Auxiliary Fuel Tank Installation 1st December 2007.
The fuel cap. I machined this from 4 layers of 1/8" aluminum. It will sit flush on the turtle deck skin. To install the cap you push it in the hole and tighten
the allen screw which draws the two disks together and squashes the o ring out to make a very tight seal. The starboard tank mounting brackets. Notice the forward
support angle sits ON the longer on and the rear one sits on the floor, the reason for this is the floor slopes up towards the rear and would cause the tank to lean
forward if both angles were sitting on the longeron. The center brackets, these are to prevent the tank from moving sideways and also add strength to the
The starboard tank in position. There is a section of angle mounted on the cross tie box which sits on top of the tank at the front to prevent the tank moving
upwards. To remove the tank you have to move the top backwards to clear this bracket and then lift upwards. An internal shot of the starboard filler.
I glued this piece of tubing onto the tank so the rubber hose fits over it, this is the same aluminum tubing I used for the filler.
A couple of shots of the filler hole with dimpling to accept the 4mm countersunk allen screws.Notice the apparent distortion in the skin in the right hand photo yet on
close up it is impossible to detect. Even running your hand over it you cannot feel it.
This is most of the parts for the whole installation except the pump , electrical wiring. And the second tank.Notice I have used Araldite to join the pipes. I have
built several of these and when trying to separate them I have destroyed the tubing in the process. (It is super strength Araldite) Before I install it I will glue in
a couple of small gussets in the small angle. One inside and one outside just to be sure. Same with the flange which is also glued on.
In the center photo notice I have machined a small grove for the fuel cap o ring to sit in when tightened, this makes it near impossible for the cap to come out when
tightened.( Without the grove it is still VERY firm.)
The filler and cap , not 100% flush yet I have to machine a little off the inside lip. The tank installed minus the straps.A couple of shots of the filler from
inside.You can see the bracket I riveted to the cross tie box to stop the tank from coming up.
The breather tube , I thought for ages how I was going to do this and one day I was looking at a piece of tubing left over from the pitot and I came up with this.
I blocked it off on one end, drilled a few holes in it and poked it through the tank handle with some araldite. It is very strong as it's supported at both ends. I
will attach a piece of flexible tubing to it and take
it out the bottom of the fuselage.
The gasculator finally in , what a battle that was, getting the connections in and sealed, no grommet yet and no cover till I check every joint for leaks.My new
fuel system schematic.
This is the bottom half of my tank breathers. I used 1/2" aluminum tube with a machined reducer because I did not have any 1/4" left. As it turned out this made
the mounting very easy , I drilled 2 holes through them and screwed them to the
tank support brackets.There is plenty of space around the screws for air to flow. A view from the top and the bottom.
Right hand tank in and connected ready for fuel. I have not connected up the Left hand
one at the moment , I won't need it for the first few hundred hours so I can do it later.
August 2012 Major design change from electric valves to a mechanical selector tap.
As much as I liked the electric setup with it,s simple operation the chance of failure was quite high. I bowed to public pressure and installed a manual selector valve , it is mounted on the spar box with countersunk screws and sits between my legs within easy reach of my left hand.
The next shot includes the new throttle plate which moves the throttle 3/4" to the right so I don't scrape my knuckles on the vertical stiffener any more.I have simplified the trim indicator, Only one LED and one micro switch is really needed. On is UP from neutral and Off is Down from neutral.
In the last shot I have installed a Micro Switch and cam on the valve. The switch will operate the fuel pump when the valve is in the Aux position. Therefore changing tanks is still only a single operation. If the electric pump fails the engine driven pump will be able to draw fuel through the electric pump.
I have added a toggle switch on the panel to test the above theory by turning the pump off when the auxiliary tanks are selected and to turn the pump ON if the micro switch ever decides to go on strike.
The latest auxiliary fuel tank. Slightly more capacity ,32 liters over 21 liters. Fits under the seat and will reclaim my lost baggage space , Also moves the moment forward by 225 mm (9")
I can still use the external filler point with a couple of right angle bends.