1.7 Maneuvering Engine Balance Changes

Spark - being nerfed since 0.90.

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 April 11, 2019 by Jestersage

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.

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...

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.

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.

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.

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 April 11, 2019 by qzgy

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.

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

 

And several other little SSTO too.

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

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.

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 April 12, 2019 by OHara

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

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... 

 

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 

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 

 

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.

No huge change so not a problem.

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  this kills all designs based on the old specs.

2 hours ago, Kergarin said:

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

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

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 April 16, 2019 by The_8_Bit_Zombie

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 April 16, 2019 by Kergarin

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

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).

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....