O-10 Monopropellant Engine & Vernor LFO RCS Thruster

[Jouni]

The ant engine is just utterly terrible.

Another comparison: The O-10 is basically a 24-77 engine using monopropellant instead of LFO. It has 3.3% lower Isp, the same thrust, and 3x higher TWR.

[eempc]

Rather than calling for nerfs based on paper calculations before the update has even been released, why not wait and see how it works first? Or is this too sensible?

And if you still don't like the O-10, so what? Modify its config to something *you* find acceptable.

It's a freaking single player game.

[Red Iron Crown]

Rather than calling for nerfs based on paper calculations before the update has even been released, why not wait and see how it works first? Or is this too sensible?

And if you still don't like the O-10, so what? Modify its config to something *you* find acceptable.

It's a freaking single player game.

We're discussing the applications and balance of the new parts. Please go away if you have nothing to add to the discussion.

[magnemoe]

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.

The vernier is designed to move huge ships or asteroids around. If your ship is heavier than 500 ton a ton extra for control is nothing you probably save the weight by not having to carry all the monoprop, it however can be used together with monoprop where you use the 8 monoprop truster blocks for rotating and correcting trust errors from vernier, the verniers will do most of the directional movement.

The ant engine is just utterly terrible.

I agree, its nice for adjusting satellite orbits, however if you need more than 3-4 oscar tanks you are better off using a 48-7S as it will give more dV.

The 48-7S wins at two oscar but its heavier and you often want the tanks to mount equipment on.

[Sky_walker]

Another comparison: The O-10 is basically a 24-77 engine using monopropellant instead of LFO. It has 3.3% lower Isp, the same thrust, and 3x higher TWR.

24-77 uses liquid fuel which has much lighter tanks when they're empty (that's ~50% difference) and it's far easier to add large liquid fuel tanks than large RCS tanks (which basically require using multiple parts instead of just one, especially if you want it to be longer than wider).

Equation and comparison isn't even remotely as simple and one-sided as you want to make it.

[Red Iron Crown]

24-77 uses liquid fuel which has much lighter tanks when they're empty (that's ~50% difference) and it's far easier to add large liquid fuel tanks than large RCS tanks (which basically require using multiple parts instead of just one, especially if you want it to be longer than wider).

Equation and comparison isn't even remotely as simple and one-sided as you want to make it.

At the risk of repeating myself: 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).

You're right about needing more parts for a given capacity, though.

[Renegrade]

Rather than calling for nerfs based on paper calculations before the update has even been released, why not wait and see how it works first?.

Ignoring the inappropriate comments for a moment, I do agree that this is entirely speculation. I, in fact, expect the O-10 to have different stats in the live version (I really do think a typo was involved). That being said, it wouldn't be the first time a crazy engine was added, and it merits discussion.

As a clarification, I have no objection to LF/O RCS thrusters or monoprop engines, so long as they don't wreck existing balance and replace half a dozen engines in half a dozen specialized niches.

[cpast]

I at first had thought mass was more than 0.03. If mass were higher, that would make more sense.

[Red Iron Crown]

I at first had thought mass was more than 0.03. If mass were higher, that would make more sense.

It might be revised before release. I ran the TWR calculation 3 times and triple checked the mass in Manley's video, was sure I had made a mistake.

[UmbralRaptor]

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.

But the example has a 290 s engine with higher dV, and a Kerbin TWR >1!

Increasing the mass of the O-10 would get rid of this problem, and it wouldn't take much of an increase either.

Yep.

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)

The variation in mass ratios is why I'm only interested in the FL-R1 case. Everything else traps you in terrible mass ratios. Also, just so we're clear, the Probodbodyne LFO tanks are better than all but the largest RCS tank:

[table=width: 600, class: grid]

[tr]

[td]Name[/td]

[td]LiquidFuel[/td]

[td]Oxidizer[/td]

[td]Wet Mass[/td]

[td]Dry Mass[/td]

[td]Mass Ratio[/td]

[/tr]

[tr]

[td]Oscar-B[/td]

[td]5.735[/td]

[td]7[/td]

[td]0.136[/td]

[td]0.025[/td]

[td]5.44[/td]

[/tr]

[tr]

[td]ROUND8[/td]

[td]10[/td]

[td]12.2[/td]

[td]0.078675[/td]

[td]0.015[/td]

[td]5.245[/td]

[/tr]

[/table]

The high TWR likely allows for much hilarity, but I don't expect a replay of the replay of the 48-7S. If anything, the 24-77 and SRBs (when money isn't an issue) are in danger.

if you need more than 3-4 oscar tanks you are better off using a 48-7S as it will give more dV.

If you need that many Oscar tanks, you probably want an FL-T100 instead.

edit: I need to block out some SSTO designs. But provisionally, I expect ones built around the O-10 and FL-R1 to have payload fractions of 5-7%. (Actually pretty unspectacular)

Edited July 16, 2014 by UmbralRaptor

[Spanier]

Will the Vernor engine work, when radially attached to a decoupler with fuel tanks beneath

[Temeter]

Mind that the FAQ also said over hundred parts had been modified for a rebalancing. So some the calculations might be a bit off beginning with 0.24.

This time around, we were not just hunting for bugs, we were also listening to every bit of feedback from the testers about game balance, which is something that you can only improve by playtesting, and required a lot of careful adjustments of hundreds of values. We’ve already tweaked parameters on over a hundred parts, if we're not mistaken, correcting inconsistencies and making sure their values make sense for what they are.

[Red Iron Crown]

Mind that the FAQ also said over hundred parts had been modified for a rebalancing. So some the calculations might be a bit off beginning with 0.24.

I suspect that is pricing only. Just like the "new UI" is the old UI with additions for managing the new features.

[Temeter]

I suspect that is pricing only. Just like the "new UI" is the old UI with additions for managing the new features.

I thought the same, but the way it's worded sounds more spectacular to me.

Also bad gateway

[Aragosnat]

I suspect that is pricing only. Just like the "new UI" is the old UI with additions for managing the new features.

Could be just that. But, so far have been tring to find the thread or blog that mention. They where going to bring some of the older engines like main sail more in line with the new NASA parts.

[Red Iron Crown]

Could be just that. But, so far have been tring to find the thread or blog that mention. They where going to bring some of the older engines like main sail more in line with the new NASA parts.

That rings a bell, it was in one of HarvesteR's update updates I think. Mainsail will be more efficient than the LFB. Maybe they're doing a whole balance pass since they're tweaking .cfgs everywhere anyway for pricing, that would be great.

[Renegrade]

But the example has a 290 s engine with higher dV, and a Kerbin TWR >1!

They're still in the same range (2500-ish), but the O-10 has like.. five or six kerbin TWR, which can let it leverage various TWR-sensitive things like Oberth effect/suicide burns/land on heavy grav worlds etc.

The variation in mass ratios is why I'm only interested in the FL-R1 case. Everything else traps you in terrible mass ratios. Also, just so we're clear, the Probodbodyne LFO tanks are better than all but the largest RCS tank:

[table=width: 600, class: grid]

[tr]

[td]Name[/td]

[td]LiquidFuel[/td]

[td]Oxidizer[/td]

[td]Wet Mass[/td]

[td]Dry Mass[/td]

[td]Mass Ratio[/td]

[/tr]

[tr]

[td]Oscar-B[/td]

[td]5.735[/td]

[td]7[/td]

[td]0.136[/td]

[td]0.025[/td]

[td]5.44[/td]

[/tr]

[tr]

[td]ROUND8[/td]

[td]10[/td]

[td]12.2[/td]

[td]0.078675[/td]

[td]0.015[/td]

[td]5.245[/td]

[/tr]

[/table]

You've got the stats/names kinda mixed up in the rows there... the OscarB is 5.375/7 fuel, but 0.078 / 0.015 mass (my own calculation says 0.07872222.. wet mass fyi, and the game says 0.0787). That was a bit confusing when I was going over my numbers from earlier for verification.

That being said, I made an error as well. I must have been dividing the fuel mass by the dry mass prior to get those 4.x numbers. That's what I get for not doing this as a perl script~

Anyhow 5.2-4 is similar to the 5.0 "mid-range" RCS tanks -- slightly better rather than slightly worse. My delta-v numbers for my probe actually came from VOID+RCS Build Aid, so they're un-impacted by that little whoopsie.

The high TWR likely allows for much hilarity, but I don't expect a replay of the replay of the 48-7S. If anything, the 24-77 and SRBs (when money isn't an issue) are in danger.

Speaking of the 24-77, what's the deal with the radial engines (aside from the radial "ant")? I could understand them being slightly worse than their inline equivalents (assuming the 24-77 is a radial 48-7S and the Mk55 is a radial LV-T30/45), but they have a rather large Isp gap....

EDIT:

That rings a bell, it was in one of HarvesteR's update updates I think. Mainsail will be more efficient than the LFB. Maybe they're doing a whole balance pass since they're tweaking .cfgs everywhere anyway for pricing, that would be great.

A balance pass would be awesome.

[ouion]

I would use 0-10 engines for capsules and as a emergency escape engine.

[SpaceSphereOfDeath]

I would use 0-10 engines for capsules and as a emergency escape engine.

Basically, the escape tower everyone was SO excited about is now redundant.

Fabulous (although I suppose you could use them in conjunction, 22Gs anyone)

[Renegrade]

Basically, the escape tower everyone was SO excited about is now redundant.

Fabulous (although I suppose you could use them in conjunction, 22Gs anyone)

Well, the O-10 could still be nerfed prior to us getting it... and doesn't look as cool as the escape tower.... does coolness count against mass fractions and delta-v and such?

[SciMan]

I see the O-10 being more useful for low mass / low part count powered landing systems for Kerbin.

FL-R25 + 4x O-10 = powered landing for the 2.5m 3-seat capsule, with the possibility of adding parachute backup still available.

FL-R10 + 2x O-10 = same for the 1.25m single seat capsule.

Then again, I don't usually min/max my designs to take advantage of every part's little quirks that make them "overpowered".

(in quotes because overpowered is purely subjective in almost all cases)

Actually I've got a bit of a confession to make: I hardly ever use the 48-7S in space, because trading ISP for TWR just seems like it wouldn't happen IRL, and I usually try to keep at least some kind of link to RL in my space program. Also, taking advantage of the quirks of the various parts usually drives up part count, which I'm very against doing.

[LethalDose]

Rather than calling for nerfs based on paper calculations before the update has even been released, why not wait and see how it works first? Or is this too sensible?

And if you still don't like the O-10, so what? Modify its config to something *you* find acceptable.

It's a freaking single player game.

We're discussing the applications and balance of the new parts. Please go away if you have nothing to add to the discussion.

I think the first post raises an excellent point that adds a lot to the discussion: It's absurd to call for the nerf bat prior to seeing how the engine performs practically in the game. Theory-crafting is great, so long as it's taken with a grain of salt, which happens far too infrequently IMO.

Yes, O-10's TWR is through the roof, but the ISP is crap, it requires a heavier fuel, and we have no idea what effect the part price is going to have for the game. As long as the O-10 does it's job well enough to be useful without doing the job of other engines so well it supplants them as well, then it's balanced. And we simply can't know if that's the case until release.

[Red Iron Crown]

I think the first post raises an excellent point that adds a lot to the discussion: It's absurd to call for the nerf bat prior to seeing how the engine performs practically in the game. Theory-crafting is great, so long as it's taken with a grain of salt, which happens far too infrequently IMO.

The numbers actually describe how the engine will work in game. My response to the post you quoted was an attempt to curb the typical "just edit them" and "don't like them? don't use them" responses to balance issues, which are not useful when talking about how the parts fit into the stock mix. They're just offtopic noise.

Yes, O-10's TWR is through the roof, but the ISP is crap, it requires a heavier fuel, and we have no idea what effect the part price is going to have for the game. As long as the O-10 does it's job well enough to be useful without doing the job of other engines so well it supplants them as well, then it's balanced. And we simply can't know if that's the case until release.

"Heavier fuel" is not a significant thing, nor is it accurate (monoprop is less massive per unit than LF/O). Isp is essentially a measure of thrust produced per unit mass of fuel, it ignores varying fuel densities. The worst that can be said it that monoprop has poorer mass ratios for most of the tanks, though the 2.5m tank has a comparable ratio to the liquid fuel/oxidizer tanks.

It is still useful to discuss the relative balance and usefulness of the new parts without respect to cost; this will matter for sandbox players, the career endgame, and for experienced players who are unlikely to feel very constrained by budget. Of course it is a bit speculative because we don't know how or if all the other parts have been changed, but there's nothing wrong with a bit of speculation before the update drops, and I imagine the discussion will continue after it does and we have practical experience to talk about.

[cpast]

If you do factor in cost, it does balance out a bit more; MP is 30 cents per kg ($1.20/unit, 4 kg/unit), while LF/O is around 9 cents per kg (80 cents for a 5 kg unit of LF, 18 cents for 5 kg O, and one kilo LF/O is .45 kg LF and .55 kg O).

[GusTurbo]

Could you do a SpaceX-style soft-landing on a Mk1-2 pod using O-10 thrusters and the on-board monopropellant? That seems like a promising use of this.