Is RCS propulsion for low grav planets/moons worth it?

[Ambassadoing]

I was wondering if it was a lot more efficient to use RCS propulsion for use on return pods from low grav bodies like Mun and Minmus.

[internetrules]

almost definetly not

if you want to know for sure look at an RCS thrusters ISP in vac then compare it to other thrusters in VAC

[Ambassadoing]

Originally posted by internetrules:

almost definetly not

if you want to know for sure look at an RCS thrusters ISP in vac then compare it to other thrusters in VAC

You forgot fuel price.

[internetrules]

Originally posted by Ambassadoing:

Originally posted by internetrules:

almost definetly not

if you want to know for sure look at an RCS thrusters ISP in vac then compare it to other thrusters in VAC

You forgot fuel price.

the price of fuel is so minimal that i pretty much ignore it

[Joe™]

Monoprop has a lower ISP than standard fuel, but last time I checked the monoprop engines were not counted as having mass (the tooltip lies) so this makes up for its low ISP by not adding any weight to the payload. They might have changed it but give it a try. I used them for returning pods from Minmus but I didn't try Mun.

[internetrules]

also pro tip never have RCS in symetrys of 3

i did that yesterday and then tried to dock........

it did not go over well

[maj.solo]

It is ok to use RCS as propulsion if the craft is very light weight. Like a

docking port
probe core
reaction wheel
one FLT800 tank
( and no engine at all )
vernor RCS engines.

using vernor engines makes you use Lq+Ox for everything docking, rotating, and propulsion. Vernor engines are good enough if you detach something light from a mother ship and all you intend to do is alter the trajectory some.
I can't imagine they be practical for landing or interplanetary travel. Someone ELSE have to come here and say "Yeah I done that with vernor engines!!"
How much milage you get for the fuel you need to check the ISP values. I don't know if ISP is listed for RCS thrusters ... but in my experience I think vernor engines drink quite a lot of fuel. Going to check ....

Vernor 260 Vac

RV105 240 Vac
( but now you need to carry monopropellant ... you KNOW you DO NOT have a freaking clue what will happen on your mission or how much you will use )

Rockomax Poodle 350 vac
1.25m terrier 345 vac
Kerbodyne Rhino 340 Vac
Rockomax Skipper 320 Vac same a svivel / spark

I am sipping beer and been awake for 1.5 day. I am not sure I can figure this out. But ISP alone don't tell the entire story if you remove a rocket engine from the design.

My feeling is ditching the engine and use lower ISP RCS thrusters only have a positive effect for short hops with not so much burning done.
I think ISP dictates how the efficiency is going to be if you make very long burns, several minutes long burns and generate several throusands dV like you do interplantetary. Then ISP might be the parameter most important. It grows and grows until it overshadow everything else.

And if so the RCS thrusters are leaking like an old lady. Naah, not to be used for interplanetary travel.

[internetrules]

consider mag.solos post to be peer reviewed and agreed with

also both the RCS thrusters that use mono have an ISP of 240

[internetrules]

note this information isent as relevant as i thought it was after reading what OP actually said but im gonna post it anyway

for 6k you can get 750 mono and 8 RV-105 RCS thrusters which will give you around 750 seconds of use if all thrusters are active

and for 7k you can get 4 advanced inline stabilisers with 2 extenable solar panels and 8 z-100 batteries

(note prices include the Probodobodyne HECS)

weight for mono solution is 3.8 tons

weight for stabilisers solution is 0.49 tons

with the weight saved with stabilisers you could put some fuel tanks and a terrier on for an extra 1k that will weigh 3.8 tons

[DarkRaven]

Short answer: No

Longer answer: Using stock, for a given stage, assuming you are aiming for similar thrust values and are only switching out engines and fuel, you will almost always get more dV out of LFO than Mono and assuming a sane build, the price will be similar, if not maginally cheaper with LFO as the price of the Mono will offset the price of the LFO engines.

That being said, if you're planning to dock the return stage, a Mono thrust system may be better suited, mostly for convienence.

Addendum: Mono also has the advantange of not requiring the fuel and engine(s) be directly connected. Whatever floats your boat.

[maj.solo]

Originally posted by internetrules:

note this information isent as relevant as i thought it was after reading what OP actually said but im gonna post it anyway

for 6k you can get 750 mono and 8 RV-105 RCS thrusters which will give you around 750 seconds of use if all thrusters are active

and for 7k you can get 4 advanced inline stabilisers with 2 extenable solar panels and 8 z-100 batteries

(note prices include the Probodobodyne HECS)

weight for mono solution is 3.8 tons

weight for stabilisers solution is 0.49 tons

with the weight saved with stabilisers you could put some fuel tanks and a terrier on for an extra 1k that will weigh 3.8 tons

HECS is my favourite when I have not yet completed the tech tree. I fly so much manually anyways since the game AI fly so badly.

[internetrules]

Originally posted by maj.solo:

Originally posted by internetrules:

note this information isent as relevant as i thought it was after reading what OP actually said but im gonna post it anyway

for 6k you can get 750 mono and 8 RV-105 RCS thrusters which will give you around 750 seconds of use if all thrusters are active

and for 7k you can get 4 advanced inline stabilisers with 2 extenable solar panels and 8 z-100 batteries

(note prices include the Probodobodyne HECS)

weight for mono solution is 3.8 tons

weight for stabilisers solution is 0.49 tons

with the weight saved with stabilisers you could put some fuel tanks and a terrier on for an extra 1k that will weigh 3.8 tons

HECS is my favourite when I have not yet completed the tech tree. I fly so much manually anyways since the game AI fly so badly.

right now i really want the 1.25m AI core so i can make my probes look not ♥♥♥♥

[GeneralVeers]

From an engineering standpoint, using RCS as your main drive is entirely workable.

I've done it myself, using the Vernor RCS thruster. Works handily on Minmus. It's also doable on Mun, but you have to be real careful of your thrust-to-weight ratio. With a couple of my Mun landings using this design, the lander didn't have enough gas to take off and make orbit. It ran out of fuel while still sub-orbital--meaning the mothership had to do an emergency dive, intercept the lander, dock with it while both ships were on an impact trajectory, then point the nose upward and get orbital, FAST.

That mission made great news headlines back home on Kerbin. :)