Rate of climb not achieved in airplane

[Arpitshah1]

In a plane the Centre of mass is just ahead of the centre of pressure, so it is stable.

When elevator movement is given, it does go nose up but it doesnot climb. Instead in it tries to come down.  How to make it climb.

P.s Rhodes34 airfoil if used inclined at 8deg

Basically I want to know what affects the rate of climb and vertical velocity

[KerrMü]

Hi Arpitshah1

Welcome to the forums.

It´s not easy to make recommendations on how to improve your plane without screenshots, but I´ll try anyway. You could try to angle the wings a little bit upward. This should raise the lift quite a bit. In KSP straight wings are (almost) lift neutral, so that you can use them as fins on rockets as well.

The other tip would be: Keep experimenting. Building good planes is a bit tricky, but very rewarding if you get it just right.

[Arpitshah1]

Thank you. 

Actually photos are not available as of now. 

actually the thing is that wing is already 8degrees inclined and is producing enough lift for cruise. But the problem is that it is able to cruise only at low altitude and when i try to take it higher it just doesnt go. Only the nose goes up while the plane as whole tries to come down. (I guess the correct term here would be -stall, not sure)

 

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[Foxster]

I'd guess it's just a bit under-powered. Try tacking on one more engine. 

[KerikBalm]

Well what do you consider the limit for "low altitude"? what is its starting TWR? what engines are you using, what is your cruise speed?

Thrust drops off as you get higher, air gets thinner and you need to go faster, what is your "cruise speed".

What angle are you trying to climb at? you really need to give more detail to get helpful feedback

[FrostedShoe]

Is it possible your pitch control surfaces are stalling? Try setting their authority lower and see if that helps?

[ZooNamedGames]

Should also keep in mind that KSP’s aerodynamics are significantly dumbed down to reality. So applying realistic physics to the game is a poor notion.

If you’re wanting realism in the Flight model, I advise using Farrem Aerospace Research as it replaces the ingame aerodynamic model with one based on real aerodynamics. 

That said, wings don’t function as wings in KSP; they instead act as pieces of foam that generate lift. Angle of Attack and details like that are fed into an equation and aren’t factoring flight changes.

[TheKorbinjer]

Try reducing weight. Any Monopropellant in the fuselage is just redundant weight.  Cut the fuel you have in your craft in half. If you do that, yes you lose range, but you will get better results out of it. 

 

If you want to keep the weight, try increasing the area of the wings; make them longer/fatter. 

Edited December 25, 2017 by TheKorbinger

[DualDesertEagle]

On 24.12.2017 at 5:34 AM, Arpitshah1 said:

In a plane the Centre of mass is just ahead of the centre of pressure, so it is stable.

When elevator movement is given, it does go nose up but it doesnot climb. Instead in it tries to come down.  How to make it climb.

P.s Rhodes34 airfoil if used inclined at 8deg

Basically I want to know what affects the rate of climb and vertical velocity

 

On 24.12.2017 at 7:27 AM, Arpitshah1 said:

Thank you. 

Actually photos are not available as of now. 

actually the thing is that wing is already 8degrees inclined and is producing enough lift for cruise. But the problem is that it is able to cruise only at low altitude and when i try to take it higher it just doesnt go. Only the nose goes up while the plane as whole tries to come down. (I guess the correct term here would be -stall, not sure)

 

 

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8 degrees isn't much by itself but if more is added to that by pitching up on top of that the angle of attack becomes too steep pretty soon.

As said before KSP doesn't recreate actual aerodynamics but I've NEVER pre-angled the wings of any of my aircraft, not along the lateral axis anyway.

Also, we need more info on the thrust to weight ratio, the general aerodynamic shape of the plane and in what way u put it together so u ought to take some screenshots. Until then, let's start by telling us the weight of the plane vs the engine(s) u used coz going by ur description I can only assume that ur plane simply isn't moving fast enough to be able to climb any more. I may be stuck with 1.0.2 but I know for certain that a 0.625 m jet engine in the newer versions doesn't come anywhere close to being powerful enough to haul a craft made of Mk3 parts. Same goes for a single Wheesley in most cases.

[Zeiss Ikon]

Simple answer: if you raise the nose from a level flight cruise and the craft loses altitude instead of climbing, you're going too slow.  The old aviation rule works pretty well in KSP, too: "Elevator controls speed, throttle controls climb rate.  Get it backward, and you'll find the ground rising up to smite you."

If your craft can't go faster and still can't climb, it may be either the air getting too thin (my last Wheesley powered spaceplane, also hauling 900 units of Lf/O and a Reliant, had that problem around 10 km altitude), or the craft is too heavy for its power.  If the former, you may get some help by adding additional intakes.  If the latter, more (or better/higher tech) engines is the solution.  What intake type you have also limits your speed (the lower tech ones all start losing efficiency around 300 m/s), but if you can't climb at 250 m/s, you're too high or too heavy, and you need more wing.

[ave369]

High altitude means thin air. Thin air means low lifting force. Therefore, you just hit the ceiling for your plane design. The ceiling can be raised by either increasing speed or increasing wings, or both. It also depends on what engines you use, some engines are low speed and some are high speed. Don't hope to go hypersonic on a Wheesley, you need at least a Panther wet mode, or, better still, a Whiplash. If you use Whiplashes and still do not have enough speed, try adding more.

[Arpitshah1]

Thank you everyone. It has been a great help. Problem solved successfully!