Small Gear Bay Unstable.

[Moesly_Armlis]

This is stock 0.25 x86 with a probe core (low reaction wheels torque) an FL-T400 with one Small Gear Bay in front and two SGB in the back.

When launched it does not stay upright and rolls over, belly up.

Increasing the seperation distance of the back two SGB helps but then the vehicle will drift starboard.

Video of the experiments.

Seems this was not happening in 0.24 as I built this craft style before.

These screen shots are from the recent test. Using an FL-T800 with SGB in setup similar to the first experiment.

The two SGB at the back are at the innermost position.

Drift to starboard is the only result.

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I have experimented with the launchpad instead of the runway with the same results. Could it be a problem in the physics, or is this Kraken related? This bug/feature sure makes building stable wheeled vehicles a pain.

Fed up. Going back to rockets now.

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Edited December 6, 2014 by MoeslyArmlis
Much Further Testing

[vexx32]

This appears to be a consequence of the overall wheelbase being too small rather than it necessarily being too narrow. From your tests, it seems that using the smaller fuel tanks as well as landing gear placed quite close together causes it to overbalance. I can't say I would consider that a bug, necessarily; anything with such a small wheelbase is going to be pretty unstable regardless of however else you balance it.

[sal_vager]

The drift is because there's no real friction and the KSC is a flat surface on a sphere, any point away from the exact center will feel a gravitational pull towards the center, simple

[Moesly_Armlis]

After understanding the stability issue the East by South East drift was the other issue. Thanks and cookies.

All vehicles starting on the runway (also been using stock planes) that I have tested always head towards ESE.

So if the runway was directly on the equator would the vehicle head due East?

[sal_vager]

Yep, as they are in essence drifting downhill, if the runway was dead on the equator they'd drift East.

That's why rovers on the pad drift towards the VAB, of course it's a slight slope in that direction as far as gravity is concerned

[Moesly_Armlis]

Yep, as they are in essence drifting downhill, if the runway was dead on the equator they'd drift East.

That's why rovers on the pad drift towards the VAB, of course it's a slight slope in that direction as far as gravity is concerned

That is so Kerbal!

Also explains why I have had so many plane crashes ending up on the east side of the runway. Problem I have is that my planes use a long stretch take-off.

Edited December 6, 2014 by MoeslyArmlis