I have been looking at a F-117 Stealth fighter for some time in about 1/3 scale. If you enlarge the cockpit area about 10% in the vertical a real person will fit. It's a ducted fan, something that few have made successful. However, I think it is possible to make a workable DF installation. There was one at Oshkosh this year. I'm thinking of a center mounted single engine, a Mazda seems a good choice, with belt driven fans. The other option is to use two, 2-cycle engines such a Hirths. They would produce more power and the reliability issue would be offset by there being two of them. The full size aircraft engines produce about 21,000 lbs of thrust. That's about 40% of the gross weight. If you built the scaled down version in the 1200 lb gross weigh range you would need about 500 lbs of thrust. That's on the high end for a Mazda, but in the range. Also, the wing loading of a homebuilt would not be scale and would be much lower. There's always the question about the full size F-117 requiring a computer to fly it. That's true, but there are many examples of large scale RC F-117s that fly just fine without even using gyros. Since the F-117 is all flat panels you can build it any of several ways. Use a tube frame and fabric it like the FMX-4 Facetmobile. Make it from plywood using foam sandwich panels for the flat parts. Or, you could make it from foam and fiberglass or carbon if you have deeper pockets. A possible approach would be to build a large scale RC model of the intended design and instrument it using a system like Eagle Tree offers and off-the-shelf electric ducted fan units. Many homebuilt designers have gone this route. Such a project would certainly be an attention getter. Any thoughts?