Assume you had an airplane with magical engines that didn't need fuel, air or power, to operate. What thrust to ground weight ratio would the airplane need to reach orbit? By ground weight I mean mass times 9.81.
Assume not needing fuel, air or power is the only magical property of the engines and the aircraft is otherwise made from modern day technology.
Obviously a thrust to weight ratio greater than 1 would work, but I have a hard time reasoning what would be a realistic minimum.
Every time I think about it, it seems that if the airplane could lift off the ground it could reach orbit, but that doesn't seem right. My reasoning is that since both drag and lift are proportional to velocity squared (see here) as the airplane gets faster, it could just climb to a higher altitude and lower density to compensate. The airplane would just go faster and faster (and go higher and higher to keep a constant lift and constant drag) and eventually reach orbit.