This may save some repetition to Kevin. If you want to add to/rewrite/suggest something different feel free.
to help you out here are some pointers.
the Fox36X is a bit of a fuel hog, but not as bad as a Nelson. With two full syringes(60 ml)the Fox36X should run 4-5 miinutes. The bladder is about 70mm long, approx. 120-40mm long with _2mm wall and 6.5mm o.d. with a fuel line fitting in one end and a plug(piece of empty 22casing, a bit of plastic or aluminum, whatever. Just make sure it DOESN'T LEAK or the fuel can destroy the plane.
Plastic line connectors with opposite fittings on a small plate can be useful when filling the bladder. Use a fishing slide clip abour 30mm long, Its best to solder the slider so it doesn't slip at the wrong time.
That brings up needle valves. Almost all the stock needel valve assemblies use too blunt a needle. The simplest way to slow the fuel flow is by making the taper about 50% longer.You want to be able to adjust the flow from a fast drip to a solid flow about 3inches long in 1/2 turn.
OS had a 1a needle valve for the 10 and 15 engines but those are very hard to find.
The stock needle on most OS engine can be taken apart by pulling the needle out of the knurl and chucking it into a drill or a lathe(any size) and using a sharp file or Dremel too to make the metering section 50% longer
A T8fluorescent tube cover is about 1-1/4in. in diameter. A 7 in. piece will hold about a bladder with ease. I don'thave a VooDoo handy, but going by a fuzzy plan, the mounts are space a bit more than 1.25, so it should fit a T8 cover.
By a bit of chance most sink drain tubes are 1-1/4 in diameter. Get a 12-16 in. one. I built a jig, a couple piices o 12mm ply spaced ~36mm apart. Use the foam block with wing in it to size every thing. A lightweight electric drill makes short work of making the cavity for the T8 tube.
Space the tube down a bit so the top of the wing is about 3mm below the surface and close to the high point of the wing, ahead of the spars.
Make a window about 9-10mm wide over the tube after gluing it in place. and a round or oval entry hole 3mm from the motor mount.
For the smaller planes the T10 tubing, ~3/4in (or 18mm) diameter. I've got red-coated tubing with a 1/4in id and a 1/32in wall. It doesn't hold up as well as the heavier tubing, but that applies way too much pressure for the little engines.
Most people use 20-30% nitro for the big engines with 20% synthetic lubricant, often with 5% castor oil, especially for iron/steel setups like the 36x.
That covers combat bladders pretty much. Call or email on Stunthagar to get in touch. I'm still having trouble with the earthlink address.
Cheers,
Phil Cartier
717-566-3810