Rotations and SAS during time warp

[michelcolman]

Hi,

I've been playing KSP for a few weeks now, and I'm new to these forums. Forgive me if this issue might have been discussed before, but I couldn't find it in the first 10 pages or so.

When the craft is rotating when you activate time warp, it suddenly stops rotating (only doing an apparent rotation relative to the body you're orbiting because the absolute attitude remains the same). I admit I often use this glitch to cheat a little bit on craft that don't have a lot of attitude control (start rotation to desired attitude and then press "." and "," to instantly stop the rotation) but it kind of feels wrong. Maybe there's a good technical reason for this, but if at all possible, it would be nice if this could be changed.

Also, SAS does not work during time warp but it DOES contiue to use energy! I have often found myself with dead batteries after timewarping through the solar system with SAS accidentally left on. It should either be officially off (and not use energy) or actually work if it does remain on. Right now it's the worst of both worlds, draining energy while not working.

Also, some kind of warning or auto-off feature would be welcome for SAS. It's really easy to time warp through a multi-month solar system excursion and then realise that you just completely drained your batteries. Can trash an entire mission in a few seconds of inattention.

Thanks,

 

Michel

[Red Iron Crown]

1 hour ago, michelcolman said:

Also, SAS does not work during time warp but it DOES contiue to use energy! I have often found myself with dead batteries after timewarping through the solar system with SAS accidentally left on. It should either be officially off (and not use energy) or actually work if it does remain on. Right now it's the worst of both worlds, draining energy while not working.

This has not been my experience, as far as I can see SAS and reaction wheels do not consume energy when under time warp. Are you sure you're not mixing up the energy consumption of probe cores, which does affect ships under warp whether SAS is on or off?

I agree that the killing of rotation during time warp is a bit jarring and easily exploitable (though it's easy to avoid exploiting it, too). There are mods out there that preserve the rotation even during warp, so it does seem to be possible.

[michelcolman]

I've experienced it several times already: warp throughout the solar system without any trouble (batteries hardly losing any charge at all), then warp with SAS on and boom, all empty. A few times I caught it just on time with the batteries only half depleted and then continued the journey with SAS off and not using any power. So I'm pretty sure SAS is using electricity during warp. Nothing else was consuming energy anyway, just a kerbal in a basic module.

I haven't tried any mods yet, but I'll certainly have a look at those.

Thanks!

 

[swjr-swis]

4 hours ago, michelcolman said:

When the craft is rotating when you activate time warp, it suddenly stops rotating (only doing an apparent rotation relative to the body you're orbiting because the absolute attitude remains the same). I admit I often use this glitch to cheat a little bit on craft that don't have a lot of attitude control (start rotation to desired attitude and then press "." and "," to instantly stop the rotation) but it kind of feels wrong. Maybe there's a good technical reason for this, but if at all possible, it would be nice if this could be changed.

Also, SAS does not work during time warp but it DOES contiue to use energy! I have often found myself with dead batteries after timewarping through the solar system with SAS accidentally left on. It should either be officially off (and not use energy) or actually work if it does remain on. Right now it's the worst of both worlds, draining energy while not working.

Agreed that it's the worst possible combination, and that it would be very welcome to have rotation persist through warp.

But only if they also make SAS continue to keep attitude through warp at the same time, please. Right now having it stop all rotation is the next best thing (or least worst thing), as it at least makes things somewhat predictable. Having rotation work but not SAS through time warp would create a nightmare of having to check all craft in orbit after every warp, to ensure they did not end up with their panels oriented all wrong.

[michelcolman]

Indeed, SAS should continue to work and, with SAS off, rotations should continue. I do understand that physics don't work during warp, but they could keep the attitude fixed to the SAS target (if it's already kind of close to it, so you can't cheat by quickly going in and out of warp to instantly align to the SAS target) and keep rotating the craft at its last rotation rate if SAS is off. Rotation doesn't require physics, they can just rotate the coordinates and attitudes of all the components of the craft in a matter of nanoseconds without needing the physics engine.

 

And low battery warnings during time warp would be nice to have, too. Time warp should slow to 1x and give a warning when you approach zero battery and are consuming energy.

[pandaman]

As much as I use this 'trick' a lot it does feel kinda 'wrong'.

So if it could be made so that rotation continues in time warp then rest assured that Squad won't get any nasty 'you broke this cheaty feature and now I can't play anymore' posts from me.  I'll just learn to deal with it.

[michelcolman]

I may admit to using the instant rotation freeze "feature", but it has also annoyed me a lot more often. I often make rockets without RCS and just the absolute minimum of reaction wheels, and would like to just start a tiny rotation and then warp forward as the craft slowly rotates to the new orientation (as it probably works in real life, with attitude corrections taking hours to use as little electricity and RCS as possible). But now you have to start the correction and then wait for the craft to slowly rotate. If you warp, the rotation stops. That's quite frustrating. And just plain unrealistic.

[UnusualAttitude]

I would be OK with persistent rotation during time warp, but only if the interaction between RCS and SAS is improved. As it is, on larger ships and on small probes alike, they constantly over correct, and half of your RCS propellant is wasted as your craft jiggles and wobbles it's way to the requested heading. Using cheaty timewarp to kill rotation is sometimes the only way to mitigate this effect. 

[Matt77]

I've been using the mod Persistent Rotation for a long time, and prefer it to the stock implementation. I used to exploit it to cancel rotation all the time.

Now, unless I cancel rotation then the spin will just continue. If a probe has limited solar panels I deliberately tumble it so a panel will get power sooner or later.

I don't think I've ever ran out of power due to SAS use during warp.

 

[Benoit Hage]

I agree with the OP. However, we can't let the rotation happen without few tweaks. It has to be non-physic. Otherwise, imagine a ship rotating a revolution a minute for a journey of 3 month, that would make 130k revolutions to show in a time lap of few seconds.

Surely a mod like persistent rotation should be stock.

Concerning the SAS consuming batteries, it seems strange. Are you sure your ship's solar panel wasn't simply facing the sun with some other device draining batteries, like a light?

[michelcolman]

No, I'm sure SAS is draining the batteries. I don't have solar panels, just batteries, a basic Mk1 pod, a CH-J3 fly-by-wire avionics hub, fuel tanks, engines and separators. With batteries full, engines off, SAS on, the batteries slowly drain (which is normal, using the reaction wheels). If I activate warp, they continue to drain (at a rate multiplied by the warp factor, i.e. a matter of seconds at high warp factors). If I go back to x1 warp, turn off SAS, then activate warp again, battery levels remain constant no matter how long I warp.

Now I do feel it's normal that SAS drains batteries *if it works*. But if it doesn't actually work during warp, it shouldn't be consuming energy. And in any case, drained batteries can be such a show-stopper that a warning would be more than welcome. I lost count how many times I lost a mission because I accidentally left SAS on.

[swjr-swis]

@michelcolman I tested this because I haven't seen this happen. It's not the reaction wheels, it's the CH-J3 avionics hub.

1. Small truss, Z-200 battery and small inline reaction wheel on the launchpad, wheel torque enabled. All by themselves, even at top warp, EC remains at 200 units, which is what I would expect with the reaction wheel being idle.
2. Same as 1, but now with Mk1 command pod on top. No change in result, the EC remains at 250 units even at top warp. Enabling SAS makes no difference (the reaction wheels remain idle since there's no any rotations to counter).
3. Same as 2, but now with SAS enabled and click on hold normal to keep the wheels 'running'. The ship topples over and settles in a jittery balance, and the battery starts draining. However, as soon as I initiate warp the wheels go idle, and the draining stops, even at top warp.
4. Same as 2, but with CH-J3 hub on top. By default no drain at all, but as soon as you engage SAS there is a drain, even though reaction wheels of pod and the separate one are 'idle'. Rightclicked pod and separate wheel to disable torque on both - still a drain. Drain keeps going even through warp. Rightclick on CH-J3 and toggle SAS off (which really means disabling the CH-J3): drain stops.

The CH-J3, when enabled, will drain EC even through warp. This is to be expected and is consistent with the probe cores which also drain EC through warp.

One could make an argument that command pods really should drain EC as well, even with their reaction wheels disabled - life support if nothing else needs EC. But that's for another thread.

[michelcolman]

I must have misunderstood something about SAS, because I thought you needed some sort of extra equipment, like the CG-J3, to enable it? The Mk1 by itself doesn't have SAS, does it? The science page lists a number of different pieces of equipment that offer SAS, often only partially (prograde/retrograde, for example). I picked the CG-J3 because it has prograde, retrograde and maneuver.

As a side note, I always wondered why you can't just ask the pilot to hold prograde or maneuver direction. I mean, they are pilots, right?

[Red Iron Crown]

The Mk1 pod will have the SAS abilities of the pilot kerbal aboard it. The CG-J3 allows non-pilot kerbals to have some SAS modes available, at the cost of constant EC drain like a probe core. So I think we've found the source of your trouble with EC drain under warp.

A sufficiently experienced pilot kerbal can hold prograde or the maneuver direction just fine.

[michelcolman]

OK, I suppose when I first tried it, my pilot didn't have any experience yet. Should be OK now after several Mun missions. I'll give it a try, thanks!

[Andem]

Physics CAN work during time warp, as seen in besieged. SQAUD chose not to do it, and it probably is due o the limits on 32bit systems.

[Red Iron Crown]

12 hours ago, Andem said:

Physics CAN work during time warp, as seen in besieged. SQAUD chose not to do it, and it probably is due o the limits on 32bit systems.

KSP has a timewarp mode in which physics still work...

[Psycho_zs]

As I suggested in Persistent Rotation thread, I'll copy it here. Controls for Global, Sun and Planetary reference rotation could nicely fit with other pilot assistance modes controls:

If PR would be made stock, this is how it can be presented in UI.