The following scenario puts an aerial tanker in orbit over KSFO at 3000 ft AGL. The tanker uses the 737 model, but you can use any model (a KC-135 model can be found at: http://home.comcast.net/~davidculp2/hangar/hangar.html). The center of the orbit is actually west of KSFO, and the eastern edge of the orbit passes over the airport. Note that AI aircraft do not react to wind, therefore your speed and bank angle will have to vary along the orbit since your "user" aircraft *does* react to the wind. I recommend using the T-38 as your airplane for four reasons: (1) it has a radar screen which may be needed to find the tanker; (2) it has the speed to catch the tanker; (3) it uses a JSBSim FDM, which means it can onload fuel; (4) it has a green light added to the instrument panel, between the fuel gauges, which comes on when you are in the refueling envelope. Right now the air refueling envelope is very loose, and I plan on tightening it up in the future. Currently no aerodynamic effects of refueling are modeled (i.e downwash, bow wave, vortices). Dave Culp, davidculp2 at comcast.net ESSO 2 aircraft ufo AI/Aircraft/KC135/KC135.xml 37.61633 -122.38334 3000 020 280 -15