S1 fuel vent

[Gaston]

FWIW...
I flew yesterday with the S1 with the fuel vent elongated to as high as 6 inches above the top of the tank.
and as soon as I lower the nose while in approach for landing, fuel is expelled from the vent at the first bump in the air,
seems not worst , not better than it was with the very short elbow. I think , the main factor is the intensity of the bump.
I had a few approach will full fuel with no fuel expelled as well as a few approach by the end of my 60 min flight with lower level of fuel and bigger bumps that got some fuel burst from the vent...

I'll fly with it a little while and see what I find...

Gaston

 

[n3480h1]

Would it be possible to add a small fuel filter or something like a small restrictor to the end of the vent line to limit the amount of fuel expelled during thermal bumps? Not enough to restrict air venting, but maybe enough to limit the spill? Or a one way check valve for air in/no fuel out?

Tom

 

[Gaston]

Hello Tom

yes it could be done (filter),very good idea.... but with a little work.
Check valve would probably be easier , in fact I had some kind of one way check valve on my s2 that was used to limit fuel loss when the tank was overfilled... Now I take care not to overfill $$$$$$$$
It could be used on the S1...

PS .....due to the nature of the bird, best solution is probably to fill it only to 9 gallons, so the one gallon free space could eventually take care of the issue...
More to come...

 

[EricM]

Here is a one-way valve I installed in the fuel vent on my SII. It lets air in and out but keeps the gas in. Most motorcycle shops which cater to dirt bikes have these in stock.

 

[Schmleff]

I was about to make one of those by would much rather but one! Do you have any more details?

 

[EricM]

It's called: Free Flo No Slop gas cap vent hose. Available here:

http://www.rockymountainatvmc.com/p/931/1171/Free-Flo-No-Slop-Gas-Cap-Vent-Hose

 

[soneraii]

Here are pics of what I ended up doing with my S-1 fuel vent system.

This morning I filled the tank to above the top of the fuel vent, then put the airplane in a 25 degree nose up attitude. Then I opened the fuel valve and flowed about 14 gph. Never had any fuel vent out of the fuel vent inlet on the bottom of the fuselage. At one point I held a finger over the fuel vent inlet and the rate of fuel flow slowed significantly. Removed my finger and it again flowed freely.

Keeping in mind that inflight I would have a little bit of air pressure against the fuel vent on the bottom of the airplane. It appears that this system will be fine and I will probably not vent fuel inflight nor will the fuel against the fuel inlet on the top of the tank prevent a good flow to the carb.

Thanks for everybody's input.

Kevin

 

[964SS]

That looks like the system that came with my IIL

 

[Gaston]

Hello Kevin

this is the same as on my S2L, and it works perfect...

But I would remove the useless loop you have...

the vent is very different on my S1 as it is vented from top front of the tank¸,thus spilling fuel when nose down in rough air, and tank is almost full, and this even with the vent 6 inches long over fuel tank top...

 

[soneraii]

Hey Guys,

Thanks for your responses.

Gaston, the useless loop does two things that are not apparent. First it allows some flex in the limited space between the panel and the tank versus a pure hard line and second and less obvious it compensates for the misalignment between the AN fittings on the panel and the tank. But I like the way you think!

Kevin

 

[Gaston]

Hello Kevin
I agree with the 2 things this loops will permit, but it will also permit fuel to be trapped in when tank is half full and lower , and then will show a false reading, when you most need it to be the accurate...
I would get rid of it...for sure.

Your plane is such a nice piece of hard work, it may do without that...

Gaston

 

[soneraii]

What if I simply layed the loops over so that they are horizontal??

Kevin

 

[Gaston]

Kevin that's the solution.
this way no quantity of fuel could be trapped in the bottom of the loop...

and this is pretty easy I think...

Gaston

 

[soneraii]

Gaston, your assessment of the problems with the vertical loop were most accurate. You were very right!

I had filled my fuel tank completely full and let it sit over night to check for leaks anywhere in the system. All checked good.

Now, I decided to drain all the fuel out as I continue assembly. I opened the fuel shutoff valve and drained all the fuel through the hose that connects to the carb. Upon emptying the tank completely the fuel sight gauge showed about three inches of fuel! I picked the tail up and down a few times and it still showed about three inches in the sight gauge. I loosened the fitting at the loop, some air apparently went into the line and the sight gauge immediately showed no fuel remaining!

Nuff said. Gonna modify that!

Kevin