SSTO not building speed

[KingDominoIII]

My SSTO cannot build up enough speed to take off. It spins around and veers off in different directions. I can't upload images right now, but I can tell you it is three medium retractable landing gears. I am on sandbox.

Edited December 28, 2016 by KingDominoIII

[Aegolius13]

Most of the time this is because the landing gears are not perfectly straight down.  Use the rotate tool and hit the "f" key to change the rotation mode to Absolute.  Then rotate all three axes so that they're straight down and point ahead.

You may also want to turn off steering on the rear landing gear (right click in VAB).  

If none of that works, try moving the various gear forwards and/or backwords a bit and see if anything changes. 

Also, what speed are you spinning out at?  Even a tuned plane can't go too much over 100 m/s before problems can set in.  Do you have enough wing, angle of incidence, and/or control authority to get airborne?

[bewing]

Also, passive stability comes from having low drag in front of the CoM, and bigger drag behind the CoM. So you can often help this issue by reducing the friction on the front gear to .4 or less, and increasing the friction on the rear landing gear to maybe 1.5 or higher.

[Mikki]

And think about keeping your main landing gears quite close behind your CoM, so your elevons in the back can pitch your plane easier, imagine a fulcrum in flight axis.

[foamyesque]

47 minutes ago, Mikki said:

And think about keeping your main landing gears quite close behind your CoM, so your elevons in the back can pitch your plane easier, imagine a fulcrum in flight axis.

Make sure they're behind your CoL, though, or you'll tend to lift your rear gears off first, which will cause spinouts.

 

4 hours ago, Aegolius13 said:

Also, what speed are you spinning out at?  Even a tuned plane can't go too much over 100 m/s before problems can set in.  Do you have enough wing, angle of incidence, and/or control authority to get airborne?

 

Says you. I've hit Mach 1 on the runway

[KingDominoIII]

Hey guys,

I've tried all of your advice and my SSTO is now making it off the runway without murduring Jeb. Thanks!

[Palaceviking]

Do any regular users of this forum not specialise in SSTOs? 

[wumpus]

3 hours ago, Palaceviking said:

Do any regular users of this forum not specialise in SSTOs? 

Here's a whole thread suggesting that the runway exists to test rovers and quick and dirty science collecting: 

There is a certain urge to keep costs low in this game (even though it likely doesn't matter at all in career mode unless you set the required grind to "high"), which leads to SSTOs.  After so many launches, I'd like to keep my time to orbit a bit quicker.  I'd also recommend avoiding spending excessive time on recovery (which the "recovery" mod helps with, otherwise "flight manager" lets you recover each stage manually) as that tends to eat up your time with basic drudgery.

http://forum.kerbalspaceprogram.com/index.php?/topic/122488-rules-of-thumb-for-building-cheap-and-cheerful-rockets/  nifty thread for cheap rockets (recovery not needed)
http://forum.kerbalspaceprogram.com/index.php?/topic/146273-113-the-cheap-and-cheerful-rocket-payload-challenge/  examples of above.