How can I make an SSTO?

[Alpha 360]

I have done my homework on SSTOs and everything and when I design one, it spins out on the runway when I try to lift off.  I'm sounding like I'm keeping my cool, but I am quickly losing it. Please help

 

[Mastikator]

1. Show pics

2. Make sure the COL is behind COM

3. Make sure wheels are pointing straight down.

[Streetwind]

4. Make sure you say "spaceplane" because rockets can also be SSTO.

[Jimbo Jangles]

5. PICS!! Especially in the SPH with CoM, CoL, and CoT indicators on. 

11 minutes ago, Mastikator said:

3. Make sure wheels are pointing straight down.

3.1 Use the rotate gizmo and press "f" to switch to absolute mode instead of local. Make sure angle snap is on and you can line them up perfectly flat and straight. 

6. A better description of your takeoff run. At what speed do you rotate? At what speed does your plane spin out? 

57 minutes ago, Alpha 360 said:

it spins out on the runway when I try to lift off.

7. If it spins when you rotate (pull back on the stick), check if your control surfaces are set to one axis only, right click menu - pitch, yaw, roll. If your ailerons or canards or anything else is set to more than one of these, that could be your problem. 

8. Are your rear landing gear steerable? Did you disable the steering in the right click menu?

[stenole]

Although your problem is likely related to your landing gear, spinning may also be a symptom of yaw instability. If this is the case, if you rotate your aircraft to sit sideways, the CoL will not be sufficiently behind the CoM. This is most simply fixed with a tail fin.

But if your problems are on the runway, chances are that it is a landing gear problem.

Checklist:

• All landing gear points towards the direction the plane is supposed to go.
• All landing gear is standing straight up and down.
• The landing gear is not attached to a part that flexes too much when the plane is resting on the ground. This will cause the landing gear not to sit straight.
• Assuming a tricycle placement of the landing gear, the back landing gear should be relatively close to the CoM, and the front should be towards the very front. This will put more of the weight on the back landing gear. As a result your aircraft won't as easily tilt sideways and start to want to turn.
• Assuming tricycle placement again, turn off steering on back landing gear.
• Assuming tricycle placement, turn friction control off for the front landing gear and set it manually to a low number 0.3 or less.

If you follow the checklist, your landing gear can be eliminated as the cause of your problems.

A picture of your plane would be very helpful. A one line description of your problem is not really good enough to yield advice that isn't already available on the forum by searching.

[eddiew]

Remember that wheels (including spaceplane landing gear) are in a shocking state right now.

Runway donuts are a common bug, so your problems are possibly not your fault. Provide pictures and we'll very quickly tell you which case is true 

[cubinator]

Two big FL-T tanks and a Swivel will get a small satellite or command pod into orbit with fuel to spare. 

[Snark]

Moving to Gameplay Questions.

[Xyphos]

 

[bewing]

Try setting the friction on your front wheel(s) to .4 or less. This often fixes the spinout problem.

[Hodari]

9 hours ago, stenole said:

Although your problem is likely related to your landing gear, spinning may also be a symptom of yaw instability. If this is the case, if you rotate your aircraft to sit sideways, the CoL will not be sufficiently behind the CoM. This is most simply fixed with a tail fin.

But if your problems are on the runway, chances are that it is a landing gear problem.

Checklist:

• All landing gear points towards the direction the plane is supposed to go.
• All landing gear is standing straight up and down.
• The landing gear is not attached to a part that flexes too much when the plane is resting on the ground. This will cause the landing gear not to sit straight.
• Assuming a tricycle placement of the landing gear, the back landing gear should be relatively close to the CoM, and the front should be towards the very front. This will put more of the weight on the back landing gear. As a result your aircraft won't as easily tilt sideways and start to want to turn.
• Assuming tricycle placement again, turn off steering on back landing gear.
• Assuming tricycle placement, turn friction control off for the front landing gear and set it manually to a low number 0.3 or less.

If you follow the checklist, your landing gear can be eliminated as the cause of your problems.

A picture of your plane would be very helpful. A one line description of your problem is not really good enough to yield advice that isn't already available on the forum by searching.

Also make sure you're using the right size of landing gear and that you have enough for the weight of your craft..  And that your engines are all firing equally and one of them isn't flaming out sue to insufficient air intake.

[TwinKerbal]

The reason why you are spinning out may be related to the fact that the wheels are too close to each other. I like to put my landing gear on the wings and then use offset to move the front gear down to where I want it. If the wheels are too close to each other the plane may fall over or have takeoff issues.  Also make sure you have enough intakes.