Plane won't pull up well.

[mole55]

How do you make planes pull up sharper and stay in a climb?

[Gaarst]

Please post screeshots so that we can see what your plane looks like: it will be easier then to solve your problem.

Anyway, the most general causes of a plane not pulling up are:

- your center of mass being ahead of your center of lift: this will force your plane to pitch down, and therefore will make it harder to pull up, even if SAS can hold its pitch. Try to move your wings or add fins to make the two as close as possible, also keep in mind that, as fuel is consumed, your CoM will most likely move.

- not enough control surfaces: for pitch, try adding fins, elevons... at the back or at the front of you plane, the further they are from your CoM, the more they will act on your plane (see torque definition)

[Hagen von Tronje]

How do you make planes pull up sharper and stay in a climb?

- More lift. Add more wings, better wings, canards, etc.

- More thrust. Maintaining a steep angle of ascent requires the thrust to accomplish that.

- More control surfaces up to a point. Shortage of elevons may make your plane unresponsive, but more of them won't make you able to ascend any better assuming you can attain the correct AoA.

- More intake. Assuming you use jet engines, as you ascend your intake will tend to decrease due to thinning atmosphere. This is countered by either having more intakes or by going fast enough that sufficient air is forced into the ones you have. See thrust - too steep an ascent = stalling out.

- Less mass. More crap, less fly, simple formula. Cut some extra weight to see better results.

- Wing placement. As mentioned above, putting wings all the way the back can be a big mistake. It's best to design your wings as a single movable structure (i.e. everything attaches to innermost wing panel) so you can test it in different positions to get the desired performance.

[Alshain]

-Not only do you not want your center of mass behind your center of lift, which makes the plane unstable... you also do not want your center of lift too far behind your center of mass. This makes the plane overly stable and slow to turn or pull up.

-Make sure your pitch control surfaces are as far away from the center of mass as feasible. Pitch on the center of mass does nothing, that's where roll belongs (unless you are doing elevons instead of ailerons and elevators)

-Wheel placement. If getting off the runway before cheating the hill at the end is your problem, move the rear wheels closer to the center of mass. It's a lever, the wheels are your fulcrum, the pitch is your force, the front of the plane is your load.

[ajburges]

What most people gloss over is that if you can't pitch-up, your stability is overpowering your control authority. This is why you see the suggestions of both making the craft less stable and increasing control authority.

The actual answer depends on desired craft behavior. If you want your craft to be more resistant to stalls, you keep the high stability and add/move control surfaces for control authority. If you want your craft to be more efficient, you reduce aerodynamic stability so you need fewer control surfaces (which add drag).

My light and medium space planes tend towards less stable craft. Larger planes tend towards more stability since that is more tolerant of control mistakes (due to physics lag)

[xtoro]

Note that when you post s pic of your plane, make sure its in the SPH with the COM and COL showing. I make them so that they overlap 50%. But your fuel has to be balanced.

[CalculusWarrior]

If you've balanced CoM well etc, yet it's still maneuvering sluggishly, place a pair of canards near the front of the craft. Those dramatically assist with maneuverability, but can lead to an unstable craft if you pull off too many maneuvers with them.

[Randazzo]

If you'd like, I have some simple examples you can download. To use them, you'll need to add them your KSP/saves/YourSave/Ships/SPH folder.

They are named for what they are:

• NoseUp - Tends towards tilting the nose up. Makes for sharp turns and climbs but you risk losing control.
  
• TooStable - So stable it doesn't want to do much of anything but fly straight.
  
• SweetSpot - What I consider to be just right. Ample control, but suitably stable. You'll have to work pretty hard at losing control.
  

I'd suggest having a look at the Center of Mass versus Center of Lift in the hangar (notice how small the differences actually are, yet how much they contribute to the planes balance), and right click on the fuel tanks and drain them to see how the control is going to change as you drain fuel. Another aspect to consider is drag, and the intake mounted just above the jet engine is adding a degree of drag on the tail, contributing to the overall control of the craft. All of these are flown by me with SAS on, your results may vary without it, though it's considerably easier to do so if you use a flight stick.

You can also trim craft in flight with Modifier Key + directional control (on PC that's Alt + W,A,S,D,Q, or E) and reset the trim to "center" with Modifier + X.

Edited August 18, 2015 by Randazzo

[ajburges]

If you've balanced CoM well etc, yet it's still maneuvering sluggishly, place a pair of canards near the front of the craft. Those dramatically assist with maneuverability, but can lead to an unstable craft if you pull off too many maneuvers with them.

The reason canards offer such good maneuverability is because many designs place engines and significant fuselage sections in back. This in turn moves the CoM way back. Since the CoM is far back, any forward control surface will have a ton of control authority. Since control authority can be visualized as shifts in your CoL, this also explains why they can cause you to leave a stable flight envelope if you get too aggressive with them.

As I mentioned earlier, if you lack control authority, your CoM is not well balanced for the control surfaces you have.

[AlextheBodacious]

trim. Rotate stabalizers up.