Filter/reducer
Next for a pressure reducer, get some of the Master Air Screw (MAS) disposable fuel filters (fig. 5). I've found them in both the blue and gray color.  They're both the same.  Carefully heat one end of the filter until the plastic starts to melt. Roll the end on a hard surface until the end is sealed off. Then make a very small hole in the sealed off end (fig. 6). There are several ways to do this. You can heat a small straight pin to make the hole. I use a small hand drill that I got at my local hobby shop and use a .020" drill bit to drill the hole (fig. 7).  Which ever way you make the hole try to keep it small, in the range of .010" to .020".

Throttle pinch off
Next you need to make a shut off/pinch off that is throttle controlled. This is more for just stopping the engine from flooding after you shut the engine off and you still have fuel in the bladder. Remember that the fuel is under pressure and flowing even if the engine isn't running.  Over the last six months of flying SSC we've come up with a variety of pinch off designs.  My first pinch off on the Bandito (fig. 8) I used the same basic idea that Lee used. Using a large servo arm like the Hitec red ones, I drilled out one of the holes so that small sized fuel tubing will slide through, not the medium size that you normally use. I glued a small block of hard wood onto the servo case. The height of the block was just short enough for the servo arm to pass over it. I adjusted my servo travel so that in the throttle idle position of the transmitter stick I had the servo arm pinching the fuel tubing shut against the wood block. I sanded the edge of the block of wood round so the it wouldn't cut the fuel tubing when it's pinched and fuel proofed the wood with CA because of engine exhaust in the area.  I've use the same method of pinch off on my SSC Smack as Lee's Falcon (fig.9) by gluing the pinch block to the frame or fuselage next to the throttle servo and running small fuel line through a large red servo arm. With the SSC warbirds Lee came up with two variations that worked very well.  The first one was just a 90 degree bend in the throttle linkage and squeezing the fuel tubing against the firewall.  The fuel line is held in place with a couple of small eye hooks (fig. 10-11).  The second variation pinch off uses a loop in the throttle linkage (fig.10).  It pinches the fuel line the same way and you don't need the eye hooks holding the fuel line in place.  The red tubing that you see in some of the pinch offs is a very thin walled flexible fuel tubing that you can get from George Cleveland.  It's nice to use but not necessary, I've been using the pink small silicone fuel tubing that I get at the hobby shop and it seems to work fine.  A tip, there's a difference in the wall thickness of at least a couple different brands of the small silicone fuel tubing.  Don't use the thick wall with a real small ID tubing for this application.  At my hobby shop the blue is the thick walled and the pink is a normal thinner walled tubing.  You can see a big difference between the two.

Secondary RNV
Next feed the small fuel tubing to a OS remote needle assembly PN# 21181902 (fig. 13). This RNA is just a replacement needle assembly for a 10 or 15 size engine and has nice fine threads for good adjustment.  The key to the secondary needle value is feeding the fuel to it backwards.  As you can see from the picture the fuel flow is into the needle orfice and out the nipple.  Which is opposite of what you would think to do.  The reason you want to do that is because the orfice and needle gives you very good pressure control.  If you were to feed the fuel into the nipple as normal the RNV is likely to leak around the needle threads and the o-ring and cause you engine setting problems.  That was the mistake I made the first flight I made with the bladder system.  You can see in the picture (fig. 8) of the Bandito that I've got the RNV hooked up normal, feeding the fuel into the nipple, which is wrong for this application.  I use the secondary RNV because my Magnum engines have a coarse needle adjustment and so I just back out the Mag needle to 3 or 4 turns and use the OS RNA to needle the engine.  If you are using an OS 15LA engine which has a RNV you could turn the fuel lines around and use it and not have to have the secondary RNV.

Bladder containment
Next I needed something to put the bladder in. When filled with fuel the 3/16" tubing expands to around an 1 3/4 (1.67") in diameter and the 1/4" tubing expands to about 2" (1.9") so I was simply looking for something slightly larger as a containment. The reason the size of the containment or cavity is important because you don't want the bladder being squeezed by too small a containment.  This creates false pressure at the beginning  and you set your needle for that slightly higher pressure.  When the bladder shrinks away from the sides of the containment or cavity then the pressure drops to the true pressure of the bladder and your engine will go a little lean.  If you are using a wing cavity and there's just tape on the top and bottom of the cavity, the tape will give enough that you won't have a problem.  But in a hard cavity like a pill bottle or a small water bottle like I've used on the Bandito you have to keep the bladder loose. At first the closest thing I could find was a little children's size bottled water container (fig.14). Bigger then I needed but convenient.  Later I found a pill bottle that was the right size.  Lately I've been using a wing cavity in both my SSC Smack and SSC warbirds for the bladder (fig 9, 15).

Fueling syringe
Next you need a fueling syringe (fig.16), the larger capacity, bigger diameter syringes you find at the hobby shop don't work well for fueling these bladders.  You need a veterinary syringe.  I picked up a half dozen 2oz veterinary syringes at "Tractor Supply" which is a local feed store.  I cut down the needle to a more convenient length and ground the end smooth so it wouldn't tear or cut the fuel tubing.  They make various sized needles for the syringes.  Get 16 gauge or larger.

Fuel line clamp
You'll need some kind of tool to pinch off the line coming from the bladder. Again there's a lot ways to do that, At first I just used a pinch off clamp (fig. 3) that a lot of the helicopter guys use that I had handy, though it didn't turn out to be real easy to use. You need something bigger and that's easier to handle and the little inline clamp was too small for me.  I've since used hemostats, a modified cloths pin, and little clamps (fig. 17) that I found sold in packages of 6 or 8 at Home Depot.

Bladder preparation
After you've put together your bladder you'll want to "train" it.  Using your syringe and holding the bladder tightly in you hand with just the end exposed put some air into the bladder (fig. 18,19).  Doing this with a new piece of bladder material insures that it will fill from the far end each time you put fuel in it.

Fueling the bladder
Just a couple of tips, to fuel the bladder take the fuel line off the back side of the pressure reducer/filter and fill the bladder directly don't make the mistake of taking the fuel line off at the RNV and trying to fill the bladder with the pressure reducer in the line.  You'll never get the bladder filled trying to push fuel back through the reducer, trust me!  The other thing with using a bladder system is that you must become closer to your pinch off clamp then you are with anything else, even your wife.  If the clip isn't on your fuel line you should have it with you!  I clip it onto my shirt so I always have it.  Back to fueling the bladder, with a two oz syringe you'll have to fill the syringe at least twice to fill the bladder.  Which means you simply fill the bladder, clamp off the fuel line with your clip, reload the syringe, stick it back on the fuel line, release the clamp and remember that the fuel in the bladder is under pressure and is going to want to push the plunger out of the syringe that is already full of fuel!  Making a mess with fuel everywhere.  So hold onto that syringe!  A fellow pilot put a small screw into the syringe at the very end so that the plunger can't come out.  It's a good idea and I think I'm going to do the same thing with mine.  Also, time for a safety reminder, wear eye safety protection at all times when fueling!  The nitro fuel can cause blindness!  It doesn't make any difference if you're using a fuel tank or a bladder system you can have an accident pumping fuel and get it in your eyes.  In addition to eye protection, it would be a good idea to always carry a water bottle to wash out your eyes in an emergency.

Engine setup
Now to get the engine running. I set the needle on the engine carburetor out 3 or 4 turns and left it alone. I later put a tie rap on it to stop it from backing out but not before I had lose a needle!  Lee uses a piece of fuel tubing to hold it in place.  In any case, secure the needle with something so that you don't lose it.   I set the OS remote needle at about 1 1/2 turns. With a full bladder, take the pinch clamp off the line and hold the line pinched off with your fingers. Release the line long enough to get fuel flowing up to the carburetor and then a second or two longer to prime the engine. Now pinch the line off again with your fingers and hold it. With the throttle wide open, start the engine and wait until it comes up to full rpm and starts to drop off, then release your fingers pinching the line and the engine will come back up and run. I had to turn the needle on the OS RNV in about a 1/2 turn to get the engine about right. Then in a little more to get on peak. When you're first setting the RNV and it's too rich, you can keep the engine running while you're adjusting by pinching and releasing the fuel line periodically.  I backed the needle off a couple of clicks and did the old pinch and release of the fuel line to see that I didn't leave it right on peak rpm and then go lean in the air, just like a normal setup. In fact with my Magnum 15 if I set the needle so that when I do the quick pinch and release on the fuel line and the engine comes up onto peak and then just ever so slowly drops off of pinch, not just drops off of peak immediately, then the needle is set perfect. Another tip, if you end up in the air with the engine a little lean and you don't what to come down to re-needle, you can throttle back just a little which will reduce the amount of air into the carbuetor and bring the fuel mix back up.  Another way of saying it is that your throttle is only adjusting the air to your carburetor and not the fuel.  There's no adjustment of the fuel flow taking place in a bladder system.  As long as you're not real lean you can get your mixture back where it should be and not lose a lot of power or burn up and engine in the process.

That's all there is to it. Again the only problem I had on my first flight was the OS RNV wouldn't hold a constant setting and I just had to turn my fuel lines around on the RNV backward to what I thought was normal. The first picture of the Bandito (fig. 8) shows the lines hooked up as you would normally expect. In the second picture (fig. 20) the line from the bladder and pressure regulator are shown going on the long straight side and the output from RNV should come out the nipple side. Just the oppose way you would normally think. Again the reason is you want the pressure going through the needle orifice first and then out. That way the needle more accurately controls the fuel flow. If you feed it into the nipple side, the fuel wants to leak out through the needle threads and 0-ring. Probably another good reason not to feed directly to you engine's needle valve assembly.  In fact Lee recommended that I put a piece of fuel tubing over the needle to help seal it.

I hope this helps you get your bladder system up and flying!