Thursday, June 19, 2014

Glasair Fuel Tank

 Doug's Glasair II-S FT was built with extra capacity over the original design.  It holds 69 gallons, which is plenty for an IO-360.  Under ideal conditions, Doug could make the flight from Mojave to Oshkosh non-stop with VFR reserves and no wind using an efficient, slow, high altitude cruise profile.  However, conditions are rarely ideal, so he added 15 gallons representing about 2 hours of surplus flight time.  That equates to 20% of the planned flight time.

The tank itself is a 15 gallon gasoline transport container used for ATV and motorcycle off road adventuring.

A bulkhead fitting was installed in the cap.  Using a flop tube for pickup eliminates the potential for a leak at a fitting installed in the bottom of the tank.

A low pressure 12 volt Facet Posi-Flo pump should easily move the fuel.  This one has a built in check valve to increase the dry-lift.  This was necessary due to the use of  a flop tube.

 A test of the uninstalled system was made to ensure there were no leaks and measure the current draw of the pump as well as the ability to self prime across a 30" lift.  It took 42 minutes to transfer 15.5 gallons.  The pump was rated for a higher flow rate but the pressure drop due to the lift apparently slows it down.  Still, that is almost 3 times faster than the Glasair burns fuel in cruise.
 The connection to the aircraft was made at a preexisting ball valve just above where a co-pilots right knee would be.  That valve is normally used to move fuel from the wing tank to the fuselage tank for C.G. control.

The Glasair's fuselage tank holds just over 8 gallons, so the fuel will be transferred in two episodes.
 The pump will mount to an existing screw on the right side seat pan.  Clear line was used on the low pressure side to allow a visual check that transfer is occurring and when the tank is empty.

The right side stick was designed to be easily removed and re-installed.  Many non-pilot passengers prefer the additional room.
The electrical connection will be a cigar lighter plug.  The pump draws less than 2 amps and Doug's cigar lighter style power point can offer up to 20 amps!

This system was designed to be easily installed and removed.  It take just a few minutes and very few tools to do so.

Check back later for the results of flight testing the temporary transfer tank.

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