Thought I would update my Delta Vortex build and experiences. This aircraft has retract gear which made the fuel tank location to be back in the center of the wing as the nose gear took the original fuel tank location. The fuel tank is about 11" to 12" behind the engine. The original configuration had an OS 91FX installed. Tank distance and the old style needle valve(bubbles) didn't run reliably. Next configuration was a new OS 91FX with a Cline Fuel pressure system to correct the tank to engine distance. It ran but not well. It is my opinion that the OS 91FX venturi style carb is not really compatible with a pressurized fuel system. Now I have installed a new YS61 pumped two stroke side exhaust engine. Yesterday the first test flight went very well. I have also changed the radio system from 72Mhz to the 2.4Ghz JR R921 receiver with a JR X93903 transmitter. During the radio change I used a five-cell battery that replaced the four-cell battery. The battery is in the very aft bay between the rudders. The YS 61 seemed to weigh exactly the same as the replaced OS 91FX. The 16 oz Hayes fuel tank was reduced to a 13 oz Hayes tank. All of these changes obviously shifted the CG aft just a bit. When flying inverted before the changes, a bit of forward stick was required to maintain level flight. Now little if any forward stick is required when inverted. So the CG is now just about perfect. With all controls centered for the first test flight after the engine and radio changes, no trim whatsoever was required after takeoff. The plane is built perfectly straight and is now balanced very well CG wise. Hopefully, after all these months of engine, fuel and landing gear hurdles, she will start to be a good and reliable flier. A couple of pics of the new YS 61 pumped two-stroke engine.

Nov 20, 2007 Update: Six flights now and not a single fuel issue. I think the fuel issues are over and many nice flights awaits this Vortex.