Help with spaceplanes.

[Archer_Rules]

Recently started trying to make a plane mainly for science and contracts. Built one and it keeps veering left and right but its pretty random. When it does go straight it launches just fine I just can't figure out why its not stable. I've tried using a vertical tail fin and not using one but I can't figure anything out. Wheels are in between big wing and tail wings. 2 FL-T400 fuel tanks with the basic jet engine/air intake. Picture below. couldn't figure out how to insert image from url but heres a gyazo picture.

 

https://gyazo.com/e62b39fb998ad23e134f69d787faf912

Edit: Goes left/right on the runway. Once it takes off its all smooth. 

Edited July 3, 2021 by Archer_Rules

[Dman979]

Hey, @Archer_Rules, and welcome aboard! I've moved your question to Gameplay Questions and Tutorials- you'll get more relevant information here.

To insert a picture into your post, you have to use the image's direct URL. Yours is https://i.gyazo.com/e62b39fb998ad23e134f69d787faf912.jpg, which shows up as

 

[bewing]

There are many possible sources of a veering problem for airplanes. In fact, veering is so common that it's in the FAQ for this forum. However, one of the easiest (and most likely to work) solutions for veering is to turn on Advanced Tweakables, select the front wheel in the editor, look at its context menu, switch "friction" from auto to manual, then reduce the friction setting down very low (.1 to .4 is usually good enough).

 

 

[Caerfinon]

2 hours ago, Archer_Rules said:

Recently started trying to make a plane mainly for science and contracts.

When I started making planes, I found this tutorial very useful. Some information is dated, but overall it's a pretty good guide. @bewing is correct, changing the friction on the front wheel is also a good suggestion

 

[herbal space program]

17 hours ago, Archer_Rules said:

Recently started trying to make a plane mainly for science and contracts. Built one and it keeps veering left and right but its pretty random. When it does go straight it launches just fine I just can't figure out why its not stable. I've tried using a vertical tail fin and not using one but I can't figure anything out. Wheels are in between big wing and tail wings. 2 FL-T400 fuel tanks with the basic jet engine/air intake. Picture below. couldn't figure out how to insert image from url but heres a gyazo picture.

 

https://gyazo.com/e62b39fb998ad23e134f69d787faf912

Edit: Goes left/right on the runway. Once it takes off its all smooth. 

Your problem in a nutshell is that your plane is too nose-heavy. To fix it:

1) Move your engines downwards , so they are closer to your center of mass and therefore not pushing your nose towards the ground all the time.

2) Move your nose wheel as far forward as you can, and displace it downwards a bit, so that there is less weight resting on it and your nose is a bit higher than your tail. By the looks of it, you could actually displace your rear wheels downwards a bit as well to give your tail more ground clearance. In any event, the rear wheels should be fairly close to your Com and the front one as far forward of it as possible.

I'll bet if you just do those two things, your plane will take off and fly a whole lot better. Just make sure also that the CoL indicator in the SPH is just a bit behind the CoM indicator. If it's not, offset either the wings back or the engines forward to get it there. I say that because it could be that your CoL is ahead of your CoM the way the plane is now, but the resultant tendency to pitch up is being offset by the high placement of your engines.

 

 

....Oh, and disable the steering on your nose wheel if it's on.  That usually responds so strongly to control inputs when you're going fast on the runway that it's more likely to put you in the ditch than keep you going straight. Lowering the friction setting as suggested above will largely do the same thing by nerfing your steering authority.

...Lastly, putting a tail fin on it couldn't hurt, as you have nothing but your cockpit right now to give you any yaw authority.

Edited July 3, 2021 by herbal space program