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Bladder type or long range fuel tank

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Bladder type or long range fuel tank

Old 07-19-2004, 03:15 PM
  #1  
AlphaOrion
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Default Bladder type or long range fuel tank

I have been cranking my mind with the idea for some sort of long range or long run fuel system for glow or gas engines (with variable throttle i.e. for use on a standard 4 stroke glow engine). I specifically need some sort of wing mounted tanks, and although I have read in several forums on the difficulty of using these tanks, I have faith that the system could be implemented with some sort of pump or a sealed bladder. The bladder idea came upon me during a recent hiking trip. I purchased a Camelback personal hydration system for the trip, and was amazed at how easy it is to suck the liquid out from the bladder type structure. I figured that I could somehow apply this to my long range system. I was checking out jett engineering tanks and they seem like the ones for the job. I know these are for pylon, but could they be used for throttle engines? how about using TWO tanks one mounted on each wing?

Has anyone experimented succesfully using bladder-only type fuel tanks? how about the two tank wing mounted configuration, would I need a pump?
Old 03-01-2014, 01:14 AM
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Interesting! I am working on a similar project right now. My plan is to build a 4 channel RC plane for my .049 Cox Medallion engine, loosely based on the Baby Ringmaster. So far I have worked out that Nitrile rubber gloves are able to hold glow fuel with no problem. I have figured out that a 100CC tank will give me about 1/2 hour of running time at full throttle and that the wrist section cut off a surgical glove is about the right capacity. RTV silicon seems to work as a sealant/glue. This will be contained in an outer tank which will be conected to the pressure take off point on my engine. If all works out the tank will be mounted in the center section of the wing. BTW I found your post in a Google search for Bladder type fuel tank. You may find this of interest. http://www.google.com/patents/US2736356 There are a lot of other links a photos in the search results also. I wlii post pics once I have a tank completed and maybe a video. I am making the external tank from clear plastic (Folgers instant coffee) so I can observe how the bladder works in different positions.
Old 03-01-2014, 07:20 AM
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JohnBuckner
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Good morning fellow cross country/endurance enthusiast. The longest endurance flight (that is remaining at the takeoff field for the entIre flight) that I have achieved is is 6 hours and twelve minutes non stop. The airplane is a much modified Senior Cadet with an extended wing by 10 inchs and carrying almost a gallon of fuel in three tanks plumbed in tandem and the power was provided by a lovely OS .65AX with no fuel pumps at all.

This ship is set up also with a single central float of considerable reserve bouancy for a 'dreamed' about flight over water.

I also a little over a year ago flew from Laughlin Nevada to Lake Havasu Arizona down the Colorado river with a Bridi Sun Fly !!! on twin floats also powered by a OS .65AX and this ship carried 72 ounces using four tanks plumbed in tandem in the nose and along the top of the fuselage from the firewall to even with the trailing edge of the wing, Agine no pumps.

The tanks that Dub Jett sells are called bubbless tanks as are the bubbless types that are called Tetra tanks all of these involve an internal bladder inside a hardshell case with muffler/header pressure applied between the hardshell and the bladder. These are wonderful tanks with great fuel delivery performance but also as you noted quite small and once you go beyond the largest Tetras become impractical especially when you trying to package as much fuel into as little space as possible.

I have always avoided wing tanks for the reasons you have noted and while yes the introduction of pumps would almost certainly be required and that's added complication I have preferred to avoid.

If you are interested I would be happy to post pictures of these ships and fuel systems

John

Last edited by JohnBuckner; 03-01-2014 at 07:24 AM.
Old 03-02-2014, 01:37 PM
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rlipsett
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a ys engine will give you a pressurized fuel system so you will have positive fuel flow without the use of a pump
Old 03-02-2014, 08:44 PM
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JohnBuckner
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Ugh I hate it when I forget to check the date on a thread
Old 03-03-2014, 08:14 AM
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AMA 74894
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at least only the FIRST post was 10 years old...

YS engines are very nice to work with, yes..
but they don't make anything near .049 size... so I think YS is out.
Old 05-30-2014, 09:29 PM
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Default tetras

Hey John I would like to see your pics etc and am very interested in the tannks you mentioned as being sold by Dub Jet that are called bubbless or tetras. I am looking for something around 4 ounces to I've me about a half hour of flying time. BTW I didn't notice the ten year old date on this thread either but I guess it don't matter, and I have restarted a forgotten subject it seems.
Old 05-31-2014, 04:27 AM
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JohnBuckner
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Terry It may be an old thread but cross country is one of my passions in this wonderful hobby/sport. getting ready to leave to the flying field this morning and will come up later this morning with lots of pictures on thoughts

John
Old 06-02-2014, 10:30 AM
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hi Terry apologies for not getting back sooner things have been pretty hectic. Here is a link for the tettra tanks from central hobbies:

http://www.centralhobbies.com/Fuel/fueltnk2.html

Now you have to keep in mind that bubbless tanks are bladders encased in a hard shell tank but they are not pressure bladders like the old pen bladder types. The bubbless require muffler pressure which is applied between the hard case and the bladder. I suspect that any of the half A type mufflers would not be sufficient.

I will post up some pics of disassembled bubbless in a few moments. Now there also is tandem type tanks which are essentially just like an ordinary muffler pressure single tank only plumbed in tandem. Perhaps you could use a slightly larger engine which uses a conventional muffler like some of the .09's out there. these would work with tandem tanks.

Also will post up some simple Pictures to illustrate the tandem plumbing and some of my successful cross country airplanes:

John
Old 06-02-2014, 10:35 AM
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Last edited by JohnBuckner; 06-02-2014 at 10:49 AM.

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