Putting a panel mount tank back in will reopen the SB#29 problem. If your CG is not too far aft, the cheap fix is adding ballast in the forward cowling or the firewall where the old tank was removed. Add just enough to bring the CG within limits when loaded.



Fuel in wing tanks normally gravitates and sloshes toward the trailing edge. It doesn’t matter how high the tail appears to be in relation to the wing. The wing ( and thus the wing tank) is at a positive pitch during climb and cruise. The only time a wing tank has fuel concentrated toward the leading edge is during descents.


Early models of the Kitfox did not have wing tanks and used a panel tank under the glare shield. It was in effect a large header tank. The panel tank geometry is such that the fuel supply port is never uncovered in normal attitudes. Wing tanks are, by comparison, very flat. During descents with low fuel quantity the supply ports on the wing tanks may become uncovered. To prevent fuel starvation the engine is supplied from a header tank. The header tank is large enough to supply the engine with fuel during extended descents. Generally about 20 minutes or more at idle power.


The original location of the header tank under the panel does not work well with wing tanks. In steep climb attitudes the wing tanks may be lower than the panel tank and it is possible for fuel to flow backwards. To correct that problem, the header tank was moved to a location low and behind the seat. This new location ensures header tank fuel does not flow back to the wing tank(s). See service bulletin #22 and #29.


All tanks must be vented. An unvented tank can develop a vacuum lock in the tank or the supply lines.


At rest, a vent line will have fuel in it at the same level as the highest fuel tank. If you have clear vent lines you may see fuel higher or lower than fuel in the wing tanks during flight. This is quite normal as changes in attitude will cause fuel to flow up or down in the vent.


Another option is to go with larger wing tanks and install a smaller header tank behind the seat like the current model 7.


John Pitkin