3.75 reaction wheel!

[Arugela]

I've been trying to build a really big 3k-10k ton vehicle. It's going fairly well except for the fact I have to use large reactions wheels in the range of 400 parts to get a proper torque to control the vehicle. This leads to several problems including wobbling and an inability to strut them all down(the wobbling). This game needs a new XL 3.75 reaction wheel to help with larger craft. This would be the size of the Kerbodyne S3-14400 tanks. I'm really curios why it doesn't already exist. they have the standard but no convenient way to control it.

1. Should it exist.(I really need one atm!)

2. Why doesn't it already.

The introduction of a 3.75 reaction wheel would reduce my parts count from 384 to only 96 parts(Assuming 120 torque.).... This is sorely needed. I'm making a giant mining/space station modeled after a ship from another game. It works very well except for this aspect for the most part. And you need that many to get good turn ability.

The parts count reduction would obviously help the ship for the other reasons and make it much more flyable and less laggy from performance issues also. I have no idea why there isn't one already. It would be easy to make visually. It would be like the 3.75 decoupler but fatter more than likely and appropriate stats. It should be one of the easiest things to add to the game. All the parts of that size even have the same aesthetic. So, easy peasy!

Edited October 5, 2015 by Arugela

[Rath]

Yes please.

[Arugela]

Does anyone know if they are planning to add more reaction wheels?

In fact, will they also be adding new bigger landing gear also? Particularly the non wheel variety.

Edited October 6, 2015 by Arugela

[CaptainTurbomuffin]

IMO, reaction wheels are overpowered. I have been suggesting larger and stronger reaction wheels, but everyone told me that that would be too OP.

[Frozen_Heart]

IMO the entire 3.75m line needs fleshing out. Reaction wheel, batteries, service bay, hitchhiker, capsule, and lander can would all be welcome. At the moment you can only really make launch vehicles with them.

[CaptainTurbomuffin]

At the moment you can only really make launch vehicles with them.

Aren't they supposed to do that? If such items were added to the stock game, probably I would never use them besides sandbox, due to the inefficiency of not staging such huge parts (I mean the size3 rockets). They are good for first-stage, or for SSTOs. But for SSTOs, you have those Mk3 parts. But anyway, I cannot avoid admitting that a Size3 orbital engine would be nice. Mostly for spaceplanes.

[Alshain]

The 3.75m line is mean to be primarily lifters as I understand it. While KSP allows for some crazy things, if you look at craft like the Saturn V Apollo, the lifter is larger diameter than the CSM. If they add all the pods and service bays and such to that line then people will just want a larger lifter line. Once they add the bigger lifter (5m?), then people will want that line to have command pods and service bays. It's a never ending cycle. The biggest line is supposed to be rockets only because you need a bigger rocket to lift the next size down CSM (or crazy contraptions with asparagus staging and dozens of engines).

Edited October 6, 2015 by Alshain

[RidingTheFlow]

I think the idea was anything above 2.5m gets too big and supposed to use vectoring/RCS/vernor thrusters

Though I wish we had better thruster variety in stock (ion thrusters in particular).

[MKI]

All the "Useful parts" are smaller than the dedicated "Launcher size parts"

They added Vernor engines to help you balance out HUGE craft, at the cost of needing fuel to run them.

Since Vernors have enough thrust of small engines a few at correct points on a craft can help you control them in atmosphere and in space no problem.

I never had the problem of not having control over my "large" craft. Even my most unorthodox just ended up being controlled by Vernors.

[Arugela]

I'm currently working a very large 5-10kton vessel and the reason I would want one is parts counts. I was using up to 384 large reaction wheels to spin the craft. This is very bad for stability and lag. And annoying to strut down properly if even possible. so it would help tremendously. Making a 120 torque rotation wheel would allow me to get it down to 96 parts. It would be a huge help to large ships and big stagings. It could even be very power hungry and help.

Maybe if they make two 3.75 version. A thinner one with 60 and a double thikness one with 120.

Also a 1.25m Ion would be fantastic. If it scaled to the smaller one and maybe was more power hungry it would be great. Say 50-60\66 thrust. It would wonderful for larger ships and stations. Or can a 2 thrust ion move a 1k plus vehicle or space station for turning?

The 3.75m line is mean to be primarily lifters as I understand it. While KSP allows for some crazy things, if you look at craft like the Saturn V Apollo, the lifter is larger diameter than the CSM. If they add all the pods and service bays and such to that line then people will just want a larger lifter line. Once they add the bigger lifter (5m?), then people will want that line to have command pods and service bays. It's a never ending cycle. The biggest line is supposed to be rockets only because you need a bigger rocket to lift the next size down CSM (or crazy contraptions with asparagus staging and dozens of engines).

And they have a limit on the size of the VAB and SPH now. So it's not an endless cycle. You are limited by practicality. So with that change it is now feasible to support the larger parts more. They can only get so tall now! My vehicle is currently capped by a height of 75m made up primarily of 3.75m parts. It can't get much taller. There is literally only a few meters or tens of meters left below the vehicle with the nose all the way up at the max position. So I can't do much more with it. That solves that whole issue of endless expansion.

And my ship is basically a flying space stations that will have probes and stuff for setting up planetary utilities. It fits what the larger stuff is for. It's just a mining ship that can land on smaller bodies and refuel and get setup for other ships to dock and refuel a little.

Bigger landing struts would be great too!

Edited October 7, 2015 by Arugela

[Darnok]

+1 It could be used as structural 3.75m part

[Red Iron Crown]

The 3.75m line is mean to be primarily lifters as I understand it. While KSP allows for some crazy things, if you look at craft like the Saturn V Apollo, the lifter is larger diameter than the CSM. If they add all the pods and service bays and such to that line then people will just want a larger lifter line. Once they add the bigger lifter (5m?), then people will want that line to have command pods and service bays. It's a never ending cycle. The biggest line is supposed to be rockets only because you need a bigger rocket to lift the next size down CSM (or crazy contraptions with asparagus staging and dozens of engines).

I agree with the idea that 3.75m parts are intended for lifters. The one part really needed is a probe core for stage recovery, but that might be better served by a small and light radially attached one (having used radial probe cores from mods I've found them useful in a lot of situations).

[RidingTheFlow]

I agree with the idea that 3.75m parts are intended for lifters.

It makes some sense, but it doesn't appear to mesh with rest of present stock mechanics to me ATM. Thing is, 3.75m parts are kind of go with Mk3 parts and I tend to use both widely for large interplanetary crafts - mainly because there simply no compact/inflatable stock station modules. And when you have to transport hitchiker+MPL module, you need cargo bay/rack larger than 2.5m already.

And its pain because they removed gimbal from stock LV-N. That's one of reason I want stock ion RCS so badly, just to avoid need for this unrealistic "huge OP reaction wheel stack".

[Red Iron Crown]

Ion RCS would be just as OP and unrealistic as reaction wheels. No one wants to spend an hour turning their ship. For big nuclear ships I just carry some oxidizer and vernors.

[RidingTheFlow]

Ion RCS would be just as OP and unrealistic as reaction wheels. No one wants to spend an hour turning their ship.

Umm, why? Try placing stock ion engine where you normally place vernor and see how fast it turns your ship.

Since ion engine is already here in stock, I fail to see why simply making it controllable by steering makes it OP.

It also requires expensive research & quite a lot of electricity (probably more than reaction wheels will need anyway).

Edited October 7, 2015 by RidingTheFlow

[Red Iron Crown]

Stock ions are as unrealistically OP as stock reaction wheels, they have thrust several orders of magnitude higher than real life ion drives. This is a gameplay concession as it makes burn times reasonable (and we don't have high warp while thrusting). I don't see the benefit of adding an equally unrealistic RCS version when we already have more realistic RCS systems in the game, and a realistic-thrust ion RCS system would take waaay too much time to turn the ship.

[RidingTheFlow]

Stock ions are as unrealistically OP as stock reaction wheels, they have thrust several orders of magnitude higher than real life ion drives. This is a gameplay concession as it makes burn times reasonable (and we don't have high warp while thrusting).

Well, the concession to have boosted ion RCS is the same - just because we don't have time warp while rotating

Not that it matters really because even now you can go around it just by stacking several 2.5m wheels.

[Red Iron Crown]

Well, the concession to have boosted ion RCS is the same - just because we don't have time warp while rotating

Not that it matters really because even now you can go around it just by stacking several 2.5m wheels.

Ah, but the concession for the thruster is to allow something in the game that is done in real life (ion thrusters are a real thing). Why make a concession to add something unrealistic (ion RCS is not a real thing)?

[RidingTheFlow]

Why make a concession to add something unrealistic (ion RCS is not a real thing)?

Please... Are you saying it's impossible to make *real* ion engines to rotate something (albeit slowly)? It all just a matters of placement & control program.

Same as vernor thruster in KSP is simple small LFO engine which controlled by steering input (instead of main throttle).

[sal_vager]

Ion RCS is not a real thing, it is currently only considered for use as a main drive as the extremely poor thrust makes them unsuited to maneuvering, and unless ion drives become much more powerful it is never likely to replace other real technologies such as reaction wheels, control moment gyroscopes, gravity gradient stabilization, or conventional hydrazine monopropellant thrusters.

In fact, searching for ion RCS only seems to return the Kerbal forums.

If you would like ion RCS you are welcome to ask a modder, but it is extremely unlikely to be in stock KSP.

Edited October 7, 2015 by sal_vager

[RidingTheFlow]

Seriously guys, you are ridiculous.

http://dawn.jpl.nasa.gov/technology/ion_prop.asp

Each of Dawn's three 30-centimeter-diameter (12- inch) ion thrust units is movable in two axes to allow for migration of the spacecraft's center of mass during the mission. This also allows the attitude control system to use the ion thrusters to help control spacecraft attitude.

But this argument goes nowhere and you right that it's easily moddable (and not even needed since reaction wheels even more powerful anyway), so I think I'll stop here.

[Red Iron Crown]

Please... Are you saying it's impossible to make *real* ion engines to rotate something (albeit slowly)? It all just a matters of placement & control program.

Same as vernor thruster in KSP is simple small LFO engine which controlled by steering input (instead of main throttle).

Not impossible in theory, just never done or considered. Link me to one serious proposal or prototype from real life and I might think differently.

Vernors are realistic, bipropellant RCS is a real thing if less common than monoprop or cold gas.

More practically, how much turning are you doing with RCS that an ion RCS system is worthwhile? When you consider the additional mass (compared to Vernors they are ~18x heavier per unit thrust, ignoring the electrical system) you need to burn through an awful lot of xenon to make it break even.

Edit:

Seriously guys, you are ridiculous.

http://dawn.jpl.nasa.gov/technology/ion_prop.asp

That reads like thrust vectoring rather than RCS.

[RidingTheFlow]

That reads like thrust vectoring rather than RCS.

I think you should easily realise that even static RCS thrusters are "thrust vectoring" - just instead of rotating one nozzle, you have two+ nozzles and switch them on/off - this rotates actual vector of thrust (applying the needed force to ship you need to rotate it or translate it).

[Red Iron Crown]

Pardon me, I misspoke. I mean a gimballed engine, i.e. the major component of its force is not used for rotation.

[RidingTheFlow]

Pardon me, I misspoke. I mean a gimballed engine, i.e. the major component of its force is not used for rotation.

http://www2.l-3com.com/eti/product_lines_electric_propulsion.htm

I hope you know what "momentum dumping" is, how its related to RL reaction wheels and why it can't be done by just low-gimbal engine.

Really, ion engine is just a device to apply thrust (force). Which means that in certain situations any competent engineer *will* consider using it for rotation (since there is no "good force" or "bad force" to rotate your spaceship with).