Fuel flow for Rotax engine

[bertrand]

Hello

On the Rotax engine , the gaz flows from the engine-driven fuel pump to the two carburetors thru a 5 hole connector
one hole for "in flow" , one for "out flow" carb1 , one for "out flow" carb2, one for pressure gauge and the last one for fuel return to tank  .

It seems that two sensors are needed and that we have to add the two measures  (does the EMS do that calculation ?) , but is there any other solution that anyone has successfully experimented with only one sensor ?

Something like :  first a 4 hole connector ( in from pump , out , pressure , return) , then the flow sensor , then à 3 hole connector ( in from flow sensor , out carb1 , out carb2) .


Bertrand

 

[dynonsupport]

Bertrand,

What kind of Rotax is this? A 912 or 914?

If it requires a return line, you do need a second sensor, but the EMS doesn't support this yet. The best solution is to get the differential fuel flow system from Matronics. This gives you a second sensor and a box that calculates the difference in flow between the two. You can use the output of this box to go into the EMS.

 

[bertrand]

Many thanks

It's a 912 S (in fact a 912 ULS-FR) .

I was quite sure that the "mechanical" solution I suggested wasn't so good ...

Bertrand

 

[dynonsupport]

Bertrand,
We're not experts on the Rotax installations yet, but we thought only the 914 used a return fuel line. You might want to double check that the return line is needed on a 912.

 

[bertrand]

I 'll check .
Bertrand [smiley=dankk2.gif]

 

[bertrand]

You were right . There is no return to tank on my plane despite what Rotax says on the Installation Guide . I didn't built that plane and did not pay many attention to this .

Bertrand

 

[9qwerty]

I have a D10a EMS now up and flying with ONE fuel flow sensor. I have taken the feed from the pump into a 4 way cross. One line from this goes through a restrictor back to the tank. One to the fuel pressure sensor and the last to the fuel flow sensor and then to a tee to both carburettors. The return to tank line is to reduce the posibility of vapour locks, especialy as the Rotax is designed to run on Mogas.
Really great to fly behind and the single sensor works well.
Paul Mitchell

 

[triple7driver]

I would DEFINITELY use the return line on ALL 9 series rotax ! Vapor lock is not fun at 200' in the climbout :-/ ask the folks over at JUST aircraft.