Noob here, my plane keeps shifting left and crashing and i dont know why

[modybird]

Here are some pictures, help would be appreciated

http://i.imgur.com/iyDMH6C.png

http://i.imgur.com/CseKTS9.png

http://i.imgur.com/79XUh8J.png

[Verband]

Upload craft file plz

[Kyle Worden]

You see how your blue lift arrow points down? this is because your lifting area is unstable, think of a ball sitting on the top of a hill, any nudge will make it fall, the same principle is happening to your airplane.

 

Some quick fixes that should help:

1. make the wings parallel to the ground, this applies to the elevators as well

2. Make the plane a little bit longer, this will make it more massive, and a little bit more stable

3. double check afterwards to make sure the lift arrow is pointing upwards.

4. rotate your landing gear so that the wheels are perpendicular to the ground, they are currently canted inwards, and this will cause steering issues on the ground.

 

Hope this helps.

Edited June 22, 2017 by shadoxfilms

[Aegolius13]

Do you mean it pulls left on the runway, or after you've taken off?  (or both?)

2 hours ago, shadoxfilms said:

 

4. rotate your landing gear so that the wheels are perpendicular to the ground, they are currently canted inwards, and this will cause steering issues on the ground.

This is the most common cause of turning while on the ground.  It works best to toggle the rotate gizmo to "Absolute" mode and make sure they're completely straight in all three dimensions.  If you have access to them, the retractable landing gear tend to work better in general.  

It's probably not the direct cause of turning left, but your engines (and thus your center of thrust) are above your center of mass.  This will likely put some torque on your craft, making it want to pitch down.  That may also make it tougher for your plane to take off, exacerbating problems on the runway.  The easiest way to fix this is to keep engines all at the middle of the plane, but you can also do some fancier tricks with angling engines, or using sets on different sides of the center of mass.  The mod "RCS Build Aid" is very helpful for diagnosing this kind of torque. 

Between the three tailfins and the elevons, you have a LOT of control authority relative to the size of your plane.  Sometimes excess control authority can cause instability.  You could try turning down the control authority tweakable, switching to smaller surfaces, or using a part like the Delta Deluxe that has a smaller fraction of moveable area (as a side bonus, it's lighter too).  If you haven't already, you may want to try setting it so the elevons only do roll, the horizontal stabilizers only do pitch, and the vertical stabilizer only does yaw.

It looks like your horizontal stabilizers have a bit of anhedral (they point down).  This can make a craft less stable.  You might try them parallel to the ground, or pointed upward a bit (dihedral).

From the front view, it looks like your antenna is mounted a bit off-center.  This would only be a small effect, but could contribute to some instability in the yaw axis.

Also, not related to the issues you're having, but the swept wing is a devious noob trap.  While it looks cool, for some reason it's twice as heavy as the other wings for the amount of lift it generates.  

[bewing]

I am assuming you mean on the runway. The wheels you are using do not steer. They also have a slight bias to turn left. If you put an LY05 wheel on the front (which can steer) it will probably change things a lot. You may discover further issues in flight, of course.

 

[Reactordrone]

Even if you get the lift vector the right way up it's quite nose heavy with landing gear right at the back of the fuselage. This will make it very difficult to rotate for take off and when you deflect the horizontal tail fins they will obstruct the engine thrust.

[Noud]

i think it is some kind of bug... all my planes rovers or anything moving over ground turns slightly to the right.. tried everything but nothing worked i could not even get the most simple rover to drive in a strait line on a lv3 runway, or grass near ksc  

[Tex_NL]

A problem as common as it is old. And it has been answered and discussed dozens of times over the past few years.

 

[Kryten 2X4B 523P]

ok, where to start..

Tail - rotate the tail fins so that theyre level. This is probably the source of the lift arrow pointing the wrong way. Move the tail fins and rudder backwards to the end of the tail connector.

Rear Wheels - ditch both, theyre unsteerable. Replace with a single, small steerable wheel which will turn the plan into whats called a "taildragger" - 2 wheels at the front, one at the rear. It will steer from the back then.

Front wheels - rotate them in absolute mode until theyre straight in all axes, and move them back a bit so theyre closer to the Centre of Mass (COM)

Wings - these wings are a bit of a pain to use actually - use the rotate tool so theyre not swept back as much - this will move the Centre of Lift (COL) closer to the COM, but you still want it to be behind the COM a bit. Finally give the wings a little upward rotate so the wing tips are higher than their connection to the fuselage. This will give you some clearance for take off & landing. Holding shift while rotating will let you move in smaller increments.

Engines - mount these on the tail connector and rotate them straight, and move them so theyre just below the COM line - this will make sure the thrust isnt blocked by the tail

Control surfaces - remember to set the control authority for each control surface - for a light plane like this you want the wing surfaces to be set to roll only, on the tail the rudder should be yaw only and the tail should be pitch only. Drop the authority level to about 50 to start, you may want it lower.

 

And you should end up with something like this - which doesnt fly too badly actually:

Front:

 

Side with COM / COL / COT

Edited June 22, 2017 by Kryten 2X4B 523P

[nicoaraeradu]

For me simply turning SAS did the trick

[Guest]

Sometimes one of my jet engines blow out so be aware of the engine

P.S I can't tell if your engine is one or two because I'm on mobile

Edited July 26, 2019 by Guest