Monoprop lifter engines proposal and it's usage in general

[NiL]

So, monoporpellant (to me, at least) looks like a obvious KSP analogue to hypergolics, not only due to it's use in RCS, lower specific impulse and the real-life monopropellant being usually hydrazine, but also because it was used in a couple of major mods with engines, the source of inspiration for which used hypergolics IRL. Those are, unfortunately, nearly all upper stage engines - but in real life there are rockets using hypergolics on lower stages (Proton as an example, through @Beale transitioned to using LFO even in his RCS, so it's unlikely we'd ever see it in Tantares' Proton). In general, it pains me to see a stock (!) resourse so horribly underused - confined nowadays only to RCS and a couple of small secondary engines. Proton engines have a pretty distinct look and could look great in some cryoengines style mod, but I doubt any major modders would be interested in such developement, as I haven't seen much love for monoprop in KSP community.  But that's my thoughts on the subject, that do y'all people think of all this? 

[Guest]

I think you may be mixing up some terms there. An hypergolic propellant is one that ignites when it comes in contact with another (ie doesn’t need a separate ignition source like say the engine in a car does). The other major benefit is they are liquid at room temperature (easy to store). Usually you will have a ‘fuel’ and an ‘oxidiser’.

In modern parlance, ‘hypergol’ is often used to refer to dinitrogen tetroxide N2 O2, (oxidiser) with hydrazine (fuel) (most commonly aerozine50 a mix of hydrazine and a derivative UDMH). But it’s the fact they are used hypergolically that that name derives from.

Now the interesting thing with hydrazine is it can be used hypergolically (as hydrazine or a derivative or both) or as a monopropellant (ie on its own). As the latter, it has a lowish power but decent efficiency so is often used for manoeuvring thrusters (RCS). It was/is used for the engines of some small landers like the recent Mars landers as well (and I think the Dragon from SpaceX).

Things like the space shuttles OMS were powered with (I believe) a variant called MMH which isn’t a monopropellant as it uses oxidiser as well. Again low power but decent efficiency. The Puff engines in KSP have this wrong as they use monopropellant but we’ll allow them one slip up .

Now according to Wikipedia, the Proton first stage used a fairly standard Russian N2O2 / UDMH mix (therefore hypergolic). In KSP terms this is liquid fuel/oxidiser which Tantares uses correctly.

Hydrazine used as a monopropellant would not generate enough thrust to lift anything significant (if at all) into orbit (as per the game). So this part is right as well.

TL;DR  monopropellant refers (usually) to pure hydrazine which is efficient but not too powerful so used for manoeuvring or small probes.

Rockets that lift off from Earth are hypergolic (2 components that ignite when mixed) and usually an oxidiser (N2O2) with a fuel (N2H2 or a derivative such as UDMH). 

Therefore it’s easy to confuse the 2 as both contain hydrazine but it’s what’s mixed with it that makes the difference.

 

[Spaceman.Spiff]

5 hours ago, NiL said:

So, monoporpellant (to me, at least) looks like a obvious KSP analogue to hypergolics, not only due to it's use in RCS, lower specific impulse and the real-life monopropellant being usually hydrazine, but also because it was used in a couple of major mods with engines, the source of inspiration for which used hypergolics IRL. Those are, unfortunately, nearly all upper stage engines - but in real life there are rockets using hypergolics on lower stages (Proton as an example, through @Beale transitioned to using LFO even in his RCS, so it's unlikely we'd ever see it in Tantares' Proton). In general, it pains me to see a stock (!) resourse so horribly underused - confined nowadays only to RCS and a couple of small secondary engines. Proton engines have a pretty distinct look and could look great in some cryoengines style mod, but I doubt any major modders would be interested in such developement, as I haven't seen much love for monoprop in KSP community.  But that's my thoughts on the subject, that do y'all people think of all this? 

Have you seen the Stockalike Hypergols mod?

Maybe making engines for that would be interesting. 

[NiL]

1 hour ago, Spaceman.Spiff said:

Stockalike Hypergols

Oh, didn't knew it existed. Sounds interesting, I'm not really sure why add another oxidizer, as it complicates things, but newertheless thanks!

 

2 hours ago, FruitGoose said:

I think you may be mixing up some terms there. An hypergolic propellant is one that ignites when it comes in contact with another (ie doesn’t need a separate ignition source like say the engine in a car does). The other major benefit is they are liquid at room temperature (easy to store). Usually you will have a ‘fuel’ and an ‘oxidiser’.

Haha i know, my bad for not clarifying - I know that hypergolic engines use oxidizer, but because of  Puff and all mod "hypergol-ish" engines using just monopropellant I always thought of it as of in-game artistic assumption by Squad