O-10 Monopropellant Engine & Vernor LFO RCS Thruster

[Red Iron Crown]

Two new parts are being added in 0.24:

O-10 Engine

An engine powered by monopropellant and controlled with the throttle.

Mass: 0.03

Thrust: 20

Isp: 220 atmo 290 vacuum

TWR: 67.9

No gimbal or alternator

Cost: 800

Vernor Thruster

A single direction thruster fueled by liquid fuel/oxygen and controlled with attitude and translation controls.

Mass: 0.08

Thrust: 12

Isp: 140 atmo 260 vacuum

TWR: 15.3

No gimbal or alternator

Cost: 1400

Stats from Scott Manley's video

.

My initial thoughts:

- Tough to evaluate cost without more context from the KSP economic model.

- Really hoping these small parts are not physicsless.

- The extremely high TWR of the O-10 may make it the new 48-7S. A cluster with LVT-30 thrust would mass 0.33 tons.

- The high TWR is offset by poor Isp, and monopropellant tanks' best mass ratio is 8.5:1, less than the best LFO tanks.

- Can simplify fuel management with simpler flow rules and unified engine/RCS fuel.

- The high thrust of the Vernor will make RCS control of large ships much easier.

- It will also simplify fuel management through unified engine/RCS fuel.

- LFO fuel flow rules may be tricky with control thrusters.

- Really wish it was a four- or five- way block rather than a unidirectional port.

How do you see these parts fitting into your game? What are their best uses?

[Sandworm]

I'm holding off judgment on the "vernor" until I see how it handles in space. Hopefully it won't be instantly responsive and won't scale down like the normal RCS ports do. If you can dock ships with it, then what is the point of monopropellant RCS?

O-10 Engine is just silly. The 45* thing is just wrong. If we had fuel boil off or some other reason to use monopropellant for thrust then it would at least be useful.

[dryer_lint]

Considering my lifter usually gets into orbit with a good amount of fuel left, I might ditch the RCS and use a bunch of Vernor thrusters. The O-10 might be cool for probes, I dunno.

[Worst at Video Games NA]

Of all the changes being made, the Vernor is what I'm most excited about, actually.

Running out of monoprop halfway through a docking procedure is just frustrating. The struggle is real.

[SciMan]

To be honest, I'm less impressed by the vernor engine than I am by the possibilities of config tweaking using it's part module.

People will FINALLY be able to make RCS that uses more than one resource at a time without using a complex assembly of part modules that might or might not work the way they expect it to. Ion RCS for probes and satellites, air+electric or air+fuel RCS for atmospheric VTOL craft, all kinds of possibilities for that.

[LameLefty]

I wonder why they named it the "vernor" engine rathe than the proper "vernier".

[Jouni]

- The extremely high TWR of the O-10 may make it the new 48-7S. A cluster with LVT-30 thrust would mass 0.33 tons.

- The high TWR is offset by poor Isp, and monopropellant tanks' best mass ratio is 8.5:1, less than the best LFO tanks.

On the other hand, it has an extremely bad thrust-to-cost ratio, at least compared to the LV-T30 we've seen in the videos.

I'm not sure what are the right efficiency metrics anymore. We can apparently get a full refund for all parts, if we can just land them on the runway.

[Caelib]

I tend to agree with most of what you stated, especially on the uni-directional port. It seems like they don't want it used for anything besides launch stabilization. I am a stock purist so I hate having to add RCS fuel just for docking ... was hoping the Vernor would solve that problem ... but from the looks of it, probably not.

[magnemoe]

Q-10 is nice for docking tugs, that is a small craft designed to move parts around for docking,

like this.

The vernor is nice for masvice ships like the station in the background and then redirecting astroids, here you often need sideway trust to as you is a few degree off center of mass.

The Q-10 can be used for getting pods away from launhers during about and then braking before landing, downside as I see it is no separate fuel, not a huge issue during takeoff but a problem then doing abort during landing.

[Exclipse]

I will certainly be using the Q10 for tugs, means you only have to have one type of fuel on board your tug and you can maneuver and thrust.

[cpast]

Since Vernors seem not very helpful for docking (unless you stuck one on each side for translation and had powerful enough reaction wheels, I guess), the Q-10 seems to fill the role of main power on light craft needing 6-dof movement (e.g. tugs, low-gravity landers, light orbital crew/science transfer vehicles). That way, you only have to deal with one fuel system (right now, I actually use tugs that have just RCS blocks for this reason, relying on 'H' and 'N' with no special main power).

[problemecium]

They called it the "vernor" to avoid debates over what constituted a proper vernier engine and whether the part would count as such.

I think it will really shine when tweaking interplanetary encounters. Now, rather than having to turn around and retro-burn if you overdo it a bit, or use tons of RCS fuel on account of your ship weighing 850 tons, you can just turn on the vernors and backpedal a smidgen to get your intercept back.

[Renegrade]

That O-10 really does have crazy TWR.

Here's the 0.23.5 breakdown, with the O-10/Verner added:

Someone needs to break out the nerf bat and give the O-10 a good beating.. the 'Vernor' could probably use a light beating too...and the 48-7S, but we knew that already.

I'm holding off judgment on the "vernor" until I see how it handles in space. Hopefully it won't be instantly responsive and won't scale down like the normal RCS ports do. If you can dock ships with it, then what is the point of monopropellant RCS?

Mr. Manley's video seemed to show it as basically just an RCS thruster running off of LF/O. Instant on/off, proportional thrust, etc.

The real downside there is that it's like the linear port, a lot less flexible than the quads. Quads are also currently massless/non-physics objects too, if I recall correctly.

[cpast]

That O-10 really does have crazy TWR.

Here's the 0.23.5 breakdown, with the O-10/Verner added:

http://alpha.renegrade.net/images/TWR_ARM.png

Someone needs to break out the nerf bat and give the O-10 a good beating.. the 'Vernor' could probably use a light beating too...and the 48-7S, but we knew that already.

The O-10 has *really* bad ISP. Why's it need a nerf?

[Randox]

I'm happy to get a more powerful RCS port, even if it is mono directional. A bit more power for forward and reverse would be quite welcome for docking.

[Jouni]

The O-10 has *really* bad ISP. Why's it need a nerf?

It has otherwise the same stats as the ant engine, but with 5x the thrust.

[Temeter]

I like the new parts. The loss of flexibility and weight are clear disadvantage's of the vernour. You need like 10 of them for full rcs coverage, weighting 0.8 ton. And that's only if you can actually put two of them directly at the front and back. Monoprop will remain standard for more reasonably size craft.

It has otherwise the same stats as the ant engine, but with 5x the thrust.

The ant engine is just utterly terrible.

[UmbralRaptor]

Initially I was expecting the O-10 to be grossly overpowered with that TWR. But, the Isp and mass ratio limitations mean that its rather unlikely to replace conventional engines. Performance is fairly decent when compared to SRBs, though its obviously much more complex and expensive.

[table=width: 500, class: grid]

[tr]

[td]Name[/td]

[td]Thrust[/td]

[td]Wet Mass[/td]

[td]Dry Mass[/td]

[td]Mass Ratio[/td]

[/tr]

[tr]

[td]12x Vernor, 1x FL-R1[/td]

[td]240 kN[/td]

[td]3.76 Mg[/td]

[td]0.76 Mg[/td]

[td]4.9474...[/td]

[/tr]

[tr]

[td]RT-10[/td]

[td]250 kN[/td]

[td]3.7475 Mg[/td]

[td]0.5 Mg[/td]

[td]7.495[/td]

[/tr]

[tr]

[td]16x Vernor, 2x FL-R1[/td]

[td]320 kN[/td]

[td]7.28 Mg[/td]

[td]1.28 Mg[/td]

[td]5.6875[/td]

[/tr]

[tr]

[td]BACC[/td]

[td]315 kN[/td]

[td]7.875[/td]

[td]1.5[/td]

[td]5.25[/td]

[/tr]

[/table]

The Vernor offers some interesting options, but if only an engine could be toggled between throttle and RCS... >_>

edit: And of course for any craft where the Fl-R1 is too much mass, but the FL-T100/200/400 is okay, the LFO engines will completely dominate the Vernor in ÃŽâ€V. Yes, even the LV-1.

edit2: come to think of it, the ROUND8 and Oscar-B have slightly better mass ratios than any of the size 0/1/radial monoprop tanks...

Edited July 16, 2014 by UmbralRaptor

[xcorps]

I think they have some very interesting possibilities for multihop lander design and small EVA craft.

[Tortoise]

If I remember in the video of the first contract video, it gave a reward of 4000 funds (I might be wrong).

So, one little vernor thruster would cost 1200 funds?

[CalculusWarrior]

Someone needs to break out the nerf bat and give the O-10 a good beating.

While the TWR is certainly insane of the O-10 by itself, monopropellant tanks are a lot heavier than their fuel tank counterparts. So in practice the engine won't perform as well as that chart suggests.

[Renegrade]

The O-10 has *really* bad ISP. Why's it need a nerf?

That TWR is crazy, and with such a low mass, you could actually beat a lot of the 390/350 specific impulse engines, on light payload, and have insane thrust.

Of course the thrust might even be so high that it's useless without some sort of MechJeb-y affair, as it goes shooting off into interstellar space with the slightest tap of lshift... I suspect they made a mistake with the mass, as the name/thrust/vac Isp suggests it's supposed to be used like the shuttle's OMS...

Take for instance, the following craft (an example I threw together as a mini-sub-probe I typically launch):

(3xZ-200, all four of the tiny science instruments, 6x OxStat, 1x whip antenna) - Mass - 70 kg

two ROUND8s bring that up to 120kg dry, 342kg wet.

Ant engine->2.580 km/sec (1.1 twr)

48-7S->2.393km/sec (6.9 twr)

LV-909->1.170km/sec (6.053 twr)

LV-N->0.702km/sec (2.360 twr)

Now swap out the two ROUND8s for a FL-R10 RCS tank for 120/320 mass.

1xO-10->2.410 km/sec (5.82 twr)

4xRV-105 thruster quad->2.597 km/sec (1.27 twr)

While the delta-v is slightly less for the O-10, it's still very much in the same range, and the TWR is crazy high. You could take great advantage of suicide burn landings, as well as the Oberth effect.

Using one might be impractical (you can build a lot of really crazy things with RCS Build Aid's "engine" tab though), but as a radially attached, RCS device, Squad might make it massless like the RV-105, bringing it up to 2.790km/sec and increasing the TWR to 6.37 times the number of O-10s you attach.

Please disregard the following if you're already aware of it: Isp isn't the end all and be all of engine efficiency. The Tsiolkovsky rocket equation's ln(wetmass/drymass) portion makes that ratio in the middle very critical, particularly for light payloads. Note how the LF/O engines have sorted themselves by Isp, with the best Isps having the worst delta-v for this scenario, with their crushingly high dry mass. Also, the higher delta-v rockets presented here are lighter, meaning the lower stage(s) can be smaller OR have better delta-v (or some fraction of both).

Increasing the mass of the O-10 would get rid of this problem, and it wouldn't take much of an increase either. Increasing it to 0.09 would make it only 1.9km/sec and reduce it's TWR to 22.65 without really impacting the target vessels (large orbital ships). Note that the 48-7S has a similar issue as having the highest TWR of any pre-ARM liquid engine, but also a decent sea level/vac Isp..

The ant engine is just utterly terrible.

See above. Even prior to the ant buff, I used them a lot with RT2 to make tiny relay probes that were basically a PB-NUK, one of the omni antennae, a probe core, a ROUND8 and an ant. They were a bit pokey, but worked well enough and were very light.

UmbralRaptor, the RCS tanks are all over the chart in terms of efficiency. The -R25 and small radial tank are fairly bad (3.666:1 / 3.1333:1 respectively), but the FL-R10 and StratusV are both 5:1, and the FL-R1 is a whopping 8.5:1. The typical LF/O tanks (FL-T100+) are 9:1, and the Round8 is around 4.2-4.5 with the Oscar being horrible at around 4.12-ish. (we're getting some truncation in the display for the tiny LF/O tanks I'm pretty sure, but I doubt it's enough to bring them over 5:1)

Edited July 16, 2014 by Renegrade

[tntristan12]

I'm personally quite excited about these additions. I'm planning on using them as redundant systems for the cases where I prematurely run out of monoprop or LFO. They will also come in handy for small sats and large stations respectively.

[Renegrade]

I'm personally quite excited about these additions. I'm planning on using them as redundant systems for the cases where I prematurely run out of monoprop or LFO. They will also come in handy for small sats and large stations respectively.

I have to say I like the idea of an RCS-burning engine for a single-fuel small craft or probe, but I prefer the ones that RLA Stockalike provides

[Red Iron Crown]

On the other hand, it has an extremely bad thrust-to-cost ratio, at least compared to the LV-T30 we've seen in the videos.

I'm not sure what are the right efficiency metrics anymore. We can apparently get a full refund for all parts, if we can just land them on the runway.

I'm in the same boat. I haven't quite gotten my mind around which metrics will be best to use for evaluating parts when cost is a factor. Thrust/Cost? Isp/Cost? Thrust*Isp/Cost? This game is about to change a lot.

While the TWR is certainly insane of the O-10 by itself, monopropellant tanks are a lot heavier than their fuel tank counterparts. So in practice the engine won't perform as well as that chart suggests.

Not at all. The 2.5m RCS tank has a mass ratio of 8.5:1, compared to 9:1 for 1.25m and 2.5m LFO tanks and 8.2:1 for the 3.75m tanks. The Isp is the real balancing factor (and cost, but how that will play out remains to be seen).

I think the Vernor will be really useful for me on bigger ships. I use the MechJeb function that disables RCS attitude control while keeping translation active; using reaction wheels for attitude saves fuel and means I need fewer of these expensive thrusters. I hope they are tweakable for thrust, there is a big gap between the 1KN regular thrusters and the 12KN Vernon.