Yes, it does have that option. It comes in either another set of two 12 gallon tanks or the two 15 gallon tanks. I was told they can be mixed and matched in any combo of 24, 30, 48, 54 or 60 gallons of total fuel that way. Again, I was thinking more about weight when I was talking about only a central 10 gallon tank and distributed behind the passenger seat for balance. I just want about 10 gallons more, not 24 to 30 if I used the Zenith extended range tanks. I suppose I could get tanks put in, but you're adding more a lot of extra cost for those tanks and with my weight, would probably never fill them completely. My thinking was to get that 500+ mile range without having to add 2 expensive and weighty auxiliary tanks when filled. My thoughts were the two 15 in the wings and whatever l could fit fitted into the space behind the seat. Hopefully 7 to 10 gallons. Its a mote point really, I'm starting to like the TurtlePac option if I need more range with no passengers.

Jay,
The auxiliary tanks are a "Factory" option for the 701, it's in the plans. I don't see why this wouldn't also apply to the 750 or the 801. Just make another fuel tank and install it in the next rib bay. You can either plumb it separately or you could plumb it to the primary tanks as though it were all one tank. If your connections between the two are large enough the "auxiliary" tanks might not even need their own fuel caps.
Doesn't the 750 have an extended range option, or auxiliary tanks?
I haven't had an opportunity to study the 750 plans but I would think they are very similar to the 701.

I am planning on using a ULPower 360iS which is 130 HP yet only weighs 172.8 lbs which includes all accessories, oil and exhaust, air cooled, no reduction gear. It's built with FADEC and fuel injection so it should be pretty economic and runs off mogas or avgas 100. I know I am adding some features that will add a bit more weight than normal, and that's why I'm trying to streamline where possible. I'm estimating that this engine will use about 7.0 gals per hour and if I can get a cruise of around 100 mph through streamling, no slats using VGs, cut drag where possible and with 30 gallon tanks that would give me a range of around 425 miles. That would get me to Chicago from where I live without refueling. I would like a range of 500 however, which means I need approximately 10 more gallons someplace. I was looking into turtlepacs in the passenger seat if they don't stink up the inside of the plane or possibly put a small tank in that recessed area behind the passenger seat with a capacity of around 5 to 7 gallons as a fuel sump. Just kickin around ideas right now. That's why I'm always interesting in ideas that you and the other builders have done or experienced.

Jay,
Depending upon the engine you choose the flight time on the extended range tanks is (in my opinion) more than sufficient. be careful about customizing your airplane unnecessarily. the range of the 750 will be much farther than your bladder and available day light (6-8 hrs?). In addition to minimizing your useful load, you might find that most modifications have a diminishing return. I only say this from experience. :)
What engine are you thinking about?

Thanks Brady. I'll probably contact you about customizing my tank when I get to that stage of the work (I haven’t started yet, but will go for the rudder kit next month). I appreciate the quick answer to my question. Just out of curiosity, do you think there would be room between one of the wing ribs to build a tank that could hold a gallon or two more fuel than the 15 gallon extended range fuel tank that Zenith offers or is that space pretty much optimized to the max from what you have seen in the building your 601?
Jay

Jay,
These flush caps are the same ones used in the 601 kit. I got them from Aircraft Spruce. you will need to replace the bung in the fuel tank which will require welding. I would be happy to re- weld your tanks for you. you can email me if you are interested.
brady at magnificentmachine dot com.
Cheers, Brady

Brady;
I saw your custom fuel tanks and was wondering if that was the only way to get the shorten fuel neck and flush cap that is built into your wing? I haven't seen the tanks that come with CH 750 kit, but that stickup kinda bugs me a little because of the extra drag it will create. I mean the CH 750 will never go super sonic (grins) but every little bit of extra speed I'd be grateful for. If your plane isn't scratchbuilt, do you know of any way to modify those tanks and necks to get it recessed into the wing and make a flush fuel cap possible from the kit?
Jay

Alan,
when I installed the flush caps; I just "winged it". So, I have no drawings, sorry.
My tanks are vented the same way Cessna has done it for years. there is a tube that goes through the bottom of the tank to the upper most forward corner. It's cut at a 45* angle at both ends and both angles face forward.
The caps are the same ones the 601 uses. I'll try to find you a part # if you will remind me... :)
Cheers!

Hi Brady,

Can you send me some details on your flush tank caps, they look great, I am also going to install extra aux tanks for the same reasons as you have, shooting and fishing, do you have a drawing of your caps and how have you arranged for your tank venting? I have a few ideas on venting, if it is done wrongly it can make things go awful quiet.

Alan Cameron