Quad RCS Thruster - fire all directions simultaneously

[itsaps]

Hello community members!

I'm quite extensive messing around with mods on my RSS RO 1.22 Version. Recently I got the feeling it would be nice to have a fuel vent for getting rid of those toxic and reactive fuels in rcs systems etc. before reentry or recovery. Searches in the forums suggest mostly the http://kerbalspaceprogram.com/tac-fuel-balancer-v1-0/ which would do the job, but there is one thing that bothers me with it: no effects - there is no smoke tail coming with it... 

 

So here is my idea for a "simple" solution: Take a normal quad rcs asset, modify the .cfg with minimum thrust values and single fuel source modes (like the rcs selection in RO, just split the components up to prevent hypergolic reactions) and increase the fuel drain rates to realistic values. The rcs has already the beautiful firing effects and staging and enabling comes along with the "stock" version but what I have not figured out yet:

Is it possible to modify a quad rcs so to use all four directions thrusters together so the total applied force is nearly 0?  Fore by throttle and always full action would be preferred... After this I would try to link a different sound to the firing, would be nice tho.

Otherwise, if anyone gets an idea for any other fuel vent solution for RO fuels I would appreciate your opinions. 

[Geonovast]

Have you taken a look at the dump valves in Smart Parts?

Also, since you like the vapor effects, you might like this too:

 

Edited January 28, 2018 by Geonovast

[itsaps]

7 minutes ago, Geonovast said:

Have you taken a look at the dump valves in Smart Parts?

 

Also, since you like the vapor effects, you might like this too:

 

Thank you for your response! Yes had a look at them but the thing is, smart parts does only drain one tanks content and then you cannot select which resource... And the vapor vent is afaik only the effect but not the drain of fuel...

[Geonovast]

1 minute ago, itsaps said:

Thank you for your response! Yes had a look at them but the thing is, smart parts does only drain one tanks content and then you cannot select which resource... And the vapor vent is afaik only the effect but not the drain of fuel...

Oh, I know vapor is just the effect.

How many RCS tanks are you considering?  You could always just put a vent on each tank you want to drain, or constantly transfer resources from the other tanks into the tank with the drain.

I'm not familiar with RO, so I inferred you only had one resource to dump.

[itsaps]

5 minutes ago, Geonovast said:

Oh, I know vapor is just the effect.

How many RCS tanks are you considering?  You could always just put a vent on each tank you want to drain, or constantly transfer resources from the other tanks into the tank with the drain.

I'm not familiar with RO, so I inferred you only had one resource to dump.

Hmm I thought of that already, but often I have a few round and pressurized tanks placed inside some fairing or storage bay - so the vent placed directly on the tank could possibly not be accessed. In RO you get a plugin, which lets you configure which resource is used by an rcs port (you select it in the VAB). There are pressure only resources like helium and there are hypergolic resources like UDHM + NTO. In real life if the hypergolic fuels are mixed, they instantly react and produce thrust. 
For a realistic experience, I would like to maintain the thrust values for pressure-only-resources and lower the thrust for the hypergolic ones, where I need a vent for each one of the resources.
So I already can assign a RCS thruster to have like 0.1kN  Thrust and just use UDHM for example. But it fires only with the typical control and center-of-mass scheme... I'm trying now to force a engine like behavior on them (so if you throttle up -  just "vent is open" and fire on all ports, independent of the COM or controls) but had no success yet.

 
Do you think I can grap the plugin behavior of the e.g. Smart Parts mod and use it for throttle action on the RCS port? 

[Phineas Freak]

@itsaps You could also "MM clone" one of the linear RCS thrusters, lower the Isp values (since valves do not have too good of an Isp, probably around 50 to 70 seconds) and reduce the thrust value to a minimum (so it will act as a non-propulsive vent - or put two of them facing against each other). You can then configure the propellants like it was a normal RCS thruster and have it set to an action group for toggling.

Ideally, you could extend that by using custom engine configs to cover all available propellants (current RCS thruster definitions only include a limited range of gases, monopropellants and bipropellants).

Edit: IIRC RCS are also "global", so you do not need to worry about cross feed.

Edited January 28, 2018 by Phineas Freak

[itsaps]

5 minutes ago, Phineas Freak said:

@itsaps You could also "MM clone" one of the linear RCS thrusters, lower the Isp values (since valves do not have too good of an Isp, probably around 50 to 70 seconds) and reduce the thrust value to a minimum (so it will act as a non-propulsive vent - or put two of them facing against each other). You can then configure the propellants like it was a normal RCS thruster and have it set to an action group for toggling.

Ideally, you could extend that by using custom engine configs to cover all available propellants (current RCS thruster definitions only include a limited range of gases, monopropellants and bipropellants).

Edit: IIRC RCS are also "global", so you do not need to worry about cross feed.

That was my idea too so that's exaclty what I've done, but the activation is the problem...   Even the linear thruster is only responsive to the rotation/translation controls. If I could get rid of that, the problem would be solved...

[Gargamel]

@itsaps TAC fuel Balancer has a dump feature. 

[sebi.zzr]

On ‎28‎.‎1‎.‎2018 at 3:58 PM, itsaps said:

That was my idea too so that's exaclty what I've done, but the activation is the problem...   Even the linear thruster is only responsive to the rotation/translation controls. If I could get rid of that, the problem would be solved...

So when you clone the part you want to use add these lines to module

MODULE
{
 name = ModuleRCSFX
 useThrottle = true //will act like engine with throttle
 fullThrust = true  //if you want always max thrust
}

 

[itsaps]

1 minute ago, sebi.zzr said:

So when you clone the part you want to use add these lines to module

MODULE
{
 name = ModuleRCSFX
 useThrottle = true //will act like engine with throttle
 fullThrust = true  //if you want always max thrust
}

 

Uh that's a very good hint, I'll try that soon!!

[saxyomega90125]

Ship Manifest also has a resource dump function, but I think the OP wants a mechanic to drain RCS using realistic means. I always just hold down N while I burn - real craft use RCS to maintain attitude for reentry, but since that isn't as critical in KSP I use it to help offset the mass change from the loss of ablative shielding I get with DR that Trajectories won't account for.

RCS units are already set so that nozzles facing at an angle less than or equal to 45 degrees from dead aftward (I think that's how it figures it out) are automatically available via throttle when the craft has no proper engines active and RCS is engaged. If you're having trouble, I wonder if that mechanic could be interfering with your part clone?

If still going for the OP idea, I think it would be better to do a mode toggle on RCS nozzles in the right click menu so you can set it as an action group, and add an option to add to staging if you like. Making it apply to all RCS should be as simple as applying it to any part that defaults to being an RCS unit. The trajectory alteration from mass decrease due to fuel jettison might require a corrective maneuver, or I might refuel a craft after entry and descent, and in either case I would want normal RCS control back at some point. Not to mention, I already have enough fun dealing with staging!

[itsaps]

On 26.2.2018 at 10:24 PM, itsaps said:

Uh that's a very good hint, I'll try that soon!!

Sadly this was not what I was looking for....

 

On 28.2.2018 at 6:15 AM, saxyomega90125 said:

Ship Manifest also has a resource dump function, but I think the OP wants a mechanic to drain RCS using realistic means. I always just hold down N while I burn - real craft use RCS to maintain attitude for reentry, but since that isn't as critical in KSP I use it to help offset the mass change from the loss of ablative shielding I get with DR that Trajectories won't account for.

RCS units are already set so that nozzles facing at an angle less than or equal to 45 degrees from dead aftward (I think that's how it figures it out) are automatically available via throttle when the craft has no proper engines active and RCS is engaged. If you're having trouble, I wonder if that mechanic could be interfering with your part clone?

If still going for the OP idea, I think it would be better to do a mode toggle on RCS nozzles in the right click menu so you can set it as an action group, and add an option to add to staging if you like. Making it apply to all RCS should be as simple as applying it to any part that defaults to being an RCS unit. The trajectory alteration from mass decrease due to fuel jettison might require a corrective maneuver, or I might refuel a craft after entry and descent, and in either case I would want normal RCS control back at some point. Not to mention, I already have enough fun dealing with staging!

You got some aspects right, but all in all I wanted to get rid of any force while dumping fuel. If the "dump" RCS port would be for dumping only this would not be bad at all, one could still put on normal ports for manoevering and control the dump ports via action toggles, just on and off...

But I think I would have to edit the .mu models itself so to exchange the RCS Thrusters with normal Engine thrusters on a 4 way RCS. This is to tricky for me now and I would go for a different solution now:

Take the 1kN tiny engine which runs on different fuel sources, edit exhaust and consumption rates, drop the thrust and place 2 of them in mirror alignment around a very tiny fuel tank. Save as a subassembly and done. This satisfies me needs for now.