I first tested it at a higher altitude. The reason being is because the day before I almost lost it when the engine sagged as I pulled up to a hover. In that case the power came back before I hit ground, and I was able to recover. So I was aware of the potential problem. I thought that the reason it quit the previous day was a result of too lean of a setting, so I richened it. The next day after richening it, I tested it fairly high first and it showed no signs of quitting. Later in the flight I brought it lower and had just pulled up and 3-4 seconds later it died. Maybe the reason it didn't quit during the high altitude hover test is because there was more fuel in the tank and the engine was running richer. Later as I brought it lower, there was less fuel in the tank and the engine was most likely running leaner.

Several days before when the temperature was about 15 degrees warmer, the engine would run on the leaner setting and I was able to hover just off the deck for 20-30 seconds. I think that since the temperature yesterday was colder and the air more dense, when pointed vertical at lower throttle, the muffler pressure just couln't keep up with the demand for fuel required by the richer setting. So I guess bottom line is in colder weather it is more difficult for muffler pressure alone to keep up with the demand for fuel than in warmer weather in these giant glow engines. When I tip test it on the ground I will make sure there is little fuel in the tank.

Greg