KSP Spaceplane C/G and design help

[Clark1961]

Shrinking the wings down makes me think that I'll need a lot of thrust to get/stay in the air,

Ya might wanna spend some time thinking about that concept. Maybe include thinking about runway length and a gravel sensor for the nose gear (that last bit was a joke).

 

[overdrive148]

Ya might wanna spend some time thinking about that concept. Maybe include thinking about runway length and a gravel sensor for the nose gear (that last bit was a joke).

Now that you mention it, I could drop on a few 21 ton solid rocket boosters and forget the wings and center of lift

I have a gravel sensor installed in all of the parts I use in my aircraft, the signal for gravel detection being a massive explosion

I stay in the VAB. When I've messed around in the SPH I always run into the CG CoL issues as well. The problem is the engines are too heavy for their size. They really need to be longer and integrated more into a nacelle. The other issue is you can't put fuel in the wings. You should go into your part cfgs and make it so you can put fuel in the wings. It's only 4 lines of code.

I should probably warn you that neither will likely impress a pilot, but it's at least far more predictable. The other outstanding issue is the thrust to weight of the engines and such, but other mods address that. Also, the patch for wet wings above will help. I'm tempted to write a module manager patch to do some of this.

The wet wings sound like something that's viable for sure. Do the wet wings add mass for fuel? And if so, do they distribute weight evenly across the surface of the wing or?

 

[mkosmo]

The wet wings sound like something that's viable for sure. Do the wet wings add mass for fuel? And if so, do they distribute weight evenly across the surface of the wing or?

Yes, it'll add mass (which will be consumed as the fuel is consumed). The bigger problem: The part only applies a moment to a single point with stock physics, so yes

 

[JOhnH]

As my wife's CFI kept telling her, "more right rudder!"

Not cropped because effort.

Basically impossible to get in the air no matter the landing gear distance from the C/G (close to it or farther) including the same configuration and distance in the original. SAS on makes it get about half way down the runway before it slips. SAS off means the kerbals die much quicker.

I tried to correct it in the video but obviously it didn't work. Full deflection including using reaction wheels and 3 of 4 surfaces on each wing dedicated to pitch didn't get the nose up at all. Looks to be an unsuccessful model.

 

[overdrive148]

As my wife's CFI kept telling her, "more right rudder!"

You can see the control deflections in the bottom left corner - they are at 0 when things start to slide and hit the fan. I tapped it a couple times to try to counter (holding it down goes quickly to full deflection) and when things went sideways I was holding it down.

There's no torque involved so something in the layout like that was screwy, I think it was due to the reversed flight model because the exact same plane flying in the other direction flies great on and after takeoff.

And for that takeoff I had 9 reaction wheels trying as hard as they possibly could to maintain that heading

 

[warthog1984]

Shrinking the wings down makes me think that I'll need a lot of thrust to get/stay in the air, and then we're dealing with more of a winged rocket instead of a space plane. Hm.

Also canards basically come in one size and shape unless I add a 'wing' and an elevator, which combined add more lift and displace the C/L more than just the canard alone.

The issue is CG vs CL, not lift itself. Drop the canard completely (it's not adding much control for the lift it gives), extend the nose to get the CG forward, and shrink the wing to get the CL back.

Again, most real-life delta wings and spaceplanes (X-15, X-70, Concorde, F-104, etc...) look like long skinny darts for a reason.

You will use up a lot of runway, but it should work.

 

[overdrive148]

Oh man, KSP just released to 1.0 full version. Among a ton of other things...

Aerodynamics:
- Complete overhaul of the flight model.
- Lift is now correctly calculated and applied for all lift-generating parts.
- Drag is now pre-calculated automatically based on part geometry, and applied based on part orientation in flight.
- Both lift and drag are dependant on density and the speed of sound; both properly calculated from temperature and pressure.
- Stack-mounted parts can occlude each other for drag calculations.
- Lift-Induced drag now properly simulated.
- Stalls are now properly simulated.
- A new body-lift system meaning parts can induce lift even if they are not designed to do so.

This is probably going to make it way more complicated to get this thing flying or not, who knows. Just gotta download it...

 

[mkosmo]

I'm downloading it now... curious to see the new aerodynamics and how they compare to old-stock and FAR.

 

[overdrive148]

I'm downloading it now... curious to see the new aerodynamics and how they compare to old-stock and FAR.

Did you see the airbrakes? So excite!