More Fuel lines and Rudder wrap up

Back to the fuel lines and getting those wrapped up. The hose package from Tom really makes this section easy. It’s mostly just hooking up the hoses between fittings and torquing them properly.

Below are the short supply (bottom chambers of the fuel valve) and return lines between the Andair valve and the tunnel bulkhead fittings. These must go downward and aft as the slots in the tunnel there are for the control sticks between the front seats.

Here you can see the return line passing by the fuel pump/filter module and connecting to the Andair valve right by the “F” marked on metal support bracket.

A similar shot as above where you can see the return line attaching to the firewall fitting.

With that done, there are 2 custom hose lengths that need to be figured out. As the filter/pump module might not be placed exactly the same between any 2 people. The 2 custom hoses are from the Andair valve to the input of the pre-filter and from the output of the post-filter to the firewall fitting. The latter being the easy one. The one from the valve to the pre-filter is very tight. The hose is pretty rigid for such a short run and doesn’t have a good bend radius as a result. Below you can see me trying to figure out the hose length needed using some extra hose Tom sent to measure  with.

Fitting and hose attached to Andair valve and marking where the fitting to the pre-filter is located


Cut the hose to length and put second mock fitting on that end.

As you can see it’s a very close fit and I’ll need to discuss with Tom what the best thing to do here is. I almost suspect a hard line might need to be made for this short run. Hes on vacation and I didn’t want to bother him, so I’ll get that figured out over the next week or so. I might be able to move the pump/filter module forward a little bit in order to get some more room between the two. The below pic shows the mock up of the supply line  (the right-most line) from the post-filter to the firewall fitting. Much more room to work with here. Of course there’s still a little tiding up to do here with mounting adel clamps to the tunnel bulkhead for additional support of the lines.

The next dilemma was to figure out how to route my return line under the seats and more specifically where to drill a 2nd hole in the side skins for its exit to the wing tanks. I went with the brake lines in the middle tunnel fitting and fuel lines on the outside. The supply goes on the forward (right as shown here) fitting per plans, and the return goes in the aft location (left as shown here). As you can see, the white gear weldment gets in the way of a straight shot out to the side skins. One must route the return line forward a little bit around the gear weldment, but also avoiding interference with the brake line. I can certainly see why some people chose to route the brake line in the aft location and the fuel lines in the middle and forward position. It was at this point that I solicited some opinions on VAF and also stepped back and looked at pictures of the area between the fuselage and the wing tanks to help guide my decision. Best to step back and do some research prior to drilling holes in the side of the plane willy nilly.

Two proposed areas for a hole on the side skins marked by red circles. 

The following picture I stole from another builder. It depicts the area in question. On top, is the side skin of the fuselage. Forward is on the left. Bottom is the fuel tank. Here you can see the hard fuel supply line coming out of the stock hole in the fuselage at the top, bending right and downward into the tank fitting. The red arrow indicates the approximate position of my return fitting on the tank. It’s just forward of the tank vent which has a red cap or tape on it in this picture just to the right of the arrow. One thing that I noticed is that if I were to drill a hole in the most-forward position indicated on the picture above, I might interfere with the aileron control rod or interfere with the tank attach bracket (the medal piece all the way to the left in the picture.) So I decided to keep it close to the supply line in a very similar spot as this builder did. His return line is the blue 90* AN fitting just above and behind the supply line.

fuel return

This is what I ended up with. I won’t really know for sure how well the hose with a 90* end will work until much later on in the build. At least not until I test fit my wings.

Then it was securing the lines to the system control brackets. This required a little dremmeling to open them up a bit more to accommodate the larger diameter lines. The return line passes under the brake line on its way out. There is a little air gap between them, but I’ll probably wrap some spiral separator on one of them to avoid any rubbing via vibration.

So while waiting for Tom to get back from vacation and help with the custom hose lenghts for the 2 hoses remaining, I went back and finished up the rudder section of the plans. This section is also pretty easy. Just a matter of bolting the pedal assembly in place and routing the lines.

The final part of this section is to run the rudder cables and connect them up to the rudder assembly.

Cable ends that’ll connect to the rudder itself
Adel clamps in tail holding the plastic sleeves in place
Cable routing through tailcone
Cable routing through tunnel in fuselage

Rudder cable attached to rudder

Now it’s on to section 39, the control system.  Control sticks and pushrods will be installed in this section.


Fuel System, Rudder Pedals, Goodies

I needed to decide on whether to put the pre-filters for the fuel lines under my seats or in the tunnel. Tom at TS Flight Lines had suggested 2 methods. Either a single pre-filter and post-filter mounted above the fuel pump module, or have 2 pre-filters one for each supply line under my seats. In either case, the post-filter would be in the tunnel. Advantages of under the seats are that less room in the already tight tunnel would be taken up. Some also may argue ease of maintenance, although I’m not 100% sold on that. The cons are that attaching the pre-filters to the tunnel bulkhead fittings as Tom leaned towards (which allows for a single hose assembly from the fuel tanks to the pre-filters) was causing lots of extra work. The pre-filter in that location interfered with the systems bracket that holds the lines in place off the bottom skins. I was going to have to cut that partially out to make room for the filter and also adjust the top part of the bracket too to fasten to the modified lower half of the bracket.

Advantages to filters in the tunnel are: there is only 1 pre filter module (less cost) and less modifications, saving time. The main downside is that it takes up more room in the tunnel.

Below are pictures of the 2 methods:

Method 1: Under the seats
Method 2: In the tunnel as part of the pump module assembly (Adel clamps to hold it together are missing here)

I ended up going with method 2. With this method, the pump module will actually be installed backwards in the sense that fuel flow will be going forward to aft (or top to bottom as shown in the picture above as the firewall would be towards the top of the picture). The idea here is a hose will connect the valve selector to the pre-filter on the left. Flow through the pump module and into the post-filter on the right. Then a hose will connect from the output of the post-filter to the firewall fitting to the engine. I liked the idea of a self contained unit, which required less hacking of the existing structure to make it work, and seeing I made the aluminum plate that the pump module sits on removable with 6 screws, maintenance should be as easy as removing 2 hoses (in and out) from the filters, unscrew the plate, and remove the whole assembly to work on it on a bench.

I then ordered my fuel line hoses after making that choice. In the interim, I started working on the rudder pedal section of the plans.

I prepped, primed, painted, and riveted the pedal assemblies, then attached them to the powder coated arms that span the width of the airplane.

I then attached the master brake cylinders to each pedal and inserted the fittings into the cylinders. Note a few are missing here in this picture. One of the pitfalls of going off plans. Seeing I’m using the flexible lines, I didn’t have enough AN822-4D fittings for all the holes, as Van’s provides some brass fittings which are intended for their way of doing the lines. Seems every time I turn around I need to order something new from Aircraft Spruce… Guess I’ll keep them in business.

Rudder pedal assembly in place temporarily

Some time away from the shop on a long weekend away in Kansas, and a bunch of items came in. My fuel lines, and a bunch of stuff from Aerosport including rudder pedal extensions, throttle quadrant, carbon fiber center console, and a NACA vent controller for controlling air to the overhead console vents.

Fuel lines! (all except 2 which I need to measure for)
NACA vent controller (bottom), Throttle quadrant, and rudder pedal extensions
Center console in approx location.

Fuel selector placed in approx location between the seats

So for now it’ll be back to finishing up the fuel system before completing the rudder pedal section.