Hello there, I need help: I bought a pulsejet at BMS - very nice and high quality jetengine. The problem: what is a bladder tank and how is its function? I saw a (bad) drawing of building one, but I don´t understand how it works. I only know that there is a constant pressure on the fuel! Does anybody have some detail photos?

Richard

The guys who fly control line combat use them, and can direct you to suppliers. It is basically a sealed off piece of rubber tubing. You fill with a strong syringe and expand the tubing. This gives you a fairly uniform pressure throughout the flight. There is a fellow in the USA who flys RC pulse jets with bladder tanks. He has a website and probably someone here knows it. The guys I know who fly CL pulse jet speed use a hard metal tank pressurized with a line from the tailpipe. Hope this helps.

Jim

A traditional type bladder tank works like a balloon - only you fill the "balloon" with fuel instead of air. Just like there is constant pressure on the ballon as long as there is air inside, there is also constant pressure on the fuel in a bladder tank - until the fuel is gone and the bladder returns to it's pre-filled size.

O.k. did I understand this correct: I only need a strong tank and put in the fuel under preasure? To regulate it I need a pressure controller!
But why is there a plastic bottle ouside and a tube inside?

Sorry- it doesn´t make sense to me[]

Those who use metal tanks: is it an similar setup like in 2-4 stroke engines? Put a line from muffler to tank?

Thanks for your fast help!!

The pressure is provided by the inflated bladder (inflated with fuel). Because the bladder stretches when it is filled with fuel it is under constant pressure until the bladder "deflates". No regulator is required.

Keep in mind what I've described is a traditional bladder tank, like has been used for many years by the controlline fellas. But they may have newer, more complex versions for more sophisticated jet models (I'm not into jets).

If the bladder is inside a plastic bottle then I believe the bottle acts as a containment vessel should the bladder rupture. And if the bottle is airtight, it would also add extra pressure to the bladder inside the tank because as the bladder expands with fuel being pumped into it, the space the bladder has to expand into would be confined. The ones I saw in my eariler controlline days just expanded into the nose section of the fuselage, which was not airtight. So just the "stretchiness" of the balloon provided the pressure.

I used to use baby pacifiers. Just disassemble and use the rubber bulb they suck on. Make sure that it is very secure to the fuel tube 'cause there is a lot of pressure.

the fellow who flys RC pulse-jets is Bruce Tharpe of BTE. do a google search and you'll find him. his set up uses a cline regulator between the bladder and the engine. the main reason for the bladder is to have a bubble free fuel supply...all it takes is one bubble and the engine dies.

also, the correct material to use is latex and it don't work with gasoline


dave

Hi- yes I found him, but nothing about the cline regulators on the WEB-SITE!?!? Does anyone know where to buy them?

I don't know much about them but Tettra makes them.
I see them advertised at Central Hobbies.

tommy s

for the cline regulator go to [link]http://www.billsroom.com/pcfs/[/link]

another regulator for less money [link]http://www.ironbaymodelcompany.com/Webpages/Accessories/Accessories.html[/link]

or hack a walbro/zama carb and make your own regulator. the cline and ironbay are regulators are based on the same principles and even use the same parts [link]http://home.wanadoo.nl/pereivers/regulated_fuelsupply/a_regulated_fuel_supply.html[/link]

and here's a nice site with info on bladders for pulse jets [link]http://home.earthlink.net/~famcaine/pulsejets/PulseJet.htm[/link]



dave