How should Reaction Wheels work?

[PatPL]

Reaction wheels should create resource "Momentum" or something. If momentum is full, you can't use reaction wheel, until it's unloaded using Monopropellant and RCS nozzles.

[Stargate525]

Considering how much the SAS wiggles and overshoots maneuvers, I'm against anything that burns resources to give us SAS functionality.

And, Squad... Isn't it a little... LATE... to be asking whether you should change core game functionality?!

[Sirrobert]

Considering how much the SAS wiggles and overshoots maneuvers, I'm against anything that burns resources to give us SAS functionality.

And, Squad... Isn't it a little... LATE... to be asking whether you should change core game functionality?!

It's never to late to improve your game

[zekes]

I like them the way they were in .22 to .25 - simple, worked. They are very Kerbal and I think turning them down would really hurt some of the awesoem capabilities of KSP.

I'd also like the buttons on the lower left of the navball to not be so utterly poor at keeping something straight. I mean, it's about 1000 times worse than Mechjeb steering - it's like they put a pigeon control device in the nose.

[BudgetHedgehog]

I'd just like for them to actually hold a position. I know a plane is capable of holding say, a 20 degree pitch up attitude, but if I stop tapping S while SAS is engaged, it slowly sinks back down. So I end up just going tap tap tap tap tap tap tap tap tap tap tap tap.. granted, this may be due to FAR's atmosphere, but with 1.0 air acting like air, it's not unreasonable to assume it won't behave the same way.

Tap tap tap tap tap tap tap tap tap..

[Daze]

I'd just like for them to actually hold a position. I know a plane is capable of holding say, a 20 degree pitch up attitude, but if I stop tapping S while SAS is engaged, it slowly sinks back down. So I end up just going tap tap tap tap tap tap tap tap tap tap tap tap.. granted, this may be due to FAR's atmosphere, but with 1.0 air acting like air, it's not unreasonable to assume it won't behave the same way.

Tap tap tap tap tap tap tap tap tap..

This this and this. It's one of the most annoying thing in KSP, changing attitude every second with planes because if you press S it will stay in position but the SAS can't do it for some strange reason

[regex]

I think for stock, simply reducing the torque for any given reaction wheel to about 1/10th (or less) what it is now would work well. That would put more of an emphasis on RCS. Saturable wheels would be cool but I think a sufficient nerf would reduce their importance enough that it wouldn't really matter.

[PatPL]

Or place RCS in first research tier, remove reaction wheels from pods and drones (Or make them weaker) and place reaction wheels higher in tech tree.

This would encourage players to use RCS

[mattinoz]

One thing I think should be considered now that SAS is a embedded in the pilot should control of reaction wheels be decoupled from the sas switch.

The pilots course directive controls should always active and work with control surfaces or engine gamble then have the option to turn on the resource consuming RCS and/or reaction wheels separately.

[kujuman]

At the least I'd like to see significantly increased eC requirements of using RWs. That helps prevent perma RW use and is more intuitive than saturation and such. A fully "realistic" implementation of saturation in which you need to use RCS to desaturate the wheels ignores things like the timewarp bug (if you rotate up to saturation and then timewarp, you now have fully saturated wheels in one direction even though you shouldn't) and using gravity or magnetic gradients to de-spin. So a simple module to write (say...2 hours?) becomes a much bigger headache.

[John FX]

Actually, that sounds alright, letting them lose saturation and cool off over time wouldn't leave you spinning or cheesing timewarp to stop your rotation.

You still need RCS or an engine to translate, and rather than weaker wheels they should be tweakable.

Oh and some of the probes don't even have reaction wheels, I think that's just fine

I like the idea of saturation that fades over time (maybe the reaction wheels just get hot under power)

I also really like the idea of tweakable torque, I imagine lower torque would use less electricity. I also think there should be less overlap between RCS and torque wheels to give RCS a bit more of a role. I imagine that will happen during a balancing run through the parts.

I must say though that I don't like probe cores with no torque but not so much that it bothers me greatly. I've learned to just put a reaction wheel on there as well.

Additionally, I'd like torque wheels to have a 'damp' option which just damps all movement. The current 'hold position' flickers between two points which imparts rotation if you turn off the SAS. I notice it particularly on my tiny A.L.S.E.P on Mun. I just can't get them to sit still. It wastes power too.

[sal_vager]

Trouble is, even fading saturation isn't "good enough" for some players, and while reaction wheels do get hot, linking their function to heat isn't realistic enough.

You really cannot please everyone all of the time...

RCS is great for lots of things, R-wheels will only rotate you after all, and it's not unheard of for satellites to have no rotational control.

Oh and fixing SAS hold is on the todo list, no need for even more modes

[Superfluous J]

I like saturation tied not to raw ability but to the axes and directions, with the ability to desaturate them by paying RCS. Maybe you don't even need RCS thrusters for the purpose, it just costs rcs fuel and we pretend there are tiny dedicated thrusters specifically to desaturate the wheels.

Also, so long as as you can turn at least 180 in all directions, you literally don't ever need to desaturate the wheels, just be a little smart with how you turn.

And of course wheels would saturate very quickly with SAS on when landed, and for that purpose I think there should be a way to automatically turn off SAS upon landing. Or maybe automatically turn off reaction wheels when landed and turn them back on when you take off.

[Tuareg]

erm, fix me if im wrong but reaction wheels are reaction wheels when they are used to change direction and there saturation is a problem but while stabilising a landed craft they work like momentum wheels and as it about running the wheels on constant high speed in 90degrees to the stabilisation direction so the saturation doesnt affect it at all. a momentum wheel, as long as it can spin (aka has enough energy) can stabilise a landed craft even if its standing only on 1 single leg? sure, that effect is far weaker but its still there...

[Superfluous J]

erm, fix me if im wrong but reaction wheels are reaction wheels when they are used to change direction and there saturation is a problem but while stabilising a landed craft they work like momentum wheels and as it about running the wheels on constant high speed in 90degrees to the stabilisation direction so the saturation doesnt affect it at all. a momentum wheel, as long as it can spin (aka has enough energy) can stabilise a landed craft even if its standing only on 1 single leg? sure, that effect is far weaker but its still there...

You know what? I was thinking of them wrong. I thought if you wanted to rotate left to right you increased or decreased the spin on the "left/right" wheels, but that's not correct, is it? They're more like gyroscopes, which would eventually spin down.

Awww heck I change my vote back to "leave 'em like they are, it's no fun to run out of rotational authority no matter if it's 'realistic' or not."

[CaptainKipard]

I'd rather not find myself in a position where I can't stop rotating due to saturated wheels.

Whereas I'd like some more failure states in a game, because it makes things interesting. The only things that can go wrong right now is destruction, or running out of resources. Let's get some more.

Reaction wheels should create resource "Momentum" or something. If momentum is full, you can't use reaction wheel, until it's unloaded using Monopropellant and RCS nozzles.

A momentum "resource" is hacky and would break immersion. You could measure it I guess but it shouldn't be a resource.

And as always, I'm in favour of more realism, so whatever this means is what I want.

Edited February 15, 2015 by Cpt. Kipard

[Red Iron Crown]

erm, fix me if im wrong but reaction wheels are reaction wheels when they are used to change direction and there saturation is a problem but while stabilising a landed craft they work like momentum wheels and as it about running the wheels on constant high speed in 90degrees to the stabilisation direction so the saturation doesnt affect it at all. a momentum wheel, as long as it can spin (aka has enough energy) can stabilise a landed craft even if its standing only on 1 single leg? sure, that effect is far weaker but its still there...

That's almost exactly backwards. A wheel used to change a vessel's orientation has no net angular momentum gain, at beginning and end of the maneuver the vessel has no net rotation. (In KSP anyway, IRL there are other factors like aero drag and gravity gradients that can add angular momentum).

For a vessel landed on one leg, the wheel must spin ever faster to counteract the force of gravity; eventually it reaches the limits of either its bearings or tensile strength of the wheel itself, this upper limit on wheel RPM is the saturation point. The rate at which the wheel must be sped up is proportional to the fraction of the vessel's mass that is wheel; that's why a kid's gyroscope can stay up for long periods without adding speed (its mass is almost all wheel), while a spacecraft presumably has almost all of its mass not rotating would quickly saturate its wheels trying to stay upright.

[Tuareg]

That's almost exactly backwards. A wheel used to change a vessel's orientation has no net angular momentum gain, at beginning and end of the maneuver the vessel has no net rotation. (In KSP anyway, IRL there are other factors like aero drag and gravity gradients that can add angular momentum).

For a vessel landed on one leg, the wheel must spin ever faster to counteract the force of gravity; eventually it reaches the limits of either its bearings or tensile strength of the wheel itself, this upper limit on wheel RPM is the saturation point. The rate at which the wheel must be sped up is proportional to the fraction of the vessel's mass that is wheel; that's why a kid's gyroscope can stay up for long periods without adding speed (its mass is almost all wheel), while a spacecraft presumably has almost all of its mass not rotating would quickly saturate its wheels trying to stay upright.

nope its not true... a highspeed rotating wheel can balance the craft, no need of changing speed. thats called gyro effect... you can try it at home with a bicycle wheel... but it balances the craft in the direction 90degrees from its rotation. changing the crafts alignment need acceleration of the reaction wheel.

on this little diagram if you want the craft to rotate along the big red arrow, you have to give spin to the wheel along the smaller red arrow. but if the wheel is spinning on constant high speed it balances the craft along the green arrow and as long as the speed doesnt change it has no effect on the rotation along the red arrow... saturation is a problem as if the wheel spins on its topspeed along the little red arrow there is no way to rotate the craft along the big red arrow. if you wanna spin it down (desaturate) it will rotate the craft to the opposite direction. but it doesnt matter for the stabilisation effect along the green direction because in that case the effect is caused by the centripetal force not the torque

Edited February 15, 2015 by Tuareg

[Red Iron Crown]

It works fine for a bicycle wheel because almost all of the mass is spinning, so the need to add rotational speed is not noticeable. Try using a spinning wheel to hold up something more massive and the effect will appear.

[Tuareg]

It works fine for a bicycle wheel because almost all of the mass is spinning, so the need to add rotational speed is not noticeable. Try using a spinning wheel to hold up something more massive and the effect will appear.

http://www.gathering.org/espresso/pages/tg05/newsarchive/Segway/view_top.html

well, this thing has 2 little gyros and can carry a human

[Red Iron Crown]

http://www.gathering.org/espresso/pages/tg05/newsarchive/Segway/view_top.html

well, this thing has 2 little gyros and can carry a human

It desaturates its gyros by reacting with the ground when it can. It can't maintain an unbalanced state in perpetuity. It certainly can't maintain a level attitude with only one wheel in contact with the ground.

[Tuareg]

It desaturates its gyros by reacting with the ground when it can. It can't maintain an unbalanced state in perpetuity. It certainly can't maintain a level attitude with only one wheel in contact with the ground.

momentum gyros doesnt need desaturation, only reactionwheels... you dont seem to get what the difference is between them. reactionwheels act with force into the direction they rotate, momentumwheels act in 90 degrees to that direction and has nothing to do with saturation. flywheel is a reactionwheel, bicycle wheel is a gyro

[Red Iron Crown]

momentum gyros doesnt need desaturation, only reactionwheels... you dont seem to get what the difference is between them. reactionwheels act with force into the direction they rotate, momentumwheels act in 90 degrees to that direction and has nothing to do with saturation. flywheel is a reactionwheel, bicycle wheel is a gyro

If we're pointing out what each other don't seem to get, you don't seem to be getting that the mass of the wheel needs to dominate the mass of the entire contraption for it to maintain itself in an unstable posture. That basically never happens in KSP.

All of which is irrelevant. The wheels in KSP are reaction wheels, not momentum wheels; they are modelling (in a somewhat flawed fashion) a wheel that spins to change attitude, not one that maintains a constant spin to keep from changing attitude. So what is your point exactly? That they should be heavy momentum wheels so that they can hold a vessel upright in an unstable position? Why would that be desirable?

[Tuareg]

they are modelling (in a somewhat flawed fashion) a wheel that spins to change attitude, not one that maintains a constant spin to keep from changing attitude.

and so other than using them constantly or just spin them up from time to time whats the difference between them? a wheel will be reactionwheel if we use them like that and can be momentum wheel if we spin them up... thats it, no other differences, except that as i already wrote many posts ago, the sideway effect is smaller than the active effect and this should be modeled if we want to change something as i agree that a pod shouldnt keep a craft on one leg, while a separate reaction wheel module can hold a light craft easily on one leg especially on low gravity...

and no, gyro wheel dont have to be big and heavy to maintain stabilisation on far bigger things... they need to be fast. you dont seem to know how powerful a little gyro can be.

[Red Iron Crown]

and so other than using them constantly or just spin them up from time to time whats the difference between them?

In theory, very little. In practice, a lot. A momentum wheel needs relatively large mass and high speed, with speed variance not being very important. A reaction wheel needs high precision control of the wheel at much lower speeds, to control how much torque is being added. It is extremely difficult to build a device that satisfies the requirements for both, so we don't, generally speaking.

a wheel will be reactionwheel if we use them like that and can be momentum wheel if we spin them up... thats it, no other differences, except that as i already wrote many posts ago, the sideway effect is smaller than the active effect and this should be modeled if we want to change something as i agree that a pod shouldnt keep a craft on one leg, while a separate reaction wheel module can hold a light craft easily on one leg especially on low gravity...

That's an interesting perspective. I'm not sure that RWs should be usable that way from a gameplay perspective, but it's a valid opinion.

and no, gyro wheel dont have to be big and heavy to maintain stabilisation on far bigger things... they need to be fast. you dont seem to know how powerful a little gyro can be.

Let's not devolve into insinuations about my knowledge or lack thereof, that's argumentum ad hominem and gets a failing grade from me. Argue the post and not the poster, please.