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Water/Soda Bottle Fuel Tanks

FIJI Water Bottle
Fiji Water Bottle
Use a Water or Soda bottle as a gasoline fuel tank for your R/C Airplane!

Why use a Water/Soda Bottle as a gas tank? Good Question!
Here are a few reasons:
  • Many Water/Soda Bottles are the perfect shape/size for specific planes.
  • Many Water/Soda Bottles come in larger sizes (32oz or 1 Litre - even larger) which works well for larger airplanes.
  • Many Water/Soda Bottles are crystal clear - which makes diagnosing fuel flow problems simple - you can easily check your fuel tank line, or clunk without removing or taking apart your fuel tank.
  • Water/Soda Bottles are very reliable - screw top caps and Viton O-rings make for a reliable seal.
  • With current accessories - Water/Soda Bottle tank assembly and maintenance is really quick and easy.
The following tutorial outlines the basic setup for a Water/Soda bottle gasoline fuel tank for a Giant Scale R/C Airplane.



Tools You Will Need:

Items you need
Tools you will need
You will need the following tools - Pliers, Side cutters, Xacto knife, screw driver, Sharpie Marker, Allen Key, and a drill.












Items You Will Need

Items You Will Need
  • Water/Soda Bottle - We highly recommend FIJI Brand Water Bottles. The come in several sizes (This is a 16oz - 1/2 Liter size. The have a great shape for most planes - squared edges, and a great angled neck. These can be purchased at most grocery and convenience stores
  • Fuel Tank Cap compatible with your Water/Soda Bottle - There are several options - for ease of use, the PSP FIJI Water Bottle caps can't be beat! These are available at Thunderboltrc.com at this link: Click Here
  • Clunk - We recommend these Felt Filtered Clunks by Walbro. These are available at Thunderboltrc.com at this link: Click Here
  • Fuel Tank Fittings - Depending on the Fuel Tank Cap you are using, you may need Fuel Tank Fittings. The PSP FIJI Water Bottle Cap only has one nipple, so at least one fitting is required. PSP Fuel Tank Fittings can be found at Thunderboltrc.com at this link: Click Here
  • Fuel Line - You will need fuel line for inside of your tank - We recommend Viton Fuel Line - it performs very well. Viton is available at Thunderboltrc.com at this link: Click Here
  • Wire Ties


Prepare the Bottle

Remove Water Bottle Cap
Prepare the Bottle
Remove the Water Bottle Cap, drink the water, and remove bottle label. You can toss the cap, as you won't need it.










Prepare the Fuel Line

Prepare Fuel Line
Prepare Fuel Line
Determine the length of Fuel Line that you will need - To do this, measure the distance between the edge of the bottle opening and the bottom of the fuel tank. Then adjust your length by subtracting the length of the clunk. Once your line is cut, trial fit the line to the cap and clunk and see if the works in your tank - you want to make sure that the clunk will be close to the back/bottom of the tank without getting "hung up".





Install Fuel Line to Cap

Fuel Line on Cap
Fuel line on Cap
Install the Fuel Line on the Bottle Cap barb - make sure the Fuel Line is fully on the barbs. Secure the Fuel Line with a wire tie.









Install Clunk on Fuel Line and Cap

Install Clunk
Install Clunk
Install the Clunk on the Fuel Line and Cap. Make sure the Fuel Line is fully inserted over the Clunk barb. Secure the Fuel Line with a wire tie. Place the Fuel Cap, Line, and Clunk assembly aside for now








Mark Vent Fitting hole

Mark Vent Hole
Mark Vent Hole
For this tutorial, we are installing one Fuel Tank Fitting (A Single Barb Vent Fitting). (This is the simpliest setup - There are other options, you could install two Fuel Tank Fittings - one Double Barb Fitting for a second fill clunk, and one Single Barb Vent Fitting). Use the washer from the Fuel Tank Fitting as a reference to position the Fitting drill point. Make sure that the Fitting is installed on a flat surface - you don't want the Fitting to be installed on a curved surface. Also, watch where the Fitting will exit inside your airplane fuselage. If you have a bulkhead, watch that the bulkhead doesn't interfere with the Fitting. Once the washer is positioned - use the Sharpie Marker to mark the center of the washer as the drill point.


Drill Vent Fitting Hole

Drill Vent Fitting Hole
Drill Vent Fitting Hole
Carefully Drill the Vent Fitting hole - use a 3/16" drill bit. Clean the edges of the hole with an Xacto knife if necessary (make sure the hole is very clean so that you get a tight seal).








Insert Vent Fitting

Vent Fitting Inserted
Vent Fitting Inserted
Insert the Vent Fitting through the bottle cap opening. Use your finger to push the Fitting up through the Fuel Tank.









Secure Vent Fitting

Secure Vent Fitting
Secure Vent Fitting
Inside the barb of each Fitting is a braised Allen Key socket. You can use an Allen Key to hold the Fitting while you tighten the nut. Add a drop of thread locking compound to secure the nut from vibration.








Install Fuel Cap, Line, and Clunk Assembly

Completed Fuel Tank
Completed Fuel Tank
Install the Fuel Cap, Line, and Clunk Assembly - don't forget the Viton O-ring, and make sure the clunk moves freely. Test the Fuel Tank to make sure you have no leaks. This can be done by attaching Fuel Line to each barb and submerging the Fuel Tank in water. Plug one line and blow in the other - you will feel the pressure build in the tank - if you don't see any air bubbles in the water, the Fuel Tank has good seals. If you see air bubbles in the water, you have a leak. That's it you're done!