Bursting Bladders

You know, I never considered that. It is close, but not right on it. I'll move it and see. That's a fresh bladder in the picture.

The heat might make the latex soft wherever it hits. You don't want hot fuel if you can help it either.
Rusty

I thought this thread was gonna go in an entirely different direction.   

flyjsh wrote:I thought this thread was gonna go in an entirely different direction.   

Saturday night Beer Pong?  

UV light will shorten the shelf life of the tubing.

Usually takes 6 beers to burst my bladder......

RknRusty wrote:

flyjsh wrote:I thought this thread was gonna go in an entirely different direction.   

Saturday night Beer Pong?  

I wish. I duty in at 0645 tomorrow.  

Cribbs74 wrote:3 bladders in 4 flights. What gives? Perhaps the tubing is old? I have had it for about a year now.

Last one burst overhead, thank goodness I can sprint still!

Geez... I don't have any experience with bladders Ron.. but I've read where "Rusty" (in particular) takes precautionary measures to have an eyewash bottle handy.. in the case that a bladder bursts while fueling.

As far as degradation goes.. I keep all of my silicone/latex rubber stored away from any light source. Were these "consecutive" flights Ron.. or 4 flights spread out over time? Are you spraying (cleaning-off) your bladder-equipped models with anything different lately.. that could be attacking or "drying-out" the bladder material after a flying session?

Maybe a "spritz" of silicone spray lube on the "exterior skin" of the bladder; where most of the expansion occurs.. would help, after a flying session?

At combat matches, we even cover our bladders with a rag to keep the sun off a full bladder. I can see how a little heat from the engine would cause trouble. Try slipping a piece of pop can between the engine and the bladder as a heat shield.

duke.johnson wrote:At combat matches, we even cover our bladders with a rag to keep the sun off a full bladder.  I can see how a little heat from the engine would cause trouble.  Try slipping a piece of pop can between the engine and the bladder as a heat shield.

Cox made a heat shield on some models (I just bought an Acro-Cub that has one, never knew the heat shields existed).  Not sure how they affect performance.  If you need the part number and want to go to the trouble of finding one, I can dig it up.

Some info I found on bladders.. most of you who use them, probably know all of this already.. but it may be useful for those (like me..) who've never tried them. It clearly explains their construction, benefits and limitations.

http://www.clcombat.info/bladder.html

Ken and Shawn were trying to fly a match last year and popped one everytime they filled it. It turned out to be a very tiny epoxy protrusion from either their fuelproofing coat or the container's attachment coat. Recall if i contain mine at all, I use a soft fabric mesh sheath. I have only had one pop during fueling when I was filling one of the early first ones I ever made.

I pretty much come unglued when that stuff happens. I have just enough patience for the first burst but the 2nd and 3rd usually puts me over the edge. As Rusty says, it only takes the smallest protrusion of foreign matter to do it. The temperature has a lot to do with it. I don't fill the bladder and wait for the match to begin. I fill just prior and I never leave my fuel in the sun or the plane. I cover the bladder compartment with a shop rag. If my plane is on the line waiting to go, the rag is covering the bladder tube so the sun doesn't heat it. They burst instantaneously. Another thing I've noticed, it happens starting in Sept. I start the plane, things go pretty well and 1/2 way through the flight it goes overlean. This is the cold starting to play havoc with the bladders, fuel flow and the fact the bladder become lazy in terms of pressure are responsible. I switch to full synthetic on my Norvel's when the temp goes down. The bladder while looking perfectly intact develops a weak spot in the rear when used in the cooler temps. If you use these later when the temps are warmer, they're generally short lived. Ken

Pen bladders are a thing of the past. While they do make them still and they're a bit difficult to locate they're not the same product of 40 years ago. This is essentially true with everything. At our vintage combat meet last year Larry Scarinzi was using pipette bulbs due to his planes from 50 years ago not having a compartment sized for a blader. These would give a good run but generally by the second and third run they were delivering false pressure due to them weakening and then they would break. Larry used miniature bowling pins sawn in half for his planes back in the day. These bowling pins were made of a plastic similar to ping pong balls. He would dope over them and hope they wouldn't melt. The bladder tubing depending on what your using is far superior to everything that was used in the past. The reinforced surgical tubing is a good choice. I use latex for my 1/2A's due to lower pressure, but this stuff will fail without warning. Ken

I am not sure what restrictions to bladders apply in CL competition, but my recommendation is to use simple party balloons. The material withstands the nitro fuel for long. I have had such bladders in my R/C planes in use for almost 2 years and they have not decayed at all. I put a normal rubber tank stopper in the balloon throat that squeezes on the stopper, and 2 silicone tubes through the stopper, one for filling, one for feeding.

It is true though, that the bladder is inside the fuselage and is therefore not exposed to sunrays.





This one accommodates some 2 oz of fuel without pressurizing it, that is enough for a TD051 for a full-throttle run of 10-12 minutes or so. Your CL application may need a smaller tank, I understand.

Is "Latex" the most commonly available fuel-bladder material? (pardon my lack of knowledge here guys) I was curious about the properties and availability of "other" types of rubber tubing.. so I did a search for thin-wall silicone tubing and came up with some interesting choices... but it would depend on if the tubing could be inflated and "trained" for this intended use. Then again.. if there was a superior bladder material available, I'm sure that Texas Timers would sell it.

"Fluoro-silicone" seems to have great properties for glow-fuel tubing in general. "Vanguard Products Corp."" stocks this tubing in a 1/8" OD x 1/16" ID (.031" wall) size.. as well as other sizes with thicker walls.

http://rubberextrusion.vanguardproducts.com/product/elastomeric-extrusions-and-moldings/tube-shape-elastomeric-extrusions-and-moldings?

roddie wrote:Is "Latex" the most commonly available fuel-bladder material? (pardon my lack of knowledge here guys) I was curious about the properties and availability of "other" types of rubber tubing.. so I did a search for thin-wall silicone tubing and came up with some interesting choices... but it would depend on if the tubing could be inflated and "trained" for this intended use. Then again.. if there was a superior bladder material available, I'm sure that Texas Timers would sell it.

"Fluoro-silicone" seems to have great properties for glow-fuel tubing in general. "Vanguard Products Corp."" stocks this tubing in a 1/8" OD x 1/16" ID (.031" wall) size.. as well as other sizes with thicker walls.

http://rubberextrusion.vanguardproducts.com/product/elastomeric-extrusions-and-moldings/tube-shape-elastomeric-extrusions-and-moldings?

Bump..     Anyone have any thoughts they'd like to share on this?

600 ft minimum order? I haven't even gone through 1 foot of my 6 foot order through texas timers! I think this is a business venture scale.

Phil

I only know what little I've observed from our silicone fuel tubing. It's not very elastic after an initial limited range of... stretchability. I know when I have sliced it for tight fitting o-rings for my Big Mig venturis, it pops easily after a small limit of stretching. I don't think you could blow it up like a balloon as we do with latex.
Rusty

RknRusty wrote:I only know what little I've observed from our silicone fuel tubing. It's not very elastic after an initial limited range of... stretchability. I know when I have sliced it for tight fitting o-rings for my Big Mig venturis, it pops easily after a small limit of stretching. I don't think you could blow it up like a balloon as we do with latex.
Rusty

Thanks Rusty, That's what I was wondering.

Phil Cartier along with most combat suppliers provide reinforced surgical tubing. Phil's tubing is available for 1/2A, medium wall for .15-.25 engines and then he also has a very thick wall bladder with high pressure for fast engines in the .36 size. Phil however uses the thick wall tubing for pretty much all of his needs. Needles are extremely important when choosing bladder tubing. I use Phil's red 1/2A bladder material on Cox 128TPI. Early on, I was using Texas Timers tubing. While it did work well, lifespan was somewhat short and in the cold weather, they lasted approx 2 flights. Cold weather is very harsh on bladders. I switch to Phil's heavy wall bladder tubing in the winter. The bladders are 2" long. In the cold, the bladder doesn't collapse properly which initially on the ground is very rich, 4-5 laps into the flight the engine starts going overlean. I switch to full synthetic(Cox engines as well) in the winter due to this problem and use the heavy wall bladder to insure proper fuel delivery to keep the engine run stable. Castor fuels are very problematic in the cold and will not flow properly causing many run complications. Ken

Ken, when you use full synthetic, as in zero castor, how cold are you talking about, sub freezing? I can conceive of the Cox engine doing fine that way everywhere but the ball socket, but I'm surprised that that scorching hot interface is okay with it. Maybe that's actually a useful application for the low castor Super Fuel. I wouldn't know however, as I'm not near tough and determined enough to go out in the Northern weather you guys are accustomed to.
Rusty

Ken Cook wrote:Phil Cartier along with most combat suppliers provide reinforced surgical tubing. Phil's tubing is available for 1/2A, medium wall for .15-.25 engines and then he also has a very thick wall bladder with high pressure for fast engines in the .36 size. Phil however uses the thick wall tubing for pretty much all of his needs. Needles are extremely important when choosing bladder tubing. I use Phil's red 1/2A bladder material on Cox 128TPI. Early on, I was using Texas Timers tubing. While it did work well, lifespan was somewhat short and in the cold weather, they lasted approx 2 flights. Cold weather is very harsh on bladders. I switch to Phil's heavy wall bladder tubing in the winter. The bladders are 2" long. In the cold, the bladder doesn't collapse properly which initially on the ground is very rich, 4-5 laps into the flight the engine starts going overlean. I switch to full synthetic(Cox engines as well)  in the winter due to this problem and use the heavy wall bladder to insure proper fuel delivery to keep the engine run stable. Castor fuels are very problematic in the cold and will not flow properly causing many run complications. Ken

Thanks also Ken, It's good have as much info as possible in a thread, for people like me who've never tried using a bladder, for knowing what to buy, where to find it.. and what to expect from a given set-up.

You mentioned Castor-based fuels being resistant to flow in cold temps. Approximately how cold? Where bladders are pressurized; ensuring good fuel-flow.. would this become even more of a problem when using suction/hard-tank set-ups? I imagine it's a gradual thickening of the fuel.. but at what temperature does it become problematic? Would adding some methanol to the fuel mix help until it's just too cold?

Our problems start in the fall around the last weeks of October into November.  typically. The temps that are around 45 degrees and colder.  In the sun, you feel pretty toasty, but the planes don't fair well on the 50/50 fuels I use. Mind you this is on bladder only. The full synthetic fuel doesn't coagulate like the castor blend fuels do.  The bladders don't provide the same pressure throughout the run as they do in the warm climate.  I rarely use full castor fuels at all and haven't been doing so for more than 15 years. Yes, I do run Cox engines on full synthetic which is a total oil content of 24% full synthetic heli fuel in the temps I mentioned above. I'm well aware of what can happen, so far I've seen no problems as some have claimed.

1/2A is off for us after our last contest which is the 1st week of November. The problems are overwhelming due to starting and overlean runs . We just switch to speed limit until the weather warms up. Ken