Time for a rant.

(The pix shows a Sullivan 10oz tank I just did this morning. It is ‘okay’ but not really good and there is no satisfaction for me from such a sorry job. It will probably work for a couple of years before turning to crap, causing me repeated dead-sticks with the sport plane in which it is installed (again).)

The worse part of making model airplanes is…. the fuel tank. Some people complain about hinging, some detest soldering, and so forth – but I am convinced that building the tank is much more hateful.
First of all, the manufacturers give you a tank KIT, not a tank. The little parts inside could easily be prebent in mass - to exact standards. The stopper could maybe be made of something less infuriating to try to push the tubes through, damaging them in the process so the tank will fail after a while. The assembly could be worked out so that, even if you have to do it, it is less of a pain and less likely to incur damage. I think the engineering of these things is generally abominable.

- I know that there are European tanks, not easily available in the USA, which may be far better – I wouldn’t know. It doesn’t matter because I can’t get them anyway.
- I also know that electric power would solve all my tank issues. Of course this would introduce a whole new universe of irritating problems.

I would bet that there are TRICKS to building tanks that I haven’t heard - better ways to BEND brass tube, better ways to SLID them through the stopper without using pliers which screw up the tubes, etc. and better ways to MOUNT the tanks other than the half-a#### methods I use.

I would love to hear about them.

It would also be good to know if there are people out there who will build a tank for someone else for a reasonable price. I would love to phone or e-mail someone and order an ASSEMBLED Sullivan 12oz slant tank, or whatever my current project calls for.

If the size and shape works for you, Hayes tanks are fairly easy to build.

http://www3.towerhobbies.com/cgi-bin...SM&C=QCA&V=HAY

I dont think the engineering is bad as much as the betterment has stopped in 1975. Sometime I am going to try the Tetra tanks, which have to be the best. For your scale planes, why not build one out of tin plate to the shape you want and use the stopper like the Hayes.

Hi allanflowers
Your prayers have been answered. I too suffered with the Sullivan type tanks you refer to. One day at my hobby store they had no more Sullivan tanks so I tried another type. It is the Hayes tank. As soon as I installed it I saw it as a superior tank to anything I have ever seen in our hobby (28 years flying R/C). After a few flights I purchased enough new Hayes tanks for my small fleet and discarded the Sullivan tanks before they gave me any problems. The best part of the Hayes tank is that it uses a very small O-ring seal. By being small the seal and the hole it engages with is extremely strong. Some of my Hayes tanks are over 6 years old and seem to last forever. I don't have to bend any tubing.

If your have problems with bending your pipes. fill them with water and freeze them. Once they come out of the freezer you can bend them without a kink.
Phil

Use Hayes tanks, they are reliable, strong and easy to setup. Tower sells them.

Here is my 2 drops of fuel. I have never liked the slant style tanks. They just never seemed to work for me. Now to bend the tubes, put a piece of cable through them, bend, pull cable out. The bends do not have to be perfect. I have used my fingers many times. Just curve them a little, they do not have to be an exact 90degrees. Just get them close.

Use some spit, water, window washer fluid, fuel, to lube the tubes up before you put them into the rubber stoppers.

Leave the clunk about 1/4 or so away from the bottom/end of the tank. I have had ti where the cut outs were not big enough and the engine would create enough suction to hold the clunk against the back.

I have many of these tanks.

http://www3.towerhobbies.com/cgi-bin...&I=LXD718&P=ML

I have used the stock tanks that come with ARF's for my YS .63 engine and they do work.


Dru.

I agree that the Hayes tanks are the best, but if you must use the brass tubing type, here are my suggestions. Cut the tubes to length required by rolling the tube under an exacto blade. Clean the inside of the cut end with the same blade (since it's now too dull for wood cutting). Use a pipe cleaner or rolled piece of paper towel through the tube to clean out the filings. Bend as per above suggestions. Use WD-40 to lube the tube as you slide it into the stopper. Push it in with a wood block, not your fingers...ouch! Lube the stopper with WD-40 and slide it in. The WD-40 will dry and help secure and seal the tubing and stopper.

Paul

On topic of tanks etc, I've always wondered why brass tubing are still used... exposure to glow fuel makes it go green with time, forming a slime. (I'm using good quality fuel and mostly Dubro tanks). I've had a couple of tanks where the brass tubing became brittle and cracked lengthwise into "slivers", almost like glass splinters.

There are now tanks available with a plastic screw type stopper with fuel type nipples already moulded in it. It works so much better - no brass needed but these tanks are very difficult/scarce to get.

Why not use stainless steel/aluminium (one get it with some tanks) or above plastic nipple type stoppers?. Is it a matter of cost or just tradition?

If you really don't want to assemble your fuel tanks you might be able to buy what you want from Hangar 9. They have a number of tanks available that are already assembled ready to use - if you are ok with a two line tank setup. Just go to the Hangar 9 site and search for fuel tanks.

Ed

If you're worried about the brass tubing reacting with the nitro and going green buy a few lengths of copper tubing from your local hobby shop and use that instead. It's softer (and therefore easier to bend) than brass and doesn't react to nitromethane. I purchased some "tube bending springs" from my hobby shop too - they're a set of long springs of different diameters with a flare on one end. You put them over the tubing so it can't "crunch up" when bending, then remove the spring when done.

If you get nice long lengths of copper tubing you can fit it so one piece of copper goes all the way from inside the tank to outside the firewall, and reduce the amount of silicon line (that needs replacing) inside the fuselage. Of course, you'll still need to replace the piece of silicon inside the tank periodically. While I'm on the topic, sticking a 1 inch piece of copper tube in the middle of that bit of silicon line in the tank will help prevent the clunk from moving forward of a hard landing.

I've actually wondered why we don't have/make slim tanks that we can build into the wings, similar to full scale planes. On most single engine planes it would involve longer fuel/pressure lines and a disconnect for each line but it would give longer flight times without worrying about affecting the CG (since the tank would be on top of the CG). It might be a problem with some planes that use retracts etc, but it'd be great for everything else, especially multi engine planes like the DeHavilland Mosquito, Douglas DC3 etc that have the gear folding into the nacelle, require multiple tanks, and have limited space in the nacelles for tanks.

I do not understand why people in this thread rate Hayes so high. I no longer purchase hayes tanks, as I have had 2 that leaked right off the shelf. In both cases the leak was in the tank seam, an obvious quality control issue. I know of another member of our club that also had 2 Hayes tanks leaking in the same manner.

Hi nk3t
I'm one of those who believes that the Hayes tanks is the best thing since sliced bread. The O-ring seal is what sold it for me. When I was working as a Mechanical Engineer I designed hundreds of applications for O-rings and was always impressed with the simplicity and reliability. On the Hayes tank nothing is machined so there could be a quality problem. Did you always use the Vaseline on the O-ring that is recommended in the installation instructions? I used the Sullivan tanks for over 10 years. One day I was having engine run problems and noticed the large white Sullivan rubber plug was shredding and coming apart. Little bits of white rubber were all over the place, including the carburetor. Apparently age and fuel had attacked the white rubber. I immediately threw out every Sullivan tank I had and replaced it with the Hayes tank. I think some of my Hayes tanks have been in use for over 5 years. I have taken the time to give you a detailed report on my experience. I would like to read your story. Thanks for reading mine.

I've used three Hayes tanks and none leaked. So, my somewhat limited experience tells me they are good.

A few tricks that are helpful for me...

Lubricate the tubes and stopper before you push the tubes through the stopper holes. Any liquid will work. I use fuel. Trying to push a dry tube through a dry stopper does not work well at all. I push the tube through the stopper while the tube is still straight. That way I can press the stopper down onto the tube with the tube pressing against my worktable.

There are different alloys / hardnesses of brass tube. Some are much softer and easier to bend than others. See what your LHS has for sale and try several different kinds. The are inexpensive. I have found some that are easier to work with than the brass tubes that come in a tank kit.

I have not had much luck with aluminum tubing. It breaks easily. Maybe there are better alloys / hardnesses that would work better but I have not found any.

A Dremel cut-off wheel works well for cutting tubing. Clean up the ID with a drill bit and clean up the OD with a small file. Flush the tube out afterwards.

Hayes tanks work great for two line setups but do not work for three line setups. In cowled in engines, I like a third line for fueling and defueling the tank. While the Hayes tanks does have a third nipple that can be drilled out for a third line, that only works for fueling since you can not run a fuel line inside the tank to the back/bottom of the tank for defueling. Please do not suggest that I use a fuel valve in the tank/carb line for fueling because I find that that tends to be unreliable in the long run.

Bruce

Bruce, I'm not sure if your reply was to me or not...

I mentioned the Hayes tank to the original poster because he seems to want an alternative to a tank with bent metal lines.

To use a Hayes tank for a three line system, I guess you could stand to model on its nose for defueling.

Each installation has to be looked at to determine what will work best. For my PT-60, Astro Hog, and Uproar (all two line setups); the Hayes tanks work great. My Corsair has three lines and has a Dubro tank.

The SLEC tanks from the UK are the ducks nuts. The fuel feed line and clunk you set up and screw in to the front of the tank, there are two pressure/ fill barbs at the top and all the hose/fueltube fittings are recessed so if the tank slides forward, they dont get kinked. They are hard plastic with a square profile, very easy to make a home in your plane for , dont leak , no brass tubes to bend, no uneven unsquare "bulgy" surfaces , and are a good thing. Try em, I think the poms are onto it with these tanks.

Old trick, Get some weed eater line the right size for your tubing insert bend and pull line out. good luck!

Here is a thought about fuel tank investment:

Fuel tank: 10 bucks
Servos: 30 - 50 bucks each (decent ones)

In other words, fly a thousand dollar plane on a ten dollar junkbucket fuel tank! HAHHAHAAAA amazing!

I am in the habit of checking tanks for leaks before installing them into planes. I assemble the tank according to the directions, and blow into them while submerged in a bowl of water. The Hayes tanks have a visible seam that indicates where the mold comes together. This seam area is where I have had problems. The other leaks I have seem from a fellow flyer were in the corner of the tank, where the material thinned out to a small pin hole. I do not have any complaints with the engineering of the tank, it appears to be a good design. I have however run into manufacturing defects. Having personally seen 4 such failures, prevents me from purchasing Hayes tanks, or recommending the purchase of Hayes tanks.

Read this:

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=1068]Let's Talk Tanks[/link]

Hi nk3t
Thank you for an excellent report. If Hayes allows the referenced seam to be exposed on the surface the O-ring bears against, they are idiots. A cutting reamer or a hot tool would eliminate the seam at little cost; an O-ring seal needs a good surface to seal against. I just looked at one of my used Hayes tanks, but I did not want to take it apart to look at the surface in question. Next time I'm at the hobby store I will look at one. I may even send Hayes an inquiry e-mail. Have you ever seen the Sullivan large white plug shred as I described in my earlier e-mail? I don't really remember if it was a Sullivan; it was the large plug and was white. I do not purchase cheap, unknown things for my planes.

K&S makes a set of small tubing benders that work pretty well. They look like long springs, the tubing fits inside and you can bend it without kinking, to a point.

Rick

I wish I had posted this before I ruined a day building that tank (I also built one a few weeks ago for another sport plane and it was hell too).
THANKS for some great ideas on the various problems with these things.
I have gotten fairly good with tube bending (using a braided cable inside and the spring thing outside) but it is really hard to control the bends as to exact location and radius. Usually they look a little kinked and that offends me too. I will try some of the other bending ideas and maybe even try copper tubing.
The ideas for lubricating the tubes for inserting will help a lot! My old hands keep me awake at night as it is, and forcing the tubes through the stopper is brutal.
I will look at the Hayes and Dubro tanks with a fresh eye. I usually want a three line system but there are ways.
I saved out MinnFlyers great article because it is so clear and informative. It also shows ways of doing the installation with less tube bending, particularly on the fill and clunk lines – assuming I drop the idea of the “slant” tanks (which just force the necessity for more tube bending than the end cap type).
I heard that the Slec tanks may be available through Hobby Lobby so I will order one to see what it is. Also I will check out the assembled tanks at Horizon.

Again, many thanks to you all.