Aux fuel tanks

[sonex892.]

How does Steve's tank mount? Hard to tell what holds it in from the pictures.

Piano hinge Bryan. There is an 032 stiffener on the other side of the hinge and a clip at the bottom


Plans are here on a very inactive Sonex yahoo group. If you dont have access and want a copy, PM me with your email.
https://groups.yahoo.com/neo/groups/sonexbuilders/files

[fastj22]

Here's my aux tank solution.

[WaiexN143NM]

Hi john,
Looks good! Is that the same set up jeff schultz came up with? I think for legacy models the tank behind the seat is pushing it regarding cg. When my father and i get into our waiex together thats 400 lbs in the seat. As fuel burns out of the main tank the cg moves aft and pitch get pretty light. Wouldnt want any more weight back there unless flying solo. Converting #183 to a b model may be best. Tanks in the wings may be better for cg , but may alter stall / spin , acro capability. Inboard wing fuel tanks like the rv series would be nice.
See u at OSH 2016.
WaiexN143NM
Michael

[fastj22]

My solution is a Jeff Schultz modified design. He had some extra stuff (check valves) I thought were unnecessary. And he used a slightly different tank style.

[sonex892.]

When my father and i get into our waiex together thats 400 lbs in the seat. As fuel burns out of the main tank the cg moves aft and pitch get pretty light. .
WaiexN143NM
Michael

With my behind the seat tank, its not the C of G that is the problem its max gross weight. With the 400 lb on seat condition described above with a full tank I would already be 10 lbs over the 1150 lbs gross.

The aux tank in my Sonex is very usefull with 300 lb on the seats. A snip from my weight and balance spreadsheet

And if you have trouble transferring the fuel, you may be really aft CG on landing.

Another good reason to pipe directly to the engine and not transfer. Piping directly is a bit easier with a bing carb as it uses a mechanical fuel pump anyway. I also have one electric backup which which supports both tanks. The electric pump has never been required. The mechanical pump works for both tanks
Steve
Sonex 892

[WaiexN143NM]

Hi steve,
Your'e exactly correct, when we load both of us in the aircraft, about 400 lbs in the seats we always leave a couple gallons low on a full tank, as we are up against gross wt. We also have have a full paint job, big tail wheel, adahrs unit, avionics bay below the baggage area, a couple antennas, it all adds up. Also there is a noticeable lightening of pitch as fuel burns off and the cg moves aft. I guess what im trying to say is watch your weight, and be aware of cg issues. I love your tank. I think for me is a good set up when flying solo and having more range. I sent you a PM. Would love a set of plans. Very similar to the tank offered from spain , but his full kit is around $1110 US plus shipping. Could build one much cheaper. Thanks for your postings.
WaiexN143NM
Michael

[peter anson]

Hi Steve,
Do you run off the auxiliary tank until fuel is low and then switch over to the main tank? Do you have a fuel level sender in the aux tank? Your arrangement of pumping straight from the aux tank is attractive because it is so simple, but I had imagined running off the main tank first and then replenishing the main tank from the aux using a separate pump.

Peter
Sonex 894

[sonex892.]

Hi Steve,
Do you run off the auxiliary tank until fuel is low and then switch over to the main tank? Do you have a fuel level sender in the aux tank? Your arrangement of pumping straight from the aux tank is attractive because it is so simple, but I had imagined running off the main tank first and then replenishing the main tank from the aux using a separate pump.

Peter
Sonex 894

Hi Pete
Depending on the fuel qty in the aux I normally take off on the main then switch over to aux. Then alternate tanks every 30 minutes. Doing this keeps the plane in good trim and keeps the maths simple, each 30 mins I plan for 10 litres.
No fuel level indicator in the rear tank. I use a dipstick to check qty before flight.

Steve
Sonex 892

[WaiexN143NM]

Hi all,
Received a reply from Jose from spain, he only sells plans to north america, price $80 .
All shapes are DXF and DWG format for CNC cutting.
WaiexN143NM
Michael

[edclee]

I have wing tanks. Bill Clapp made them. They are 4” diameter aluminum tubes in the large lightening holes in the ribs just forward if the main spar and hold just over 5 gallons each. I use transfer pumps to the main tank. More info for anyone wanting to do it.
Sonex Corvair N72EL


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