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Oct 05, 2019, 09:21 PM
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Fuel Tank Installation on Aeromaster Biwing


I am currently building an Aeromaster Biplane with a glow plug .45 engine and a 6oz round tank as can be seen in the attached picture. I have the following questions on the best method for filling and venting the tank, securing fuel lines to the brass tubing and use of fuel filters. One concern is that there will be very limited access to the tank, associated devices and tubing connections once the skin of the plane is installed. Also attached is a picture of the partially assemble tank components.

1. To fill the fuel tank prior to a flight, do you disconnect the fuel line from the engine and fill the tank using the fuel line and then simply reconnect it to the engine or do you have a separate fill line run to the tank? The tank came with only two brass tubes (fuel supply and vent). The package that the tank came in shows a Sullivan S750 high flow rate Fuel Filler Valve that indicates it should be mounted thru the cowl or fuselage. Have anyone ever used this item? It would seem it would be best to disconnect the line from the engine and fill it though the fuel line. If I were to use the Fuel Filler valve I am nut sure how accessible it will be once you install all the electronics and servos as well as the board to support this equipment since there will be no access from the top.

2. The tank contains a vent line. Where do you normally terminate the vent line?

3. The two brass tubes need to be cut down because they are too long. What is the minimum amount of the brass tube that should stick out of the tank to allow for the connection of plastic tubing? I am trying to keep the fuel tank as close to the firewall a possible so I am trying to have piece of pipe that will still provide adequate connection of the plastic tubing..

4. The fuel tank kit came with small metal ties for securing the ends of the plastic tubing. Is this commonly used since I have not seen this before?

5. Do you install a fuel filter in any of the lines? The package the tank came in recommends using a Sullivan "Double Screen Premium Filter" No. S187. Is this needed or is a filter on the container of fuel that you use to fill the tank adequate?

Certainly appreciate anyone's input.

JB007
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Oct 06, 2019, 07:39 AM
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To answer in order.

1. It can be done either way, but with most open engine installations, fueling is done by simply unhooking the fuel line that goes to the carb from the installed inline fuel filter, pumping fuel into the tank, then hooking the line back up to the filter.

2. There should be a pressure fitting on the engine muffler. The vent line should go to that pressure fitting so the the tank will have a small amount of pressure to push the fuel to the carb. This makes for a much better idle, when the engine doesn't have a lot of fuel draw.

3. The fuel line coming out of the tank stopper won't need to be longer than about 1/2 inch. Also the fuel tubing will be silicone fuel tubing, not plastic.

4. Some people probably use the included tie wires, I don't and have never had a fuel line come of inside or outside the tank in over 50 years. Sort of like using a belt and suspenders, it can't hurt, but probably isn't needed.

5, Yes, you need to put a fuel filter in the line that goes to the carb. It makes for easy refueling, but it also can catch things that can stop up the internals of your carb. At one time my first wife keep a little long haired dog in the house. Several times I had an engine that got hard to start, only to find the fuel filter full of white dog hair, ever though I never saw any hair on any of my fueling equipment.

One other thing, you might want to install a larger tank. A 6 ounce tank is a bit small for a .45 and will make for some short flights if you run at full throttle a lot.
Oct 06, 2019, 10:47 AM
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Hi Allen,

Thank you very much for your help!

Item 1. I will get a fuel filter. If I understand your directions it will be necessary to install the filter next to the engine so it is accessible to disconnect and reconnect the fuel line from the filter. The tank package recommends using a Sullivan S187 double screen premium filter. The filter appears to be about 2-1/2" long (based on package size, there are no dimensions available for the filter). With very limited space next to the engine I am not sure how I am going to fit this filter, the fuel line to the filter and the fuel line between the filter and the engine in the limited space. Is this recommended filter excessive where a smaller filler will do the job? Is there a filter you would recommend for the job?

Item 2. Will connect the vent to the muffler port as noted. Does this line normally get routed through the fire wall or the cowl since the port on the muffler is behind the firewall? I would think it would be done through the top of the firewall and looped back to the muffler but would certainly like a second opinion.

Item 3. The line I purchased is rated for fuel so that should be fine.

Item 5. Fortunately I have no dogs or cats so that shouldn't be a problem!

Due to the construction of the body for the bi-wing design I must use a round tank that is limited to the 6 oz tank size. The drawing indicates an 8 oz tank but the actual dimensions of the tank on the drawing make it a 6 oz tank. The 6 oz tank I purchased fits snug in the body exactly the way the drawing shows. I guess I will have a few minutes less of run time.

Thank you again for your help and support. Have a great week!!!

Jack
Oct 06, 2019, 11:59 AM
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Both silicone fuel lines from the tank should go through the firewall. Looks like you need to move the engine forward a little. The fuel line for the engine should have a filter in it. I use the short, screw together single screen type, like this. https://www.towerhobbies.com/cgi-bin...?&I=LXD743&P=M When you fill the tank just pull the fuel line off the engine and fill through that. The pressure line from the muffler becomes the overflow when filling the tank. The pressure line needs to be long enough to go to the pressure tap on the muffler.

In the picture you can see the fuel line to the carb and the pressure line from the muffler. The engine is sideways but the install is the same.
Last edited by JimboPilotFL; Oct 06, 2019 at 12:18 PM.
Oct 06, 2019, 12:34 PM
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Thread OP
Thank you for the picture, clarification on the routing of the lines and the recommendation on the filter. I only wish I had known it a few days ago since I just order something from Tower Hobby and received confirmation on shipping yesterday. What's another shipping charge anyway.

Best regards and thank you again for your help!!!

Jack
Oct 06, 2019, 12:39 PM
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Thread OP
Allen,

By the way, I located the engine as indicated on the plans and won't be able to move it a millimeter since the blind nuts and the motor mounts are epoxied in place. But thanks for the suggestion.

Jack
Oct 06, 2019, 01:22 PM
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It looks from your picture that there is some room on both sides of the tank and plenty of room fore and aft. An eight ounce tank won't be that much bigger. It should fit with a little carving. Most filters are less than inch in length. As already stated, you should run the two lines from tank through the firewall. If you have a quarter inch of room behind the engine, that will probably be enough room to bring the lines through the firewall and turn them without kinking. If they touch the engine it wont't hurt the lines as the engine doesn't get hot enough to burn silicon fuel tubing. When you fill the tank, be sure you pull the line off the filter going to the tank, not off the carb. If you pull the line off the carb, any debris will be pushed into the outlet side of the filter and can then go into the carb, possibly stopping it up.
Oct 06, 2019, 09:38 PM
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Allen,

I had bought an 8 oz tank. The problem is that if I try to fit the tank in by cutting out some of the formers there is now no longer any room to fit the rod to the throttle on the engine since the tank now sits against the Ply-strut lock plates that supports the cabanes for the upper wing . Se the attached picture of the sectional view of the plane with the tank. My 6 oz tank is the exact diameter of the tank shown. The 8 oz round tank is significantly larger in diameter. I found only one 8 oz tank that was round and would fit but the diameter was much smaller so the tank was a lot longer taking up space that I will need for the servos etc. This is why I decided to stick with the 6 oz tank realizing I will have only about a five minute run time.

I do have two question for you. Have you built any planes where the tank is no longer accessible or removable once you complete it? Right now I would be able to remove the tank but if I install the servo for the gas throttle close to the tank, which would appear to be the ideal location, I will no longer be able to remove the tank.

The tank I purchased has a rubber type stopper that expands as you tighten a screw. Do you normally test this type of tank before it is installed in the plane to make sure it does not leak? This is the first time I have used a tank of this type and thought testing it might be a good idea. Any thoughts? The only problem I have will be my wife when she complains about the odor of the fuel when I bring the tank back in the house even though I have emptied the fuel.

Have a great week!!!

Jack
Oct 07, 2019, 08:04 AM
Registered User
Have you checked to see if a square 8 ounce tank could be fitted? That might give you the room you need for the throttle push rod. As for removing the tank, is there any way you can make the servo mount removable. Putting hardwood rails down each side of the fuselage would allow you to mount a ply servo tray with screws that you could remove to get to the tank. With a new tank I usually don't pressure test them, I've put enough of them together over the years to know if something is not right. If reusing a stopper on an old tank I sometimes put a piece of fuel line on one of the brass tubes blow into the tank while holding my finger over the other tube. If air can't get out, fuel won't.

Your wife can smell glow fuel? I've never heard that before. People complain with gas powered aircraft of not being able to bring them in the house because of the smell but I've never heard of any one complaining of the smell of glow fuel. Actually I have a friend that just bought a gas powered plane and most of the time I go to his house that plane is sitting in the living room and I've never notice the gas smell, so I wouldn't think you would have any problem with the odor of a glow fuel powered plane.
Oct 07, 2019, 11:56 PM
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Thread OP
Good evening Allen,
Well I took your advice and cut away a portion of the former out to fit the 8 oz round tank as you can see from the attached picture. It is now a really tight fit. There is a very small space between the tank and the motor mount which I can hopefully route the rod for the throttle. I decided to do a little rework with the top of the plane and make the canopy removable so I will have access from the top and bottom which will make it easier to install some of the components. I like you idea of making a removable servo tray. I also tried your suggested pressure test by blowing into it while covering the other port with your finger. Worked perfect! Thank you for your help!!! Have a great evening!

Jack
Oct 07, 2019, 11:58 PM
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Allen,

Here's the picture.

Jack
Oct 16, 2019, 10:53 AM
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For your throttle push rod use a Sullivan semi-flex cable .063 x 36" P/N S515 been using them for years. Yogi


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