 2011, 12:29:42 PM »

Quote from: Howard Rush on August 30, 2011, 06:45:47 PM

This is a strange twist on an old joke. About 1960 somebody-- maybe Darwin-- sold a metal tank with a flexible pickup. It went clank, so it was given the name Clank Tank, which amused everybody. Somebody adapted this to a plastic tank and called it, also onomatopoeiacally, a "clunk tank". Now Garf has reverted to metal without reverting to the former nomenclature. It needs a new name. I move it be known as a Tink Tank. It's still onomatopoeiacal, but uses alliteration, rather than rhyme. Where's Dennis Moritz when you need him?

I simply call it the "Garf clunk tank". That comes close enough to suit me.

Chucky · « **Reply #23 on:** August 31, 2011, 01:27:50 PM »

Al Rabe built a metal uniflow clunk tank for his Mustunt in 07.

http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=294163&mesg_id=294163&listing_type=search

Although he did not name his tank, he does refer to the venting scheme as "Siamese uniflow", giving credit to those who had done so with plastic tanks. So can we call this a Siamese tink tank?

Robert Zambelli · « **Reply #24 on:** August 31, 2011, 02:42:51 PM »

I stayed away from clunk tanks for quite a while but after trying them, I'm sold.
As far as I'm concerned, the Hayes tanks are the best on the market.
I put one (3 ounce) on the prototype P-40 and immediately got the best runs I've ever had with it.

The Big Bullet also has a Hayes 3 ounce but I had to modify the pickup line as seen in the photo. I will try it soon.

Bob Z.