bladder problems!

Tell us what you do to get the best performance from your engines.

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Hat Trick
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bladder problems!

Post by Hat Trick »

I'm having a problem running Webra .36's in my RC combat planes and am looking for some advise! I'm running a mouse can muffler and Powermaster fuel 15% nitro and 21% oil with a McCoy 9 plug and yellow bladder tubing from George Cleaveland. 9 x 6 prop cut down to 8.5 I have 2 planes with the same exact setup and both do the same thing. I've ran this exact setup with 25 size engines without problems like this.
The engines start out fine and run strong with no sagging in hard maneuvers at all. After about 2 or 3 minutes the engine starts to cut out in hard maneuvers. This then progresses into the engine surging even in level flight. I've set the needle valve as rich as it is possible and still keep the engine running and the same thing happens. The times are pretty consistent. Today when I flew the sky was clear blue and I could see that the engine was getting leaner as the flight went on. Went from a big smoke trail to almost none when the surging starts. The only thing that is different is that the weather here is much colder now. I've never flown a bladder in 30 to 40 degree temperatures before. Could it be that the bladder behaves oddly in cold weather? The other thing I've noticed at times is that the bladder seems to be spinning in the compartment. After I land there are no kinks in the line but you can tell that the line is twisted more than it was at launch. The problem starts when the diameter of the bladder gets smaller than the bladder compartment. At the beginning of the flight the bladder is pushed against the covering on the compartment and holds it in place better. I was thinking of putting some latex foam under the bladder to keep it held in place better when the diameter starts to decrease.

I'm getting frustrated and am looking for any advise!
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Which_way_is_up
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Post by Which_way_is_up »

You probably already know this but got to cover all the possibilities. If you fill the bladder to the point that it's pushing against the walls of the cavity that it's in then the pressure will be higher initially and then drop as the bladder shrinks away from the walls. So you set your needle for the higher pressure and then when the pressure drops the engine goes lean.

To verify if this is the problem do not fill the bladder as full, making sure that the bladder is loose within the cavity and see if you have the same problem.

The problem could be exaggerated by temperature and the wall thickness of the bladder material.
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boiler
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Post by boiler »

I was under the impression that you would get a richer run when the bladder pulled away from the wall. Gee I love the tanks.
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Which_way_is_up
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Post by Which_way_is_up »

In fact the more I think about this the more I think that because of the particular material of your bladder that it may not be maintaining a constant pressure because it it not uniformy contracting because of the temperature.

Is the bladder material particularly thick?


Don't get temperatures that low here in Texas to test my theory![:D]
Hat Trick
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Post by Hat Trick »

The compartment only has covering material over it top and bottom so it doesn't see any pressure from that. The material is the yellow silicon that George Cleaveland sells. I think that is what a lot of guys use?
Lee Liddle
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Post by Lee Liddle »

I`d agree with Roy. Eiminate false pressure as the problem by starting a flight with a loose bladder. If that doesn`t help, then it`s most likely that the bladder tubing is loosing it`s elasticity due to the cold. When you`ve used the bladder once or twice is it streched in the middle? Any bladder will do this if you use it long enough, but they do it quicker in cold or very hot weather. I use a natural colored laytex. I don`t like the yellow stuff.

The only thing that I disagree with Roy on is when he says that it doesn`t get cold enough in Texas for him to test your problem. It gets plenty cold. I`ve flown when my problem was ice crystals in the fuel line. It`s just that Roy doesn`t fly if it`s below 60 degrees[:0]. How long has it been since you filled up a bladder anyway Roy?[:D] He he, Well that`s too long.
Rabbit Leader
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Post by Rabbit Leader »

<font size="6">CLUNK!</font id="size6">
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Which_way_is_up
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Post by Which_way_is_up »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Rabbit Leader</i>
<br /><font size="6">CLUNK!</font id="size6">
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Yea, I've seen how well your "clunk" works! [:0]
Lee Liddle
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Post by Lee Liddle »

It`s more like <font size="4"><font color="red">Clank</font id="red"></font id="size4">
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Post by Rabbit Leader »

Zero's tanks work..'47's tank works...avenger's tank works..that's okay, my averages next year will speak for themselves...BANZAI!![:p]
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Post by Hat Trick »

I'm not sure what you mean by stretched in the middle?? I do use the tanks for a long time. thats what I liked about the yellow ones. The latex ones don't last long at all. What size latex do you use and where do you get it. How long can you use them? They seem to detereiorate when exposed to fuel. A lot of the time I only have time for a flight or two and may not fly agai for a week or so. Do you toss a bladder after a couple days? I think I have some latex somewhere.
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Which_way_is_up
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Post by Which_way_is_up »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Hat Trick</i>
<br />I'm not sure what you mean by stretched in the middle?? I do use the tanks for a long time. thats what I liked about the yellow ones. The latex ones don't last long at all. What size latex do you use and where do you get it. How long can you use them? They seem to detereiorate when exposed to fuel. A lot of the time I only have time for a flight or two and may not fly agai for a week or so. Do you toss a bladder after a couple days? I think I have some latex somewhere.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

I made my bladders for daily use. Make it for the day and at the end of the day throw it away! It runs you about 15 cents worth of latex and that way you always have consistent results!
Lee Liddle
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Post by Lee Liddle »

I mean one area of the bladder is streched beyond it`s normal relaxed size and the rest is normal. I generaly just use a bladder for the day, at a contest they may not last that long if the weather is too hot or cold.
Pat_Willcox
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Post by Pat_Willcox »

Mike, Try making a strap on bladder where you can fly and see if the bladder is getting a glitch while in the wing. Be sure and use similiar bladder and just take a few #64 rubber bands with a clove hitch knot on foth ends of bladder. I usually fasten bladder to somewhere just aft on trailing edge of wing and then fasten the forward rubber band around the engine area. Put about four ounces in bladder and fly it. If it leans out as previous, then you need thicker wall bladder material or else use fresh bladders all the time. If set up runs OK, then you need a modified bladder. Get a Elbow fitting so that the bladder has a 90 degree bend for the exit from the bladder. This will stop the bladder from rotating in the bladder compartment. BTW, Lee put me onto just using the floresant bulb plastic tube material for a very simple and efficent bladder compartment holder. Just cut a 6" piece and tape it into wing. Leave a gap big enough to slide in the bladder and use some clear tape on both sides of tube to keep in place. Works great. Another thing that is a remote possibility is those engines getting a bind in the lower end when they heat up.

Pat
CStein
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Post by CStein »

Mike i flew my wing last weekend and had no problems with the bladder it was about 40deg.
i bought 25 foot from mcmastercar i think its latex ill look tommorow. i also got to crash
test one !! Was playing with reflex and didnt have hose over the clevis and i lost the right elevon motor mount held up well but the wing split on both sides on the trailing edge

Corey
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