----- Original Message -----

From: Tracy Crook

To: Rotary motors in aircraft

Sent: Thursday, February 16, 2006 8:51 AM

Subject: [FlyRotary] Re: Fuel return line

I usually resist the urge to shout but will make an exception here.

 

DON’T DO IT !!   This was designed for the Bendix type fuel injection which is a TOTALLY DIFFERENT animal.

 

Not to put too fine a point on it but, people have died as a direct result of using this scheme with EFI.

 

 There is one example of this that worked (on EFI) but it required a vapor/liquid separator and a small air cooled fuel cooler to be functional - an absurd level of complexity IMO.  A return line is not that big a challenge.  

 

Tracy

 

Subject: [FlyRotary] Fuel return line

Looking for coments, and figured this was the right group to get them.

 

My plan is to copy Tracy's fuel system with one tank feeding the other, and the second tank feeding the engine with a return line.  But today I looked at one of the drawings Vans sent me (DWG 31A for the RV-8).  It is for the RV-8A, so I had ignored it before.  It shows the return line from the engine (or pump) connecting back to the feed line just after the tank selector valve.  This seems to me like an easier answer. I wouldn't have to add a second pump to move fuel between tanks, and the return line would only have to go to the valve, instead of all the way to the wing. 

 

Will this work?  Or am I missing some obvious cavitation/starvation problem?

 

I've attached the part of the drawing that shows it best.  Instead of running the return from the pump, it would return from the fuel rail.

 

Thanks in advance.

 

Chris

 

P.S.  I pick up my mount from Fred next Thursday.  So I should soon be building my cooling system and plenum.  I'll post pictures as that develops.