Stacking ASAS to overcome balance and torque issues

[Princepapa]

I've been experimenting lately with space planes with no aerodynamic surfaces, mostly VTOL, and I've noticed that adding more ASAS modules increases the level of control I have over the craft. Has anyone done any extensive testing on this? Do we know if there is a cap on the amount of torque you can get from these modules, or can you just add them forever until the desired level of control is attained?

[Johnno]

I've noticed that adding more ASAS modules increases the level of control I have over the craft.

That's exactly what they're designed to do.

Has anyone done any extensive testing on this? Do we know if there is a cap on the amount of torque you can get from these modules, or can you just add them forever until the desired level of control is attained?

I haven't done any extensive testing, nor do I know if there's a cap. I've added a few on some of my planes though, think one of mine had 6. The thing is, they eat power and are quite heavy, so it's a tradeoff. If you're having trouble controlling your plane you'd be better off with a redesign or tweak of CoM / CoL than just chucking reaction wheels at it.

[Princepapa]

Oh yes, there are certainly BETTER ways to manage maneuverability, but this is KSP, better isn't always better...or something...

[Burninate]

0.21 SAS torque will likely be considered grossly overpowered in the future. It's too easy to just stack SAS and batteries with an RTG until you can control anything.

At the *least*, a rebalance increasing the energy usage per torque by a factor of 10-100 is probably in the works.

[mellojoe]

I frequently use multiple ASAS units on my crafts. The old non-automatic SAS was redesigned as a "reactionary control wheel". I wil often have a combination of both ASAS and reaction wheels. On my tiny SSTO spaceplane I just made, I included both an ASAS and a reaction wheel. Definitely helped stability. On my heavy lifter rocket, I have 5 ASAS units. 3 on the core and 2 on two drop tanks. Keeps it stable while it is insanely heavy, and then keeps it manueverable when it is insanely long and skinny.

[blizzy78]

Just to clear up any confusion that might be there:

- ASAS is no more (since 0.21)

- SAS is the "computer", it uses reaction wheels, RCS, wings, and the like, but it can't do anything if used alone.

- To provide actual rotational capabilities, add reaction wheels, RCS, wings, etc. for SAS to use

- You only need exactly one SAS computer per craft. There is no use in stacking multiple, although it doesn't hurt at all if they come with torque-providing parts, for example.

[Johnno]

- You only need exactly one SAS computer per craft. There is no use in stacking multiple, although it doesn't hurt at all if they come with torque-providing parts, for example.

And to add to this, all probecores and manned modules (hitchhiker container being the exception) are equipped with SAS. The old 1.25m ASAS is now the same as the old SAS, both are now just reaction wheels whileas the ASAS version weighs more.

Old 1.25m ASAS = Inline Advanced Stabilizer, mass 0.5

Old 1.25m SAS = Inline Reaction Wheel, mass 0.3

Beyond that they have identical stats.

The only part that has SAS but no extra torque would be the Avionics Package.

[DMagic]

There is no more ASAS as a function, but there is still an ASAS module, the 2.5m grey wheel, which adds torque. It would be nice if they would change the name of that.

I don't think there is any limit to how much torque you can add, but each reaction wheel adds mass and size to your craft. Eventually I think it would just get too big to handle. That, or you would have so much torque that the whole thing would shake, try turning on SAS with just a 1 man command pod to see what I mean.

[Aqua667]

I had a SAS module and 3 other reaction wheels and my new destroyer. (2 of which were actually part of the torpedoes). I had Mechjeb turn the ship prograde, and it was quite literally spazzing out. I turned off one of the wheels, it seemed a lot better. Too much reaction force causes the SAS to overshoot the target, it forces it the other way, overshoots again, the other way.......

TL;DR Too many reaction wheels are bad.

[blizzy78]

I had Mechjeb turn the ship prograde, and it was quite literally spazzing out. I turned off one of the wheels, it seemed a lot better.

Please note that as of MechJeb 2.0.9, it doesn't use SAS at all, which I personally think is a shame. It literally tries to be better than SAS, but fails.