What is the most useless thing in KSP?

[vv3k70r]

On 12/3/2020 at 12:59 PM, king of nowhere said:

if you must point your rocket in one direction, and you are not and have no reaction wheels, are you going to turn on the rocket in the wrong direction and use gimbaling to eventually move it right? i can't believe this can work

Almost every vehicle works that way. Overpowered reaction wheels exist only in KSP.

 

 

[Superfluous J]

7 minutes ago, vv3k70r said:

Almost every vehicle works that way. Overpowered reaction wheels exist only in KSP.

Space probes like Voyager and Hubble do not reorient themselves using engines. They do in fact orient themselves with reaction wheels and rcs thrusters.

I am by no means an expert but I don't think any space vessel that had to aim a lot of different ways relied entirely on the gimbal of the main engine to orient itself when it didn't also need to thrust forward.

That said, I've successfully rotated my probes with gimballing engines in KSP and if you don't care so much about your resultant trajectory it works just fine.

[vv3k70r]

4 minutes ago, Superfluous J said:

Space probes like Voyager and Hubble do not reorient themselves using engines. They do in fact orient themselves with reaction wheels and rcs thrusters.

So You do not consider RCS as engine?

Reaction wheels works fine until they get max values in same plane and then... engines are about to ignite to free them. Whatever engine You fire it is Your main engine during this event - there is no other thrust aplied.

 

Edited December 8, 2020 by vv3k70r

[Superfluous J]

3 minutes ago, vv3k70r said:

So You do not consider RCS as engine?

Reaction wheels works fine until they get max values in same plane and then... engines are about to ignite to free them.

I don't consider them the main engine, no. Well sometimes I make a little vessel that acutally uses a single rcs thruster as a main engine but not usually.

Sorry that I said "engine" and not "main engine" in that first sentence. But as the conversation up until this point was about the main engine I didn't think to.

[vv3k70r]

1 hour ago, Superfluous J said:

Sorry that I said "engine" and not "main engine" in that first sentence. But as the conversation up until this point was about the main engine I didn't think to.

Misunderstanding. I refer to that every vesel use external force (against environment) to change orientation. Plane, car, ship, bicycle, spacecraft. During this change have a thrust vector and is not corecty oriented. It dosent prevent us from making manouvers. If it is main engine it is still not a problem.

I think that idea that reorienting do something bad to manouver base on the node placing in KSP where changing orbit dosent update manouvers results. But then we are about to dig how we estimate position by clock diference from given telemetric nodes and how to navigate using clock (as for example in dark or underwater).

On the begining of space flights there were no reaction wheels but manouverability were present. If You see the manouver mechanics time is important, because burn have a duration and during this time it cannot be corectly oriented as for 0 time burn. Same factors aply to any control system using whatever force given to outside of the vessel or recived (as aerobraking in KSP).

For most people it is easier to grasp idea of 0time burn node on direct position because mechanics is much easier that way to explain in formulas. When ther is a curve things starting to be a bit more complicated.

I guess that misunderstadnign comes from idea of perfect manouvers aginst unperfect manouver planing in KSP for such ocasions as using whatever engine is main for changing orientation. dV aplied to orientation change against orbital velocity dosent afect orbit on any important factor for transportation (for sync orbit it does). I docked vessels using main engine - is there any more precise manouver?

 

If we refer to 3d game diference between those two solution is rotating pivot without moving against reference position to the frame (celestial body) any other then orbital speed. The other of two is moving this pivot during manouver when You rotate it. Try both, save 2 game saves, look at the diference in position and rotation in persistent file - it have many digits, diference would not be much.

Edited December 8, 2020 by vv3k70r

[foamyesque]

KSP's reaction wheels are literal magic. Things like the Hubble or the ISS do use them for attitude control and fine pointing, but there's a world of difference between precisely torquing an orbital telescope to a ten-thousandth of a degree, and shoving an airplane around in midflight :p

[Superfluous J]

10 minutes ago, foamyesque said:

KSP's reaction wheels are literal magic. Things like the Hubble or the ISS do use them for attitude control and fine pointing, but there's a world of difference between precisely torquing an orbital telescope to a ten-thousandth of a degree, and shoving an airplane around in midflight :p

Of course. Many things in KSP are much more (or less) powerful than in real life for game balance. But that doesn't change the fact that if they want to point Kepler at the right quadrant of the sky, they use reaction wheels to do it.

[jimmymcgoochie]

The idea of using nothing but engine gimbal to control attitude for a burn fills me with horror; there’s always a better way, whether that’s reaction wheels (even in RP-1 there are reaction wheels good enough for pointing small probes) or RCS thrusters.

 

The most useless thing I’ve found in KSP is the drain valve and its 5 seconds of ISP- there’s always something better to do with those resources as you can get thrust or possibly power generation (throttle so your TWR is below 1 when landed) from them instead of literally throwing them away.

[king of nowhere]

3 hours ago, vv3k70r said:

Misunderstanding. I refer to that every vesel use external force (against environment) to change orientation.

 

yes, ok, but there is a large difference between using an rcs thruster, that's precisely aligned to ggive torque, and using a main engine, whose thrust vector goes very close to the CoM and provides very little torque and a lot of unwanted thrust. i belive it can be done, and it may even be more efficient on some extremely light probes. that does not make it advisable.

a very small reaction wheel, something in the 10 kg range, would be useful.

30 minutes ago, jimmymcgoochie said:

The most useless thing I’ve found in KSP is the drain valve and its 5 seconds of ISP- there’s always something better to do with those resources as you can get thrust or possibly power generation (throttle so your TWR is below 1 when landed) from them instead of literally throwing them away.

there's already been a discussion on this. if you have a rapier, or a mix of rocket and nuclear engines, you may want to dump oxidizer.

[Corona688]

 

4 hours ago, vv3k70r said:

Misunderstanding. I refer to that every vesel use external force (against environment) to change orientation. Plane, car, ship, bicycle, spacecraft. During this change have a thrust vector and is not corecty oriented. It dosent prevent us from making manouvers. If it is main engine it is still not a problem.

Only recently has this kind of precision in main engines made this possible.  Before then, they packed things with RCS or vernier engines for correction.

Quote

On the begining of space flights there were no reaction wheels but manouverability were present.

Generally by RCS.  Not only was the main engine inaccurate, it wasn't generally throttleable, or even restartable.  The LEM had the world's first variable, restartable main engine IIRC.

Once again things appear in the tech tree not by the order humans developed it but by the order the game devs added it.  So we're forced to rely on reaction wheels for early game.

Edited December 8, 2020 by Corona688

[jimmymcgoochie]

1 hour ago, king of nowhere said:

there's already been a discussion on this. if you have a rapier, or a mix of rocket and nuclear engines, you may want to dump oxidizer.

As Donald Sutherland said in Backdraft:

Burn it. Burn it all.

[king of nowhere]

1 hour ago, jimmymcgoochie said:

As Donald Sutherland said in Backdraft:

Burn it. Burn it all.

burning oxidizer would consume rocket fuel too, which you can burn in the nerv for greater efficiency.

i have a spaceplane with a mix of darts and nerv. fully fueled, burning the rockets until there is no oxidizer and then the nerv, it has a range of 4000 m/s. if i dump the oxidizer, i have 4500 m/s.

I need the darts to get in orbit, but once there, i have no reason to keep oxidizer

[Mikenike]

On 12/2/2020 at 10:52 AM, Corona688 said:

KSP's built-in docking mode.  I've never found any documentation for it, or seen anyone suggest it;  it just kind of exists in a vacuum of uselessness.  As far as I can tell it does nothing but deprive you of half your controls.

It is non-funtional in EE I believe. I have never had to use it. I use the Lazy Lowne Method

[vv3k70r]

3 hours ago, Corona688 said:

Only recently has this kind of precision in main engines made this possible.  Before then, they packed things with RCS or vernier engines for correction.

Size of the engine and it technical purpouse is mater of nomenclature in design. In a perfect world there is no need for any other engine then one. It could be pointed any directon?

We trying to solve this issu making engines that can achive something like this abstract of perfection. Using any other source of thrust is just technical solution for imperfect, avilable tech. It is not only engine - computing power, telemetry, actuators, sensors, valves, procesing speed on this axis. With procesing speed is an issue of energy suply, with energy supply came issue with cooling and so on.

Coupling lot of engines was a solution, and it will be again when we build something that size there be no other avilable. Redirecting asteroids could be one of such COM problem to solve this way. Other way we can land, attach, add vector, jump to enother position, attach, add vector and so on. Who knows what kind of solution would be easiest to achieve for next generetions?

3 hours ago, Corona688 said:

Generally by RCS.  Not only was the main engine inaccurate, it wasn't generally throttleable, or even restartable.

And there is more like reaction time (delay to start, delay to stop), low temperature that allow to set there direct sensors, reliability and more words on "r".

3 hours ago, Corona688 said:

Once again things appear in the tech tree not by the order humans developed it but by the order the game devs added it.  So we're forced to rely on reaction wheels for early game.

I suspect it is made for easy-in. Game troubeling players with real technical issues coud not sell that good. I suspect it is reason why reaction wheels are overpowered (I'm now at the end of trip around Mun on reaction roller with poor Bob inside - he visited almost everything from pole to all big craters and some smaller). Who would play with nonresponsive space ship? It would be just a bad game.

1 hour ago, king of nowhere said:

burning oxidizer would consume rocket fuel too, which you can burn in the nerv for greater efficiency.

If You have nuclear engine in space burning fuel in any chemical reaction is a pure waste of dV. Nuclear engine is a tool for taking combustion engines to place, where nuclear would not do any usefull job.

 

[vv3k70r]

4 hours ago, king of nowhere said:

yes, ok, but there is a large difference between using an rcs thruster, that's precisely aligned to ggive torque, and using a main engine, whose thrust vector goes very close to the CoM and provides very little torque and a lot of unwanted thrust

COM could be shifted, and it is in most real vessels (mostly thrown away for adjusting angle of atack during entry in atmosphere).

4 hours ago, king of nowhere said:

that's precisely aligned to ggive torque

This is matter of computing. Early RCS were overpowered because of asymptotical corection to achieve. PID today and in early days are on completly diferent level.

4 hours ago, king of nowhere said:

i belive it can be done, and it may even be more efficient on some extremely light probes. that does not make it advisable.

We were speaking about manouver nodes. In any case the point You set manouver with burn time before and after would never be reached - it will be passed around. So if it is more or less around because of gimbal dosent play much role if You can cut complexity of the vessel. If You do a manouver we can gues You need a thrust. If You will have a torque just shift a bit COM (there is lot of real solution do do this), give a very small thrust, turn it off and wait for corect pointing of the main engine. It will not spot turning around with engine turned off.

4 hours ago, king of nowhere said:

a very small reaction wheel, something in the 10 kg range, would be useful.

Absolutly yes. And in real case - at least 4 of them and thrusters. Because our world is not so perfect as KSP and sending a rescue mission to service some scrap far away is almost never an option.

But in case of travel (as for misile) You can get away just on the main engine. It depend how You value Your craft. And its crew^^

Edited December 8, 2020 by vv3k70r

[Bej Kerman]

On 12/7/2020 at 7:02 PM, sturmhauke said:

On 11/30/2020 at 6:29 PM, Bej Kerman said:

You transferred to Eve... So you used a transfer window.

That's not how the phrase "transfer window" is normally used. Generally it means "a period of minimal dV requirement to maneuver between two bodies", not "any possible maneuver between two bodies, regardless of dV cost". That's more like smashing through the wall because the window is too far away.

Well if they think transfer windows are useless, they are either experienced with building torchships, or still sending SRBs to 5000m to satisfy mission conditions. Probably the latter.

[foamyesque]

10 hours ago, jimmymcgoochie said:

The idea of using nothing but engine gimbal to control attitude for a burn fills me with horror; there’s always a better way, whether that’s reaction wheels (even in RP-1 there are reaction wheels good enough for pointing small probes) or RCS thrusters.

 

Gimbal control is by far the most effective way to perform attitude control in a burn, excepting perhaps atmospheric control surfaces. It's non-burn attitude control that it struggles with, since any rotation inevitably requires some translation if you're using gimballing, whereas RCS can null out and reaction wheels don't produce thrust as such (although they do generate angular momentum from nowhere, which means you can build some interesting contraptions).

[jimmymcgoochie]

9 hours ago, foamyesque said:

 

Gimbal control is by far the most effective way to perform attitude control in a burn, excepting perhaps atmospheric control surfaces. It's non-burn attitude control that it struggles with, since any rotation inevitably requires some translation if you're using gimballing, whereas RCS can null out and reaction wheels don't produce thrust as such (although they do generate angular momentum from nowhere, which means you can build some interesting contraptions).

I was referring to using engine gimbal to point the spacecraft in the direction of the burn while the engine was on, rather than using RCS or reaction wheels to do it- during a burn gimbal is the best way to do it, but only once you’re pointing the right way. Firing the engine when you’re pointing in any random direction and relying on the gimbal to turn the ship around to point the right way is farcical.

[foamyesque]

5 hours ago, jimmymcgoochie said:

I was referring to using engine gimbal to point the spacecraft in the direction of the burn while the engine was on, rather than using RCS or reaction wheels to do it- during a burn gimbal is the best way to do it, but only once you’re pointing the right way. Firing the engine when you’re pointing in any random direction and relying on the gimbal to turn the ship around to point the right way is farcical.

 

It's actually something I do all the time. Engine gimbals give you enormous torque compared to basically anything else, excepting reaction-wheels on small ships and appropriately sited aerodynamic control surfaces. With particularly large craft I will often crack the throttle in order to align, and then zero out the (minor) translation drift over the course of the burn. And with small craft I begrudge any pennysworth of mass not strictly dedicated to the mission :p

[Timber Micka]

On 12/8/2020 at 7:29 AM, 18Watt said:

I nominate landing legs- all of them.

I gave up long ago trying to use landing legs, even just for aesthetic reasons.  They are plain too buggy.  My experience has been its always better to land on a structural part, or even just the engines, rather than the landing legs.  They are too bouncy, and once they settle down the ship will slide around on the surface- even a perfectly flat surface.

I wish that wasn’t the case.  I like the idea of thinking about how a vessel will absorb landing forces, and how it will sit on a surface without damaging components.   Sadly, it’s too frustrating to use them.   So I usually just land on my engines.

Ah yes you're so right. Sometimes they are useful to absorb landing force during hard landings but in low gravity environments they are pretty much useless.

[kerbiloid]

Quote

What is the most useless thing in KSP?

Any Kerbal but the selected one.

[Beriev]

Along with the Not-Rockomax Micronode, I'll made a case for the Probodobodyne QBE.

It's basically an OKTO-2 (no reaction wheels, tiny battery), but repackaged into a much larger core, without any major advantages. High impact tolerance? Nullified by the fact that nothing else you can add to a probe is, resulting in a crash landing which the probe can only survive for a few minutes before the battery dies. Low cost? When you add a reaction wheel to get the desired control, an OKTO is cheaper overall, and if you don't use a reaction wheel (where mass is low enough to make not having it matter), an OKTO-2 is far more effective for Delta-V. Plus, there's the issue of what is taking up so much space in that probe core that it's basically an OKTO-2 with like 10 times the volume?

I've made a stop gap solution of using them for atmospheric impactors, but I feel that they need to be buffed in one way or another. Adding a super weak reaction wheel, for example, (I mean, cubesats use them, and the QBE definitely would work as one) would make it useful for the gap between the OKTO and OKTO-2.

[Corona688]

21 hours ago, Beriev said:

Along with the Not-Rockomax Micronode, I'll made a case for the Probodobodyne QBE.

Good one.  It was the lightest probe core for exactly one year.

A science container would make it fantastic for career.

Edited December 10, 2020 by Corona688

[HvP]

On 12/2/2020 at 10:52 AM, Corona688 said:

KSP's built-in docking mode.  I've never found any documentation for it, or seen anyone suggest it;  it just kind of exists in a vacuum of uselessness.  As far as I can tell it does nothing but deprive you of half your controls.

I use docking mode as an alternate control set for rovers.

I often use a PS3 controller, especially when driving rovers. The analog stick makes steering much more responsive and holding forward on the stick is much more comfortable for long journeys than holding down a button. But since I don't want to engage the reaction wheels (which could flip the rover), I switch to docking mode for driving.

I have the translation/rotation toggle bound to R3 on the controller so that if I jump a crater in low gravity I can quickly switch to rotation control which activates the reaction wheel and I can line up my landings on slopes. Then when I land I toggle back to "translation" mode which won't roll the reaction wheels and gives me steering control again. Being able to switch between both control schemes using just one analog stick allows me to keep the RCS bindings on the digital pad unaffected. Which means that I can always use the RCS to soften the landing on low gravity worlds regardless of which controls I'm using to steer or rotate at the time.

[Mikenike]

13 minutes ago, HvP said:

I use docking mode as an alternate control set for rovers.

I often use a PS3 controller, especially when driving rovers.

Huh, I've never used it like that. Good idea for using the controller. I play EE, but occasionally with keyboard and mouse, and its really not helpful unless your on a long distance journey.