Advantages of monopropellant as primary fuel?

[Tw1]

It's kinda hipster? 

 

(But not as pretentious.) 

[Dafni]

On 12/19/2015 at 2:09 AM, Cupcake... said:

The one major advantage is that O-10 engines don't burn stuff which is great for cargo lifters, light tugs etc... as you can position the exhaust anywhere without any danger of destroying anything.

 

Cupcake...

That is very true indeed, and something I appreciate a lot.

[Guest]

To me it makes a lot more sense to stick to conventional LF/O for main engines and monopropellant for manuevering, simply because liquid fuel engines have a lot more thrust and a higher I_sp than the monopropellant engine. For small probes/tugs I guess it could work, but it's probably more efficient to have a liquid fuel or ion propulsion system and then a small reaction wheel.

One use I've found for them, however, is to put 2-4 on the capsule and disable them and the capsule's use of monopropellant until detached from the rest of the ship. This way if the pod is accidentally detatched too early or has to correct its course before re-entry, it can use the engines rather than having the pilot get out and push. (Trust me, I've learned this the hard way.)

[fourfa]

7 hours ago, Geschosskopf said:

I heard it a bit differently.  The real problem with jetpacks buring regular ship mono was that at the time Squad tested this in-house (and added the small mono tanks to the capsules for this purpose), mono used a different fuel flow mode than it does now.  Back in those days, mono tanks drained from the top down just like LFO tanks, except considering the whole ship so decouplers didn't stop it.  Thus, with the capsule usually at the top of the rocket, if the ship as a whole used any RCS en route to the destination, the 1st tanks to drain would be those in the capsule.  This created a large trap for the unwary and a large potential for ragequits, from folks forgetting to pump mono back into the capsule prior to separating the last stage below it

Squad decided this was bad but didn't want to rewrite the mono fuel flow code at that time.  So as a temporary fix, Squad created "EVA Propellant" which has the same physical properties as mono but is infinitely available in capsules.  But the intent was to rewrite the mono code at some point, which is why the capsules still have their little mono tanks even though they're never used.  Besides, by leaving the mono in the capsules, once the change happens, ships from before the update will already have the mono aboard ready for EVA use (unless the user has removed it to save weight and/or launch costs --- I've gotten into the habit of doing that myself).

That was long ago.  In the time since then, in fact several updates ago, Squad changed the mono fuel flow code so that now mono is stopped by decouplers.  This keeps capsule mono safe from the rest of the ship.  I'm thus rather surprised that EVA packs don't use mono now, seeing as all the pieces for it are now in place.  So either Squad has forgotten about this, or has thought better of it for reasons of fun, as you suggest.

 

Sorry to quote the whole post, it's a pain to trim this stuff from a phone

this sounds like a perfect opportunity for a lightweight mod. Keep all existing RCS fuel flow rules, and force cabins to refuel jet packs on cabin reentry? I would like the extra gameplay balance, and the possibility of having to maneuver a ship just-so, so that an out-of-fuel EVA Kerbal can grab a ladder... That just sounds so Kerbal. Ooh, I'm already planning a ship that can use a cargo bay for grabbing....

[cantab]

Personally I feel that if EVA fuel is to be made finite, firstly we should have EVA tethers, to prevent a simple click on that button from sending your Kerbal helplessly drifting because you forgot to check the monoprop reserves. Give the player the chance to check their actual EVA fuel before releasing the tether.

[Pecan]

41 minutes ago, cantab said:

Personally I feel that if EVA fuel is to be made finite, firstly we should have EVA tethers, to prevent a simple click on that button from sending your Kerbal helplessly drifting because you forgot to check the monoprop reserves. Give the player the chance to check their actual EVA fuel before releasing the tether.

Tethers would be good in any case because, sanity!  Then again ... tech 5 ladders :-(
Seriously we shouldn't all have to be Leonov in order to get back in our ships, especially beginners (he was tethered, of course, but that's about the only thing he had going for him)