Gary Jefferson

My Feedback: (167)

Justin, not sure but I think that pulling air through either pickup of a Y setup will still result in pulling air into the system. So, if you do a knife edge and only one pickup is pulling fuel you may still get air bubbles.

Alex48

Hi Gary

You could use the new saddle tanks and the old center tank. I had the same thoughts regarding the new centre tank. WWith the tanks in series if it struggles to pick any of the fuel up will it not get it's supply from the next tank in the loop? Perhaps someone in the know could describe how the fuel behaves in the tank when in flight. Does it slosh around much? Many manoeuvres are under positive G This would no doubt help. One thing O do know I'm not much of a fan of this new fuel set up.

Alex

Gary Jefferson

My Feedback: (167)

For anyone interested:

The capacity on the original tanks is 92 oz. each for the two saddle tanks and the small center tank mounted between them is 32 oz. for a total of 216 ounces.

The replacement tanks are 92 oz. for the front center tank and 60 oz for each saddle for a total of 212 ounces.

jetpilot

My Feedback: (48)

Gary,
Why not fly with the original saddle tanks only?
Unless your using a big motor.
Scott

rusty55125

My Feedback: (6)

If that wanted to make a better system, why not four saddle tanks? One tank on each side, in front of the CG and the same behind the CG. Then you could Y the two left together and the right together, from there you would dump into the old existing 32oz tank. This would give you little to no CG change during flight. A little more plumbing but the clunks would be a little more effective as well.
Just a thought!

Scott

Springbok Flyer

..........or even just the two new saddle tanks - that's 4 liters of fuel anyway..........

My 2cents.

Jan

Gary Jefferson

My Feedback: (167)

Scott, I think the idea for the new tanks is to move a good portion of the fuel rearward (using the new saddle tanks) to aid in rotation on takeoff.

The new rectangular tank (the tank that concerns me) only holds 92 ounces. I guess this is the amount of fuel that Skymaster believes should be situated in this location. Unfortunately, the two original saddle tanks are 92 oz each which would give me a total of 184 oz in this location.

Assuming Skymaster has properly resolved this issue and the new tanks now have the correct distribution of fuel between the tanks to fix the C.G issues, using the two original saddle tanks probably won't work.

Gary Jefferson

My Feedback: (167)

I think I have the fix for this problem which is to use three of the 32 oz kevlar tanks. I just happen to have two of these since I have two complete sets of the original style tanks. Jet Tech sells a 32 oz tank that is almost identical in shape and size that I can use for the third tank in the center. I will place all three in the same location as the new incorrectly shaped rectangular tank so that the amount of fuel in this location is very close to the 92 oz of the new rectangle tank.

The plumbing will be very simple: run the left rear saddle into the 32 oz tank on the left, run the right rear saddle into the 32 oz tank on the right. Then use a T to connect the right and left 32 oz tanks and run a single fuel line into the center 32 oz tank. Then out of the center 32 oz tank into the PST air trap. This will provide proper fuel flow for this airplane.

Also for anyone that needs extra large fuel fittings contact Jet Tech. I am using Gary Mueller's O-ring style fuel caps along with extra large diameter nipples that will eliminate any issues with flow restriction due to incorrectly sized fittings. The I.D. on his o-ring style fuel caps is 3/16", the largest I have seen available. He has 3/16" vent fittings as well.


After checking for the proper C.G. location on the F-86, it appears that 390mm (shown in the photo with red arrow), and now the recommended C.G. according to Anton in another thread, is at the former right between the new set of tanks. This means you have around 92 oz just in front of the C.G. and about 120 oz just behind the C. G.

The original fuel tank setup put all of the fuel, over 200 ounces, in front of the C.G. I assume this is what Skymaster believes caused the rotation issue on takeoff.

When I receive the new tank from Jet Tech I will post some pictures of the setup.

fred cesquim

hi folks
a friend is building one of these, and i was talking to him, so we thoght that using 2 clunks with brass tube extensions into the rectangular tank may be better....what do you think?

Gary Jefferson

My Feedback: (167)

Has anyone flown with these new tanks installed yet? Just wondering if it has solved the C.G. issue and helped reduce the length of takeoff roll...

Gary Jefferson

My Feedback: (167)

I know this is an old thread but I wanted to ask if any has used the front rectangular tank that was sent as a replacement for the original tanks. This discussion was that the rectangular shape of the tank would not let the klunk pull fuel from the sides of the tank.

Is anyone successfully using the replacement tanks as sent from Skymaster? The attached picture shows the configuration of the new tanks I am asking about.

Springbok Flyer

Gary,

I shortened the rectangular tank on each end by approximately 45mm. In other words I removed that between the dip in the centre and the end section on both sides. Easily done and straight forward to rejoin with some FG tape and resin. This has four effects:

- The single centre clunk can now pretty much reach everywhere.
- The tank is now 2000ml, down from 2750ml. Total tank capacity without UAT is now 2x1800 + 1x2000ml = 5600ml (190oz) = more than enough fuel.
- The rearward bias fuel load will aid at take off and the forward bias fuel will not be so much at landing.
- With the shorter front tank it is now a lot easier to route cables and tubing around and past it.

Cheers,

Jan