Alcohol resistant fiberglass wing tanks for Kitfox IV

[cap01]

if you have a 91-92 kit and the tanks haven't been changed they are definitely the old style tanks and not alcohol resistant . mine is a 92 kit and had the old tanks , they were the small tanks but gray like they had been painted . like was mentioned , no serial number . I think there were some pictures of both the old and new tanks in one of my albums . if there is a serial number , it will be scribed on the inboard end of the tank .

[mr bill]

I recall John McBean telling me that all tanks shipped since either 2007 or 2010 (can't remember which--suffering CRS) are alcohol resistant.

[snowpaw]

Many thanks all,
I know I have the old type since the plane is from 1991/92 but want to know what to look for if buying tanks posted on e.g. Barnstormers. I don't want to end up getting the wrong tanks. I assume that most second hand tanks for sale would be of the old non-alcohol resistant type.

Ulf

[SWeidemann]

What about someone making tanks out of METAL? This would eliminate any of the problems with whatever fuel is available and might become available in the future (such as biofuel, etc.).

[Av8r3400]

Skot, the metal tank issue was tackled way back by Avid Flyer. They failed due to the wing flexing, causing cracks in the tanks. Followed by the inevitable leaks.

The modern Kitfox wing is still a very similar to this design to the original Avid wing. This wing design still flexes. A lot.

In order to make a metal tank work, it would need to float in the skeleton of the wing, between the ribs and spar tubes. In order to do this there would need to be drag/anti-drag braces going through the same bay as the tank. This would mean fuel tanks similar to the Piper design with tubes going through them to accommodate these braces.


Possible, yes. Complex, definitely. Practical, well...

[DesertFox4]

I type too slow. Below is my response which says the same thing as Av8r3400. Only thing Av8r3400 beat me to the post. Oh well. I'm posting anyway as it represents 10 minutes of work that I don't want to delete.

What about someone making tanks out of METAL?

Skot- many a thread has been dedicated to the "why not aluminum tanks" subject here and on several other Kitfox/Avid sites as a cure for the alcohol problem associated with older fiberglass tanks.

Problem is. They don't work. Many have tried all the way back to the early Avid and Kitfox models.

The fuel tanks are a structural element of the Kitfox wing. They are glued to both the front and rear spars. The fiberglass tanks will bend/give with the flexing inherent in our wing design. No problems. No leaks, usually.
Aluminum tanks will not accept the continuous bending loads induced during flight and will break at the welds leaking fuel into the wing. Not a desirable situation which results in much time and labor to replace the aluminum tanks.

[SWeidemann]

Okay, I get it. My vision was narrowed by my Luscombe with metal wing tanks however that wing structure can get along with or without the tanks inside. The air loads are handled my the spars and the stressed skins around it. The tanks are strapped inside. I do understand that to change out the wing tanks on a Kitfox is a major job. In my Rotax class the instructor told us to seek out premium auto gas without ethanol however there is a "Thirty Day Rule" for auto gas (with or without ethanol) for auto fuel going bad and causing problems with lots of components not including the fiberglass fuel tanks. Yesterday a Lockwood staffer told me it was best for the fiberglass tanks to run Avgas. At any rate I think I will drain my tanks (of premium no ethanol auto gas) this week since the plane will be down for repairs most likely more than 30 days. Thanks folks for your info.

Skot

[tommg13780]

The ethanol can be removed from the gas. It's not a difficult process but somewhat time consuming. I "washed" about 300-400 gallons to avoid damage to my Kitfox II fiberglass tanks for a season. If someone is interested I can detail the process.