I would immagine the engine was spark ignition even if using glow fuel. His later engines were, and you can lean it out much more and have the engine run. His later engines used camping stove fuel, a very clean unleaded gas; he could have added nitro to that also, which is good for endurance. Also I think you could get a Fox .59 in spark. Also he would need the fuel capacity to get to the altitude as the climb had to slow as power and air density dropped.