Author Topic: The Factory Prototypes, HC-1, H-3, H-390, H-391 & H-391A part 2  (Read 10173 times)


Re: The Factory Prototypes, HC-1, H-3, H-390, H-391 & H-391A part 1
« Reply #15 on: April 28, 2021, 04:27:26 PM »
Doug, I haven't seen this mentioned anywhere thus far. On the Helioplane there doesn't appear to be any fuel filler necks on the wing or fuselage. the only mention of the fuel system is a brief sentence about the Ex-Cell-O fuel injection system it is equipped with. In the 2 cockpit photos that have been published it appears they removed the normal Vagabond fuel tank behind the instrument panel (I assume for safety or center of gravity considerations). With the engine sitting low and with the reduction drive mounted, there could be enough volume for a small tank on the forward side of the firewall in the space above and behind the engine with the filler neck access being through the cowl with the side latches opened. The only other option would be an aft fuselage tank like on the early bonanzas but there isn't a visible filler neck. I reached out to the Smithsonian but they haven't been able to connect me with anyone that knows about the airplane. It's a shame the prototype isn't easily accessible so we can learn more about it...

Doug Johnson

Re: The Factory Prototypes, HC-1, H-3, H-390, H-391 & H-391A part 2
« Reply #16 on: April 28, 2021, 07:55:03 PM »
I renumbered this to part 2

ST, In a conversation about auxillary fuel tanks I remember something about the first couple of prototypes having a 25 gallon removable fuel tank in the baggage compartment. This was later changed to a fuel 25 gal fuel bladder that was hung in the baggage compartment and later became an available option for the H-391 as a long range tank.

I seem to remember this fuel bladder as being one of the mods done to the Helioplane by the EAA at oshkosh before it went to the Smithsonian for storage.

ST, do you have any Helio photos to share?  You mentions photos that aren't in these 3 posts