One correction to my own post: when you go from level to climbing flight, the primary cause of the increase in the forces opposing thrust is that the weight vec

One correction to my own post: when you go from level to climbing flight, the primary cause of the increase in the forces opposing thrust is that the weight vector now has a component opposing it. That's how it is for cars, and anything else moving on land, as well. Gliders maintain airspeed because their weight has a component opposing drag, which is how it is for things rolling downhill, as well.