pedromvf

Dear all,

I am sure it is a very simple question to all of you but puzzling to me. I have been using nitro engines in my airplanes and decided to acquire a 26cc petrol engine to use with my cessna 182 from China Models. I am not sure how I should connect the tank. The muffler do not come with the tank connection but I know that the Walbro carburator has a diaphragm pump that (maybe) eliminates the need for pressurizing the tank. I believe I should leave the muffler connection open to the atmosphere to avoid creating a lower pressure in the tank but I am not sure. Can someone of you offer me any help with the connection?

Another thing is regarding the tank. The model came with a tank similar to the one we use for methanol. Is it safe to use with petrol?

Thanks a lot.

JoeAirPort

My Feedback: (41)

Yes the tank vent goes to atmosphere with a loop going to the back of the tank. Also use a petrol stopper. Dubro makes one and it is dark red in color. I would not use anything else. I would use barbs on the brass fittings and zip ties to keep the tygon fuel lines from slipping off in flight. Also you can cut little pieces of the next size brass tubing and solder them on for some cheap barbs that work great.

pedromvf

Thanks for the information Joe.

May I ask what do you mean by barbs? I was planning to use little cable ties to keep the silicon tubing from slipping off. Regardin the petrol stopper. I am not sure if I can get one from where I live. Can I just leave the tubbing connected to the outside of the fuselage? Will the tank spill fuel in flight when the engine is working?
Cheers

Pedro

JoeAirPort

My Feedback: (41)

Barbs are something that fuel line pushes onto but can't be pulled off (it's like shark teeth, they point back to hold the prey). You solder it on the end of a piece of brass tubing to keep the fuel line from falling off. You use a cable tie on one side of the fuel line and it can't slip off.

Don't use silicone anything on the tank, it will melt in the petrol fuel. Also you need a petrol stopper for the same reason. The glow stopper will melt and fall apart in the petrol fuel. You can just put the vent to the bottom of the plane but looping on top of and just to the back of the tank keeps it from spilling in down lines and when you tilt the plane forward on the ground. It's a good idea and we all do it (well I think most of do anyway).

Tired Old Man

My Feedback: (1)

The tank itself is suitable for petrol, glow fuel, or smoke fluid. However the stopper material is critical. Those designed for glow fuel, which are the ones that are usually included with the tank, will quickly disintegrate when subjected to gas/petrol. Sullivan makes a stopper that's stated to work for petrol, but still decays quickly. Dubro and hayes both make a stopper designed specifically for petrol applications. They are a madatory item for petrol filled tanks. The glow stoppers can begin leaking before the end of the first flight when subjected to petrol.

In reference to barbs, what is meant is applying something to the brass tube exiting the tank than makes a rounded bump on the brass line larger than the line itself. This is to prevent the petrol line from slipping or passing air since the standard yellow tygon tubing will swell a little after getting wet with petrol. It doesn't require anything fancy. A Dubro solder on fuel barb, a slightly larger piece of brass tubing, a couple of strands of electrical wire soldered onto the tubing, all will work. If you choose to go this route do so on both sides of the stopper. Make sure the tubing is through the stopper first!

Many have no trouble at all with a simple electrical zip tie cinching the fuel line onto the tubing. It's your choice which direction you wish to take, but do not use wire to cinch the fuel line to the tubing. That method frequently cuts into the fuel line, causing a leak.

Most people simply route the tank vent line out the bottom of the plane to hang free in the air. The amount of petrol that can be lost through the vent tube is debatable, but generally not much of a factor. As Joe mentioned, you can pretty much eliminate vent line losses if you run the vent line long, exiting the tank, routing the vent line so that it runs up and over the outside of the tank towards the rear of the tank and is then returned forward of the tank to exit the bottom of the plane The line is secured in place with a section of velcro or some other method that will keep it in place on the outside of the tank but not pinch it closed.

If you have a nipple already installed on the gas engine muffler, bear in mind that it was intended for smoke fluid, not muffler pressure to the tank.

Rfabbre

My Feedback: (6)

One more thing---the DuBro gas tank stopper that I have is Dark Brown. Avoid Black or White ones.

Gus155

Should be able to get the stuff from Al's Hobbies. got some stuff from them in the past. they are in finchley.
also MY hobbies in Leytonstone.

Dr1Driver

DON'T use Tygon. It will soften and expand with age and exposure to gasoline. Use only neoprene.

Dr.1

JoeAirPort

My Feedback: (41)

Amen to that. I did my last tank in tygon a while back. It just doesn't work well as clunk line unless you have a one pound clunk. Outside the tank I find that it's fine, but even there, in the cold, it gets stiff and the fuel dot is hard to get on and off the tygon.

With neoprene I make the clunk line two pieces with a brass nipple in the middle. If you don't, it folds back (at least using the super flexible stuff that Hayes makes - the only stuff I use).

ram3500-RCU

My Feedback: (221)

I use large 'fuel dots' to load fuel (mounted through the side of the fuselage near the tank and plugged with a stopper while engine in running), an extra large line to the carburetor, and a third line for venting attached to a tube that is bent up to the roof of the tank on the inside and connected to a fitting in the bottom of the tank compartment. This fitting is threaded on the inside for a 4-40 screw in plug, installed when in storage and during transport. This prevents any fuel loss on my wifes carpet. A very good thing, really.

altavillan

My Feedback: (1)

http://manuals.hobbico.com/gpm/gpma1285-manual.pdf........... This will get you started it's from a GP Cap instruction manual. Scroll down to tank install. Search Tower for what a gas stopper should look like. Dubro is the best choice. Vent the line out the bottom away from exhaust but not so far back you can't see it overflow. Build a loop in the vent line and secure it to the top of the tank that creats an air pocket and prevents fuel from flowing out while flying. Tanks can be made with two lines but if you use two lines you need to prevent air from intering the system after fueling.

altavillan

My Feedback: (1)

A two line system

Tired Old Man

My Feedback: (1)

Your bench looks worse than mine did when I was home....

ram3500-RCU

My Feedback: (221)

I can't say much, I thought it looked better than mine.

pedromvf

Dear All,

Thanks a lot for your comments and experience. I was ready to use the same material I normally use in my methanol engines, I did not think it would be so different.
I guess my big Cessna will have to wait until I get all the necessary material.

Thanks to all of you guys.

Pedro

P.S.: Nice picture looks pretty clean and neat, I meant the airplane, not the floor, although mine is probably worse!

Happy New Year

Dr1Driver

There's a bench under there?

I am left handed, so I build from left to right until I reach the edge of my bench, then I clean it all off and start over - kinda like a typewriter.

Dr.1

Tired Old Man

My Feedback: (1)

Naw, that's not the floor. The floor's clean. It's definately his bench

pedromvf

Yeah! I agree, it is note the floor, sorry! There is definitely a bench there... and a sofa, a dog... Have you seen an airplane???