For a certain weight, climb angle is proportional to excess thrust, which means thrust minus drag. Increase thrust, or decrease drag, and excess thrust is increased.
Originally Posted by
FlightDetent
Along these lines: if that aeroplane from the graphics had a better wing (longer L vector) it would climb faster - I really wish not to be wrong about that.
No matter the wing, L would have to
exactly equal W cos gamma, no more no less. Any longer, and we would no longer be in equilibrium. (We would accelerate upward, yes, temporarily - a transient - but a better wing is not necessary for that: a longer L is already available, so long as we're not stalling, by merely pulling the yoke back. If we were already at Vx, then drag would increase, excess thrust would decrease, and we would either be forced to pitch down to capture the new slower speed and shallower climb angle, or naively hold the nose up and decay the speed until we stall). However, a better wing (i.e., better L/D ratio) would yield a steeper climb due its
lower drag.
To make it climb steeper as it is, tilting the vectors, can only be achieved by adding more thrust to keep the equilibrium. No dispute there, the fact that showing throttles forward is needed to go up is not yet lost on this magenta child. There's hope yet
Not sure what condition you're fixing by the phrase "as it is," but to climb steeper (aka increase excess thrust), in addition to increaseing thrust, we can also decrease drag. Say we're starting from a fast equilibrium condition, way on the front side of the drag curve: climbing at a shallow angle (or flying level, or descending... it doesn't matter) at 300 knots. We pitch up a little bit, and slow from 300 to 250. Two things happen:
A) The transient - short term - L is greater than W cos gamma: We pitch up, accelerate upward, and slow down
B) The new equilibrium - long term - L is equal to W cos gamma: At the new slower speed, thrust is the same but drag is less, therefore excess thrust and climb angle are greater.
Both things have to happen, but it's waay too easy to only think about A. It seems deceptively obvious, as a part of the "vehicle goes where the nose is pointed" intuitive mentality that is so hard to break people out of, and it may seem like a waste of neurons to consider it past "duh, if you pull up you'll climb steeper;" but it's the wrong explanation (and a deadly one; aviation history is red with the blood of pilots who intuitively pulled up sans thrust, and their passengers). A is really only the mechanism by which B is established, and B is the real reason we're climbing steeper now.