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MarkvirsII

My SSTO spaceplane keeps on veering too the left

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Posted (edited)

SO My Spaceplane keeps veering off course I have checked eveything I know of but it still happens. Does someone know what I need to do

 

Pics: Side top http://prntscr.com/ndgwxp  < UPDATED

Downside: 

Frontal:  http://prntscr.com/ndgxyd

Backside: http://prntscr.com/ndgye4

Wing side: http://prntscr.com/ndgy7k

SO does anyone know what is wrong I need to be able to get into eve orbit.

 

EDIT: I went and used a other spaceplane from steam and it still veers too the left 

EDIT: I uploaded new pics

Edited by MarkvirsII

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Welcome, @MarkvirsII.   The view from above shows a tailfin on the left,  but not on the right, outer rapier.   
It is easy to pick up a part to move it, and then replace it without the mirror symmetry being selected. 
KSPs editor tries to autoset symmetry based on what you place a part onto, but computers often guess human intentions wrongly.
Many of your image links are repeats of the image from below; you can edit your post if you want to change the links.

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Posted (edited)

I re-added the tailfin but it still veers too the left

EDIT: I also updated the image for topside

Edited by MarkvirsII
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Moved to Gameplay Questions. 

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Posted (edited)

@MarkvirsII - Check that your landing gear is perfectly straight. I'm sorta assuming that "veering left" means veering left on the runway, not in the air. That problem is not unheard of, and probably down to wonkey wheel physics, but is exaggerated if the wheels are tilted out even a bit.

On windows I think, if you press 'f' while in the editor, the rotation tool goes into absolute mode and will rotate things relative to the global coordinate system, not the individual part.Then you can enable angle snap and rotate stuff until it is vertical.

Also, if you are trying to make an ssto, it wouldn't hurt to a) use the fat-s wings - they have fuel storage and wing surface, so not completely dead weight and b) mk 2 fuselages are for some reason I think draggier and carry less fuel for more dry mass and therefore, have less dV. It might be worth changing to a mk 1 based fuselage. The downside is less heat tolerance, but you are already using some so it shouldn't matter. Also, do you really need 4 rapiers on a craft that size?

 

 

Edited by qzgy

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Brevity is a virtue, but you are maybe too brief.  Assuming you are veering on the runway, the next standard suggestion is to try trim up (alt-S), or pulling up a bit (S-key) during the takeoff roll. 

Nosewheel aircraft tend to wheelbarrow, especially in KSP where people make their own aircraft and they might not be naturally trimmed to lift the nose wheel.  Your side view makes me suspect your airplane might naturally nose down.

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Having a plane veer to the left on takeoff is a very common problem. In fact, it's so common that there are actually some suggestions on the FAQ in this forum.

There are many possible causes, and many possible fixes.

My typical suggestion is to understand that passive stability in general comes from having very little drag at the front of your craft, and high drag at the back end. This is true both while you are in the air, and on the ground. When you are on the ground, your wheels have a lot of friction. Wheels with high loads have even more friction. What this ends up meaning is that your nose wheel may end up having a lot more friction/drag than your rear wheels.

To fix it, in the SPH open the menu for the front wheels. On the friction control, set it to manual and adjust the friction on the front wheel down to 40% or less. Even 0% works.

 

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Unfortunately it is a very common problem as mentioned by everyone above. There's definitively a fix/workaround for most of the causes, if you don't mind posting your craft file I can have a look at it.

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Posted (edited)
10 hours ago, MarkvirsII said:

SO My Spaceplane keeps veering off course I have checked eveything I know of but it still happens. Does someone know what I need to do

 

Pics: Side top http://prntscr.com/ndgwxp  < UPDATED

Downside: 

Frontal:  http://prntscr.com/ndgxyd

Backside: http://prntscr.com/ndgye4

Wing side: http://prntscr.com/ndgy7k

SO does anyone know what is wrong I need to be able to get into eve orbit.

 

EDIT: I went and used a other spaceplane from steam and it still veers too the left 

EDIT: I uploaded new pics

  • Put Dampener and spring to desired levels. The more weight the vessel has the higher both numbers need to be set to. The numbers are arbitrary so you should play with them. If the space plane damps up and down during the takeoff roll you should put dampener and friction higher.
  • Small unevenness in ground contact can cause more friction on one wheels causing the vessel to turn. That is why it is best to attach the main landing gear to the center stack of your vessel (space plane or rocket) and then use move:tool to drag them to the desired spot under the wing and use rotation with absolute mode to straighten them relative to the vessel. If this is the case you might have the gears attached to the parallel tanks or worse the wings. Notice how wings flex under aerodynamic stress? Can you imagine unevenness when rolling down the runway with 15Ton per wheel while the wing holds the landing gear?
  • Besides the above point I mentioned friction. It is best to have more friction on the back wheels and less on the front wheels. The difference doesn't have to be great, for instance a Friction setting of 0.9 on the rear with 0.7 on the front should work miracles. It is often better to have friction below 1.0 (unless your vessel is very heavy it should be more) so there is some drifting effect so that they don't anchor into the ground when rolling. That in and of itself can cause the veering even when this effect isn't noticeable at first glance.
  • Use autostruts by right clicking a part in the editor, activate "advanced tweakables" in main menu general settings to allow autostruts. Use grandparent on all center stack fuel tanks, then grandparent on the parallel fuel tank directly attached to the center stack and the other parallel parts to heaviest or root part. It is possible the weight of the engine bays wiggle or sway micro metrically under engine thrust causing unexpected sway causing the space plane to turn unexpectedly.
  • Use SAS, it is a very common mistake but you should never forget.
  • Only put the front or main landing gear to steering enabled. Preferably the landing gear closest to the CoM for more natural steering (main landing gear in your case)
  • There's a radial and symmetry mode in the editor toggled through when using the X key. (The M or MM is the symmetry mode icon in the lower left corner. The radial symmetry mode when toggled to using X represents the 2, 3 4, 6, 8 numbers. It is possible you accidentally used the radial symmetry mode while being selected at 2 and you snapped it on slightly a-symmetrical varying by a degree so it isn't visible, please check this. Or you put the landing gear to the parallel tank which was radially attached while being snapped on symmetrically and you put rotation on the main gear which are now attached uneven.
  • Put landing gear closer together. I know putting them wide causes the space plane to be more stable but any leverage due to wiggling of part attachment between both gears will increase as the landing gears are put wider. FWIW, you should be able to put them closer and still be very stable.
  • While it would seem strange for a rolling takeoff, I know that the heavy mass wants to move in front under acceleration. That is especially the case if the front is more draggy while being lighter (which it is since you use Mk2 parts) while the back is super heavy. I see you have 1 LV-N and 4 Rapiers. Your main landing gear is also further to the back. Maybe it's wise to redesign so the 5 engines are moved a little bit closer forward. In any case, for a rolling takeoff higher friction on the back wheels should also remedy this effect.
  • Are you swaying from the runway without control inputs? In case that you do have control inputs know that rear stabilizers that are put both to pitch and yaw counter effect each other which may cause the sway, automatically if SAS was turned on. Since you have 4 rear stabilizers it would be best to put on pair to yaw and the other to pitch.
Edited by Aeroboi

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Posted (edited)

I think I remember a twitch streamer mentioning something about KSP having an issue with multiple tail fins. I cant remember the specifics though.

Remove them all and only use one for testing. Make sure its perfectly upright. (90 degrees to the main craft).

Hope that helps

One other thing...is this using a joystick? try removing it?

Is there some sort of device connected to the computer that could be causing that to happen. try removing that

Edited by Anth12

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53 minutes ago, Anth12 said:

One other thing...is this using a joystick? try removing it?

Is there some sort of device connected to the computer that could be causing that to happen. try removing that

Good advice. I play with an xbox pad a lot (on PC) and they need really large deadzones to avoid accidental drift. I think mine are 30% from memory.

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