• 1.7 Maneuvering Engine Balance Changes


    Maxsimal

    Maneuver Engine Re-Balance

    Among the other features in 1.7 are a few art revamps for various maneuver engines.  And amongst the feedback for those engines, some of the community pointed out that a couple of these engines aren’t as useful as others, due to their stats.

    The team decided to take a look and yes, we did see some tuning issues – so we decided to update select numbers of the engines we’re revamping.

    As with the last blog on the tuning of the MH engines, the goal here is balance and making sure each of our engines has a niche and a use, while making the smallest number of changes possible.

    So first, here are the raw numbers of the engines we’re changing, as well as some reference numbers of similar engines that aren’t changing.

     

    Engine Comparison

    Thrust (Vac)

    ISP Vac

    ISP ASL

    Mass

    Vac TWR

    ASL TWR

    Cost

    Cost/kN Thrust

    Tech Level

    Gimbal Range

    EC/s

    Crash Tolerance

    Entry Cost

    Ant (for comparison)

    2

    315

    80

    0.02

    10.19

    2.59

    110

    55.00

    Propulsion Systems (5)

    0

    0

    7

    1500

    Spider (for comparison)

    2

    290

    260

    0.02

    10.19

    9.14

    120

    60.00

    Precision Propulsion (6)

    10

    0

    7

    1750

    Twitch

    16

    290

    250

    0.09

    18.12

    15.62

    400

    25.00

    Precision Propulsion (6)

    8

    0

    7

    1600

    New Twitch

    16

    290

    275

    0.08

    20.39

    19.33

    230

    14.38

    Precision Propulsion (6)

    8

    0

    7

    920

    Puff (for comparison)

    20

    250

    120

    0.09

    22.65

    10.87

    150

    7.50

    Precision Propulsion (6)

    6

    0

    7

    2500

    Spark

    20

    320

    270

    0.1

    20.39

    17.20

    240

    12.00

    Propulsion Systems (5)

    3

    0

    7

    2800

    New Spark

    20

    320

    265

    0.13

    15.68

    12.99

    240

    12.00

    Propulsion Systems (5)

    3

    0

    7

    2800

    Place-Anywhere 7

    2

    240

    100

    0.03

    6.80

    2.83

    280

    140.00

    Advanced Flight Control(5)

    0

    0

    50

    4200

    New Place-Anywhere 7

    2

    240

    100

    0.02

    10.19

    4.25

    25

    12.50

    Advanced Flight Control(5)

    0

    0

    15

    800

    RV-105 RCS

    4

    240

    100

    0.05

    8.15

    3.40

    620

    155.00

    Advanced Flight Control(5)

    0

    0

    15

    3400

    New RV-105 RCS

    4

    240

    100

    0.04

    10.19

    4.25

    45

    11.25

    Advanced Flight Control(5)

    0

    0

    15

    1200

    Vernor

    12

    260

    140

    0.08

    15.29

    8.23

    1400

    116.67

    Specialized Control(6)

    0

    0

    50

    4200

    New Vernor

    12

    260

    140

    0.08

    15.29

    8.23

    150

    12.50

    Specialized Control(6)

    0

    0

    15

    1800

    And here’s the thinking behind these changes.

    Twitch & Spark:

    The twitch and spark are both relatively similar in size, use the same propellant, and the twitch unlocks later than the spark.  The twitch is a surface attached engine with a good gimbal range, but otherwise the Spark is just better in every way – TWR, cost/KN, and efficiency.  In fact, the Spark is so efficient that it outpaces many larger significantly larger engines, making clusters of them a better choice than using one of them, something we generally want to avoid as we think that both game balance and realism are better satisfied by having larger engines generally be slightly better than smaller ones, at the expense of not being as flexible in exactly how many of them you use.

    Therefore, the Twitch was made about half as costly, and its ASL ISP was increased to make it a better descent engine for probes on planets with an atmosphere, or as a Vernier.

    The Spark’s ASL ISP was lowered slightly, and its mass increased, to tilt it more toward being a Vac engine rather than just a perfect all-around engine that it was.  We’re aware that the community has been using this engine for a while and kept the changes as small as possible, but this engine stood out too much from its peers when you look at the numbers to not need to adjust it.

    RCS Engines:  

    The Place Anywhere 7, RV-105 RCS, and Vernor are all engines designed to steer your ship in space, making fine adjustments to orientation and course rather than providing raw power.   Also, RCS is a much more realistic way to adjust a large craft’s orientation rather than piling on more reaction wheels. But the cost of these engines, we felt was just too exorbitant, especially given their low efficiency & the fact that they are typically placed in symmetry, so their costs were reduced dramatically.

    The mass of the Place Anywhere 7 and RV-105 also made them a poor choice compared to the more powerful Vernor and were thus lowered.

    However, these are still engines, sensitive pieces of equipment, so the crash tolerances were set more in line with other engines.



    User Feedback

    Recommended Comments



    So to reiterate it from the 1.7 thread:

    While I understand where you comes from, one of the reason why some of us are not happy with the Spark/Cub change (back in 1.6) is due to the fact that SuperDraco, which would have been represented as a radial engine, is a OP engine in terms of TWR ; and seeing that many people are trying to Make Dragon/DragonV2... That means that some parts which can be done in 1 part in the past may need 2, which may affect performances.

    I think if you create an engine with horrible ASL (SuperDraco is only 235s (SL)) but OP TWR, people will be fine. (Draco don't need to be made as Twitch will do the job.) Even if you make it DLC, we will ask you to take our money.

    EDIT: However, Spark change isn't too bad. I actually ran it through KER, and 8x Twitch is still inferior in both TWR and Delta-V, to 8x Spark but somewhat compariable.

    Edited by Jestersage

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    So for 1.8... you're introducing actual one-part bearings, and real skids, and generic tiny bumper parts, to 'balance' for the loss of the high crash tolerance of the ports and vernors... right?

    I'm going to pout a bit now.

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    Aw shucks, I don't like the Spark nerf very much. It is going to make some really efficient lander designs all the more harder to work with or scrap them entirely. 

    Now to test my Eve TSTO and to see whether it can still struggle to orbit with 7 Sparks 2nd Stage...

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    I really agree with the spark adjustments. I do use the spark a lot in my own designs, so it does hurt them a bit. But if I'm being honest, for years this engine has dominated all but the tiniest of 0.625m size probes, and almost all 1.25m size landers and satellites under 10 tons mass. It was the best engine for too wide of a range of spacecraft to be considered balanced. In fact, the slight mass increase won't really dislodge it from most designs in that range anyhow, but changing it too much would upset the game too much now that we're post 1.0 release.

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    At least on paper, these sound like good changes.  I very much appreciate the (newfound?) attention to part balance -- especially the idea that parts should not be globally over- or underpowered, and should all have a niche.

    But please, for the love of the Kraken, do something to make the Puff usable.  I have no idea how, without introducing new game mechanics that favor monoprop, but IMO it's currently the biggest dead weight by far.

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    There's a bug

    These reported ISP numbers are all Wrong. If this is what your actual plans are, then the Ingame values have not been put correctly. If this is just your notes and the ingame one is correct, then these numbers are wrong.

    Ingame Twitch - 

    atmosphereCurve
            {
                key = 0 290
                key = 1 270
                key = 7 0.001
            }

    As you can clearly see, the numbers are 290 Vac,270 ASL

    While the Devblog says, the numbers are 290 Vac, 275 ASL

    Same for the Spark

    Ingame Spark -

    atmosphereCurve
            {
                key = 0 320
                key = 1 260
                key = 7 0.001
            }

    As you can clearly see, the numbers are 320 Vac,260 ASL

    While the Devblog says, the numbers are 320 Vac, 265 ASL

    This is a pretty major discrepancy. Can we have some clarification on this? For the record, I looked them up from the [Engine name]_v2 folders rather than the original.

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    qzgy

    Posted (edited)

    While I can understand the part rebalancing a bit, I'm still gonna miss a slightly op spark... So nice for 1.25m clusters.

    Also do now have to check if it will affect bearings... hopefully it won't.....

     

    Edited by qzgy

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    I have used the Spark for just about anything vacuum for its TWR and ISP.  While this might need me to redesign and look to other engines, but the actual mass change is not that big. If you shoot for an acceleration of about 0.5 g, the Spark can move some 4 t. A change of 0.03 t is about one percent less acceleration, I can live with that.

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    Sadly, after this update my little lowtech 1-junos SSTO can't reach the orbit...  ;.;

    wvfJl78.png 

    And several other little SSTO too.

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    A Devblog within 5 months of the last? What have you done with the real devs?

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    Can we expect further balance changes in 1.8? Personally I feel that the rapier's closed cycle vacuum Isp is too low, and the atmospheric Isp is too high. The rapier closed cycle mode is basically only used in vacuum and near vacuum conditions, the rapier in airbreathing mode is optimized for high altitude flight. Closed cycle mode is so bad that people use other engines for non-airbreathing thrust. It ends up as just a more fuel hungry, heavier, slightly faster and higher flying whiplash.

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    OHara

    Posted (edited)

    The high impact-tolerance of the single-port RCS in particular, with its spherical collider, might have had an important side-effect in enabling some creative bearing designs.  There is an interesting niche of use of KSP to make devices with separate interacting craft , often with RCS ports as the teeth of the gears.  When a new-ish player expressed interest in stock propellers last week, I said "there has been a golden age of propeller designs on kerbalx recently."  A niche, but one that gives KSP good publicity.

    The risk is that a significant number of interesting designs have parts slide against each other at >15m/s, and KSP seems to treat sliding velocity as collision, so become impossible without mods or 'disable crash damage'.   So far, though, the RCS-using designs that I have tested (link link) work fine in KSP 1.7; I'll update if someone reports a specific affected craft.

    If the high impact tolerance is getting in the way of some other use, then it makes sense to lower it.  But we could rationalize leaving it at 50m/s, saying that monopropellant engines are relatively very simple, with a valve, catalyst, and nozzle, so the single-output designs are impressively tough.

    Edited by OHara

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    @Maxsimal Still no clarification on the discrepancy between the Devblog and the Actual ingame stats. If its wrong, atleast edit it?

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    On ‎4‎/‎11‎/‎2019 at 5:35 PM, Aerospacer said:

    Sadly, after this update my little lowtech 1-junos SSTO can't reach the orbit...  ;.;

    wvfJl78.png 

    And several other little SSTO too.

    actually all my small crafts amongst some records holders have stopped working… i also can throw my actual reusable career playthrough attempt into the trash can, ob which i have worked for more than 6 month… ;.;

    all those designs were based on the spark, just because it was definitely overpowered and out of balance :D

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    17 hours ago, Kergarin said:

    actually all my small crafts amongst some records holders have stopped working… i also can throw my actual reusable career playthrough attempt into the trash can, ob which i have worked for more than 6 month… ;.;

    all those designs were based on the spark, just because it was definitely overpowered and out of balance :D

     

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    Ah crap, I based my Eve lander off of the Spark. Gonna have to wait to update so I can get my kerbals off of Eve first. I understand the change though.

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    8 hours ago, The Dunatian said:

    No huge change so not a problem.

    30% more weight for the Spark and even 33,3% worse asl twr is verry huge :0.0: this kills all designs based on the old specs.

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    2 hours ago, Kergarin said:

    30% more weight for the Spark and even 33,3% worse asl twr is verry huge :0.0: this kills all designs based on the old specs.

    You can stress that more than it's worth...

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    5 hours ago, The Dunatian said:

    You can stress that more than it's worth...

    It is a big problem for existing spacecraft designs that rely on the Spark though. If a craft is engineered so that it has just enough Delta-V to complete a mission, then any changes in mass/efficiency will most likely mess everything up. (E.g. my Eve lander can no longer make it to LEO.) I understand why they changed the Spark, but it is a big deal for all existing Spark related designs.

    Edited by The_8_Bit_Zombie

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    6 hours ago, The Dunatian said:

    You can stress that more than it's worth...

    Most people were not really aware and generally use engines one or two sizes to big for their crafts, and I also ignored this engine for long, but it was the most outstanding allround engine for small to medium crafts in the game.

    Its asl twr was verry high. Only surpassed by the biggest launcher engines: mammoth, vector, skipper and mainsail.

    Its vac Isp looks not the best on the paper, but due to its verry low weight and still high Isp and thrust, it surpassed the supposedly best vac engines terrier and poodle on most crafts, giving them up to a decent size more dV on the same amount of fuel than these two. (and even way more when you fill up the saved weight with fuel)

    It's low weight and low fuel needs  also makes launch vehicles verry small.

    This combination made it the perfect and op allround engine for small to medium crafts, working as high efficient transfer and lander engine even for atm at the same time.

     

    The graveyard:

    https://youtu.be/KXdmbcPMoD0

    https://youtu.be/Ff4uvflVzoY

    https://youtu.be/iqp9SiPpP4g

    https://youtu.be/sGW2mvqF72k

    https://youtu.be/LtMBu9-c-sI

    Aborted after several month of work:

    https://youtu.be/v9wK4pFfK0A

    And that's just a small selection.

    Edited by Kergarin

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    I was able to salvage my Eve TSTO, but it got a big performance drop. 

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    On 4/12/2019 at 6:44 PM, Kergarin said:

     i also can throw my actual reusable career playthrough attempt into the trash can, ob which i have worked for more than 6 month… ;.;

    With KSP you have the choice not to upgrade (at least for that playthrough).  KSP allows multiple installs with different versions and different mods ... just download the .zip and install in a different directory.  Say 1.4.x, 1.5.x, 1.6.x, 1.7.x under a KSP directory.

    You can also mod (copy) in the old engine values into the newest version.  You may not play a vanilla 1.7 but you can continue using your career and ships with no surprises.  (See above on multiple installs, too.)

    Or you can convert to 1.7 and adapt.  Your in-game crafts will not be affected: their parts and part stats are stored in the savegame. The new engine stats will only affect new craft (launch pad or runway or similarly spawning into the world --- just being on rails does not put them out of the world).

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    55 minutes ago, weissel said:

    With KSP you have the choice not to upgrade (at least for that playthrough).  KSP allows multiple installs with different versions and different mods ... just download the .zip and install in a different directory.  Say 1.4.x, 1.5.x, 1.6.x, 1.7.x under a KSP directory.

    You can also mod (copy) in the old engine values into the newest version.  You may not play a vanilla 1.7 but you can continue using your career and ships with no surprises.  (See above on multiple installs, too.)

    Or you can convert to 1.7 and adapt.  Your in-game crafts will not be affected: their parts and part stats are stored in the savegame. The new engine stats will only affect new craft (launch pad or runway or similarly spawning into the world --- just being on rails does not put them out of the world).

    Thanks for your efforts, writing down all this.

    The point ist just.. I didn't execute most of what I have laying around here based the Spark.

    And doing it in something else than the most recent version is like failing or cheating to me. I don't like making things easier than they are stock.

    Some time ago I have even dropped my Single Stage to everywhere Grand Tour (a real one, not one of these "*except here and there"), which was almost completely recorded, when they released 1.2 with Eve's changed Atmosphere which destroyed my Eve SSTO....

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